Re: [Drakelist] Using a Drake 2NT and Drake 2B on 30m

[Dennis Monticelli]

Steve,

My experience with other tube rigs (and tuners) being used on 30M is that
sometimes the tuned circuits do indeed swing far enough (from either 20M or
40M positions).  However, the Q is always wrong and you either end up
either too sharp or too shallow.  Best to leverage the higher band (20M)
and switch in some additional capacitance with a relay.  It will be easy to
back out that mod later with no traces.

Dennis AE6C

On Tue, Jun 28, 2016 at 10:14 PM, Steve Ireland  wrote:

> G’day
>
> I’ve got a Drake 2NT and 2B, which am in the process of refurbishing.
> With the decline in solar activity, I was wondering if anyone had found
> ways to use them on the 30 m band?
>
> Maybe the 2B just needs relatively straightforward crystal addition, but
> the 2NT looks like an extra coil would need switching into the anode
> circuitry of the 12BY7A and potentially another tap put in place on the
> 6HF5 PA tank coil (am wondering if the 7MHz or 14MHz tank coil tap would
> tune there?).
>
> Any information would be much appreciated.
>
> Vy 73
>
> Steve, VK6VZ
>
>
> 
>  Virus-free.
> www.avast.com
> 
>
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Re: [Drakelist] Drake R4B 5595 kHz oscillator/mixer

[Dennis Monticelli]

It could very well be a bad crystal.  If you or a friend have a crystal not
too far from that frequency, you can wire it in and just see if the circuit
oscillates.

Dennis AE6C

On Sat, Nov 15, 2014 at 12:09 PM, Morrell Siegel mandbsie...@charter.net
wrote:

 the oscillator may be working but on another frequency. if you have a
 receiver that you can listen  around the 5595 wrap a few turns around the
 second mixer, hook it up to the receiver and tune around the frequency. you
 may have a cap or inductor that has changed value and the oscillator is
 still working. if the oscillator is working you can add or subtract
 capacitance or inductance to bring it to the correct frequency. i have done
 this many times and it works. mickey wa6fiz


 On Nov 15, 2014, at 8:50 AM, Richard Knoppow 1oldle...@ix.netcom.com
 wrote:

 
  - Original Message - From: Charles Bostian bost...@vt.edu
  To: drakelist@zerobeat.net
  Sent: Friday, November 14, 2014 1:58 PM
  Subject: [Drakelist] Drake R4B 5595 kHz oscillator/mixer
 
 
  I am trying to bring my old R4B/T4XB combination back to life after
 about
  35 years of non-use.
  The 5595 kHz oscillator part of the second mixer 12BE6 circuit does not
  oscillate.  I have tried several tubes with no effect.  As far as I can
  determine, the tube is functioning normally and I can make the receiver
  work (after a fashion) by injecting a 5595 kHz signal from an external
  source. Before I take out/test/replace the handful of Rs and Cs and also
  look for a replacement xtal, I am wondering if anyone on the list has
 had a
  similar problem.  In particular, can you recommend a source for a
  replacement xtal?  Thanks!
 
  Charles W4KEP
 
 It may well be the crystal. Replacements can be obtained from
 International Crystal. I've bought many crystals from them and all were
 perfect. They know the parameters for Drake crystals.
 You might want to post also to the other drake list at:
  http://groups.yahoo.com/group/DrakeRadio/
 
 It seems to me this is a fairly common problem.
 
 
  --
  Richard Knoppow
  Los Angeles
  WB6KBL
  dickb...@ix.netcom.com
 
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Re: [Drakelist] R7 AGC issues

[Dennis Monticelli]

I have no experience with the R7 but some experience with AGC loops in
general.  It is VERY difficult to design a good AGC and many radios get it
wrong.  For example, designing it for the user's eyes (vs ears) means
paying too much attention to the S-meter indication.  Using the loop
feedback voltage to drive the meter in a semi-calibrated way may be
convenient but it could easily result in making poor loop tradeoffs and
that is what AGC design is all about, making those tough tradeoffs in an
optimal manner.  You are trying to adjust the signal levels in the chain to
maximize linearity (in order to get good dynamic range), while at the same
time leveling the avg overall gain for the benefit of your ears.  Because
it is a loop it can do all the nasty things that loops often do, such as
overshoot, ring, and oscillate.  When you change the AGC time constant cap,
the loop dynamics and stability parameters change.  A FAST setting means
the loop attack has further amplitude to restore, meaning any tendency to
overshoot and distort will get worse.

So speaking in general terms only (not the R7 in particular), the things
one might try when overshoot and distortion on peaks is present could be
the following:

Lower the loop gain to reduce instability. For example, reduce IF gain.
Some radios have a pot for this.  This is why retarding the panel RF gain
control works.  You could try playing with the AGC threshold, but that will
probably affect linearity/dynamic range adversely and will not change the
feedback loop gain once all stages are engaged with feedback.

Use a scope to determine the stage at which the distortion is being
introduced and then change the distribution of AGC via adjusting the
resistor values that determine how much AGC gets to each stage.  If the
distortion is occurring at the end of the chain in the audio section then
changing AGC distribution won't help that.  You would need to reduce
overall gain.

Sometimes the IF filter is the primary source of delay that leads to
instability.  I once put an aftermarket 250Hz crystal filter in place of a
stock 500Hz.  The group delay (i.e burst response) went from 0.5ms to 4ms,
which caused a huge pop on the leading edge of CW in FAST and a lesser but
still very annoying pop on SLOW.  I would not expect a SSB width filter to
exhibit this degree of delay, but maybe

Try inserting a resistor in series with the AGC time constant cap and
fiddling with the value.  This will introduce a zero in the loop transfer
function which could be adjusted to cancel a pole that may be exacerbating
the loop instability.  Some radios already have a pole-zero combo (series R
and C) somewhere in the AGC loop just for this purpose, but not all radios.

Bottom line is that designing good AGC systems is a tough job and anything
we as users change within the AGC loop to compensate for original design
deficiencies will interact with other loop characteristics and the meter
readings.   It's hard to come out ahead overall, which is why so many AGC
mods to various radios end up with adverse tradeoffs.

Just my humble two cents worth...

Dennis AE6C




On Sat, May 11, 2013 at 2:16 PM, Jim Shorney jshor...@inebraska.com wrote:

 On Sat, 11 May 2013 22:52:57 +0200, Dieter Horst wrote:

 @Jim, would you say that the service manual describes the right methode
 for aligning the AGC?
 I have had my doubts about it in the past, mostly because 'fast' would
 always create trouble.


 Yes. In my discussions with John, he told me that the ACG Bias adjustment
 R1127 (A.K.A. AGC Pedestal) is basically not used, being left as set in
 the
 instructions (fully clockwise). The IF gain pot is actually used to set
 the AGC
 pedestal in this scenario. I've tried two or three alternate procedures,
 both
 of my own and other's devising, but once I understood what was going on the
 book method seemed to work the best. There are two sections, coarse and
 final
 adjustment. If things are pretty close, coarse probably does not need to
 be
 done.

 73

 -Jim
 NU0C

 --
 The universe we're in will reach absolute zero in three hours. Safe is
 relative. - Idris, The Doctor's Wife



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Re: [Drakelist] R4A-B Detector Amp Q5

[Dennis Monticelli]

Curt,

I only have the schematic for my R4-B but that should be close enough.  The
feedback connection I was seeing includes the C179 on the base which would
represent the dominant pole in the collector-base neg feedback path that
appears to exist on the schematic.  But in looking more closely at the S2
wafer switch contact arrangement, it now appears that a fixed bias current
is applied to the junction of R116, R117, and R118 when in AM mode.  If so
then that junction becomes biased to a voltage that represents the power
supply for Q5 where R117 is the collector load and R118 is the base current
bias.  The ratio of these R's is 100.  This means a beta greater than 100
would theoretically saturate Q5.  The 2N3394 carries a spec of beta that is
55 min and 110 max (the 3394 is a factory selection from the wider range of
beta that comes straight out of fabrication) so it looks like Drake was
flirting with the edge of disaster in that design.  They may have even done
a manual beta selection among their transistor stock because there were
other places in the receiver that could accept the higher beta 3394's that
were culled.  Your replacement transistor probably has a beta 100 as most
modern types do.  My recommendation is to replace the 2.2M with a higher
value or maybe better yet put one of those tiny PCB trim pots in series
(500K) and adjust it so that the collector voltage sits at a comfortable
bias point.

Dennis AE6C


On Wed, Feb 27, 2013 at 7:48 AM, Curt Nixon cptc...@flash.net wrote:

  Hi Dennis:

 Yep...the DC values do not suggest saturation.  Is the feedback you refer
 to the base bypass cap?  I thought that to be a part of the detector (the
 charge cap).  I guess I dont see anything else on my schematic that looks
 to be feedback.  Straight voltage dividing for bias and collector, just the
 diode in series with the base source.

 Pretty sure I have tried all variants of the pinouts and checked the
 devices on the Huntron to be sure.

 I'm really betting on the Gain-Bandwidth issue now.  Old devices/vs new
 ones.

 Curt


 On 2/26/2013 9:31 PM, Dennis Monticelli wrote:

 The saturation you are seeing should not be happening based upon simple DC
 specs.  Either the pinout is not correct as has been suggested or perhaps
 the new transistor is oscillating due to a higher gain-bandwidth product.
  The circuit does use a feedback connection.

  Dennis AE6C

 On Tue, Feb 26, 2013 at 12:06 PM, Tom Holmes thol...@woh.rr.com wrote:

 :-).

 I wonder if there is an asterisk on the schematic next to some bias
 resistor
 that says hand chosen.

 Oh well. Have fun!

 Tom Holmes, N8ZM
 Tipp City, OH
 EM79


  -Original Message-
  From: drakelist-boun...@zerobeat.net
 [mailto:drakelist-boun...@zerobeat.net]
  On Behalf Of Curt Nixon
   Sent: Tuesday, February 26, 2013 12:30 PM
  To: drakelist@zerobeat.net
  Subject: Re: [Drakelist] R4A-B Detector Amp Q5
 
  Hi Tom:
 
  The collector goes to hard saturation value.  Less than .2V.  I did the
 test using a
  Huntron on a few of the swaps just to be sure.
 
  I also carefully watched the base voltage established thru the detector
 diode.  It
  stays right around .5-.6V.  Even repalced the diode to see if that might
 be the
  case but same result.
 
  At this point, I guess I am going to try to find a genuine 3394 and call
 it a day.  It
  all works fine when I put in a working device from another
  R4 so suspect something particular about the device.  Transistors were a
 lot less
  controlled in 1968 so it may not be close.  Dont have a curve tracer and
 not going
  to remove it again to do an Hfe test on it the hard way.
 
  It is just a curiosity now.  I taught solid-state design and theory in
 Navy and later in
  college and thought I had seen most issues.  ;)
 
  Curt
  KU8L
 
  On 2/26/2013 12:02 PM, Tom Holmes wrote:
   Well, it was worth a shot. Since I don't have the circuit in front of
   me I can't make a more educated guess.
  
   Since you caught the lead issue, I'll assume that you also did the
   diode test on the replacement parts. I have seen a few cases where the
   NTE doc's are wrong about the leads though. When the collector voltage
   goes to near zero, is it .2 V or .6 V? The first case is a saturated
   transistor; the second is a diode junction, which would suggest the
 pinout info is
  wrong.
  
   When I get back from some errands, I'll look in my NTE book to see if
   I can find any other clues.
  
   Happy hunting!
  
   Tom Holmes, N8ZM
   Tipp City, OH
   EM79
  
  
   -Original Message-
   From: drakelist-boun...@zerobeat.net
   [mailto:drakelist-boun...@zerobeat.net]
   On Behalf Of Curt Nixon
   Sent: Tuesday, February 26, 2013 11:43 AM
   To: drakelist@zerobeat.net
   Subject: Re: [Drakelist] R4A-B Detector Amp Q5
  
   Hi Tom:
  
   Yes...there are the lead arrangement issues but I accounted for them.
   The typical EBC Vs ECB issue.  Easy in this case because they used
   the triangular hole pattern instead

Re: [Drakelist] R4A-B Detector Amp Q5

[Dennis Monticelli]

The saturation you are seeing should not be happening based upon simple DC
specs.  Either the pinout is not correct as has been suggested or perhaps
the new transistor is oscillating due to a higher gain-bandwidth product.
 The circuit does use a feedback connection.

Dennis AE6C

On Tue, Feb 26, 2013 at 12:06 PM, Tom Holmes thol...@woh.rr.com wrote:

 :-).

 I wonder if there is an asterisk on the schematic next to some bias
 resistor
 that says hand chosen.

 Oh well. Have fun!

 Tom Holmes, N8ZM
 Tipp City, OH
 EM79


  -Original Message-
  From: drakelist-boun...@zerobeat.net
 [mailto:drakelist-boun...@zerobeat.net]
  On Behalf Of Curt Nixon
  Sent: Tuesday, February 26, 2013 12:30 PM
  To: drakelist@zerobeat.net
  Subject: Re: [Drakelist] R4A-B Detector Amp Q5
 
  Hi Tom:
 
  The collector goes to hard saturation value.  Less than .2V.  I did the
 test using a
  Huntron on a few of the swaps just to be sure.
 
  I also carefully watched the base voltage established thru the detector
 diode.  It
  stays right around .5-.6V.  Even repalced the diode to see if that might
 be the
  case but same result.
 
  At this point, I guess I am going to try to find a genuine 3394 and call
 it a day.  It
  all works fine when I put in a working device from another
  R4 so suspect something particular about the device.  Transistors were a
 lot less
  controlled in 1968 so it may not be close.  Dont have a curve tracer and
 not going
  to remove it again to do an Hfe test on it the hard way.
 
  It is just a curiosity now.  I taught solid-state design and theory in
 Navy and later in
  college and thought I had seen most issues.  ;)
 
  Curt
  KU8L
 
  On 2/26/2013 12:02 PM, Tom Holmes wrote:
   Well, it was worth a shot. Since I don't have the circuit in front of
   me I can't make a more educated guess.
  
   Since you caught the lead issue, I'll assume that you also did the
   diode test on the replacement parts. I have seen a few cases where the
   NTE doc's are wrong about the leads though. When the collector voltage
   goes to near zero, is it .2 V or .6 V? The first case is a saturated
   transistor; the second is a diode junction, which would suggest the
 pinout info is
  wrong.
  
   When I get back from some errands, I'll look in my NTE book to see if
   I can find any other clues.
  
   Happy hunting!
  
   Tom Holmes, N8ZM
   Tipp City, OH
   EM79
  
  
   -Original Message-
   From: drakelist-boun...@zerobeat.net
   [mailto:drakelist-boun...@zerobeat.net]
   On Behalf Of Curt Nixon
   Sent: Tuesday, February 26, 2013 11:43 AM
   To: drakelist@zerobeat.net
   Subject: Re: [Drakelist] R4A-B Detector Amp Q5
  
   Hi Tom:
  
   Yes...there are the lead arrangement issues but I accounted for them.
   The typical EBC Vs ECB issue.  Easy in this case because they used
   the triangular hole pattern instead of the inline pattern on both the
   R4A and
   B version
   modules.
  
   Curt
  
   On 2/26/2013 10:49 AM, Tom Holmes wrote:
   HI Curt..
  
   It almost sounds like there is a different lead arrangement on the
   3393. Any well designed circuit of that era would have had to
   tolerate the typical high variability of Hfe to avoid tedious hand
   picking of parts, although that may have been done in this case.
  
   Tom Holmes, N8ZM
   Tipp City, OH
   EM79
  
  
   -Original Message-
   From: drakelist-boun...@zerobeat.net
   [mailto:drakelist-boun...@zerobeat.net]
   On Behalf Of Curt Nixon
   Sent: Tuesday, February 26, 2013 10:40 AM
   To: Drake Forum
   Subject: [Drakelist] R4A-B Detector Amp Q5
  
   GM All:
  
   Has anyone else had trouble getting  a general purpose sub working
   in the
   Q5 AM
   detector amp position?
  
   I tried several close NTE GP subs and also a 3393 which is same
   parameters
   ex
   Hfe which is slightly different.
  
   The transistor comes on but with the grounded emitter, pulls the
   collector
   voltage
   to near zero.  As soon as I put in a real orignal
   3394 from a R4A, it works as it should--good fidelity and collector
   voltage at about
   5V from the supply rail of 10V.
  
   Is this design so sensitive to Hfe as to be marginal or need to be
   hand
   selected?
   Certainly the 3393 is well within the spec range of the 3394.
  
   Thanks
  
   Curt
   KU8L
  
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Re: [Drakelist] VTVM Probe with DMM

[Dennis Monticelli]

Carbon film 10M should be stable as long as it is not subjected to
voltages near its maximum ratings for extended periods of time.  Long
term drift could occur if for example a 1/4 watt carbon film (typ 300V
rated) is soldered into a circuit whereby it sees 200 to 300V
continuously for many, many hours.  Heat buildup will compound the
drift.  Though, in no way would this drift approach that of a carbon
comp.

But for a probe, I think you have no issue with stability.  BTW,
capacitance can be further reduced by putting resistors in series.  It
will already by low, but series resistors might help you with finding
metal film of high enough value.  It will also increase the voltage
rating of your probe. The probe body is long so in-line series
connections should fit.

Dennis AE6C

On 11/22/12, Paul Christensen w...@arrl.net wrote:
 Good solution, Paul!  Mentally dividing by ten is easy enough and you
 retain all of the advantages of using the VTVM probe.

 Dennis AE6C

 Well'sorta.  The divide by ten works well and it's an easy mental
 exercise.  But in creating a 1 meg/100K divider, the load across the voltage

 sampling point is reduced from 10 meg to 1 meg.  That undermines the purpose

 of the resistive probe except that the effects from cable capacitance and
 lead inductance are swamped.  But if the source Z providing grid voltage,
 for example, is greater than 100K big errors will start setting in.

 So...next I'm going to change the 1 meg resistor in VTVM probe to 10 meg
 (like the 100x probe), and then try a variable shunt at the DMM end to find

 the value where 10:1 is achieved.  That 10 meg is a high value for low
 voltage readings and I'm not sure how stable readings will be.  I think 10
 meg is commonly available in carbon film, but tougher to find in metal
 film.

 Paul, W9AC



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Re: [Drakelist] VTVM Probe with DMM

[Dennis Monticelli]

Paul,

The best probe I have found for the purpose are the old 100X scope
probes.  They have a very low capacitance on the order of 2.5pF in
parallel with 10Meg so circuit loading is minimal.  Most have extra
voltage capability which is handy for working around transmitters.
While designed for AC  DC measurements via scopes, you can use them
accurately with DMM's because the 100X divider swamps out the loading
effect of the DMM.  The numerical accuracy of the DMM compensates for
the high voltage division ratio.

Dennis AE6C

On 11/17/12, Paul Christensen w...@arrl.net wrote:
 I finally got around to trying a good 'ole fashion VTVM probe with a Fluke
 DMM.  Recall that most VTVM probes have a switch that allows for either DC
 Volts in one position, then AC/Ohms/mA in the other position.  The DC
 position typically has a 1-meg isolation resistor, highly useful for VT grid

 measurements.   Without value compensation, a modern DMM cannot use such a
 probe and is otherwise useless for serious tube receiver work.

 I took a Simpson VTVM probe with a BNC connector and connected it to a
 Pomona BNC-to-Banana adapter with standard 3/4 centers.  With the adapter,

 the probe easily connects to a DMM.  My first measurement was a precise +12V

 source.  When using the VTVM probe in the DC position (series 1-meg
 resistor), the DMM displays +10.93V.  So, +1.07V is being dropped across the

 1-meg resistor.  Assuming the resistor is close to 1-meg in value, the input

 Z of my Fluke 8060A calculates to 10.215 meg.  Essentially, a 10:1 voltage
 divider is being created between the 1-meg iso-resistor, and the internal Z

 of the DMM.  The drop is creating the value discrepancy.  VTVMs are
 compensated in design and manufacture for this.

 I have several Fluke DDMs, including 8060A (my favorite DMM), and an
 advanced model 189.  However, peering through the manuals, I see no setup
 routine to create a user-defined DC offset.  What I want is the ability to
 measure a precise DC voltage, then enter a menu that allows me to assign a
 new display value to compensate for the voltage drop across the
 iso-resistor.  I have a lab-grade Keithley bench-type DMM that does allow
 for such an offset, but hauling it around is a pain.

 So, does anyone know of a DMM that allows for DC voltage offset?  This is
 different than the Relative button seen on many DMMs.  Relative is used to

 zero the display for any input value.  I want the same thing but instead
 of zero, assign a new value of my choice.

 Paul, W9AC


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Re: [Drakelist] VTVM Probe with DMM

[Dennis Monticelli]

Good solution, Paul!  Mentally dividing by ten is easy enough and you
retain all of the advantages of using the VTVM probe.

Dennis AE6C

On 11/21/12, Paul Christensen w...@arrl.net wrote:
 Dennis' suggestion of using a 100x probe got me to thinking of an
 alternative as the 100x scope probes are sorta' pricey, even on the used
 market.  As Dennis points out, the 100x scope probes are useful when
 sampling high voltage, typically greater than 1KV.  Since my focus has been

 with the grids of tube receivers, these measurements (even into the hundreds

 of volts) are adequate with the right 10x probe.

 The 100x probe uses a 10 meg sampling resistor with a 100K shunt at the
 scope input.  Most scopes have a ~ 1 meg input Z.  The input Z of my Fluke
 8060A computes to 10.5 meg and is a value that is probably close to most
 portable DMMs.

 Taking Dennis' suggestion, I used a 1 meg Simpson VTVM probe and shunted it

 with a value close to 100K to create the necessary 10:1 ratio.  A 200K pot
 was used to find a value that produced an exact 10:1 ratio.  For the Fluke
 8060A and my Simpson VTVM probe, that value is 112.5K.  I then created shunt

 consisting of two resistors in series whose total value is 112.5K and
 inserted this combination into a Pomona dual banana jack.  Different shunt
 jacks can be created if one wants best accuracy over a choice of DMMs in the

 shack.

 In the links below, notice that the Simpson probe is connected to a
 BNC-to-dual banana adapter with standard 3/4 pin spacing.  The adapter has

 holes to allow shunting from a dual banana connector; the latter of which
 has the 112.5K resistor combination.  The black plug simply plugs into the
 red plug.

 http://tinyurl.com/bc6ggo8

 http://tinyurl.com/b56tfm5

 Testing this idea in the real world shows that Dennis' idea works in a 10x
 configuration.  For example, when a +12V source is measured, the DMM reads
 1.2V.  It's then just a simple matter of multiplying displayed results by a

 factor of 10 which is a whole lot easier than using the DMM's RELative
 button and trying to find a 1.07V source as the calibrating reference.

 It appears good accuracy can be achieved when using a DMM with a traditional

 VTVM probe.  The VTVM probe has the benefit of a 1 meg isolation resistor
 which is highly useful for grid readings.  The trade-off is the requirement

 of multiplying displayed readings by a factor of 10 -- the same as mentally

 moving the display's decimal place to the right by one digit.

 Paul, W9AC


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Re: [Drakelist] Exploding Cap' ???

[Dennis Monticelli]

Sounds like an arc over and there is usually some trace of carbon but
it can be hard to identify at times.

Another possibility is a cracked ceramic bleeder resistor.  I am not
familiar with the AC-4 but my L7 power supply uses large ceramic
resistors and I had one develop a crack that was not casually obvious.

Dennis AE6C

On 8/25/12, Damien Mannix damienman...@hotmail.com wrote:




 Hello all, I am embarrassed but most grateful for all the kindness and
 helpful advice given to me.  Too many to thank individually but many many
 thanks to all. The safety advice is taken very seriously and I will be ultra
 cautious bearing in mind my inexperience. Already I am puzzled.  Astonished
 in fact.  A most careful examination of every component in the AC4 and then
 the TR4, magnifying glass and high power flashlight and what a lot under the
 TR4, shows no sign of distress to any component!!  Clearly the bang came
 from somewhere, I was not dreaming, so I guess it is time to carefully take
 some voltage measurements from the AC4 as a first step. DamienG3XER   
 


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Re: [Drakelist] R4B Transformer temp

[Dennis Monticelli]

The transformer and nearby audio output tube do heat up that corner
seriously.  Many of us prolong life with a small fan.  I just take a
computer fan (larger diameter preferred), put some rubber feet on it,
and then simply place it on the top cover of my R4B over that area.
The fan is oriented so that the hot air is drawn upward.  I run the
fan on reduced voltage so it is not heard.  It's a simple non-invasive
trick and makes a big difference in temp.

Dennis AE6C

On 6/17/12, Eugene Balinski euge...@nni.com wrote:
 All,

Was poking around the operating table the other day when
 my hand happened to brush across the top of my R4B.  I
 noticed that even through the top cover, the transformer
 seemed very warm - virtually hot.  I will assume that this
 is not normal (never noticed it before) and is indicative
 of a problem ?

If this is an issue, any ideas on where to look ?  Leaky
 cap in PS ?  Audio and performance seem nominal

 73 and thanks,

 Gene K1NR

 -
 Web mail provided by NuNet, Inc. The Premier National provider.
 http://www.nni.com/

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[Drakelist] Diagnosis Repair of R-4B AVC problem

[Dennis Monticelli]

Hi guys,

I thought I would relate a problem that my R-4B developed and what it
took to repair it.  The first symptom was some mild hum modulation
transposed only upon strong CW signals.  I thought that odd as it
certainly didn't fit the typical power supply hum scenario.  The
receiver sat dormant for weeks and then used during the WPX CW contest
this past weekend.  The hum was worse and now classical AVC problems
became evident.  Backing off the RF Gain did not completely attenuate
the signal.  When switching to standby, the S-meter was not going
fully up scale.  Clearly, the AVC voltage was lacking and probably
contaminated by hum.  Sure enough the AVC neg power rail diode, D6,
had failed generating only about -17V (normal is -80V)with a whopping
4Vpp of superimposed 60Hz.  D6 had turned into a non-linear 1K
resistor.  Also R141 showed signs of mild toasting.  It measured 3.3K
vs 4.7K as marked.  I suppose the extra AC current that had been fed
to C91 (which I had upped to 22uF vs 8uF during a general recapping
years ago) was a little too much for the half-watter.  A IN4006 and a
fresh resistor brought the rig right back to normal.

BTW, I did check the usual suspect tubes for grid emission while out
of the case and found no issues.

Dennis AE6C

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Re: [Drakelist] Trouble with TR4 ?

[Dennis Monticelli]

FYI.  After the DeOxit treatment I usually follow with ProGold.  The
latter is a preservative for precious metal surfaces, but also leaves
a lubricating film.  If the switch contact plating is worn through or
lightly touching, I can see where leaving some lubrication behind may
help.  After DeOxit dries there isn't much lubricating action.

As with DeOxit, use it sparingly.  In fact, it takes even less ProGold
to do the job. My tiny costly bottle will probably last a lifetime.

Dennis AE6C

On 3/5/12, Richard Knoppow 1oldle...@ix.netcom.com wrote:

 - Original Message -
 From: m coffey r79b...@gmail.com
 To: drakelist@zerobeat.net
 Sent: Monday, March 05, 2012 4:16 PM
 Subject: [Drakelist] Trouble with TR4 ?


 First, I would like to thanks those who p osted info
 on whitening
 pointer knobs and the TR4 tube shields.

 Now, after having cleaned the switches and
 cleaned/reseated all the
 tubes, etc., I am trying out receive side on the radio
 with a 75ft. random
 wire. 20 and 80 have signals, but thats about it. Fairly
 low volume and no
 movement on the S meter ( S meter zero works fine). Also
 when switching
 between 20, 40, 80M, the sideband switches everytime and I
 have to correct
 it with the sideband switch ( normal?). When the
 calibratetor is used, I
 have it fine on 80 and 20 (with a constant low tone in
 background) but not
 on 40. Also no indication of calibrate on S meter. I got
 spare tubes with
 the radio (boxed but unchecked) and went through and
 subbed all the tubes
 in the receive line one by one, no change.
 Thoughts, suggestions? Mike.

 I found the some positions of the bandswitch on my TR-4
 were persistently intermittant.  I would clean them with
 Deoxit and work them and all would be fine.  Then, the next
 day all 10 meter bands were dead. I finally cleanded the
 switch and coated it lightly with Tuner-Lub. That resulted
 in a pretty much permanent fix. I am not sure what happens
 to these switches but suspect the pressure of the contacts
 against the sliding part becomes weak. Rotary switches are
 _supposed_ to be self cleaning because of the sliding
 action.  I suppose it works better if switches are
 constantly in use.  I had a similar thing in an SP-600-JX
 where the IF bandwidth switch became intermittant. Cleaned
 several times with Deoxit but it became noisy and
 intermittant again in a few days. Here again Tuner-Lub seems
 to have given a long term fix.  Of course, there may be
 other problems with the TR-4 but I suggest that even if you
 have gone through and worked the screws and cleaned the
 switches to do it again. Its simple and might fix the
 problem.

  Its also possible that the thing is way out of
 alignment.  If the above voodoo doesn't fix it I suggest
 going through the alignment procedure.

  Its normal for the side band indicator to switch with
 the band. Its set up for the most commonly used sideband on
 each band.




 --
 Richard Knoppow
 Los Angeles
 WB6KBL
 dickb...@ix.netcom.com






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Re: [Drakelist] AC-4 (bias mod)

[Dennis Monticelli]

Guess I'll just toss in my 2 cents worth.

Converting a Drake to class C in CW mode only by simply changing the
bias of the PA may not be a good idea depending upon how it is driven
and to a lesser extent how much Q and harmonic filtering is in the
tank circuitry.  I have not studied the schematic so I'll just leave
it at that.  But I really don't think class C operation in general
should get a bad rap.  It's a perfectly legit class of operation and
like any mode there is a right way and a wrong way to implement it.
It has a major advantage in terms of improving efficiency and thus
reduction of heat in the finals.  I have measured my Viking II PA with
good instrumentation at 79 to 80% over the core bands on multiple
occasions.  We're talking 144W out for 180W in. The final is parallel
6146's, fixed plus drive-induced bias, and a heavy duty tank with
continously optimized Q due to slaving a rollerducter to the plate
tuning cap.  As for driving power, you generally need a little more
with class C, but not a lot more (assuming beam power tubes and
assuming we're talking CW, not plate mod AM).   To control clicks one
should shape the drive signal shoulders softer than what one would
normally do when driving a linear amp because the turn-on and turn-off
characteristic of class C is more abrupt.

There is nothing fundamentally wrong with class C for CW.  In fact
some cell phones use it.  I think modern rigs avoid it simply because
the PA is already linear for other reasons and already has a fan to
get rid of heat.  The maker would have to design the driver stage a
little differently and the antenna coupling circuitry as well.  I
guess that is not worth adverstising additional 10's of watts of CW
output power on the brochure.

Dennis AE6C


On 1/20/12, Garey Barrell k4...@mindspring.com wrote:
 Gary -

 Obviously the bias would remain in the Class AB1 area for SSB and AM.

 Applying a keyed signal to a non-linear amplifier is a bad idea.  Every time
 the drive is started or
 stopped there is the opportunity for additional distortion products to be
 generated.  Some SSB
 distortion is caused by biasing the amplifier too high or too low, resulting
 in 'compression' or
 limiting the waveform to less than it's peak.  More distortion.

 Perhaps we have an amplifier expert on here who can definitively respond to
 your question.  There
 are no doubt MANY reasons why all transmitters switched to linear operation
 for CW, in spite of the
 'power/efficiency savings.  If nothing else than it takes large amounts of
 drive POWER, more
 trouble, including greatly increased Grid dissipation.

 To me, turning an input signal on and off to a Class C amplifier is asking
 for trouble.  A Class C
 amplifier is essentially a switch, ON or OFF, and relies on the Q of the
 tank circuits to 'smooth
 things out'.  A lot of potential headaches for a few percent efficiency
 increase.

 There are LOTS of 'ideas' on the internet that 'sound' good  :-)

 Let us know what you find out!!

 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
 and TR-4/C Service Supplement CDs
 www.k4oah.com


 Gary Winblad wrote:
 Well yeahh  Garey

 I am not suggesting we change the bias for SSB (or AM), just for CW (and
 real FSK).

 So, you would need a switch or relay added and USE it to change modes.
 Yes,
 bias it past cut-off, will result in no emission between code elements,
 but also over
 part of the cycle.

 Key clicks could be delt with...  The reason they had key clicks was
 primarily because
 they were cathode keying high voltages with no shaping as I recall. no?
 Bias is only
 on the finals, we don't key those or do we?

 Junk?  Isn't our driver pretty clean?  If not, wouldn't we have the same
 spurs and junk
 with a linear final?

 We DO have a tuned output tank circuit for the flywheel effect... no?

 BUT, if we don't have enough (voltage) drive, that might be a problem, but
 we don't
 really need full power...

 Don't ya think?  Changing bias for CW wasn't my idea, but it did sound
 good to me.
 TIA, I am trying to learn here...  There probably IS some reason nobody
 did this
 originally!

 73,
 Gary
 WB6OGD


 - Original Message -
 From: Garey Barrell k4...@mindspring.com
 To: Gary Winblad garywinb...@comcast.net
 Cc: drakelist drakelist@zerobeat.net
 Sent: Fri, 20 Jan 2012 15:31:44 - (UTC)
 Subject: Re: [Drakelist] AC-4  (bias mod)

 Gary -

 In a word  NO.

 The PA stage is operated as a LINEAR amplifier, Class AB1, meaning the
 output signal is a reasonable
 facsimile of the input signal.  The BIAS voltage is carefully chosen to
 'center' the operation of
 the amplifier in the linear portion of the tube's operating region.

 Increasing the BIAS voltage WILL reduce the IDLE current, (between code
 elements,) but will shift
 the PA to a non-linear region.  This will result in distortion of the
 signal, with the potential of
 spurious signals, clicks, and other 'junk'. This is one reason clicks 

Re: [Drakelist] Need a fan for my T-4XC Transmitter?

[Dennis Monticelli]

Well, given the low cost of surplus DC fans, the low noise when
running them on lower voltages, and the modest energy consumptionI
just leave mine on all the time!

On 1/7/12, Michael  Sue Trussell mtruss8...@comcast.net wrote:
 I need to replace my old 30 year old 110 volt fan on my transmitter. I know
 a few of you have used the twelve 12 volt fans and some have used the 110
 volt version. What I would like to know where I can get power so I don't
 have to plug the fan in every time I turn the rig on.  I would like the fan
 to come on when I turn on the power  to the transmitter, any suggestions?



 Thank you in advance



 Michael J Trussell  KA8ASN



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Re: [Drakelist] Source for pots?

[Dennis Monticelli]

Steve,

Elecraft uses control pots with black plastic shafts.  They sell
replacements, though perhaps only to kit purchasers.  Elecraft buys
from ordinary distributors so these pots are still available.  As I
recall these types did not have screwdriver slots but you could cut
that yourself.

Another idea is to use conventional metal shaft pots designed for
screw adjustment such as made by Allen Bradley years ago.  Our junk
boxes are full of them.  You could wrap the shaft in black tape for
insulation and color match, then use a Sharpie to blacken the exposed
slotted tip.  Or maybe just spray the shaft with a couple of coats of
enamel.  From a distance, it should look close to stock.

Dennis AE6C

On 1/2/12, Steve Wedge w1es1...@earthlink.net wrote:
 I couldn't find a match in Mouser's catalogue for the 500-ohm, plastic-shaft
 pot that's used for setting the S-Meter Zero on the side of the 4-line
 receivers.

 Does anyone here know of a source?

 Still looking...

 Steve Wedge, W1ES/4

 Live free or die: Death is not the worst of evils.
 John Stark.

 All my computers have my signature with various pearls of wisdom appended
 thereto.


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Re: [Drakelist] Filters

[Dennis Monticelli]

Maybe wear out isn't the best term.  Crystals can drift (sometimes
badly) and they can do that while just sitting dormant.  It is also
true that many of the older crystal filter designs paid scant
attention to phase characteristics, basically just designing for best
possible skirts.  These filters were hard to listen to when they were
new!  In other words you may have filters in which some of the
crystals have drifted or you may have filters that were always this
way.  Modern crystal filter design and DSP filters do pay attention to
phase and depending upon type can be easier on the ears.  We get used
to the new stuff and maybe we don't like the old stuff as much as we
remembered :-)   Just a theory.

Dennis AE6C

On 1/2/12, John Schroeder dmir2...@yahoo.com wrote:
 Hello group:

 This may be a silly question but, do XTAL filters wear out? I bought a .5,
 and a 2.5 stock Drake filters for 100 bucks for the both of them... They
 ring so badly, they are useless... BTW, they are installed in a R4-C, if it
 makes a difference...

 Very 73 ... John ...

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Re: [Drakelist] Slightly Off-Topic: EICO 717 KEYER

[Dennis Monticelli]

Yup.  I had to learn that the hard way.  I restored a TO for our club
and when I finished with the new caps I plugged it inon its side.
Circuit works, but no keying.  The relay must be bad.  For the first
time I looked closely at the relay and then the light build went off
in my head.  Turned the unit over and it worked fine.

FYI.  Some folks find the sidetone annoying.  It's just a sawtooth
from a neon bulb relaxation oscillator.  So I inserted a series
resonant LC circuit directly in series iwth the secondary of T2.  I
used what I had in the junkbox that provided a decent Q at the chosen
note (31mH torroid and 1.33uF worth of parallel mylars).  If the
network is too lossy the amplitude will be affected and the harmonic
attentuation not as effective.  This basically translates into chosing
a decent inductor that doesn't have a high series resistance.  I opted
for a tone (750Hz) that was a little lower than what Hallicrafters
used so the timing capacitor across the NE2 got padded with 160pF to
bring the series LC into resonance (peaking the amplitude in the
process).  The result was a very pleasing note.  The components fit
easily under the chassis.

Dennis AE6C

On 1/2/12, Garey Barrell k4...@mindspring.com wrote:
 Just don't turn your HA-1 on it's side!

 Mercury relays don't bounce!

 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
 and TR-4/C Service Supplement CDs
 www.k4oah.com


 Eddy Swynar wrote:

 On 2012-01-01, at 7:50 PM, Curt Nixon wrote:

 Just picked up a Hallicrafters TO keyer for the vintage desk also.  Same
 keyer basically.

 */Hi Curt,/*

 I think that the one major difference betwixt the /EICO/ the
 /Hallicrafters TO/keyer is that very
 same ...weak link in the chain that affected mine here, i.e. the
 /TO/used (I believe) a sealed
 mercury-wetted keying relay, whereas the /EICO/went with  that
 reed-relay-in-a-field-coil route to
 achieve its external keying...

 I say weak link as no offence to the /EICO/designers, but rather, as a
 potential source for
 trouble that may well require the owner's attention at some point in its
 future...trouble is, if
 said owner is not all that familiar with the whys  wherefores of reed
 relays / field coils (my
 right hand is raised!), then one can through a /LOT/of vexing  gyrations 
 travails in the
 trouble-shooting process that are simply not necessary...! *: )*

 */~73~ de Eddy VE3CUI - VE3XZ/*

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Re: [Drakelist] problem with deoxit

[Dennis Monticelli]

Dale,

I don't know what is the root of your R-4A problem but from your
discription I doubt it was unevaporated DeOxit.  One thing DeOxit
cannot fix is wafer switches that are no longer in good alignment or
where the wipers have lost their pressure contact..  DeOxit takes care
of surface oxides, but not mechanical issues.

Dennis AE6C

On 12/24/11, kb8bku kb8...@woh.rr.com wrote:
 Dale,

 I had a somewhat similar experience.  I hadn't written, as I was reluctant
 to badmouth the De-oxit, as that seems to be the cleaner/lubricant of choice
 with the Drake crowd.  I just figured it must be something else, and it
 probably is.  I got some of the tiny pink $3 tubes (D-100L) at hamvention to
 see what all the crowing was about.  My R-4A would cut-out on 40
 intermitantly, but rocking the bandswitch would restore operation.  It had
 been ~5 years since I had cleaned and lubed it with Blue Shower cleaner and
 lubed with Blue Stuff for tuners.  I very carefully cleaned the bandswitch
 with Q-tips and alcohol, then lubed very sparing with De-Oxit on a Q-tip.  I
 was very careful to avoid leaving cotton fibers in the switch mechanism.
 When I powered up the next day I had lost sensitivity according to the
 S-meter (signals from antenna as well as calibrator were reduced from S9 or
 ten over 9 to S5-S7).  I checked for lose tubes, etc., but found no cause.
 I rechecked the sensitivity adjustment, but no soap.

 I had begun experiencing audio hum, so while I had the radio opened, I
 re-caped the three sections of the electrolytic can at the same time as I
 cleaned the bandswitch.  The hum do go away, and I looked for any big DC
 changes (due to the re-cap) that might throw things off, but didn't see
 that.

 I have been unable to conclude that I have AGC problems, which is what I
 might  first expect.  One good thing, my 40mtr xtal osc. circuit works
 better than ever.  It has always been iffy, and I usually used the FS-4 when
 I was on 40 for that reason.

 I will let you know if I figure anything out.  Suggestions welcome, although
 I realize this isn't much to go on.  My first second, and third assumptions
 were that I disturbed something to cause my problem.  This is my first
 experience with De-Oxit. I am quite experienced with these types of radio
 repair.  I've tried to imagine what I disturbed and check that, but to no
 avail so far.

 Working at a relaxed pace,

 KB8BKU, Darryl in Dayton
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Re: [Drakelist] problem with deoxit

[Dennis Monticelli]

I have found that 100% DeOxit dries more slowly than the 5% stuff
because the latter is mostly carrier.  So allow a little extra time
before powering up, especially with pots.   A few hours should have
been enough, so it seems that you applied too much.  I almost always
use the 100% stuff but I avoid droplets.  Instead I apply the DeOxit
to one of those wooden stemmed tightly woven Q tips that are made
especially for electrical cleaning.  The Q tip then does double duty
of applicator and scrubber.  This works really well for wafer switches
and tube pins.  For socket pins, I use a wooden toothpick that is
coated with DeOxit.  Once again it serves as applicator and scrubber.
The Q tip and toothpick end up with a satisfying dark coloration of
oxides with this method.  Sufaces will glisten after cleaning but you
won't see any red pooling.

With DeOxit a little goes a very long way.  Mild scrubbing with a
rough absorbant surface such as wood or tightly woven Q tip physically
removes the dissolved oxides.

Dennis AE6C


On 12/23/11, y...@aol.com y...@aol.com wrote:
 Today I put a totally dead R-4a on the bench,replaced the fuse and off she
 went. The rig was fairly clean considering its age. The rig lit up and got
 some audio out and all functions seemed to basically work. Cleaned the
 chassis of dust ,damp cloth  and proceeded to pull all the tubes and
 test,all were good. I took a emery board and cleaned all tube pins then
 wiped the pins with Deoxit and dried with a cloth, also cleaned all the
 wafer switch contacts with deoxit,using the tiny needle bottle  being VERY
 careful to keep the deoxit to the very small amount, also cleaned all the
 pots with the deoxit  spray for pots.
 Any way let the rig sit for a few hours working all the switch's and
 pots. Reassembled the rig and powered up. The radio lite up and that was
 about all ,nothing seemed to work, rechecked the tube install,all correct,
 put back on the bench flipped the rig over  and ALL the tube sockets and
 wafer switch's looked like they were flooded with deoxit. I was careful to
 use as Little as you could of the deoxit,while cleaning everything.  I then
 proceeded to clean EVERYTHING with 100 %alcohol, tube pins,sockets, all
 wafer switch's and pots,made sure everything was dry, using a hair drier.
 Put the rig back together and turned on,the R4A works as well as my B line
 receiver,even without a alignment.
   Has there been a change in Deoxit? I have used this procedure on lots
 of Boat anchors and up till now always worked fine. Can't believe the TINY
 amount I used, crawled all over everywhere I didn't want it to go. Unless
 someone else had used some other substance to clean before me and the the
 deoxit ,I haven't got a clue. Anyone else run across anything like this? The
 deoxit was brand new a week ago. I think I will star with the 100%
 alcohol,like I used to use.
 everybody  have a Merry Christmas
 dale wt4t


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Re: [Drakelist] Nastiest Drake Gear

[Dennis Monticelli]

Now this one looks like it actually SERVED as a boatanchor!

Dennis AE6C

On 12/21/11, Steve Wedge w1es1...@earthlink.net wrote:
 I'm going to nominate this as the most-abused, nastiest-looking piece of
 Drake gear I've ever seen:

 http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItemitem=260919992177ssPageName=ADME:B:SS:US:1123

 I wouldn't even bet that the meter's working given how much moisture this
 one has seen.

 Enjoy those Drakes - but not underwater...

 Steve, W1ES/4

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Re: [Drakelist] What makes up the front end

[Dennis Monticelli]

The RF stage and Mixer plus associated filters.  Probably some folks would
toss the LO in that grouping also.  Basically it refers to what is in front
of the first IF.

Dennis AE6C

On Wed, Nov 30, 2011 at 10:55 PM, Neil M Califano cchange...@yahoo.comwrote:

 Exactly what components constitute the front end of the R4A?

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Re: [Drakelist] Stability Test and FAN

[Dennis Monticelli]

You can get the same airflow by running a larger fan at a lower speed with
the benefit being lower audible noise.  I have some surplus 4 fans that
have rubber feet attached and just sit over the hot portion of the
cabinet.  I run them at a DC value below their ratings.  They don't walk,
aren't heard, and substantially lower the peak temps within the radio.

Dennis AE6C

On Wed, Nov 30, 2011 at 5:21 PM, Bob Loving bob.lov...@sbcglobal.netwrote:

   Hi, Paul:

 I purchased a T4-XC with MS-4 speaker and AC-4 on the cheap. The rig,
 etc., are in really nice shape and the cabinets of the T4-XC and MS-4 had
 been repainted beautifully.

 The T4-XC had an 80-mm square dc fan on the back of the PA cage. Two
 screws to mount it at the top and a tie wrap on the left hand side (as
 viewed from the back). On inspection, the feed for the fan was the 12.6Vac
 filament line with only a 1N4000-series diode in series. The fan runs very
 quietly; it is produced by PPM, (Pony Precision Motor Co. in Taiwan),
 model FBA-9, brushless and ball bearing. Any 12Vdc fan would probably work
 and you can find the 80-mm fans in abundance from the computer stores. If
 you want a higher speed from the fan, add an electrolytic capacitor the
 output of the rectifier to increase the average dc voltage.

 73,

 Bob K9JU



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Re: [Drakelist] R4B PTO indicator...

[Dennis Monticelli]

This is a fairly common problem.

The strike voltage of the neon lamp tends to drift upward with age.  The
transistor used by Drake to switch the voltage does not have a high
breakdown voltage so Drake used a resistor voltage drop to reduce the
available voltage to barely enough to strike the lamp.  You have three
options:

1) Replace the lamp with a fresh one and wait for it to drift upward (that
could buy you a year or many years).
2) Reduce the value of the dropping resistor and take a chance that the
transistor won't break down under the extra voltage present.
3) Upgrade the transistor to a high voltage rating device and get rid of the
dropping resistor entirely (permanent fix and what Drake should have done in
my opinion).

Dennis AE6C

On Tue, Sep 6, 2011 at 8:01 PM, Fred or Ski wb8...@frontier.com wrote:


 I have an intermittant PTO indicator lamp on my R4B when using it with my
 T4XC.  It may work all night, then sometimes it will go out and won't come
 on with whatever you do to switch the PTO in use.  In the R4B schematic, it
 shows Q10 is a switch that is turned off when the transmitter is used for
 freq control, by a negative voltage on the INJ line to the receiver.  I
 suspect either the transistor or the neon bulb indicator.  Has anyone had
 this problem and what did you do to fix it.  Thanks to all.

 73,

 WB8YXI-Ski

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Re: [Drakelist] You just know I'm not going to have any hair left...

[Dennis Monticelli]

If the problem is an intermittant connection somewhere (i.e. a bad solder
joint) the point application of heat or cold can change the problem (either
aggravate or improve) thus allowing you to isolate the troublesome region.
Have you tried the point application of cold spray?  Often those cans come
with a needle tip.

Dennis AE6C

On Sun, Aug 21, 2011 at 7:20 PM, Garey Barrell k4...@mindspring.com wrote:

 Steve -

 NONE of the T-4X(any) had the low-pass filter on the output of the PTO.
  Only the receivers used the filter, and only in version 2 of the R-4A and
 up.

 It would be OK to just bypass the LP filter in the receiver for testing
 purposes.   Also, don't gloss over the possibility of a bad, (cracked?), or
 just noisy resistor at R49.  Or even poor solder on those associated
 connections.

 Also, don't overlook the possibility of erratic or intermittent operation
 of the BAND oscillator (listen at 18.1 MHz on 40M).

 Possible other resistors associated with V8 are noisy.  Since you have no
 jitter in TRANSCEIVE (XMTR control) the problem is in the BAND, PTO or
 PreMixer, as these are all disabled in XMTR mode.


 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
 and TR-4/C Service Supplement CDs
 www.k4oah.com


 Steve Wedge wrote:

 I'm going to have to look again.  I did swap the VR tube.

 Something Garey mentioned made me check the T-4XB schematic.  If that
 schematic is accurate, Drake put the filter inside the PTO at some point or
 just for the T-4XB.  I'm suspecting this was done for all PTO's at some
 point, as I couldn't imagine Drake building different versions of the PTO at
 the same time (of course, not everything follows what I or anyone else would
 consider logical...).  This could allow me to try temporarily bypassing the
 filter board.  I did notice that shielded cable went directly to the PTO
 when I removed it.  Given these differences, it also looks like I'll be
 ripping the receiver apart (again!) to put the original PTO back in.

 Arrrgh...


 Steve Wedge, W1ES/4

 I can't complain, but sometimes I still do.
 - Joe Walsh

 If the above message appears, it came from Steve's Son of Laptop!
 - Original Message - From: kc9...@aol.com
 To: w1es1...@earthlink.net
 Sent: Sunday, August 21, 2011 6:11 PM
 Subject: Re: [Drakelist] You just know I'm not going to have any hair
 left...


 Did you put a scope on the voltage to the PTO and watch it carefully?
 As it fails?
 73,
 Lee, KC9CDT



 -Original Message-
 From: Steve Wedge w1es1...@earthlink.net
 To: Eddy Swynar deswy...@xplornet.ca
 Cc: drakelist drakelist@zerobeat.net
 Sent: Sun, Aug 21, 2011 5:30 pm
 Subject: Re: [Drakelist] You just know I'm not going to have any hair
 left...


 That's the thing: it's a different PTO that was working properly before
 I transplanted it.

 Looks like I've got to try replacing the components on the filter
 board. Something is pulling the frequency...

 Steve Wedge, W1ES/4


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Re: [Drakelist] Fading

[Dennis Monticelli]

Yes.  Diversity reception is a well known technique, but you need a radio
so-configured or a separate box to process the inputs from the two
antennas.  The antennas must be physically separated from each other
sufficiently that a fade on one would not necessarily occur in the other at
the same time.  The good news is that the technique really does work.

Dennis AE6C

On Sun, Aug 7, 2011 at 4:27 PM, Nigel A. Gunn, W8IFF/G8IFF
ni...@ngunn.netwrote:

 Look up diversity reception



 On 08/07/2011 11:22 PM, Neil M Califano wrote:

 This is a bit off topic, but how can two receiving antennas be used to
 reduce fading?

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Re: [Drakelist] Capacitor type for PTO C146 (The Dogbone)

[Dennis Monticelli]

Depending upon the maker and the value of capacitance, a SM will exhibit
about +30 to 100PPM.  Polystyrene is a little more consistant at
around+125PPM.  Both cap types are popular when combined with iron powder
cores of low mu because they buck the mild negative TC of the core.
Polystyrenes are hard to find these days.  They have a low melting point
which is not so good for surface mount boards.  There is also the mass to
consider.  A large sized cap will take longer to thermally stabilize.  That
may be good or bad depending upon the mass of the other components you wish
to buck.   Does anyone know what dielectric comprised the original dogbone?
I would stick with that if possible.  If the dogbone is ceramic, though,
good luck determining it's actual TC as ceramic can have many tempcos.

Dennis AE6C


On Sun, Jul 31, 2011 at 2:01 PM, Garey Barrell k4...@mindspring.com wrote:

 Steve -

 Stick with the 'dog-bone'.   Hard to beat a silver mica for temperature
 stability.

 PLUS

 EVERY capacitor has 'some' temperature sensitivity, just a matter of how
 much, and  _which way_!

 I'm going from memory here, but as I recall a silver mica has a very slight
 negative tempco, while polystyrene caps have a slightly positive tempco.
  Obviously this has been taken into account and compensated for by 'the
 ladies' at Drake!

 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
 and TR-4/C Service Supplement CDs
 www.k4oah.com



 Steve Wedge wrote:

 I'm looking at options for replacing the dogbone 3000 pF SM cap in the
 PTO.  I've long heard the polystyrene caps are stable and of high quality.
 What's your opinion of using a polystyrene cap in place of the SM unit at
 C146?


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Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Dennis Monticelli]

I know from my experience in the semiconductor business that zeners
(especially those from a prior era) are notoriously noisy and can become
outright unstable to varying degrees.  You will not see this with a DVM or
other averaging type instrument.  You should put a scope on the zener and
turn up the gain as high as the scope will go while setting the time base
for anywhere from 1 to 100ms/div.  Make sure your scope ground connection is
right at the zener to keep stray pickup at a minimum.  If it is unstable you
will see the voltage jumping around in discrete steps.  A typical zener will
just exhibit white noise which looks like tall grass on the CRT.  Both the
discrete steps and the white noise will modulate the PTO.  The steps
manifest as annoying random freq shifts while the white noise just adds
to the noise sidebands of the oscillator.  The discrete jumps in zener
voltage are understood in the physics but unless folks are truly interested
in that stuff I won't go into it here.

Not to scold the Drake design team (whom I respect) and maybe mostly because
I witnessed how the sausage is actually made, but I would NEVER design a
zener into a circuit as noise sensitive as an oscillator, mixer or preamp.
I designed and built a homebrew antenna noise bridge.  Guess what I used as
the broadband noise source?

Dennis AE6C

On Fri, Jul 29, 2011 at 3:25 PM, Steve Wedge w1es1...@earthlink.net wrote:

 Well, it has been a long, strange trip here.

 Just finished a little experiment with the PTO and my K3.  First of all,
 the K3 is deaf as a post at 4.9 MHz ;-) but I did get enough of a signal
 through a scope probe hooked to the PTO output to confirm that it's the PTO
 that is shifting frequency.

 Having confirmed that, my next step will be replacing the 3000 pF and the
 zener - even though I'm fairly convinced the zener is okay (alright - I'll
 replace the 3000 pF first...).

 I have a sneaking suspicion that this may be one of the S.A.T. caps.  If
 so, it's going to be interesting since I no longer have a capacitance meter.

 Steve Wedge, W1ES/4

 I can't complain, but sometimes I still do.
 - Joe Walsh

 If the above message appears, it came from Steve's Son of Laptop!
 - Original Message - From: Garey Barrell k4...@mindspring.com
 To: Steve Wedge w1es1...@earthlink.net
 Cc: drakelist@zerobeat.net
 Sent: Friday, July 29, 2011 3:21 PM
 Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors


 Steve -

 Yes, the PreMixer signal (V8) (BAND minus PTO) is the one that is piped
 back and forth between the two units.

 All you have to do is listen to the PTO signal itself on a separate
 receiver.  0 on the dial = 5.455 MHz, 500 = 4.955.  The BFO crystal is
 5.595 MHz.  The BFO is a tube, V3, which I believe we swapped way back
 towards the beginning of this odyssey!!  I also thought you had put a
 counter on the PTO, but I guess that's another 'project'.  :-)   I typically
 have three or four of these eMail projects going at one time, which is why I
 like to keep the entire thread together.  Makes it easier to go back
 occasionally just to review just what path got us 'here'!  :-)

 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
 and TR-4/C Service Supplement CDs
 www.k4oah.com


 Steve Wedge wrote:

 You know, Garey, I've been thinking about the xtal oscillator.  It would
 have to be part that doesn't get bandswitched - which would include THAT
 transistor.

 When the T-4X controls the frequency, it sounds great and never jumps
 frequency.  In looking at the schematic, I have been aware that the two
 solid-state oscillators (PTO and LO for the band) get mixed in V8 (IIRC) and
 that this combination gets overridden by the output of the T-4X's premixer.

 Looks like I am going to need a counter to find out.  I am loathe to dig
 into the T-4X because it's working so well and the PTO is much more
 difficult to remove from it due to the volume of wires in the area.

 73,

 Steve, W1ES


 Date: Fri, 29 Jul 2011 13:31:12 -0400
 From: Garey Barrellk4...@mindspring.com
 To: Richard Knoppow1oldlens1@ix.netcom.**com 1oldle...@ix.netcom.com
 Cc: drakelist@zerobeat.net
 Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors
 (entirely)
 Message-ID:4E32EE60.4060209@**mindspring.com4e32ee60.4060...@mindspring.com
 
 Content-Type: text/plain; charset=ISO-8859-1; format=flowed

 Richard -

 Yes, one wonders..:-)   This type of 'dithering' is known in
 PTOs, but although much less
 common, a poor crystal oscillator such as the BAND or 2nd MIXER
 oscillators 'could' present the same
 way.



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Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Dennis Monticelli]

Yes, Garey, when zeners are run at current levels near their knee they do
tend to be noisier. Applying this knowledge tends to give better
results with a typical zener exhibiting white noise.  But should a zener go
unstable all bets are off.

The 78L series voltage reg is zener based.  Depending upon the brand and
when it was made it may be better than a discrete zener or not.  If you go
with a 78L made in say the last 15 years, it will probably be better.  The
best choice is a voltage regulator that is based upon a bandgap voltage
reference.  Most linear regulators made in the last 20 years are of the LDO
(low drop out) type and these are all bandgap based.  The venerable LP2951
comes to mind.  It is a low power part with an adjustable output.  The
popular LM317 is also bandgap based and adjustable, though not LDO.  The
LM317L low power version comes in a convenient TO-92 transistor package and
may be the best physical fit for PTO service.  Any of these regs can have
their output voltage set with two resistors and will accomodate output
caps.  You can also buy linear regs that are specified for low noise, but I
think that is overkill for our needs.  We just need to avoid gross noise
issues.

Dennis AE6C

On Sat, Jul 30, 2011 at 12:04 PM, Garey Barrell k4...@mindspring.comwrote:

 I'm interested in Dennis' response to this.  Yes, it's a 'more complex'
 solution, but 'may' be quieter?  I don't know if they are more 'stable' or
 not.

 I DO know that Zeners ARE noisy, reflected in their use as noise generators
 for many of the noise sources used for receiver and other testing.  This is
 especially true as they become more 'starved' for current, i.e., the lower
 the current through them, the noisier they get.  Unless Dennis shoots me
 down on that too!!  :-)

 The Input and Output capacitors on the 3-term regulators are for stability,
 (oscillation,) rather than signal conditioning.


 73, Garey - K4OAH
 Glen Allen, VA



 Paul Christensen wrote:

 The 78L10 is only 39-cents ea. in small quantities through Mouser.  I had
 always assumed that a Zener with current limiting resistor or in the
 alternative, a Zener with pass transistor would produce a quieter output
 than a monolithic regulator?

 So, is it possible that a 78L10 may be more stable as a PTO regulator, but
 may require more in/out conditioning than a Zener?   The Fairchild 78L10
 datasheet recommends a 0.33 uF bypass on the input leg, and 0.1 uF bypass on
 the output.

 Paul, W9AC

 - Original Message - From: Garey Barrell k4...@mindspring.com
 To: Dennis Monticelli dennis.montice...@gmail.com

  Which is why subbing the Zener is the FIRST thing we check, after making
 sure the spring is in place!!  :-)

 Is a three-terminal regulator such as a 78LO10 ?  a better choice??

 73, Garey - K4OAH
 Glen Allen, VA


 Dennis Monticelli wrote:

 I know from my experience in the semiconductor business that zeners
 (especially those from a prior era) are notoriously noisy and can become
 outright unstable to varying degrees.  You will not see this with a DVM or
 other averaging type instrument.  You should put a scope on the zener and
 turn up the gain as high as the scope will go while setting the time base
 for anywhere from 1 to 100ms/div.  Make sure your scope ground connection 
 is
 right at the zener to keep stray pickup at a minimum.  If it is unstable 
 you
 will see the voltage jumping around in discrete steps. A typical zener will
 just exhibit white noise which looks like tall grass on the CRT.  Both 
 the
 discrete steps and the white noise will modulate the PTO.  The steps
 manifest as annoying random freq shifts while the white noise just adds to
 the noise sidebands of the oscillator. The discrete jumps in zener voltage
 are understood in the physics but unless folks are truly interested in that
 stuff I won't go into it here.
 Not to scold the Drake design team (whom I respect) and maybe mostly
 because I witnessed how the sausage is actually made, but I would NEVER
 design a zener into a circuit as noise sensitive as an oscillator, mixer or
 preamp.   I designed and built a homebrew antenna noise bridge.  Guess what
 I used as the broadband noise source?
 Dennis AE6C

 On Fri, Jul 29, 2011 at 3:25 PM, Steve Wedge 
 w1es1...@earthlink.netmailto:
 w1es1...@earthlink.net** wrote:

Well, it has been a long, strange trip here.

Just finished a little experiment with the PTO and my K3.  First of
 all, the K3 is deaf as a
post at 4.9 MHz ;-) but I did get enough of a signal through a scope
 probe hooked to the PTO
output to confirm that it's the PTO that is shifting frequency.

Having confirmed that, my next step will be replacing the 3000 pF and
 the zener - even though
I'm fairly convinced the zener is okay (alright - I'll replace the
 3000 pF first...).

I have a sneaking suspicion that this may be one of the S.A.T. caps.
 If so, it's going to be
interesting since I no longer have a capacitance meter

Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Dennis Monticelli]

The RC on the output of the zener trick works for white noise, but I think
the freq jumps would be just as annoying.

Dennis AE6C

On Sat, Jul 30, 2011 at 2:31 PM, Garey Barrell k4...@mindspring.com wrote:

 Dennis -

 Well, I know I want to know more!  I've been out of semis so long I'm
 completely lost.  I 'know' a lot of things, (Zeners are noisy,) but didn't
 know 'why'!  An engineering brain is a terrible thing to waste...  :-)


 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
 and TR-4/C Service Supplement CDs
 www.k4oah.com


 Dennis Monticelli wrote:

 Hi Ron,
 Well, what we call a zener these days is actually not a zener (whose
 breakdown mechanism is actually quantum mechanical tunneling), but rather an
 avalanche breakdown diode.  Electrons get rippped loose by the high electric
 fields at the PN junction interface, smack into other atoms, kick loose more
 electrons and pretty soon you've got something akin to a snow avalanche.
  This is an inherantly noisy process of generating current.  When the PN
 junction is manufactured such that the avalanching occurs at the surface of
 the semiconductor chip that is bad for stability.  Various mobile ions
 (often from the molding compound itself) migrate to the region of the
 breakdown under the influence of the attractive electric field.  They
 accumlate there and alter the breakdown characteristic.  The point of
 avalanche then tends to flit from one region to another, each region with a
 sightly different voltage value.  Hence the net zener voltage jumps around
 in a random fashion.  This is in addition to the normal white noise of
 avalanche.  The worst I've ever seen is 500mV and more typically it is a few
 mV's or ten's of mV, but that is sufficient to shift an LC oscillator.
 A zener diode made in a sophisticated way can avoid the instability issue
 entirely but burying the PN junction below the surface of the chip.
 Probably more than you wanted to know :-)
 Dennis AE6C
 On Sat, Jul 30, 2011 at 11:32 AM, Ron wd8...@yahoo.com mailto:
 wd8...@yahoo.com wrote:

Dennis,
I would be interested in hearing more about the physics.  Not sure if
 the rest of the list
would be.

I studied Electronics, and then ended up in computers.  Kind of enjoy
 some good old college
lecture series now and then.

73,
Ron WD8SBB

--- On *Sat, 7/30/11, Dennis Monticelli /dennis.montice...@gmail.com
mailto:dennis.monticelli@**gmail.com dennis.montice...@gmail.com/*
 wrote:


From: Dennis Monticelli dennis.montice...@gmail.com mailto:
 dennis.monticelli@**gmail.com dennis.montice...@gmail.com

Subject: Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

To: Steve Wedge w1es1...@earthlink.net mailto:
 w1es1...@earthlink.net**
Cc: drakelist@zerobeat.net mailto:drakelist@zerobeat.net**

Date: Saturday, July 30, 2011, 12:31 PM


I know from my experience in the semiconductor business that zeners
 (especially those from
a prior era) are notoriously noisy and can become outright unstable
 to varying degrees. You will not see this with a DVM or other
 averaging type instrument.  You should put a
scope on the zener and turn up the gain as high as the scope will
 go while setting the
time base for anywhere from 1 to 100ms/div.  Make sure your scope
 ground connection is
right at the zener to keep stray pickup at a minimum.  If it is
 unstable you will see the
voltage jumping around in discrete steps.  A typical zener will
 just exhibit white noise
which looks like tall grass on the CRT.  Both the discrete steps
 and the white noise will
modulate the PTO.  The steps manifest as annoying random freq
 shifts while the white
noise just adds to the noise sidebands of the oscillator.  The
 discrete jumps in zener
voltage are understood in the physics but unless folks are truly
 interested in that stuff
I won't go into it here.
Not to scold the Drake design team (whom I respect) and maybe
 mostly because I witnessed
how the sausage is actually made, but I would NEVER design a zener
 into a circuit as noise
sensitive as an oscillator, mixer or preamp.   I designed and built
 a homebrew antenna
noise bridge.  Guess what I used as the broadband noise source?
Dennis AE6C

On Fri, Jul 29, 2011 at 3:25 PM, Steve Wedge 
 w1es1...@earthlink.net

 http://mc/compose?to=**w1es1...@earthlink.nethttp://mc/compose?to=w1es1...@earthlink.net
 wrote:

Well, it has been a long, strange trip here.

Just finished a little experiment with the PTO and my K3.
  First of all, the K3 is
deaf as a post at 4.9 MHz ;-) but I did get enough of a signal
 through a scope probe
hooked to the PTO output to confirm that it's the PTO that is
 shifting frequency.

Having confirmed that, my next step

Re: [Drakelist] R-4A PTO - transistors substituted?

[Dennis Monticelli]

For the oscillating device in the LO I would add noise to the list of what
to look for in a transistor.  This varies a lot from type to type and even
from maker to maker.  For example, the 2N is not exactly the world's
quietest transistor.  To just check to see if that osc transistor is the
root of the problem, then free subsitution is fine.  Otherwise stick to a
device that was designed for RF service, which is different than a device
designed for general saturated switching.  I know this from experience; my
company was a transistor manufacturer in the past.

Dennis AE6C

On Sun, Jul 24, 2011 at 2:20 PM, Garey Barrell k4...@mindspring.com wrote:

 Funny, I don't  recall  you working for me during college   :-)


 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
 and TR-4/C Service Supplement CDs
 www.k4oah.com



 Paul Christensen wrote:

 Or even a 2N.  Between the 2N3858, 2N3904, and 2N, the fT / GBP,
 hFE, and C in/out parameters are reasonably identical.  Probably the biggest
 variant will be the hfe value across samples, but I agree with Garey to give
 it a shot.  The PTO is only running at 5 MHz.

 During college, I worked for an engineer who's philosophy was to replace
 with 2NAnyThing that worked.  He certainly knew the widely different
 transistor parameters, but his point was that in many general purpose
 switching, amplification and oscillating circuits, 2NAnyThing is often an
 adequate substitute, taking into account the need to watch for NPN, PNP,
 FET, etc. configurations.

 Paul, W9AC

 - Original Message - From: Garey Barrell k4...@mindspring.com
 To: Steve Wedge w1es1...@earthlink.net
 Cc: drakelist@zerobeat.net
 Sent: Sunday, July 24, 2011 2:45 PM
 Subject: Re: [Drakelist] R-4A PTO - transistors substituted?


 Steve -

 I've looked in a LOT of PTOs, and I've never seen anything but a 2N3858
 in the Buffer and either a 2N3858 (early) or 2N706 (late) in the oscillator.
 No other changes required with either oscillator transistor.  The '3858 is
 just about extinct, but the 2N706 is still a common transistor.

 Defective transistors have definitely been known to cause the kind of
 frequency changes you're seeing.  So while they may even be a 'later'
 modification than factory built, and may even be a suitable substitute, they
 can still fail just like the originals.  By the way, if you look at the PTO
 schematic, the FSK 'shift' terminal is connected to the output of the
 oscillator stage.  This allowed you to  _SHIFT_  the PTO frequency by up to
 850 Hz by adding a cap from this terminal to ground.  So variations in the
 Buffer transistor CAN dither the frequency.  And yes, it does.

 I think transistors were about the third thing down on the list once you
 get through the lubrication, mechanical and ground faults.

 I know you said you were short on components, but '706s are cheap from
 Mouser, or if you can find a couple of 2N3904 (everywhere!) transistors you
 could try them just to see.  They may not work perfectly, but if the PTO
 becomes stable you'll know.  Watch the basing on whatever transistors you
 use.  Seems like they are all different these days!

 73, Garey - K4OAH
 Glen Allen, VA




 Steve Wedge wrote:

 Looking at the transistors in this PTO, I'm 99.9% sure someone replaced
 them: they are both marked NSRS / 2018, with the / being a line break.
 I'm sort of thinking that Drake used different parts for the oscillator
 and buffer for a good reason.  Aside from this maddening frequency-shifting
 and crummy audio, the frequency calibration is still good.  What are the
 chances that using the wrong transistors could be the source of all this
 grief?


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[Drakelist] R-4B audio problem traced to low beta Q7 (2N3394)

[Dennis Monticelli]

Lee, Garey,

OK.  Mystery solved.  Curve tracers are wonderful forensic tools.

Lee, when I first looked at the 2N3394 from your R-4B it's I-V curves looked
fine except for a decided dropoff in low current beta.  At first I didn't
flag this as a serious issue. The beta of all transistors is a function of
collector current, tending to peak right where the factory DC tests are run
:-)  The falloff rate at low collector current was greater for transistors
built over 40 years ago vs a transistor made today.  The 2N3394 in your
radio still meets min spec of 55 (barely) at 2mA.  However, Drake ran the
collector current at 1/8 that value and used a base current biasing method
(in common use at the time) that suffers from excessive dependency upon the
beta value, not for voltage gain but for setting up the correct bias
levels.  Your particular 2N3394 has a beta of only 25 at 250uA which is why
it set up too low.  Once it set up too low the further declining beta below
250uA made things even worse, effectively negating the compensating extra
current through the 2.2M base bias resistor (the collector voltage rises
under the starved collector current condition and would normally help
provide addtional base bias).  When you placed a fresh 2N3393 in there (min
beta of 90 at 2mA), the bias problem went away.  Not only was its beta
higher at 2mA, it probably fell off a lot less at 250uA also.

So the only mystery left is why Q7 worked well enough to leave the factory
but not at the present time.  Low current beta is dependent upon surface
states in the Silicon crystal in the region of the base structure. Early
transistor manufacturing techniques left much to be desired in terms of
surface state control and early plastic packaging (think leaching of ions)
compounded the stituation.  So I'm guessing the low current beta was
marginal when it left the factory and slid down over time.  Another
posibility is a reverse application of BE voltage (even momentary) as that
is known to degrade low current beta.  Looking at the circuit the only way
that's going to happen is an errant application of a test probe.  So most
likely it was slow degradation over time.

Anyway, the data supports your 2N3393 fix.  Given what I've learned I would
recommned that concerned R-4B users make a simple DC measurement of the
voltage across R141 and if excessively low (i.e. well below 20mV), then do
exactly what you did: replace Q7 with a fresh 2N3393 and recheck bias
levels.  R-4B owners may want to do this because R141 is not there to manage
bias, it is there for emitter degeneration, a form of negative feedback that
reduces distortion under strong audio signals.  If insufficient voltage is
developed across R141 the distortion will be greater.

Hope this explanation helps the list.  I learned something here.

Dennis AE6C
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Re: [Drakelist] R-4B audio problem traced to low beta Q7 (2N3394)

[Dennis Monticelli]

I believe it. However, I think it had less to do with the transistor being a
2N3393 and pretty much all due to just having a beta high enough to allow
the transistor stage to bias correctly.  Another transistor type with good
beta would have probably worked as well.  You kept it in the family by
choosing the 2N3393, so I prefer the route you took.

Dennis AE6C

On Sun, Apr 17, 2011 at 12:33 PM, kc9...@aol.com wrote:

 One more thing to addthe 2N3393 worked super (batter than the
 2N3394??)...in fact, at a AF gain setting of 8-9 o'clock...the audio is very
 nice at at a good listening levelat 10:00 with the RF gain down on a
 noisey band the R-4b really hears well.
 73,
 Lee




 -Original Message-
 From: Garey Barrell k4...@mindspring.com
 To: Dennis Monticelli dennis.montice...@gmail.com
 Cc: kc9cdt kc9...@aol.com; drakelist drakelist@zerobeat.net
 Sent: Sun, Apr 17, 2011 3:25 pm
 Subject: Re: R-4B audio problem traced to low beta Q7 (2N3394)


 Dennis -

 I think the saying is 'even a blind squirrel finds an acorn now and
 then, if you put him under an oak tree!  :-)

 That's why I suggested Beta, a low B-E current just made it worse.  I've
 never seen a small signal BJT fail that way, but your explanation makes
 sense.  I have seen some of the early RF Power transistors that were
 actually multiple transistors all collected in parallel and one or more
 would blow open!

 I believe R141 is ALSO a form of temperature compensation, as the
 transistor 'warms' up, the B-E drop lowers, increasing the bias
 current.  The drop across the E resistor also increases, decreasing the
 bias current.  Much more stable DC operating point.  It DOES also add
 some negative feedback for the signal, reducing distortion.  It also
 stabilizes the circuit with different transistors as without it the
 stage gain is limited ONLY by device Beta and internal resistance.  With
 the E resistor, the output is the ratio of Er to Cr, swamping device
 variations, for a gain of about 580.

 Very interesting exercise.  Thanks very much for your help and expertise!

 73, Garey - K4OAH
 Glen Allen, VA



 Dennis Monticelli wrote:

 Lee, Garey,
 OK.  Mystery solved.  Curve tracers are wonderful forensic tools.
 Lee, when I first looked at the 2N3394 from your R-4B it's I-V curves
 looked fine except for a decided dropoff in low current beta.  At
 first I didn't flag this as a serious issue. The beta of all
 transistors is a function of collector current, tending to peak right
 where the factory DC tests are run :-)  The falloff rate at low
 collector current was greater for transistors built over 40 years ago
 vs a transistor made today.  The 2N3394 in your radio still meets min
 spec of 55 (barely) at 2mA.  However, Drake ran the collector current
 at 1/8 that value and used a base current biasing method (in common
 use at the time) that suffers from excessive dependency upon the beta
 value, not for voltage gain but for setting up the correct bias
 levels.  Your particular 2N3394 has a beta of only 25 at 250uA which
 is why it set up too low.  Once it set up too low the further
 declining beta below 250uA made things even worse, effectively
 negating the compensating extra current through the 2.2M base bias
 resistor (the collector voltage rises under the starved collector
 current condition and would normally help provide addtional base
 bias).  When you placed a fresh 2N3393 in there (min beta of 90 at
 2mA), the bias problem went away.  Not only was its beta higher at
 2mA, it probably fell off a lot less at 250uA also.
 So the only mystery left is why Q7 worked well enough to leave the
 factory but not at the present time.  Low current beta is dependent
 upon surface states in the Silicon crystal in the region of the

 base

 structure. Early transistor manufacturing techniques left much to be
 desired in terms of surface state control and early plastic packaging
 (think leaching of ions) compounded the stituation.  So I'm guessing
 the low current beta was marginal when it left the factory and slid
 down over time.  Another posibility is a reverse application of BE
 voltage (even momentary) as that is known to degrade low current
 beta.  Looking at the circuit the only way that's going to happen is
 an errant application of a test probe.  So most likely it was slow
 degradation over time.
 Anyway, the data supports your 2N3393 fix.  Given what I've learned I
 would recommned that concerned R-4B users make a simple DC

 measurement

 of the voltage across R141 and if excessively low (i.e. well below
 20mV), then do exactly what you did: replace Q7 with a fresh 2N3393
 and recheck bias levels.  R-4B owners may want to do this because

 R141

 is not there to manage bias, it is there for emitter degeneration, a
 form of negative feedback that reduces distortion under strong audio
 signals.  If insufficient voltage is developed across R141 the
 distortion will be greater.
 Hope this explanation helps the list.  I learned

Re: [Drakelist] R-4B audio problem traced to low beta Q7 (2N3394)

[Dennis Monticelli]

That would be an interesting study, going stage by stage through the audio
channel of a 4 or 7 series radio.  I'll bet that when the R-4B was designed,
the Drake lab didn't have such a piece of equipment and probably went by ear
or visuals on a scope.  Maybe someone familar with what Drake had to work
with back then could shed some light on this.

Dennis AE6C

On Sun, Apr 17, 2011 at 12:59 PM, Jim Shorney jshor...@inebraska.comwrote:

 On Sun, 17 Apr 2011 15:13:23 -0400 (EDT), kc9...@aol.com wrote:

 Very good explanation...I understoof about 30% of it...but then I am a
 tech., not an engineer. Hi, Hi.

 What made this tough is that Q7 was kind of working...so I was
 checking, replacing everything BUT Q7.

 My experience as a tech in situations like this has taught me to suspect
 capacitors first, transistors next. I've seen transistors fail in some
 strange
 ways over the years. :)

 I've recently learned that disc ceramic caps are not ideal for audio
 coupling.
 You guys have got me thinking about distortion and such. I'm thinking about
 putting the TR-7 on the bench and trying out that nifty surplus distortion
 analyzer that's languising out in the garage.

 73

 -Jim


 --
 Ham Radio NU0C
 Lincoln, Nebraska, U.S.S.A.
 TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A,
 GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time!

 Give a man a URL, and he will learn for an hour; teach him to Google, and
 he will learn for a lifetime.

 HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/
 http://incolor.inetnebr.com/jshorney
 http://www.nebraskaghosts.org



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Re: [Drakelist] Testing Caps for Leakage

[Dennis Monticelli]

Richard,

That is very true.  Paper caps can leak yet look OK for capacitance and not
too bad for ESR.  I think 5uA is too high for a paper cap.  If that cap is
being used for plate to grid coupling and the grid circuit is 1 Mohm, there
will obviously be a problem.

I have a common Heathkit IT-11 cap tester and I've calibrated the eye
closures for 1uA/10uA/1mA respectively on the leakage switch.  It tests caps
just fine and will form electrolytics.

Dennis AE6C

On Sat, Apr 2, 2011 at 10:07 PM, Richard Knoppow 1oldle...@ix.netcom.comwrote:

For years I thought it was sufficient to test caps for dissipation
 factor, another name for ESR, I discovered the hard way its not. Many will
 tell you that electrolytic caps must be tested with polarizing voltage and
 that may make a difference in the measured capacitance of some but that is
 not the problem I am discussing. I discovered that many caps develop low
 _parallel_ resistance AKA leakage. Not just electrolytic but also paper and
 probably other types of caps. I found this when I was getting an old General
 Radio signal generator going and discovered that the modulation monitor
 didn't work right. The coupling cap was a 0.05 uf high quality molded paper
 cap. It measured fine on a GR impedance bridge but a new cap fixed the
 problem. The new cap measured about the same as the old one on the bridge.
 So, I decided to measure the leakage current. I did this with a small GR
 regulated and adjustable power supply and a DMM capable of measuring
 micro-amps. Most DMM's and VOM's are sufficiently sensitive to work. I found
 the bad capacitor to have a lot of leakage current (can't remember how much)
 where a new one had none detectable. I used about 300V on that one because
 it was rated that high.
I then checked a bunch of discarded caps of all sorts plus some new
 ones. Bad electrolytics of course have very high leakage (right up to being
 sort circuits).
I think the limits are around 5 ua for paper or other non-electrolytic
 types and perhaps 15 ua or a bit more for electrolytics. The current for an
 electrolytic will drop as the virtual electrode forms, if it increases the
 thing is no good.
I later obtained a General Radio megohmeter,which will make a similar
 measurement but it has a fixed bias of 500V which is too much for many caps.
 It cqan be rigged to work with a lower voltage external supply, I have not
 tried that. The only advantage it has over the supply and meter method is
 that it indicates resistance directly.
Anyway, the point is (and you know what's coming) that many bad caps
 will test good on a bridge or capacitance meter that is not set up to
 measure _parallel_ resistance with sufficient voltage.
Note that _leakage_ or parallel resistance is also why bridging a bad
 cap with a good one will often NOT make a difference, its _not_ loss of
 capacitance but increase in leakage that's the problem and putting two caps
 in parallel won't change that. To investigate a cap it really is necessary
 to lift one end and substitute another.


 --
 Richard Knoppow
 Los Angeles
 WB6KBL
 dickb...@ix.netcom.com



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Re: [Drakelist] Testing Caps for Leakage

[Dennis Monticelli]

Richard,

Any readily detectable leakage is too much for a grid coupling cap IMO.  A
cap that even partially closes the eye on the 1uA setting of my Heathkit is
grounds for replacement.  Modern caps are cheap and easy to obtain.  If you
don't like the bright colors of new axial caps, just slip a little heat
shrink over them and viola you have a mini black beauty :-)

Dennis AE6C

On Sun, Apr 3, 2011 at 5:43 AM, Richard Knoppow 1oldle...@ix.netcom.comwrote:


  -Original Message-
 From: Dennis Monticelli
 Sent: Apr 3, 2011 1:22 AM
 To: Richard Knoppow 1oldle...@ix.netcom.com
 Cc: Drake List
 Subject: Re: [Drakelist] Testing Caps for Leakage

 Richard,

 That is very true.  Paper caps can leak yet look OK for capacitance and not
 too bad for ESR.  I think 5uA is too high for a paper cap.  If that cap is
 being used for plate to grid coupling and the grid circuit is 1 Mohm, there
 will obviously be a problem.

 I have a common Heathkit IT-11 cap tester and I've calibrated the eye
 closures for 1uA/10uA/1mA respectively on the leakage switch.  It tests caps
 just fine and will form electrolytics.

 Dennis AE6C

  I don't remember where I got the 5 uA value, you could well be right.
 It doesn't take much leakage to cause problems with coupling caps. Modern
 film caps have leakage so low its difficult to detect.



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Re: [Drakelist] Blue LED Bulbs for Drakes

[Dennis Monticelli]

The LEDs in this product look just like the ones that come in the XMAS lite
strings.  That market probably drove mass production and low prices, which
in turn enabled this outfit to build a bulb.  It would probably benefit from
a diffuser in some applicatons.

Thanks for sharing your finding with the group.

Dennis AE6C

On Wed, Feb 2, 2011 at 3:42 PM, Kevin Elliott kg...@yahoo.com wrote:

  First I want to say I am sorry if this upsets the person that is making
 and selling the blue LED bulbs on Ebay and other web sites.  I just can't
 afford to pay $30.00 plus shipping for 2 bulbs.   So I went looking for a
 different source and I found one that was much cheaper.  The company
 sells #47 Blue (or other color) LED bulbs. The best thing is the price...
 $1.58 each.  The worked perfect on the main dial but were not quite bright
 enough for the meters until I took the reflector off and scrubbed it white
 again.  Now for $3.18 I can but the blue bulbs in the TR-4 or even opt for
 red since I ordered some of them and they look very nice as well.

 Here is the link http://www.centsibleamusements.com/pinball-led-44-47.aspx

 Enjoy


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Re: [Drakelist] L-4B Plate Tuning Cap Question

[Dennis Monticelli]

Is there a new replacement drive for the L4B and L7 verniers that can be
purchased?

Dennis AE6C

On Thu, Jan 13, 2011 at 2:05 PM, K9sqg k9...@aol.com wrote:

 Dino,

 This is normal operation for a vernier drive that has either sat for an
 extended period of time unused or, in less frequent cases, one that has had
 a lot of use.  There are ways of cleaning, relubing, and then repositioning
 things so the drive has renewed bite so to speak.  However, for all it
 takes to do this in terms of time and effort, one can consider just
 replacing the drive itself.  It is a matter of personal preference.  Good
 luck with your decision.

 73,

 Evan




 -Original Message-
 From: Dino Papas k...@cox.net
 To: Mail List - Drake Gear Drake Gear drakelist@zerobeat.net
 Sent: Thu, Jan 13, 2011 3:59 pm
 Subject: [Drakelist] L-4B Plate Tuning Cap Question

 Well, today in anticipation of rebuilding my L-4BPS I decided to finally 
 install
 the Harbach soft-start module in the amp (hey, its only been sitting in the
 project queue for a few yearsno sense in rushing).

 While I had it open did the normal maintenance stuff, lubed the fan etc.  I've
 had a problem now for a couple of months with the plate tuning cap turning
 action.  Somewhere between the 80m and 40m sections the turning action slows
 down to a standstill and you'd have to spin the knob several times to get it 
 to
 move VERY slowly thru its rotation.

 With the amp opened up I found that a little bit of pressure applied either 
 as a
 push or pull would get the cap to rotate at almost normal speed throughout its
 rotation.  Not wanting to screw something up I decided to leave it alone and
 check with the group.  It may just be that after 32 years the rotation 
 mechanism
 is just wearing out.

 Anyone else experience this?  If so any fixes?

 Thanks in advance!

 Dino KL0S

 BTW, the Harbach module works greatthe power supply board is built and 
 ready
 to install but think I've done enough for today!
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Re: [Drakelist] unstable R4C PTO

[Dennis Monticelli]

Zener diodes can develop an instability in their voltage knee value due to
migration of mobile charge at the surface of the semiconductor.  A random
walk of a few tens or hundreds of mV could produce your frequency problem.
Put a scope probe on the zener and set your scrope for high sensitivity.
See if you observe a jumpy voltage.

Dennis AE6C

On Mon, Aug 23, 2010 at 6:37 PM, pony...@aol.com wrote:

Hi Gang,

   Thanks for all the replies to my past message, but at this point in time,
 I'm even more dumbfounded than ever. So far I have cleaned, and oiled the
 mechanical parts, installed a ground strap on the PTO, resoldered all the
 ground wires inside. everything is free, and working as it should. Also, I
 drilled another hole in the cover to stretch that angled spring giving more
 tension.

   No avail, now I think it must be an electronic problem, as sometimes,
 when I try to tune a station, it warbles, sometimes while I am just
 listening hands off. vibration doesn't seem to change anything.
   Someone emailed me suggesting the zenner diode could be the culprit. I
 always thought most solid state devices either work, or don't work. Is it
 possible that's the problem, or could it be somewhere else outside the PTO?

Thanks for reading thisTom, WD8JPP

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Re: [Drakelist] Value of a Drake Rig

[Dennis Monticelli]

Amen.

Dennis AE6C

On Sun, Aug 1, 2010 at 3:45 PM, LEE BAHR pulsa...@embarqmail.com wrote:

 I know I am not alone when I say the value of Drake radios today has
 something to do with the great advice Garey Barrell always gives freely to
 many needing help with their Drake radios.  Garey's vast knowledge of these
 radio is a goldmine to all of us as has helped keep many of these fine
 radios working these many years after production.  His fine DVD photos made
 available have helped many of us when working on our Drake gear too.

 Day after day, I see Garey helping someone on here.   I just wanted you to
 know Garey, we notice and appreciate deeply all the help you have given to
 all of us.  I bet at some time or another you have helped most everyone on
 here with one problem or another.  I think I can say for many, nobody has
 given as much freely as you have to the group towards or beloved Drake gear.

 Lee, w0vt



 - Original Message - From: Garey Barrell k4...@mindspring.com
 To: drakelist@zerobeat.net
 Sent: Sunday, August 01, 2010 5:05 PM
 Subject: Re: [Drakelist] T/R relay source for a T4XC?

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Re: [Drakelist] cutting circuit board material.

[Dennis Monticelli]

My experience is that a bandsaw is best.  I have a small Black and Decker
table mount bandsaw with a fairly deep throat and the standard metal cutting
blade works well and is safe.  After cutting you can dress up the edge with
a hand file or sander.

Dennis AE6C

On Wed, Jul 28, 2010 at 9:39 AM, Steve Wedge w1es1...@earthlink.net wrote:

 This was foremost in my mind, and Evan has shown what were my suspicions
 all along: a tablesaw is not the best tool for the job.

 If you have access, a great tool for this application is a bandsaw with a
 fairly fine-toothed blade.  Alternatively, try a jigsaw but make sure you
 have the workpiece's cut line very close to a solid surface.  The
 better-quality jigsaws (like Bosch or Milwaukee) will do a better job
 because of the smoothness of the oscillating mechanism in the saw.

 FWIW,

 73,

 Steve, W1ES (a ham and a woodworker)

 Message: 2
 Date: Wed, 28 Jul 2010 10:36:06 -0400
 From: k9...@aol.com
 Subject: Re: [Drakelist] Phenolic and Drake Supplies
 To: jshor...@inebraska.com, Drakelist@zerobeat.net
 Message-ID: 8ccfc7958eb9474-1238-5...@webmail-m052.sysops.aol.com
 Content-Type: text/plain; charset=us-ascii
 
 Fellow Drake Enthusiasts,
 
 
 Thanks for all the emails with your comments.  Yes, it seems like window
 AC filter material might be a good choice for a fan filter.  Too, many
 surplus electronic houses sell the filter screen for various size fans.
 
 
 Did some experimenting and decided on a design change and process change
 as well.  I no longer will be using G10 or epoxy fiberglass PC board
 material; several reasons for that.  As far as cutting phenolic board with a
 table saw, my experiences were not favorable.  Yes, it is possible to cut
 that phenolic but the process is too demanding and unsafe for my taste.
  The phenolic has to be fed very slowly yet firmly into the table saw.
  Because of how brittle the phenolic is, the anti-kickback safety device
 basically doesn't grab, thus affording no protection.  If there is the
 slightest amount of binding, misfeeding with an ever so slight angle to the
 blade, etc. one or two things happen.  One, the phenolic will split to
 varying degrees, and two, one of the two pieces will go sailing in the
 direction of the operator.
 
 
 Hence, with a design change, I'm using angle aluminum stock and as for the
 phenolic, a hacksaw does a great job in just a few minutes with none of the
 problems cited above.
 
 
 When done, I'm going to document this project, possibly in one of the ham
 magazines, possibly online, etc.
 
 
 Enjoy those Drakes.
 
 
 73,
 
 
 Evan, K9SQG
 
 
 
 
 
 
 
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 *


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Re: [Drakelist] Fan on R4B and linears

[Dennis Monticelli]

I can endorse the Panasonic Panaflo series.  It is not only a quality fan,
it is relatively quiet.

Dennis AE6C

On Sat, Jul 17, 2010 at 7:55 AM, Jim Shorney jshor...@inebraska.com wrote:

 On Sat, 17 Jul 2010 09:16:50 -0500, Don Cunningham wrote:

 Evan,
 Would you share the make and model of the fans that work so well for you??
  Sounds like something I need to do here.


 Well, I'm not Evan, but I will share what I am doing with my L-4PS. The
 larger
 the fan, the slower (and quieter) it needs to run to move a certain amount
 of
 air. Or, the more volume it will move for a given speed.  I have a pair of
 ebm-papst 12 volt fans pulled from server computers, model 4412 F / 2M.
 They
 are about 4.75 inches (120mm) in size, and I run the two in series from a
 12
 volt power source, pulling air OUT on top of the PS. They seem to work very
 well, and I can't hear them running when I am sitting practically right on
 top
 of the PS. I have to check with my hand to feel the air to make sure they
 are
 running. They can be mounted as Evan describes, or some thin stick-on
 weather
 stripping material can be cut into small strips and affixed to the fans. I
 currently have mine just sitting there with nothing between the fan and the
 PS,
 they are so lightweight and made of plastic that they don't scuff.

 What is probably more important here than the type of fan is the quality.
 Avoid
 cheap sleeve-bearing PC fans like the plague, they will die on you.
 Guaranteed.
 The ebm-papst seem to be a decent product. Panasonic Panaflo fans are
 excellent, they seem to go forever. Be cautious of PC fans labeled as ball
 bearing, some of the small ones that I have taken apart have a ball
 bearing at
 one end of the impeller shaft, and a sleeve bearing at the other. I don't
 see
 this as an improvement. The new Sunon Maglev design looks interesting and
 seems to have better longevity, but they haven't been around long enough to
 make an accurate judgement.

 And remember to clean the blades once in a while, a little dust can reduce
 the
 airflow by a surprising amount.

 I'm sure Evan will have some great recommendations as well!

 73

 -Jim


 --
 Ham Radio NU0C
 Lincoln, Nebraska, U.S.S.A.
 TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A,
 GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time!

 Give a man a URL, and he will learn for an hour; teach him to Google, and
 he will learn for a lifetime.

 HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/
 http://radiojim.exofire.net
 http://incolor.inetnebr.com/jshorney
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Re: [Drakelist] Fan on R4B

[Dennis Monticelli]

I do the same thing with my R4B.  You'll find that even if you slow it down
significantly to allow it to run even quieter, the cooling effect is almost
the same.  A 5 fan moves a lot of air.

Dennis AE6C

On Fri, Jul 16, 2010 at 5:51 PM, Richard Knoppow 1oldle...@ix.netcom.comwrote:

Its too hot in Los Angeles so decided to try the fan I made up for my
 T4XB on the receiver. It works like a charm. The R4B tends to run hot
 anyway, I put the fan on top of the cabinet, over the power transformer,
 blowing out. It keeps the cabinet quite cool and even the transformer stays
 reasonably cool. This is about a 5 AC fan just connected to the line though
 a power cord switch. I will have to build another so I have one for each
 unit.
This fan makes very little noise. I wrapped some foam type weather
 stripping around the case so it sits on the foam. This both seals it to the
 cabinet and cushions any vibration.


 --
 Richard Knoppow
 Los Angeles
 WB6KBL
 dickb...@ix.netcom.com

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Re: [Drakelist] TR7 zener diode noise

[Dennis Monticelli]

Hi Garey,

I believe I can answer your questions adequately.

For a garden variety NPN pass reg (317, 340, 7800, etc) a long input lead
from the 'lytic would be 6, in which case you should stick a 0.1uF or
greater on the input. Modern linear regs are less tolerant of lead length
and may require a ceramic input bypass regardless because they have enough
bandwidth to get themselves into trouble with oscillations even with modest
input inductance from the lead.  For switching regs you should bypass right
at the pins with a substantial cap that has low ESR.  Read the datasheet
carefully regarding input and output caps (and inductors) for switching regs
as it's real easy to get into trouble with those varmints.

Regarding tantalums vs ceramics and 'lytics:  A tantalum is usually chosen
for small size at a given capacitance and better high freq performance.
Occasionally it is chosen for effective freezing temp operation (auto makers
love 'em).  I would not trust one all the way to 30MHz, however.  Even a 1uF
is probably inductive up there, but perhaps not reactive enough to be an
issue in most circuits.

In general, you can increase capacitance on the output of NPN regs without
upsetting the IC.  Keep in mind that both 'lytics and solid tantalums have
significant ESR that prevent the very low output Z of the reg from seeing a
pure reactance at the higher freq's where oscillation tends to occur, hence
these chips can handle just about any vitamin C you throw at them.  The
real question becomes at what point is it counterproductive for either cost
of low self-resonance reasons.  1uF seems reasonable, but I would have
preferred to see a 0.01 to 0.05uF ceramic in parallel in the Drake circuit.

BTW, early solid tantalums were not as reliable as the makers thought they
would be.  Quality test equipment circa early 70's from makers like HP and
Tek regularly failed from shorted tantalums later in life.  Modern tantalums
are much better and have built in fuses so when the fail they will fail open
vs shorted like the early generation.

Sure, I know about the 723.  My company built the improved version (mainly
lower noise).  What question(s) do you have?

Dennis AE6C


On Sun, Apr 25, 2010 at 2:40 PM, Garey Barrell k4...@mindspring.com wrote:

 Dennis -

 I KNEW we'd get someone who actually knew what they were talking about!
  :-)

 I hadn't ever heard about the lead length in the input side.  How long is
 long?  Does putting chip caps ON the regulator leads really buy you
 anything?  Certainly wouldn't hurt!?!

 I understood the role of the output cap, I thought, and believed that it
 shouldn't be TOO big, not so much because of inductance but to enable the
 regulator to regulate the output voltage for varying loads.  Fighting
 the cap is a good description!

 The Low Drop Out regs came along after I was out of engineering, so that is
 good information.

 The Fairchild data sheet I looked at for the LM78XX series showed a 0.33 uF
 on the output.  Drake seems to have used a 1 uF tantalum (solid) on ALL the
 ins and outs.  The tantalum cap should be ok for 3-30 MHz, but is that
 TOO much capacitance.  My experience says that a 0.33 disc ceramic would be
 less expensive than the tantalums, so I would assume that Drake thought it
 would be better.

 Are you familiar with the 723 at all?


 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 4-B, C-Line  TR-4/C Service Supplement CDs
 www.k4oah.com


 Dennis Monticelli wrote:

 My company makes IC voltage regulators.  Let me pass along some
 information.

 The purpose of the bypass caps for a conventional NPN pass regulator
 (317, 340, 7800, etc) s as follows. The input cap is to prevent possible
 oscillations if the lead from the IC to the raw DC filter cap is on the long
 side.  It is just insurance.  The output cap is to improve the transient
 load regulation.  IC regs use a feedback loop to steady the output, however,
 the bandwidth of the loop is finite.  The output cap takes over for the loop
 beyond a certain frequency so as to maintain good transient regulation.

 A PNP pass regulator (a.k.a. a Low Drop Output regulator) uses the input
 cap for the same purpose as the NPN types.  But it's output cap is not only
 there for transient load regulation, it is usually mandatory for obtaining
 loop stability.  Because of this special role, you must pay careful
 attention to it's value and dielectric type as recommended in the datasheet.

 You generally do not bypass a regulator output to decrease internally
 generated noise because the output Z is so low that it will fight the cap.
  Sometimes an IC reg will give you a pin to bypass the internal voltage
 reference portion of the chip.  But this is not common and optional to do
 anyway.

 The presence of the input and output caps can help in keeping RF out of
 the chip's internal circuitry.  If you're worried about that use a small
 value ceramic.

 Dennis AE6C


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Re: [Drakelist] TR7 zener diode noise

[Dennis Monticelli]

My company makes IC voltage regulators.  Let me pass along some information.

The purpose of the bypass caps for a conventional NPN pass regulator (317,
340, 7800, etc) s as follows. The input cap is to prevent possible
oscillations if the lead from the IC to the raw DC filter cap is on the long
side.  It is just insurance.  The output cap is to improve the transient
load regulation.  IC regs use a feedback loop to steady the output, however,
the bandwidth of the loop is finite.  The output cap takes over for the loop
beyond a certain frequency so as to maintain good transient regulation.

A PNP pass regulator (a.k.a. a Low Drop Output regulator) uses the input cap
for the same purpose as the NPN types.  But it's output cap is not only
there for transient load regulation, it is usually mandatory for obtaining
loop stability.  Because of this special role, you must pay careful
attention to it's value and dielectric type as recommended in the datasheet.

You generally do not bypass a regulator output to decrease internally
generated noise because the output Z is so low that it will fight the cap.
Sometimes an IC reg will give you a pin to bypass the internal voltage
reference portion of the chip.  But this is not common and optional to do
anyway.

The presence of the input and output caps can help in keeping RF out of the
chip's internal circuitry.  If you're worried about that use a small value
ceramic.

Dennis AE6C

On Sat, Apr 24, 2010 at 12:26 PM, Jim Shorney jshor...@inebraska.comwrote:

 Hi Gary,

 The concern here is RF bypassing. Not to keep RF out of the device, but to
 keep
 RF from GETTING out of the device. Which means smaller value ceramic
 capacitors
 in addition to any electrolytics used. Diode junctions can produce wideband
 RF
 noise that could theoretically impact receiver performance. If you look at
 the
 manufacturer data sheets for the 3-terminal devices, they recommend low
 value
 bypass caps on both input and output, as physically close to the device as
 possible. I figger that on the device legs is pretty close... This is the
 logic
 behind bypassing the Zeners. There's a repro of the QST note that the OP
 referenced on the Drake Museum web site.

 Otherwise, I saw an LM-317 based home built supply years ago that the
 builder
 had failed to include the manufacturer's recommended bypass caps in. It was
 very spikey, going from TX to RX on a 5 watt transciever caused the lamps
 in
 the radio to get real bright for a second. Installing one critical cap
 fixed
 that. Ever since then, I've been almost evangelical about following the
 data
 sheet recommendations for bypass capacitors.

 73

 -Jim


 On Sat, 24 Apr 2010 09:22:15 -0400, Garey Barrell wrote:

 Ron  Jim -
 
 Maybe I'm missing something, but according to the documentation I have,
 all of the regulators and Zeners seem to have input and output bypass
 capacitors.
 
 Bypassing multiple pins of a 723 might be counterproductive, actually
 degrading noise reduction on the output.  There is fast, high gain
 amplification going on in there!  This is still one of the best
 regulators around.
 
 Most caps seem to be larger than datasheet values, but based on other
 Drake gear I assume they are tantalum and so work as well as lower value
 caps at the higher frequencies.
 
 I don't have any numbers, but I suspect that a 1 uF tantalum is just as
 good (low dissipation and inductance) as a multilayer ceramic.
 
 I haven't worked on a lot of TR-7s, usually find that reseating the
 cards fixes them!  :-)  Perhaps early units didn't have these caps?
 Doesn't seem likely.
 
 Certainly added caps wouldn't make things worse, with the possible
 exception of the 723 Christmas tree, but I question the value.
 
 73, Garey - K4OAH
 Glen Allen, VA
 
 Drake 2-B, 4-B, C-Line  TR-4/C Service Supplement CDs
 www.k4oah.com
 
 
 Jim Shorney wrote:
  I did do some of the Zener bypassing, but did not measure the results.
 It
  didn't make things any worse, I will say that, and I have pretty good
 MDS
  numbers on my 7. In addition, I also bypassed the 3-terminal regulator
 ICs to
  manufacturer's spec with some surface mount caps on the legs of the IC
 right
  next to the body. Again, no measurements, but it didn't hurt, and I've
 learned
  over the years that they tell you to put those caps there for some very
 good
  reasons.
 
  I did find it interesting that all of the TR-7s that I have worked on so
 far
  have had the IF gain control maxed out already anyway, in some cases
 apparently
  by the good folks at factory service.
 
  73
 
  -Jim
 
  On Fri, 23 Apr 2010 17:30:55 -0700 (PDT), Ron wrote:
 
 
  Has anyone actually done and measured the results of bypassing the
 zener diodes and regulator chips as discussed on QST Feb 1989?  The author
 had anecdotal data only.  Was just wondering if there was any instrument
 measured data floating around out there.  Not really planning on doing this,
 just more of a curiosity.
 
  73,
  Ron WD8SBB
 
 
 
 

Re: [Drakelist] 2-C loud buzz

[Dennis Monticelli]

Perhaps the transformer screws are loose and when you turn it upside down
the chassis no longer vibrates in sympathy with the transformer.

Dennis AE6C

On Wed, Apr 14, 2010 at 3:49 PM, Garey Barrell k4...@mindspring.com wrote:

 Probably a bad solder joint on the filter cap.

 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 4-B, C-Line  TR-4/C Service Supplement CDs
 www.k4oah.com



 Charles Ring wrote:

 My 2-C, which I bought new in 1968, suddenly developed a very loud buzz
 which is there, unchanging, no matter what position any controls are in.
 Suspecting the main filter cap, I took the bottom cover off and turned the
 receiver upside down, turned it on and the buzz was gone. I could not
 provoke it to come back. So I reassembled it and it worked fine for a few
 days, but now the loud buzz is back. I'd expect a bad electrolytic to stay
 bad. Is there a known cause for this behaviour? I have the manual with
 schematic.

 73 de W3NU




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Re: [Drakelist] L7 problems on 160

[Dennis Monticelli]

I have an L7 run on 120VAC and have used it on 160M many times.  I only
drive it with about 50W and it gives me about 450W out, same as the other
bands.  Never had an issue and the fan doesn't even come on at that power
level.  I have never run it at higher power because I don't have 220V in the
shack.  The tubes are very old and predate my ownership by a great deal.

On Tue, Mar 16, 2010 at 3:41 PM, k9...@aol.com wrote:


 Fellow enthusiasts,

  Wonder if anybody has had bad experiences with the Drake L7 on 160
 meters.  I'm checking one out for a local ham that needs some assistance and
 have found some strange things, some, but not likely all.  The amp seems to
 have been, how do we say it, worked on.  Everything seems to be ok except
 on 160 meters.  Original tubes in the amp were soft, so I put in a known set
 that were good, and that didn't change things in terms of the problem on
 160.

  Here is the test setup.  Using a dummy load with 1:1 SWR.  Power supply
 is fine.  No parasitics observed.  Driving with a TR-7 (tests at 50 and 100
 watts).   SWR to the input of the amp is less than 1.2:1 so the input coil
 is reasonably well adjusted. Power out is only 500-600 watts DC on a
 calibrated wattmeter.  Other bands, like 80 and 40, produce closer to 900
 watts DC output.  Typically the power goes down as you go higher in
 frequency, which happens here on 80-15 meters, but 160 is way down.

  Has anybody experienced anything like this with their L7?  Inquiring
 minds want to know.

  73,

  Evan, K9SQG

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Re: [Drakelist] Deoxit debroke it.

[Dennis Monticelli]

Hard to imagine DeOxit causing the problem as you used it sparingly (vs
flooding the wafer and possible inducing swelling).  Did you exercise the
rig immediately after applying the DeOxit?  It is somewhat conductive until
dry.

Dennis AE6C

On Tue, Mar 2, 2010 at 2:34 PM, HaloNet halo@verizon.net wrote:

 Just tried some Deoxit for the first time after hearing so much about it
 here on the list.. afterwards, however, I wondered if I might have missed
 some pithy warning not to use it on Drake rotary switches?

 My T-4XB  R-4B had been working OK before I cleaned a couple of the rotary
 switches on the transmitter with a tiny bit of Deoxit per directions but
 when I fired it up again, the receiver won't mute... strange because the
 only thing done to the setup was the Deoxit on the T-4XB and I'm certain I
 didn't poke around hard enough to lift or dislodge any prongs on the switch
 so I'm baffled on this one.

 None was used on the relay and it closes OK on tune  the mute cable checks
 out and so I'm wondering if the Deoxit might have damaged a contact on the
 switches?

 Has anyone else had problems after Deoxit?  Comments would be appreciated.

 Thanks,

 Doc




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Re: [Drakelist] Possible problem with T-4XC xmtr

[Dennis Monticelli]

Howard,

Hmmm.  Give the loud pop and subsequent drop of output power, I'm wondering
if you had a brief  internal arc within one of your final tubes. A violent
arc that involves the cathode could easily destroy a region of the cathode
coating and thus reduce peak emission, yet allow the tube to continue to
operate.

But maybe you lost one of the tubes completely?  Is your resting plate
current normal?

Dennis AE6C



On Sun, Feb 21, 2010 at 3:58 PM, Howard Traxler htraxl...@earthlink.netwrote:

  Hi all, don't know that this question went out on the list:

 Friday I was tuning up my T-4XC on 80M.  Heard a very loud POP came from
 somewhere behind the front panel.  No smell of smoke or oazone.

 Never tune for more than 4 or 5 seconds at a time and never off-resonance
 more than 1 or 2 seconds.  Before this incident, the xmtr tuned up to 120
 to
 140 watts (according to my TW-1 talking watt meter); after, it now peaks at

 about 80W.  I had a QSO afterwords, so I know it's working some.  Antenna
 match is about 1.3/1.

 Do you think I did something real bad or maybe it's just a tube or a plate
 choke or something?  Where should I start to diagnose?

 Thanks, anybody.

 73, Howard, WA9RYF

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Re: [Drakelist] desolding tool

[Dennis Monticelli]

I have the Hakko and it works very well for PCBs.  There is maintenance,
however.  You do have to go through a cleaning process.

For chassis work, a good spring loaded pump works just fine.

Dennis AE6C

On Thu, Feb 11, 2010 at 10:55 AM, Jim Wagner bjwag...@bresnan.net wrote:

  I have been looking for a good desoldering unit that works. I have looked
 at Hakko and Xytronics. Looking for options of what is a good solution.
 Thanks to all who respond.

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Re: [Drakelist] RF Signal Generator

[Dennis Monticelli]

I can second the HP 606 suggestion.  That has been my primary generator for
over 20 years.  I will only add reliable, clean output and zero leakage to
Garey's comments.  If you can handle the bulk, it's a great value.

Dennis AE6C

On Tue, Feb 9, 2010 at 11:55 AM, Garey Barrell k4...@mindspring.com wrote:

 James -

 Depending upon what you intend to do with it, the price can vary from next
 to nothing, to infinity.

 That said, if you are interested in using on Drake gear, the most useful
 generator (aside from the Calibrator built into most receivers) is one of
 the XG generators from Elecraft.  The XG-2 is a 'tri-band (80 / 40 / 20)
 calibrated source with 1 uV and 50 uV outputs.  These are the two
 most-needed levels, 1 uV for Noise Figure or MDS testing, and 50 uV for
 calibrating S-Meters to S-9.  This is the generator that I use most often,
 if for no other reason than it is about the size of two thumb drives and
 runs off a coin cell.

 For general coverage, a Heathkit IG-42 or similar will give you a decent 50
 kHz to 30 MHz generator.  An external attenuator, commercial or homebrew can
 convert it to a calibrated source.  About $40

 My favorite is an HP 606A/B which covers 50 kHz to 65 MHz, is stable, has a
 beautiful attenuator and is well calibrated.  It's BIG, 10 high, 19 wide
 rack panel with cabinet to match.  Typically sells for $100 and up.

 The HP 8640B is a good generator, goes to 512 MHz I think, 1024 with an
 optional doubler.  It's only 5.5 rack panel, but weighs about as much as
 the 606!  It does have a weak point in the internal gearing, (plastic,) that
 is happening often now.  So watch EBay type sales.  There have been talks
 about making a replacement gear, but 

 Beyond this you are getting into newer stuff, from the cheap stuff from
 China that's not as good as the Heathkit, up to the megabuck units current
 with HP.  There are a couple of HP units that sell in the $200-300 range
 that are smaller and lighter and show up on EBay, etc.

 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 4-B, C-Line  TR-4/C Service Supplement CDs
 www.k4oah.com



 James Bridgers wrote:

 I would like to have a rf signal generator for my use.  Any suggestions as
 what to look for?

 Thanks in advance for your help




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Re: [Drakelist] AC4 Power Supply Modification

[Dennis Monticelli]

I can vouch for Mike's suggestion to series contacts.  I used a DPDT with
series contacts to create a HV SPDT and it worked well.


Dennis AE6C

On Thu, Dec 10, 2009 at 1:02 PM, Al Parker anc...@ec.rr.com wrote:

 Hih Steve,
   Mike had a good suggestion, here's another possibility that you could try
 with what you've already got installed --   Put a bypass cap across the HV
 relay terminals, maybe a hefty one of 0.1 (@1kv or more), with a resistor in
 series with it (the cap), maybe 25 to 100 ohms.  It depends a bit on the
 inductance that's in the HV ckt, you might have to try a few values.
  Swamping the spike upon opening is the objective.
 73
 Al, W8UT
 New Bern, NC
 www.boatanchors.org
 www.hammalund.info

 - Original Message - From: Steve Berg wa9...@tbc.net
 To: Mail List - Drake Gear Drake Gear drakelist@zerobeat.net
 Sent: Thursday, December 10, 2009 1:17 PM
 Subject: Re: [Drakelist] AC4 Power Supply Modification




 I may have asked this her before, but I thought I would post it anyway.
 One of the oldest radios in my modest collection is a Gonset G-76
 transceiver.  I bought it used from AES in 1965, but was too poor as a
 starving high school student to afford the companion power supply, so I
 cobbled one together in breadboard fashion, and used it for years.  But, the
 voltages were never quite right.  Now, Gonset power supplies are virtually
 unobtainable, but I noted that the Drake power supplies had the right
 voltages for my relic and bought one.  I plan to get the Heathkit Shoppe
 update for it.  But, here is my dilemma.  The G-76 requires that the power
 supply disconnect the 650 volt DC line from the rig during receive, and
 ground the line going to the radio.  I used to use a surplus ceramic 12 volt
 relay to do this, but that one has vanished somewhere in the past 40+ years.
  I have tried to use normal power relays, but their contacts are seemingly
 set up for breaking lower voltage DC, or are self quenching when breaking
 AC.  I have had some rather spectacular arcs in a few relays when trying to
 use them for this application.  Where might I find a 12 volt AC coil power
 relay that will reliably open a 650 volt DC circuit, and ground the far side
 that is going to the radio?  Normally this would be a simple SPDT relay.

 Also, I want to make any modifications as reversible as possible as I do
 not want to modify it so much that it would not be usable with a Drake rig
 in the future.

 Help?

 Steve WA9JML

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Re: [Drakelist] L7 PS Winter Project

[Dennis Monticelli]

Definitely do the bleeders too. I would also consider laying a slow turning
fan on the top to assist in drawing out the hot air.  I just place four
little rubber bumpers on a 4 fan (so it doesn't scoot) and run it at about
half voltage.  Heat buildup is your enemy.

Dennis AE6C

On Thu, Oct 1, 2009 at 8:51 PM, Richard Radke rar...@excite.com wrote:

 Brian,

 I've done Mike's (The Heathkit Shop) rebuild.  1st rate, clear
 instructions, pretty simple.  Replaces most everything but the 50K bleeders
 and the bias resistor.  Jeff at Harbach has those available.  I'd do those
 also.

 Rick
 W9WS




 On Oct 1, 2009, at 8:41 PM, bjon...@mindspring.com wrote:

  I picked up a L7 from ebay.  The amp itself looks to be in excellent
 condition but the power supply is a different story.  It looks like someone
 started to take it apart to rebuild the boards but they only got as far as
 removing one of the boards.  Before I try to rebuild the existing boards (I
 think I have most of the parts to do it) should I just go ahead and get one
 of the replacement/upgrade single boards? Along those lines can anyone
 suggest either the board from The Heathkit Shop or Harbach?

 Since the power supply has already been partially dismantled is there
 anything I need to watch out for when rebuilding it (either with the
 existing boards or the upgrade board)?

 Lastly... does anyone know what kind of screws were used on the case for
 the PS?  This one is missing all of the screws.



 Thanks
 Brian
 KD4UYP



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[Drakelist] experience with TR-7 CW filter

[Dennis Monticelli]

I am considering buying a 300Hz filter for the TR7 and wonder if any of you
guys out there have experience with that narrow filter.  Does it ring
excessively or have excessive insertion loss?  Also, would you recommend an
new InRad filter rather than a used Drake original filter?

Dennis  AE6C
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[Drakelist] Looking for TR-7 CW filter

[Dennis Monticelli]

Anybody out there have a 7-Line CW filter they would be willing to part
with?
Please contact off list with price and condition.
Thanks

Denny AE6C
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Re: [Drakelist] equivalent transistor for drake 2-C

[Dennis Monticelli]

Good input, Joe. Now we know that the NTE device is safe. That probably
means the Drake circuit used some explicit frequency compensation and didn't
rely on the slow power transistor for stability.

Dennis AE6C

On Fri, Jul 10, 2009 at 10:49 PM, Joe Pyles epy...@indy.rr.com wrote:

  I've replaced the audio output device in a couple of 2C's with the NTE175
 and had NO oscillation problems.

 73, Joe Pyles KC9LAD


 At 11:35 PM 7/10/2009, you wrote:

 I do NOT recommend the NTE175.  It is high speed high voltage switching
 transistor.  Because it is a double-diffused device about 50 times faster
 than the original part, the circuit may oscillate.

 Dennis AE6C

 On Fri, Jul 10, 2009 at 3:57 AM, Joe Pyles epy...@indy.rr.com wrote:

  NTE175 is listed as replacement.

 73, Joe Pyles KC9LAD


 At 09:27 AM 7/8/2009, you wrote:

 Hi folks,

 I am in the need to change the output audio transistor 40310 in my
 drake 2-C. Is there a modern equivalent of the 40310 so I can easily
 replace it?

 73,

 iz2oos

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Re: [Drakelist] Need some R-4A help:

[Dennis Monticelli]

Replacing a bad cathode bypass capacitor with a fresh one will increase hum
because the low freq gain will be improved along with better bass response.
But you shouldn't have hum in the speaker anyway (only some residual hum in
headphones at low volume) if the audio stage and B+ feed is operating
correctly.

I refurbished an R4A with like-value fresh lytics and this took the ripple
on the B+ down to 0.3Vpp.  What do you measure?  On an early R4B I did the
same only I doubled the value of the first B+ filter cap and this halved the
ripple.  Some say that extra capacitance increases thermal stress on the
power transformer, but I think the effect is minimal.  I routinely run a
small fan over the PS area anyway.

That particular R4B was mis-wired at the factory.  It was probably a
one-of-a-kind error but you might check yours anyway because the wiring
error greatly increases hum.  They had wired the audio power transformer B+
lead to the first filter cap instead of the second one.  So the second stage
filter was doing nothing for that audio stage.

Dennis AE6C

2009/7/8 Tom NØJMY n0...@hayseedhamfest.com

 I am trying to help another Drake fan, but need some of you fellows
 experteeism:

 He has hum in his early R-4A including with the AF gain turned to minimum.
  He replaced the can-cap in it (this one is the 3-section version, all 100
 mfd) and the hum dropped dramatically.

 Apparently there was still some hum left so he installed the rest of the
 kit, which replaces the two 8 uF units (C-91 and C-156) and the 10 uF
 cathode bypass on the audio output.  The hum got worse!  It's not as bad as
 when he started, but it definitely got worse.

 He also says, I have checked the schematics several times and I'm sure I
 have these in correctly.  One actually has the + end wired to the ground,
 but that is the way the schematic shows.  I think he is referring to C-91
 which has it's positive lead going to the ground pin on the accessory
 socket.

 So...what do you think?

 73,
 Tom NØJMY
 Hayseed Hamfest Co.  .   .

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Re: [Drakelist] equivalent transistor for drake 2-C

[Dennis Monticelli]

The RCA 40310 is a 4A 35V device designed for wide safe operating area up to
29W in audio applications.  It's very low cutoff freq of 750KHz strongly
suggests epitaxial base construction which is hard to find today.  The Drake
application is being gentle on the device, so you can probably get away with
modern substitutes but be careful of putting too much freq response in there
because the circuit may oscillate.  Although any number of modern
transistors would probably work, it's not easy to find modern transistors in
TO-66 packages.

The suggestion of a 2N3054 is a good one as that is a cousin of the common
2N3055 which ORIGINALLY had epi base construction.  Unfortunately the modern
manufactured versions are sometimes double diffused base and thus much, much
faster.  Your options are finding a NOS 2N3054 with an older date code or
the modern version made by Central Semiconductor (that manufacturer clearly
states epi base).

Dennis AE6C


On Wed, Jul 8, 2009 at 6:27 AM, iz oos izo...@gmail.com wrote:

 Hi folks,

 I am in the need to change the output audio transistor 40310 in my
 drake 2-C. Is there a modern equivalent of the 40310 so I can easily
 replace it?

 73,

 iz2oos

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Re: [Drakelist] new R4B member of the family

[Dennis Monticelli]

There should not be the sensitivity difference you are experiencing.  My
guess is that the 4A could use an alignment.  If you haven't actually tested
the tubes or done a few swaps, you might try that too.

BTW, congrats on the 4B.  That is the only Drake I have and I am similarly
very pleased with it.

Dennis AE6C

On Fri, Apr 17, 2009 at 6:13 PM, Chuck Grandgent ch...@chuckg.com wrote:

 Well the purpose of this post is twofold:

 First, despite periodic negative reports about the eB** place, I wanted to
 report my just received acquisition of a very nice R4B.  Decent price,
 decent shipping charge, very well packed, nicely bound copy of the R4B
 manual plus misc other relevant R4x articles, received approx three days
 from the end of the bidding (USPS Priority). I don't recognize the call from
 being on this list, so I won't identify unless there's a reason to.  In
 short, I couldn't be more pleased.

 The second reason for the post is about my R4A, and the diff between it and
 he R4B.
 I have to say, I have been happy with the R4A over the appro 10 years I
 have owned it.  I have had to do a fair amount of work on it in the AGC
 section, but I have done lots of great QSO's with it.  And to be fair, it
 lives in my garage, here in No. Florida, and what with the heat, humidity,
 and insects, it has not had an easy life.

 Anyway, my first impressioin on powering up the R4B is, that it is SO MUCH
 MORE SENSITIVE than my R4A, including the S-meter response.  Nevermind that
 the switches seem a lot cleaner, the tuning knob spins easier, etc..

 So anyway, I wanted to ask, where would you first begin to look in the R4A
 to account for the difference in sensitivity between it and the R4B I just
 got ?  I have checked all tube pin voltages, and they do agree closely with
 what they should be, and I believe the tubes are OK.

Chuck, K1OM, Alachua, FL


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Re: [Drakelist] Voltage Reulator in R-4a Question

[Dennis Monticelli]

I had the same behavior in my early serial R4-B.  It's quite a light show in
a darkened room.   The cause is definitely a bad VR tube in which there has
been air ingress.  Just stick another tube in there.

Dennis AE6C

On Mon, Mar 16, 2009 at 7:24 PM, Garey Barrell k4...@mindspring.com wrote:

 Well, it's obvious that the original configuration is obsolete and needs
 to be replaced by a piece of silicon!!   :-)

 Actually the flashing in VR tubes is often seen with leakage of air past
 the pin seals.  I have had several NOS tubes that have exhibited this
 behavior.  You may need to try more than one or two to find a good one.
  Cold  ambient temps cause momentary flashes at startup, as does high
 voltage from those pesky solid-state rectifiers that apply HV before the
  tubes warm up enough to pull the B+ down from the peak value.   But
 generally it's air..Guess these would be airy tubes, as opposed to
 gassy tubes.  :-)

 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 4-B, C-Line  TR-4/C Service Supplement CDs
 www.k4oah.com




 Curt Nixon wrote:

 Good Afternoon All:

 Here is something I have been seeing now for a while.  In my R-4a, every
 cold start in the morning, the OB2 flickers and glows VERY bright.  From
 an angle, it looks like there are flames on the inside of the rcvr.  I
 almost spilled my coffe all over trying to get back to the switch the
 first time I saw this.

 It will go on for quite some time and eventually die down to the normal
 red glow.  If I cycle the power a couplle of times, it will usually stop
 and show a normal glow on the second or third restart.

 I originally thought it was because of relatively low morning temps in
 the shack..about 55 degrees, but it seems there is really no corelation
 to temperature--occasionally after running for 6-10 hours, it will just
 start the really bright flickering.

 I have replaced the OB2 and checked all components and voltages around
 this area and they are all proper.

 The radio has been re-capped and all PS voltages are nominal.

 There is no detectable noise or other performance change while this is
 ocurring that I can tell but in 40 years of ownership, this has only
 been happening lately.

 Any Ideas??

 Thanks

 Curt
 KU8L


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Re: [Drakelist] R4C

[Dennis Monticelli]

Someone commented that how a seller deals with his customer when the
customer has a problem is very important.  I agree and RadioMart's feedback
over the years tell a clear story regarding problem resolution and respect
for an unhappy customer.  His motto seems to be that the customer is almost
always wrong and thus deserving of bad mouthing and retaliation in buyer
feedback (now a banned practice on eBay).  If you are in receipt of
equipment that is reasonably close to his exaggerated descriptions and it
arrives without shipping damage, then after-the-sale service is unimportant
and you are a satisfied customer. He has many of those types of customers.
Heaven help you if you have a serious issue with the equipment and have to
deal with this seller.  Now has he ever resolved problem successfully that
did not turn into negative feedback?  Yes, he no doubt has and it is harder
to discern those cases from the records.  But the many examples of
unsatisfactory problem resolution are there for all to see in his feedback
history.  For this reason alone, I have never bought from him and never
will.

Dennis AE6C

On Wed, Feb 25, 2009 at 3:15 AM, John Stringer johnastrin...@btinternet.com
 wrote:

 I have had only one transaction with Radiomart and it was perfectly
 successful.He offered a Drake RV7 in his usual glowing language. I asked a
 question which was promptly answered and then bid and won it.
 The RV7 was packed carefully and shipped quickly.
 On opening the box I found that the condition exceeded the glowing sales
 language and indeed it was just like new and worked beautifully.
 The R4C he now offers does look newer in the photographs than any I have
 seen,and certainly better than the two very excellent units I used to own.
 I have read of his bad transactions but think some are inevitable when
 reselling second hand equipment.I used to sell some locally in Northern
 Ireland about 30 years ago and was caught out a few times-usually with
 like
 new linears and ATU's with burned out switch contacts caused by hot
 switching.
 The important thing is that, when there are problems,things are put right
 with the customer promptly. That is just good business!  John GI3KDR

 -Original Message-
 From: drakelist-boun...@zerobeat.net
 [mailto:drakelist-boun...@zerobeat.net]on Behalf Of John
 Sent: 25 February 2009 00:15
 To: Richard J. Fiero II W5TFW; drakelist@zerobeat.net
 Subject: Re: [Drakelist] R4C


 You mean RadioMart(y)?

 ;-)

 John


 At 04:28 PM 02/24/2009, Richard J. Fiero II  W5TFW wrote:
 That SALESMAN,... ( no Names ) is at it again on e bay.  I cant
 believe, he is still getting people to buy from him !
 
Joey
 
 
 
   A.R.S. W5TFW
  Richard J. Fiero II
 
  www.w5tfw.com
  www.6mt.com
 
 
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Re: [Drakelist] Drake 2-B S-Meter Calibration/AVC

[Dennis Monticelli]

The minor changes to S-meter reading (transient or otherwise) as you
introduce or remove AVC path components (Fast vs Slow and BFO) don't
seem very revealing to me.  The slow drift in the S-meter over several
minutes is the revealing symptom.  This latter behavior could be
caused by a gassy tube whose grid is being fed from that very high
impedance AVC line as Garey has suggested or by the grid having become
contaminated and thus acting as a virtual cathode. So swapping out all
those gain-control tubes with a fresh tube one at a time would be a
good experiment.

Dennis AE6C

On Fri, Dec 26, 2008 at 3:26 AM,  py...@integral.com.br wrote:
 Garey and Dennis, thanks agian for the inputs.

 Regarding tubes, I have replaced those afected by AVC/1 and AVC/2. Nothing
 changed. Maybe I will need to try to redo this based on what Garey wrote. I
 will get special attention to the 6BA6 which is driven by AVC/1.

 These are some effects that I would like to line up and make sure you have
 the details

 - After 10-15 minutes Smeter goes to S1. If I turn the radio off and on it
 will do again, but journey is
 shorter. The S-meter will come from S4 to S1 in 5-6 minutes.
 - During the journey to S1, after start up,  if I am in Fast AVC and switch
 to Slow (introducing the 1uf capacitor), the S meter's needle deeps to the
 left and gets up again. I hear the RX background noise to pulse too. It
 does that once.
 - In any circusntance there is a slight S meter difference when I switch
 from SAVC to FastAVC and vice-versa. In SAVC it reads about half S unit
 more (to the right).
 - I have realized that when th BFO is on, the S-Meter moves a bit do the
 left.

 Normally I would answer to someone that would have posted something similar
 to it that the AVC discharge path is malfunctioning. I have checked the
 resistors in this path. I have also checked the time constant capacitor in
 the AV/2 and AV/1 circuits.

 I will have time to check spurios oscillation and/or grid leak whan I get
 back home. I will be away  until year's eve or so.

 Please send any ideas that are very much welcome.

 Best regards Fred



 On Fri, 26 Dec 2008 04:19:24 -0200, Garey Barrell k4...@mindspring.com
 wrote:
 Fred -

 I have been traveling and missed some of this thread.  Try subbing tubes
 in the AVC stages.  Often an IF tube will be gassy, and the grid will
 lose control after 5-20 minutes of warmup.  The 12BA6 is particularly
 susceptible to this problem, even in New Old Stock tubes.  You
 sometimes have to try three or four before finding a good one.   The
 AVC circuit is so hi-z that it takes very little grid current to upset
 it.

 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 4-B, C-Line  TR-4/C Service Supplement CDs
 www.k4oah.com



 py...@integral.com.br wrote:

 Dennis, merry xmas to you and yours, firts of all.



 Thanks for the input. I don not know if I my explanation was clear
 enough. The long S-meter journey to S1 just occurs after power the
 unit up and for 10 or so minutes. After that the behaivor is normal.
 Yes my first shot was a opened path to discharge the AVC circuitry.
 Unfortunately I have not found anything to blame. Did you consider
 that after the initial pb the behaivor seems to be normal ? Regards Fred


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Re: [Drakelist] t4x case type

[Dennis Monticelli]

A correction to my earlier post.  My early R4-B has the spattered not
the textured finish.  This is consistent with Garey's statement on the
crossover point from smooth to textured.

Dennis AE6C

On Thu, Dec 25, 2008 at 7:21 PM, Dennis Monticelli
dennis.montice...@gmail.com wrote:
 My early R4B is textured.

 On Thu, Dec 25, 2008 at 5:46 PM, Carey Lockhart kc5...@gmail.com wrote:
 well i think i will go with the smooth since thats what it is. i can always
 repaint later. my b line has textured paint but my older tr-4 does not.
 thanks for the help guys

 Carey Lockhart, KC5GTT
 kc5...@gmail.com
 www.kc5gtt.com
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Re: [Drakelist] t4x case type

[Dennis Monticelli]

My early R4B is textured.

On Thu, Dec 25, 2008 at 5:46 PM, Carey Lockhart kc5...@gmail.com wrote:
 well i think i will go with the smooth since thats what it is. i can always
 repaint later. my b line has textured paint but my older tr-4 does not.
 thanks for the help guys

 Carey Lockhart, KC5GTT
 kc5...@gmail.com
 www.kc5gtt.com
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Re: [Drakelist] Drake 2-B S-Meter Calibration/AVC

[Dennis Monticelli]

I have yet another wild idea.  I don't have a schematic in front of me
so I don't know if there is a buffer between the high Z node and the
AVC line that feeds the grids.  If there is no buffer, then perhaps
one of the gain controlled tubes has a grid emission problem that is
charging up the AVC line and overcoming the discharge resistor.

Dennis AE6C

On Thu, Dec 25, 2008 at 4:45 PM,  py...@integral.com.br wrote:
 Thanks Dennis. I will check that.

 On Thu, 25 Dec 2008 22:18:34 -0200, Dennis Monticelli
 dennis.montice...@gmail.com wrote:
 Well, there still may be a thermal effect.   It is hard to imagine a
 time constant of several minutes that is due to a capacitor, while a
 component or sub-assembly will undergo such time constants.  If you
 have some cold spray, you might try a short blast in specific areas to
 see if there is a dramatic change.

 As for what may be the root cause, I would check for evidence of a
 carrier bleed-through or spurious signal  or a possible weak
 oscillation that is getting through the IF chain and getting rectified
 by the AVC detector (in other words, masquerading as a real signal).

 Dennis

 On Thu, Dec 25, 2008 at 3:01 PM,  py...@integral.com.br wrote:
 Dennis, merry xmas to you and yours, firts of all.



 Thanks for the input. I don not know if I my explanation was clear
 enough.
 The long S-meter journey to S1 just occurs after power the unit up and
 for
 10 or so minutes. After that the behaivor is normal. Yes my first shot
 was a
 opened path to discharge the AVC circuitry. Unfortunately I have not
 found
 anything to blame. Did you consider that after the initial pb the
 behaivor
 seems to be normal ? Regards Fred



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Re: [Drakelist] [drakelist] Re: VA7TO 2-B: Lubricants?

[Dennis Monticelli]

DeOxit will clean the pot but not lube it.  After the DeOxit dries,
shoot it with CaiLube which will provide lubrication of the carbon
tracks and thus reduce future wear.  CaiLube can be used alone but it
doesn't contain as much de-oxidizing agent as DeOxit.  I find the
two-step approach works best.

Another grease you might consider is silver bearing conductive grease
(made by CircuitWorks).  This is most handy for capacitors where
excellent electrical contact through the bearings is required.  I find
it especially useful for variable caps in transmitters and tuners
where the circulating currents can get quite high.  It is rather
expensive but a little goes a long way.

Dennis AE6C

On Sun, Jul 27, 2008 at 10:08 AM, Grif [EMAIL PROTECTED] wrote:
 What was EPA's problem with Cramolin? I still have half of my little vial of
 Cramolin.

 Grif, KF4JG

 - Original Message -
 From: [EMAIL PROTECTED]
 To: drakelist@zerobeat.net
 Sent: Sunday, July 27, 2008 12:27 PM
 Subject: Re: [drakelist] Re: VA7TO 2-B: Lubricants?
 [EMAIL PROTECTED] made an utterance to the drakelist gang
 --

 Yes, Cramolin was the excellent one before DeOxit.  EPA had their way with
 Cramolin.


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Re: [drakelist] DMM recommendation

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I have both an old Fluke handheld DVM and a Simpson 260 (for doing
calibrations as people have noted).   The 20k/volt input Z is kinda
low by modern standards but many service manuals of the era call out
voltage readings with 20K/volt loading.  If you use a modern meter,
you may read a higher number than should be compared with the nodal
voltages.

On Wed, Jul 16, 2008 at 7:47 PM, Garey Barrell [EMAIL PROTECTED] wrote:
 Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 Alan -

 Several people have made the observation that nothing beats an analog meter
 for alignment, (peaking and dipping,) adjustments.

 You might want to keep your eyes open for one of the Heath VTVMs, some of
 which have huge meters. They are abundant at hamfests, easy to fix (as long
 as the meter movement or cover aren't damaged) and typically cheap!

 The Simpson 260 is an excellent meter, but unless you get one of the very
 latest models they are only 20,000 ohm / volt sensitivity.  This is usually
 not a problem, except when it comes time to measure a high impedance AVC
 circuit in a tube receiver.  Then the 11 Megohm input impedance of a Heath
 VTVM is handy!

 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 4-B, C-Line  TR-4/C Service Supplement CDs
 www.k4oah.com



 Alan Adelman wrote:

 Can anybody recommend a decent DMM for use in maintaining my boatanchors?
  Something with a fair sized display for my aging eyes would be great.  My
 ancient analog VOM doesn't cut it anymore.  I don't need laboratory
 accuracy, just a reliable instrument.



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Re: [drakelist] Vintage Unused R-4B on eBay

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
She means hasn't been used in over 20 years

On Mon, Jul 14, 2008 at 8:43 PM, Duane Calvin [EMAIL PROTECTED] wrote:
 I sent a message to the seller asking how it could be unused when it
 looked a lot more used than some of mine that I know have been heavily
 used.  Here is her response:



 Dear ac5aa,

 I was told the item had never been used. Yes it is old but its god.
 Tammi

 - nowthatsclever



 Wow – I'm not nearly as proud of my 100% rating on Ebay any more.



   73, Duane



 Duane Calvin, AC5AA

 Austin, Texas

 www.ac5aa.com



 

 From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
 Behalf Of [EMAIL PROTECTED]
 Sent: Monday, July 14, 2008 9:11 PM
 To: drakelist@zerobeat.net
 Subject: Re: [drakelist] Vintage Unused R-4B on eBay



 In a message dated 7/14/2008 4:06:45 PM Eastern Daylight Time, [EMAIL 
 PROTECTED]
 writes:


 http://cgi.ebay.com/RL-Drake-vintage-R-4-B-RECEIVER-unused-w-
 manual_W0QQitemZ260262834870QQihZ016QQcategoryZ50596QQssPageNameZWDVWQQr

 WOW, great rig... I just bid $9.00...
 I think I will go to $30.   just for parts
 73,
 Lee, KC9CDT


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Re: [drakelist] MN2000 balanced feeders

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I have a MN2700 and rather than search and pay excessively for the
rare Drake balun, I elected to use a Johnson Matchbox Jr as a balun
substitute.  The Matchbox makes a much better balun than a typical
core balun.  It handles a wider range of impedances and does so with
both ow loss and excellent feedline balance.  As another post noted,
you can play with feedline length to get an unbalanced tuner with
toroid balun to yield a low SWR and you can play the same game with a
Matchbox all by itself.  But by using the Matchbox together with the
unbalanced tuner makes life easier.  On those bands where the
impedance falls into a convenient range for the Matchbox alone, I run
the MN2700 straight through and use only its metering capabilities.
For the odd band or two where the Matchbox cannot bring the SWR all
the way down, I engage the MN2700 to reduce say a 2:1 or 1.5:1 down to
a 1:1.  The feedline balancing afforded by the Matchbox works just as
well when transforming the antenna Z down to say 100 ohms vs taking it
all the way down to 1:1.  The overall loss of the unbalanced tuner
plus Matchbox is lower than that of the unbalanced tuner plus toriod
balun because each component is working within an impedance range that
is close to design center vs the toriod balun working well outside its
design Z and the unbalanced tuner having to correct for a high
residual SWR that may well have a high reactive componet (ie. hi Q).
The match made with the tuner plus matchbox will usually be of lower
Q, which means broader bandwidth. They make a great combo and the
Matchbox costs less than the Drake balun.

Dennis AE6C

On Sun, Jun 1, 2008 at 6:06 AM,  [EMAIL PROTECTED] wrote:
 [EMAIL PROTECTED] made an utterance to the drakelist gang
 --

 Bill,

 Yes, the Drake B-1000 balun (which will cost half the price of the MN-2000)
 will enable use of balanced lines with the MN-2000.  However, whether it
 works
 well or not is yet to be determined.  Baluns are not designed to work over a
 large range of impedances and if the impedance presented at the terminals is
 too high/low, then there will be loss and heating.  But it often does work.

 73,

 Evan


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Re: [drakelist] antenna info

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I agree.  The black polyester double braided line with a monofilament
core is not only highly UV and decay resistant, it does not stretch.
I have nothing but good things to say about it.

Dennis AE6C

On Thu, Apr 3, 2008 at 2:31 AM, Ron Wagner [EMAIL PROTECTED] wrote:

  Ron Wagner [EMAIL PROTECTED] made an utterance to the drakelist gang
  --
  Polyester rope is a good choice (Dacron is a brand name of it).  Polyester
 will almost not decay unless exposed to chemical or flames.  Have had mine
 up for years and it is till going strong.
  73,
  Ron WD8SBB

  On Wed, 2 Apr 2008, Terrell Hamilton wrote:


 
  Terrell Hamilton [EMAIL PROTECTED] made an utterance to the drakelist
 gang
  --
  Parachute cord has worked extremely well for me - it's multistranded and
  braided as well.  I don't know if it is nylon or Dacron, but I think it
 may
  be UV resistant.
 
  Terry
  K7WLD
 

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Re: [drakelist] OA2 / OB2 failure modes

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Overload occurs after the entire cathode (inside of the cylinder) has
been lit. At this point the tube is saturated and any additional
current will cause the regulated voltage to significantly rise and
thus overheat the tube shortening its life.  But your tube had some
flicker.  Flicker is caused by small regions of negative resistance in
the current vs voltage curve (pips)that develop over time.  The
discharge jumps from one region to the other on the cathode, hence the
flicker.  I have seen this before and there are two solutions.  One,
change the current through the tube to a different level (higher of
lower) to get away from the negative resistance region.  Be sure to
stay within current ratings if you do this..  Two, just replace the
tube as you did. Flicker causes noise in a receiver and can give an
interesting light dance in a dark room.   I had this occur in my TO
Keyer.

I have also seen the flicker accompanied by a bright localized
discharge (just like you described); not to be confused with the
localized dull orange region of a tube operating just above minimum
current.  I don't know what causes that but I'm guessing gas has
intruded or been internally outgassed and that gas has contaminated
the pure existing gas causing the ionization path to become
concentrated (ie. bright).  I experienced this in my R4B, and let me
tell you, it was quite a light show.  It scared me enough to abruptly
kill the power thinking there was a tube that had developed an
internal short.  A new regulator tube fixed the problem.

So these simple regulator tubes are not so simple after all when it
comes to failure mechanisms.

Dennis AE6C


On Sat, Mar 29, 2008 at 2:58 PM, Chuck Grandgent
[EMAIL PROTECTED] wrote:

  Chuck Grandgent [EMAIL PROTECTED] made an utterance to the drakelist gang
  --
  I'd noticed my OB2 in my R4A starting to flash or flicker bright
  orange, maybe a little reddish tint.  First only at startup, then more
  and more.

  So I got a new OB2 and now have only a continuous orange glow from
  the base area, without any flickering.

  What precisely are the failure modes of these regulator tubes ?

Chuck, K1OM

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Re: [drakelist] Deoxit helps Jones connectors on a Swan 500cx,

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
You're probably right, Garey.  The thin Cd plating could well be gone
now.   Ammonium nitrate can attack Cd.  I am certainly no chemist
either and I don't know what was in that brass polish, but according
to a material book I have, intentional stripping of Cd from mild steel
or Cu involves KCIO3 with Hydrochloric acid, both at about 5%.

It is also possible for a cadmium-based corrosive layer to develop
slowly, build up thickness and in time become self passivated, leaving
a layer of pure Cd underneath.  It depends upon the nature of the
contaminants in the air and the humidity what type of film forms.

To stay on the safe side, I would just keep those pins well coated
with an anti-oxident.

Dennis AE6C


On Jan 6, 2008 3:01 PM, Garey Barrell [EMAIL PROTECTED] wrote:

 Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 Jim -

 The Jones connector pins are cadmium plated steel.

 I'm certainly no chemist, but I wonder if the ammonia, (present in most
 brass polishes,) is what got the cadmium.  It sounds like you may be
 down to bare steel, which might be a problem in future.

 Old steel chassis used to be cadmium plated, and would grow the same
 crud.  (Chemical term there.)   I think cadmium plating is now among
 the millions of things that have been around hundreds of years which
 have now been declared harmful to our health!  :-)

 73, Garey - K4OAH
 Glen Allen, VA





 Jim F. wrote:
  Jim F. [EMAIL PROTECTED] made an utterance to the drakelist gang
  --
  Results of my experiments:
 
  Tried 3 things to clean the battleship gray, tough as
  nails, oxidation from Jones plug pins that the 12VAC
  filament voltage could not even penetrate.
 
  1. Craig Deoxit (RS - very expensive) and didn't work
 
  2. Contact spray (RS) cleaner didn't work
 
  3. MWW Brass Chrome  metal polish worked.
 
  Got it from the supermarket. It is a gray paste
  that turns oxidation black when left on for a while
  and removes it in chunks with a Q-tip.
 
  The pins were so bad that I had to do it a
  couple of times then clean the residue with RS
  spray contact cleaner and Q-tips.
 
  It's much cheaper than buying and installing
  new 15 pin Jones connectors, if that mounting
  type are even available.
 
  Nice to see shiny metal coming through but don't
  know what to do about the plug receptacle.
 
  Does anyone have a cable mount 15 pin Jones
  receptacle for sale ?
 
  Without the shell is OK as I can use the old one.
 
  Regards,
 
  Jim / W1FMR
 
 


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Re: [drakelist] Deoxit helps Jones connectors on a Swan 500cx,

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Actually, ProGold is formulated for preserving contacts coated for
precious metal (like gold, platinum and silver).  But I suppose no
harm in keeping a coating on the pins and receptacles; it should keep
the air off the surface.  Go for it.

Dennis AE6C

On Jan 6, 2008 6:09 PM, Jim F. [EMAIL PROTECTED] wrote:

 Jim F. [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 Excellent !

 Nothing is simple is it ?

 The $15 RS miniature Deoxit can came with an equally
 diminutive can of Deoxit Gold which is supposed to
 coat electrical contacts. I better coat the Jones
 pins and not plan to take the radio to the beach :-)

 Actually, I don't intend to use the thing much because
 I'm a die hard CW QRPer. I'm retired and totally enjoy
 building, trouble shooting, and fixing radios, even
 more than s-x.

 Thanks guys..

 Jim / W1FMR   NH




 --- Dennis Monticelli [EMAIL PROTECTED]
 wrote:

 
  Dennis Monticelli [EMAIL PROTECTED]

  made an utterance to the drakelist gang
 
 --
  You're probably right, Garey.  The thin Cd plating
  could well be gone
  now.   Ammonium nitrate can attack Cd.  I am
  certainly no chemist
  either and I don't know what was in that brass
  polish, but according
  to a material book I have, intentional stripping of
  Cd from mild steel
  or Cu involves KCIO3 with Hydrochloric acid, both at
  about 5%.
 
  It is also possible for a cadmium-based corrosive
  layer to develop
  slowly, build up thickness and in time become self
  passivated, leaving
  a layer of pure Cd underneath.  It depends upon the
  nature of the
  contaminants in the air and the humidity what type
  of film forms.
 
  To stay on the safe side, I would just keep those
  pins well coated
  with an anti-oxident.
 
  Dennis AE6C
 
 
  On Jan 6, 2008 3:01 PM, Garey Barrell
  [EMAIL PROTECTED] wrote:
  
   Garey Barrell [EMAIL PROTECTED] made an
  utterance to the drakelist gang
  
 
 --
   Jim -
  
   The Jones connector pins are cadmium plated steel.
  
   I'm certainly no chemist, but I wonder if the
  ammonia, (present in most
   brass polishes,) is what got the cadmium.  It
  sounds like you may be
   down to bare steel, which might be a problem in
  future.
  
   Old steel chassis used to be cadmium plated, and
  would grow the same
   crud.  (Chemical term there.)   I think
  cadmium plating is now among
   the millions of things that have been around
  hundreds of years which
   have now been declared harmful to our health!  :-)
  
   73, Garey - K4OAH
   Glen Allen, VA
  
  
  
  
  
   Jim F. wrote:
Jim F. [EMAIL PROTECTED] made an utterance
  to the drakelist gang
   
 
 --
Results of my experiments:
   
Tried 3 things to clean the battleship gray,
  tough as
nails, oxidation from Jones plug pins that the
  12VAC
filament voltage could not even penetrate.
   
1. Craig Deoxit (RS - very expensive) and didn't
  work
   
2. Contact spray (RS) cleaner didn't work
   
3. MWW Brass Chrome  metal polish worked.
   
Got it from the supermarket. It is a gray paste
that turns oxidation black when left on for a
  while
and removes it in chunks with a Q-tip.
   
The pins were so bad that I had to do it a
couple of times then clean the residue with RS
spray contact cleaner and Q-tips.
   
It's much cheaper than buying and installing
new 15 pin Jones connectors, if that mounting
type are even available.
   
Nice to see shiny metal coming through but don't
know what to do about the plug receptacle.
   
Does anyone have a cable mount 15 pin Jones
receptacle for sale ?
   
Without the shell is OK as I can use the old
  one.
   
Regards,
   
Jim / W1FMR
   
   
  
  
  
 
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Re: [drakelist] Low pass filter?

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
No harm in leaving the LP filter in circuit.  Having said that, the
Drake tuners are indeed Pi configuration and do a good job of reducing
harmonics commensurate with the limitations of having only three
reactive elements involved in low passing.

Dennis

On Jan 3, 2008 1:03 PM,  [EMAIL PROTECTED] wrote:


 It is my understanding that a low pass filter is not necessary with T-4XB is
 used in conjunction with an MN-2000 trans-match because the MN-2000 utilizes
 a PI-circuit and this network basically serves as a low pass filter...is
 this correct?

 Thanks...Alan KB7MBI


 
 Start the year off right. Easy ways to stay in shape in the new year.

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Re: [drakelist] Low pass filter?

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Good point, Jim.  That's the best place for the LP filter all right.

On Jan 3, 2008 9:25 PM, Jim Shorney [EMAIL PROTECTED] wrote:

 Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 On Thu, 3 Jan 2008 20:55:17 -0800, Dennis Monticelli wrote:

 
 Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist 
 gang
 --
 No harm in leaving the LP filter in circuit.  Having said that, the
 Drake tuners are indeed Pi configuration and do a good job of reducing
 harmonics commensurate with the limitations of having only three
 reactive elements involved in low passing.


 It also bears mentioning that the filters work best into a 50 ohm load, and
 should be placed between the transmitter and the tuner.

 I swept one of the Drake filters at work not too long ago, and they do cut
 off rather sharply right above six meters. Very cool.


 73

 -Jim

 --
 Ham Radio NU0C
 TR7/RV7, TR6/RV6, T4XC/R4C, L4B, NCL2000, SB104A, R390A, GT550A/RV550A, 
 HyGain 3750, IBM PS/2 - all vintage, all the time!

 HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/



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Re: [drakelist] Need Soldering tips for Wen 75 soldering pistol

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I don't know, Jim, but I am also interested in a source for tips
because I have a Wen 75 as my backup iron.  You may have to find a
parts unit.

On Jan 1, 2008 9:52 PM, Jim Pruitt [EMAIL PROTECTED] wrote:

 Jim Pruitt [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 Since QTH lists do not seem to want to let me post this,  I wonder if anyone
 on this list can help me?

 Does anyone know of a source for soldering tips for a Wen model 75 soldering
 pistol?  It is a 75 watt gun?  I am in need of one (or more).  I know that
 Wen discontinued the gun (and I assume the tips too) several years ago.

 I am working on my R4B and my tip broke.  Now I find out that the tips do
 not seem to be available anywhere.

 Thank you.

 Jim Pruitt


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Re: [drakelist] Confessions of an Appliance Operator

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
That was a good idea to use surplus 24V fans on 12V.  Another trick
that works well is to put two identical fans in series and run them
off the voltage that normally powers one.  For example, two series 12V
fans run off 12V or two series 24V run off 24V.

Dennis AE6C

On Dec 24, 2007 8:25 AM, Eugene Balinski [EMAIL PROTECTED] wrote:

 Eugene Balinski [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 All,

One of the other solutions that is easy and quiet it to
 use a 24 volt DC fan and run it off of your station 12V DC
 supply.  These fans are usually cheap and are in generally
 in ample supply at local ham fests (at least here  in New
 England).  They come in many sizes.  As mentioned below,
 the larger ones are better for this application.

   Simply place the fan  on top of the finals, use a couple
 of plastic screw as off-set feet to avoid scratching the
 cabinet, wire it to 12VDC, and you are done.   Cool Finals.


 73, Merry Christmas and Happy New Year to all.
 Gene K1NR


 On Mon, 24 Dec 2007 01:55:53 -0800
  Dennis Monticelli [EMAIL PROTECTED] wrote:
 
  Dennis Monticelli [EMAIL PROTECTED] made an
  utterance to the drakelist gang
 
 --
  This is the same scheme that I use.  It is flexible,
  quiet, and
  completely non-invasive.  Also, I second the
  recommendation on the
  Panasonic Panaflo line.  They are clearly superior to the
  PC grade
  fans coming out of China.  Another tip: buy a larger fan
  and run it
  slower.  It will move the same amount of air as a small
  fan run at
  full speed yet make much less noise.  Also its reach is
  better so
  the warm air is drawn in over a wider area.
 
  Dennis AE6C
 
  On Dec 23, 2007 1:44 PM, john [EMAIL PROTECTED] wrote:
  
   john [EMAIL PROTECTED] made an utterance to the
  drakelist gang
  
 -
 Web mail provided by NuNet, Inc. The Premier National provider.
 http://www.nni.com/



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Re: [drakelist] Confessions of an Appliance Operator

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
This is the same scheme that I use.  It is flexible, quiet, and
completely non-invasive.  Also, I second the recommendation on the
Panasonic Panaflo line.  They are clearly superior to the PC grade
fans coming out of China.  Another tip: buy a larger fan and run it
slower.  It will move the same amount of air as a small fan run at
full speed yet make much less noise.  Also its reach is better so
the warm air is drawn in over a wider area.

Dennis AE6C

On Dec 23, 2007 1:44 PM, john [EMAIL PROTECTED] wrote:

 john [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 An option I use is a DC wall wart with selectable secondary voltage, so
 that you can move the fan (on rubber feet) from rig to rig, and adjust the
 fan speed with the voltage on the wall wart. They're less than ten
 bucks.  9V on a 12v fan is a happy medium.

 John K5MO


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Re: [drakelist] Vacuum Tube markings

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I clean the tube envelope with Windex and am careful to keep off the
markings.  Qtips can be used to increase precision. I then do a light
dry rub on the letters to take off loose surface dirt.  Works pretty
well.

Identifying worn markings can sometimes be accomplished by the hot
breath method.  Apparently the condensation is different between the
naked glass and the marked glass leading to some heightened contrast.

There are some tubes that rare ecognizable without markings, but most
of the unmarked tubes remain mystery tubes.

On Dec 5, 2007 12:39 PM, Donley [EMAIL PROTECTED] wrote:


 When restoring a tube type radio, the restoration looks better when the
 tubes are nice and shiny. But cleaning tubes is hazardous to tube
 identification. The markings usually come off easier than the dirt.

 What are recommended methods of cleaning tubes?

 Also, is there a method of reading the markings on tubes that have been
 smudged or with partially or totally removed markings? I seem to recall
 someone mentioning that the markings slightly etch the glass and there is a
 way to make the markings identifiable. Was I dreaming?

 If there is no way to identify an unmarked tube, what good is it?

 Dick
 KC9UB

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Re: [drakelist] Burning in New PA Tubes,

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I put a couple of NIB 6146B's in my TS-820 a few years ago.  These RCA
tubes were purchased new (fresh stock) some 20 years previous.   When
I applied HV and began the neutralization procedure I heard a brief
loud pop. The HV caps had been suddenly and momentarily discharged as
evidenced by the lamps doing a deep flicker.  The pop happened again
later that evening after I had put it back on the op table.  It did it
once more the next day and then nothing ever since.  I think either a
plate to cathode or plate to beam-ormer ionization trail was the
culprit.  Had I run the filaments for a few hours before application
of HV, the getter would have had an opportunity to scavenge the
out-gassing that had taken place over the 20 years of sitting.  Moral:
HV tubes should have their getters exercised before application of
plate.  I wouldn't bother with stair-stepping up the filament.  Just
let them bake for a few hours to give the getters an opportunity to
do their thing.  I wouldn't bother with receiving tubes.  It wouldn't
hurt them either.

Denny AE6C

On Dec 4, 2007 3:24 PM, DW Holtman [EMAIL PROTECTED] wrote:


 Hello,

 Just wondering on the thoughts of this group on the best way to burn in a
 new pair of 6BJ6's for a T-4B transmitter. Have heard several ideas in the
 past, ranging from applying filament voltage for a few days to increasing
 filament voltage 20% over for a short time.   Any good thoughts, and the
 reason behind them?

 Best,
 DW Holtman
 WB7SSN


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Re: [drakelist] UPay or ebay help

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
The key to understanding eBay feedback and how that may impact you is
to zero in on the negative feedback messages, which you can easily
track down by choosing 200 views per page and reading the red items.
 If you read the negatives on his seller, some things just jump out at
you.  He overstates condition. This creates most of the disputes.  He
has poor confliction resolutions skills, which exacerbates the
situation.  He invariably retaliates agains the buyer via his
badmouthing and giving them negative feedback in returnl.  I want
nothing to do with a seller like that.

Dennis AE6C

On 11/20/07, Howard Traxler [EMAIL PROTECTED] wrote:

 Howard Traxler [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 Could someone out there please give me a hand understanding this thing?
 Since you folks don't seem to like ebay, maybe someone could write off-list
 to
 [EMAIL PROTECTED]
 Thanks.

 I am watching a Drake AC-4 being sold by Radio Mart (whom you have mentioned
 before).  After his name, I see the number
 5909

 then it says
 Feedback score is 5,000 to 9,999)
 This would indicate to me that his rating is very low in that range.  But
 then it says
 Member is a PowerSeller
 Feedback:
 97.6% Positive

 'tseems to me that in a range (rough) of 5000 to 1, 6000 would be about
 20%.  but if they say 97%, ???

 I'm looking for an AC-4, so I would bid on this thing; but reading stuff
 here on the list makes me want to shy away a bit.

 Can somebody suggest what I should think?

 Thanks a whole lot.

 73, DE Howard, WA9RYF




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Re: [drakelist] New Subscriber

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Great summary, Garey.  It's worth re-posting every time a newcomer
asks a general question.

I have an early R4B I restored and think its just great.  It is in
daily use. For casual work, I find that the LC filters contribute
little to listening fatigue, unlike the tiring ringing of crystal
filters.  I have also had the opportunity to work on and listen to an
early R4A and thought it performed equally well.  The bipolar PTO
seems quite stable.  I don't think I miss having the JFETs in there.

Someday there will be a matched TX in the shack.

On 10/27/07, Garey Barrell [EMAIL PROTECTED] wrote:

 Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 Eddy -

 Welcome!  Always glad to have another one awaken to the great Drake
 equipment!  :-)

 Here is a little overview of the 2  4 Series that might help you.

 The 2-B is an outstanding CW receiver, the dial calibration is a little
 coarse by today's standards, but for just getting on the air and
 enjoying a CW QSO it works as well as any.  It has three (L-C) filter
 bandwidths, (500, 2100 and 3600 Hz,) built in along with passband
 tuning.  The 100 kHz crystal calibrator was optional.  The companion
 2-BQ Q Multiplier adds a very sharp peaking filter and a nice tunable
 null, both at the IF.

 There is no matching transmitter for the 2-B.

 The 2-C is similar, except the tubes end at the 2nd IF with all the rest
 being solid state.  Decent receiver but I don't think as good as the 2-B.

 On the plus side, the 2-NT matching transmitter is available, but is a
 Novice class, crystal controlled, CW only transmitter.  No provision
 for transceive and no VFO included.

 The R-4 is almost a 2-B, just with a linear PTO and 1 kHz dial
 calibration.  All tubes.  Very similar in operation, and will
 transceive with the matching T-4X for an excellent CW station.  Passband
 Tuner with four filter bandwidths, (400, 1200, 2400 and 4800 Hz,)
 passband tuning, noise blanker, LC notch and 100 kHz crystal calibrator
 built in.

 The R-4A (early 13 tube model) is an improved R-4, almost identical
 specifications.  PTO and Band Oscillators converted to solid state.

 The R-4A (late 11 tube model) almost identical specifications.  Product
 detector, BFO, AGC and low level audio stages converted to solid state.

 The R-4B (early) is very similar to the late R-4A, minor modifications
 and crystal calibrator multivibrator for 25 kHz markers.

 The R-4B (late) almost identical except PTO changed from bipolar to FET.

 The R-4C (early) very similar, except IF filters changed to crystal
 filters.  Only the 2.3 kHz filter is standard, 250, 500, 1800, 4000 and
 6000 Hz BW are available as options.  The 4000  6000 Hz filters are
 normally installed in a special socket under the chassis and are
 effective on AM only.  Four position filter switch.  The noise blanker
 was optional.  Entire audio chain solid state, tubes used only from RF
 to IF, all other stages and oscillators solid state.

 The R-4C (late) same.  Five position filter switch.

 The 2-B through the R-4B used L-C filters in the IF.  This type of
 filter has much gentler slopes, which means that nearby signals are
 still heard, just at reduced levels.   The crystal filters are steep
 sided, more like the crystal filters in today's receivers.
 Personally, I prefer the L-C filters for all except heavy duty contest
 use.  I like to hear what is going on around my frequency, instead of
 listening with blinders on...

 The T-4 series transmitters are all pretty much the same, the T-4X had 4
 pole crystal filters while the T-4XB and C had 8 pole filters.  The
 later ones therefore had slightly better carrier and unwanted sideband
 suppression, neither of which has ANY effect on CW operation.
 ANY 4 series receiver will transceive with ANY 4 series transmitter, mix
 and match.  There are minor things like the B line had a neon indicator
 light under the dial to show which PTO was controlling in transceive
 while the C line just turned the dial lamps on or off.  The R-4 and R-4A
 had neither, so you had to look at the switch!

 My opinion.  The R-4B is probably the best receiver overall.  It has
 great audio, smooth AGC, all the filters and noise blanker are built
 in.  The L-C filters are not quite as drop off the table selective,
 but I prefer that for casual QSOs.

 The R-4C has poorer audio, a little harsher, the better (?) crystal
 filters are extra, and the noise blanker is extra.

 The R-4 and R-4A are just earlier iterations of the R-4B, and are not
 quite as refined, although some say they prefer the early R-4A to the
 R-4B because the tube type product detector in the R-4A is cleaner.

 The 2-B isn't very far behind, except it will NOT transceive with
 anything, and the dial

Re: [drakelist] An Introduction a question about keyer for T-4XB

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Let me know how it turns out, Doug.

On 10/23/07, Doug Smith [EMAIL PROTECTED] wrote:

 Doug Smith [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 A brilliant set of mods!  Thanks -- I'm going to pursue these.
 I love that old keyer but that sawtooth wave really needs to go..

 73,
 -Doug, W7KF


 On Tue, 2007-10-23 at 22:13 -0700, Dennis Monticelli wrote:
  I dug out my schematic and it actually takes a few components.


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Re: [drakelist] L7 Capacitors Needed

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Another option is to use a transmitting ceramic capacitor of the
doorknob variety.  The smaller ones are typically rated at 5KV and
built to handle much higher current ripple than a typical bypass cap.
Their RF qualities are excellent.  I mention this because these small
doorknob caps are often found in junk boxes and at hamfests selling
for very reasonable prices.  There may be somebody on the net with
something in the 500 to 1000pF range or if you ask some friends a unit
may turn up.

If I were you I would replace both bypass caps with a single
transmitting cap in the 1000 to 5000pF range...basically whichever
value you find.  A single doorknob will probably outperform two
paralleled discs.  I noted in my L7 schematic that Drake also used two
in parallel to do plate blocking from the PA tubes to the output
network.  Clearly, Drake was shaving nickels buy using a single part
type multiple times to lower purchasing costs.  Two HV discs cost a
lot less than a single small doorknob anyway.

Dennis AE6C

On 10/23/07, Dino Papas [EMAIL PROTECTED] wrote:

 Dino Papas [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 A friend's L7 gave up the ghost mid-QSO with the self destruction of
 one of the two disc ceramic 760pF caps that bypass the HV line at the
 cold end of RFC5.  They're rated at 4KVanyone know of a good
 source for replacements?  Also obviously gotta discover what made one
 of the two fail.  RF Parts has some 0.0005 uf 10KV disks that may
 work in this application.  BTW, his L7PS is fine as tested with his
 L-4B after the L7 failure.

 Thanks much in advance!

 73 -- Dino KL0S/4

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Re: [drakelist] An Introduction a question about keyer for T-4XB

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I don't have a CMOS-4 so I cannot comment.  I have a Tick keyer that
just uses a single CMOS PIC controller and I find I can use it just
fine pretending it is non-iambic.

I agree with you regarding the memoryless TO keyer.  It is
unforgiving.  On the plus side it will teach you to send better code
:-)  It comes out of the closet at my QTH only during the vintage
contests.  I did do a simple mod to turn the raspy sidetone into a
nice sine wave.  It only took one additional component.

On 10/22/07, Doug Smith [EMAIL PROTECTED] wrote:

 Doug Smith [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 On Mon, 2007-10-22 at 23:36 -0400, Garey Barrell wrote:
  Personally I use the CMOS-4 from Idiom because it's one of the few
  that
  I can turn off that stupid iambic junk that will drive any bug user
  crazy!  :-)

 I didn't know that!  I had to drag out the manual and check it out.

 I used to be able to send good code with my W9TO keyer but bought a new
 Nye keyer in the mid-1980s along with a Bencher Iambic key.  I never
 learned how to use iambic mode and don't care about it.  However, I did
 become accustomed to the dot and dash memory and now I can hardly send
 without it -- especially below 25 wpm or so..  So, the TO keyer is not
 getting much use anymore.  (But it looks *so* good with the Drake
 4-Line!)

 The Nye and the CMOS-4 both have dot / dash memory and the memory
 function works even with a non-iambic key.

 With an iambic key connected to the CMOS-4, I don't find *any* mode that
 is not iambic capable.  What V mode are you using?  Are you running V9
 with no dot/dash memory?

 And, more generally, what is the difference between Curtis, Accukeyer
 and Logikey modes?  I've tried the various modes now and other than dot
 and dash memory options I don't see much difference.  Man, I've been
 pounding brass since '65 and I've got a lot to learn!

 73,
 -Doug, W7KF



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Re: [drakelist] An Introduction a question about keyer for T-4XB

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Hi Steve,

I dug out my schematic and it actually takes a few components.  My
recollection was only of the inductor.  Basically you place a series
LC circuit in the secondary of T2 to filter out the harmonics from the
sawtooth before they reach the speaker.

I first elected to lower the freq of the sidetone down to 750Hz
because that was more to my preference.  I simply placed 160pF across
C8 to accomplish this.

The series LC filter is then made resonant at 750Hz.  I used a 31mH
torriod in series with 1.33uF of capacitance (formed by a 1uF in
parallel with 0.33uF).  Other LC combinations of 750Hz resonance will
work as long as you are mindful of the series R of the inductor, which
determines the Q.  If the inductor is too lossy, the tone won't be as
pure.   Correspondinly if the Q is quite high then then you may have
to tweak either the oscillator or resonator capacitor to match up the
resonance to the oscillator.

I have probably made it sound harder than it really is.  The mod
worked first time for me using an inductor out of my junk box.  I
think the Q fell between 5 and 10.

Dennis AE6C

On 10/23/07, Steve Berg [EMAIL PROTECTED] wrote:

 Steve Berg [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 Hi Dennis,

 What is that one additional component, and where does it go?

 Steve WA9JML an otherwise happy TO keyer afficianado


 Dennis Monticelli wrote:
  Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist 
  gang
  --
  I don't have a CMOS-4 so I cannot comment.  I have a Tick keyer that
  just uses a single CMOS PIC controller and I find I can use it just
  fine pretending it is non-iambic.
 
  I agree with you regarding the memoryless TO keyer.  It is
  unforgiving.  On the plus side it will teach you to send better code
  :-)  It comes out of the closet at my QTH only during the vintage
  contests.  I did do a simple mod to turn the raspy sidetone into a
  nice sine wave.  It only took one additional component.
 
  On 10/22/07, Doug Smith [EMAIL PROTECTED] wrote:
  Doug Smith [EMAIL PROTECTED] made an utterance to the drakelist gang
  --
  On Mon, 2007-10-22 at 23:36 -0400, Garey Barrell wrote:
  Personally I use the CMOS-4 from Idiom because it's one of the few
  that
  I can turn off that stupid iambic junk that will drive any bug user
  crazy!  :-)
  I didn't know that!  I had to drag out the manual and check it out.
 
  I used to be able to send good code with my W9TO keyer but bought a new
  Nye keyer in the mid-1980s along with a Bencher Iambic key.  I never
  learned how to use iambic mode and don't care about it.  However, I did
  become accustomed to the dot and dash memory and now I can hardly send
  without it -- especially below 25 wpm or so..  So, the TO keyer is not
  getting much use anymore.  (But it looks *so* good with the Drake
  4-Line!)
 
  The Nye and the CMOS-4 both have dot / dash memory and the memory
  function works even with a non-iambic key.
 
  With an iambic key connected to the CMOS-4, I don't find *any* mode that
  is not iambic capable.  What V mode are you using?  Are you running V9
  with no dot/dash memory?
 
  And, more generally, what is the difference between Curtis, Accukeyer
  and Logikey modes?  I've tried the various modes now and other than dot
  and dash memory options I don't see much difference.  Man, I've been
  pounding brass since '65 and I've got a lot to learn!
 
  73,
  -Doug, W7KF
 
 
 
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Re: [drakelist] 2B knobs fixed pics.

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I am not a purist.  I like resourcefulness.


On 10/22/07, Jim F. [EMAIL PROTECTED] wrote:

 Jim F. [EMAIL PROTECTED] made an utterance to the drakelist gang
 --

 Below, find two pictures of fixed Drake 2B knobs.

 The knobs had a ring of rust where the chrome was
 supposed to be.

 I found some chrome washers at a hardware store and
 superglued them on after first concentrating the rust
 with some stuff from Walmart.

 The pictures show a fixed next to an original knob
 (on Rt.).

 Purists may object, but I enjoy looking at the radio
 while waiting to find some nice knobs :-)


 http://www.geocities.com/j_fitton/trswitch/MVC-006E.JPG

 http://www.geocities.com/j_fitton/trswitch/MVC-004E.JPG


 jim / W1FMR

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Re: [drakelist] An Introduction a question about keyer for T-4XB

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Take heed of the neg vs pos keying that Garey talked about and also
the absolute voltage.  The old Hallicrafters TO keyer with its mercury
wetted relay will key anything, even high current together with high
standoff voltage if you install the right RC snubber.

The Nye Viking ESK-001 is kind of hard to find but it features both
neg and pos (switchable from the rear panel) 300V transistor
switches, making it one of the few transistor keyers that can easily
handle both cathode keying and grid-block (like the Drakes).

I have both a TO and the ESK-001.

Be careful of the modern IC keyers on the market.  Many of them do not
handle neg keying and their max voltage is typically under 50V.  You
could always build a HV interface circuit if you wished.  I did and
use it with my low voltage keyers.

Denny AE6C

On 10/22/07, Duane Calvin [EMAIL PROTECTED] wrote:

 Duane Calvin [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 I'm with Garey - I use the Logikey from Idiom also.  I have, in my shack,
 the K1, K3 and K5.  I use the K3 with the Drake because it has two jacks on
 the back, one for positive and one for negative keying.  It's easier than
 the internal jumper.  Just FYI.  They also happen to be outstanding keyers
 with 'forgiving' paddle inputs.

 73, Duane

 Duane Calvin, AC5AA
 Austin, Texas
 www.ac5aa.com


 -Original Message-
 From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
 Behalf Of Jeff Siegel
 Sent: Monday, October 22, 2007 11:00 PM
 To: [EMAIL PROTECTED]
 Subject: RE: [drakelist] An Introduction  a question about keyer for T-4XB


 Jeff Siegel [EMAIL PROTECTED] made an utterance to the
 drakelist gang
 --
 Thanks for much for the info.

 -Original Message-
 From: [EMAIL PROTECTED]
 [mailto:[EMAIL PROTECTED] Behalf Of Doug Smith
 Sent: Monday, October 22, 2007 11:26 PM
 To: [EMAIL PROTECTED]
 Subject: Re: [drakelist] An Introduction  a question about keyer for
 T-4XB



 Doug Smith [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 On Mon, 2007-10-22 at 23:11 -0400, Jeff Siegel wrote:
  The question is,
  what is a suitable keyer to use with the transmitter?

 I have a 1960's era Hallicrafters TO Keyer with a Vibroplex Vibrokeyer
 like yours.  And, a 1980's era Wm. Nye ESK-001 keyer that I use with a
 Vibroplex Iambic key.  And, finally, a LogiKit (Idiom Press) CMOS-4
 Keyer that I use with a Bencher BY-1 key.

 All thee setups key my Drake T-4XC just fine!

 73,
 -Doug, W7KF



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Re: [drakelist] Part Question

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
The key spec for a regulator output transistor is SOA (Safe Operating
Area).  You will only find SOA described in a typical curve, almost
never in a table.  The TIP31 is an EPITAXIAL transistor.which has
to do with the method of silicon processing.  It is an older method
that is typically no longer used because the transistor ends up slow
(pretty much a don't care in regulator service).  But such a device is
tougher with regard to SOA.  So regardless of the device you buy,
first insure that its voltage and current ratings are at least equal
to the TIP31 and that it is Expitaxial vs the more modern
Double-diffused construction.  The Fairchild datasheet for the
TIP31, for example, has Epitaxial right in the title.

I don't have a catalog in front of me, but there are probably power
transistors of a similar package size available that having heavier
ratings than a TIP31 and therefore more reliable in the TR-7 power
supply application.

Denny AE6C

On 8/31/07, Garey Barrell [EMAIL PROTECTED] wrote:

 Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 George -

 John Kriner has them in his EBay store.

 http://stores.ebay.com/The-Mans-Amateur-Parts-Supply

 I believe they're $4.00.  We've discussed what they might be, and think
 they are probably a selected version of a TIP31.  But no one seems to
 know what they were selected for!  The same transistor is used in the
 R-4C power supply, and there doesn't appear to be anything special about
 the circuit that would require selection!

 They have a low hFE and are very unremarkable.   We have not been able
 to come up with any sort of data sheet or specifications for them.

 73, Garey - K4OAH
 Glen Allen, VA

 Drake 2-B, 4-B  C-Line Service Supplement CDs
 www.k4oah.com



 George Runyan wrote:
 
  I am in need of a regulator transistor for the SPR-4 (EP487). Any
  suggestions where I can purchase one?
 
 
 
  George
 
  WB6YEC
 
 

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Re: [drakelist] MS-4 location

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I strongly endorse pulling the hot air out vs pushing.  Garey hit it
on the head when he spoke about the illusion of fan exit air not being
as much as exit air:  It is just that the exit air is directed into a
smaller cross-sectional area.

If you are just trying to enhance the existing convective air flow a
little bit, then placing a fan over the top is easy and best.  For
example, I use a 12V muffin fan on reduced voltage sitting over the
right rear corner of the R4-B on little fubber feet.  That corner is
where the power transformer and output tube sits so the heat buildup
is greatest there.  You can't even hear it run yet the R4-B runs
considerable cooler.

But if you're specifically trying to cool down a set of finals (vs
just enhance existing convection) and are willing to run the fan at
full voltage, then sticking the fan on the rear of the cage (where the
obstructions are fewer) makes more sense.  A fan at full voltage near
the tubes is going to draw the heat out effectively whether it's allow
to do so vertically or horizontally.

Your rig is going to thank you for this.  A commonly used acceleration
factor in the electronics industry is a halving of circuit life for
every 10 deg C rise.  That's a real rough number but it gives you an
idea of the importanance of good thermal management.

Denny AE6C

On 9/1/07, Gary Poland [EMAIL PROTECTED] wrote:

 Gary Poland [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 I have installed fans on many of Drakes as well as on my KWM-2. I have
 always installed them in s:ch a way as to pull cooler ambient air through
 the chassis and out the back. Regardless of the way you choose to do it, the
 proof is in the pudding, mine have stayed  much cooler.


 73, Gary W8PU
 http://home.cinci.rr.com/w8pu



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Re: [drakelist] MS-4 location

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Thanks for providing the background, Jim.

The activation energy, Ea, is determined empirically for each
component type (or material type in the case of certain other
industries).  Usually the component is run at elevated temp (beyond
max operating limits)  until failure occurs so that Ea can be
extracted mathematically.  10 deg C for a halving of life works well
for semiconductor devices (we use it at work with a little windage
here and there) and it is close enough for most passives to be a
general rule of thumb in electronics.

On 9/1/07, Jim Shorney [EMAIL PROTECTED] wrote:

 Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 On Sat, 1 Sep 2007 11:04:53 -0700, Dennis Monticelli wrote:

 A commonly used acceleration
 factor in the electronics industry is a halving of circuit life for
 every 10 deg C rise.  That's a real rough number but it gives you an
 idea of the importanance of good thermal management.

 Quoted from http://www.pcpower.com/technology/optemps/ :

 The life of an electronic device is directly related to its operating
 temperature. Each 10øC (18øF) temperature rise reduces component life by
 50%*. Conversely, each 10øC (18øF) temperature reduction increases component
 life by 100%. Therefore, it is recommended that computer components be kept
 as cool as possible (within an acceptable noise level) for maximum
 reliability, longevity, and return on investment.

 * Based on the Arrhenius equation, which says that time to failure is a
 function of e^-Ea/kT where Ea = activation energy of the failure mechanism
 being accelerated, k = Boltzmann's constant, and T = absolute temperature

 --
 Jim Shorney  --.--Put complaints in this box
 jshorney (at) inebraska.com
 Ham Radio NU0C
 Lincoln, NE, USA
 EN10ps
 http://incolor.inetnebr.com/jshorney/


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Re: [drakelist] DXing with the TR7

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Got 'em on 40M last nite with an R4-B and an ARC-5 feeding 30W to a dipole.
Not first call :-)

Denny AE6C

On 4/9/07, Doug Smith [EMAIL PROTECTED] wrote:


Doug Smith [EMAIL PROTECTED] made an utterance to the drakelist gang
--
On Mon, 2007-04-09 at 15:14 -0400, john wrote:
 Fun to work the Swains DXpedition  1st call on the TR7 operating 17m, with
 the L7 loafing along at about 500 watts.  Antenna only a rotatable dipole
 @50 feet.
 The TR7 is still a great rig

Yup.  I snagged 'em the other night on 3520 KHz running an R-4C T-4XC.
I was running a full gallon into a 26 foot, ground mounted, vertical.

The 4-Line is still a great rig!

73,
-Doug, W7KF


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Re: [drakelist] TR-3 Paint

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Hmmm.  I have a very early B (serial 7011) with bumpy paint.  No
evidence of repainting.  Maybe there was a cabinet swap some time in
its life?

Denny AE6C

On 1/20/07, Gary Poland [EMAIL PROTECTED] wrote:


Gary Poland [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Ken,
  The TR-3 paint was smooth, I am fairly certain the epoxy  bumpy  paint
didnt show up until the C-Line, TR-4C, etc.

73, Gary W8PU
http://home.cinci.rr.com/w8pu



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Re: [drakelist] AC-4R upgrades

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
My company makes chips for switching supplies.  One important design
choice is whether or not to allow the filter inductor to operate in
discontinuous mode.  This simply means that the current through the
inductor is not continous; it runs out of stored energy each cycle as
the current drops to zero.  When that happens its filtering action is
impaired.

An old fashioned tube supply with a choke is no differrent even though
the frequency is much lower.  If the choke has insufficient inductance
for the minimum load current, then it will run dry before the next
cycle of the line voltage replenishes the energy.  Wwhen that happens
its ability to regulate the output voltage is seriously impaired and
the output soars to 1.4 times the RMS.  This is why Gerry recommends
that the minimum load represented by the stock bleed resistor be
heeded.  To paraphrase Gerry, only use choke input supplies when the
load current range is relatively narrow; 10:1 is too much.

Denny AE6C

On 12/12/06, Gerry [EMAIL PROTECTED] wrote:


Gerry [EMAIL PROTECTED] made an utterance to the drakelist gang
--
What you describe is typical of choke input power supplies. Text books tell
us that choke input supplies are better at regulation but that is simply not
true if you have a wide ranging dynamic load. Choke input power supplies
require a minimum load. There are formulas in the old handbooks to calculate
the value of resistance to draw a proper load current. Without a minimum
load it would be as if no choke existed (except for its DC resistance) and
the filter capacitors will charge to 1.414 times the value of AC rms. In
other words, if you have 750VAC secondary the capacitors will charge to over
1,060 volts with no load! With a properly chosen resistor this would be 0.9
times 750 volts or 675 volts. Please note the HV filter capacitors are only
rated to 350 volts for a total of only 700 volts. So as you can see, the
10k, 20w load resistor on the output of the HV side of the supply is
crucial. That resistor dissipates around 16 watts. Notice that the low end
is referenced to +250V and not ground. It should be rated for twice the
actual power dissipation or 32 watts. Put it another way, without the load
resistor, key up voltage would be around 1kV while key down would drop to
about 675 volts. I should mention that the choke has DC resistance which may
be a significant contributor to voltage drop. If you draw 450 mils and your
DC choke has 50 Ohms of DC resistance, you will drop an additional 22.5
volts across the choke. Also look at the +250 volt side and see that the
filter caps are rated to only 300 volts. This is much too close for comfort
and is really a very slim margin of safety. Typically the voltage rating of
electrolytics is related to the maximum voltage it can withstand for a given
numbers of hours at some temperature. Component manufacturers usually try to
embellish the specifications and say their caps will take 1000 hours of use
at room temperature. But in actual operation ambient temperature will be
higher than 25 degrees C and they typically don't say too much about self
heating due to ripple current which brings up temperature even more. This is
why it is always best to over rate voltage in electrolytics when selecting
components. I see that Drake realized this was not a good design and soon
changed to a capacitive input supply which is better suited to SSB service,
and less expensive. As far as I'm concerned I would avoid the original AC-3
in daily use. You wisely chose to use it on the test bench instead.

-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Donnie Garrett
Sent: Tuesday, December 12, 2006 5:27 AM
To: Tom Taylor
Cc: drakelist@www.zerobeat.net
Subject: Re: [drakelist] AC-4R upgrades


Donnie Garrett [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Tom:
I have one of the early AC3 supplies that used a HV choke.  Garey
K4OAH and I had a lot of discussions about its design some time back
after I discovered the ceramic 25W load resistor was open.  You better
check yours to see if its OK.  It will still operate but the no load
HV will float very high with an open load resistor.  I was never able
to find an exact replacement at the time I needed it so I installed a
25W wire-wound resistor in a vertical fashion with a small bolt
running through it. Somewhat similar to the original setup. I choose a
25K 25W instead of a 15K to reduce the heat dissipation produced by
the resistor.  The 25K still loaded down the HV and was near the same
as was prior with the original 15K 25W resistor which seems to
regularly fail due to running it at or near it's maxium wattage
dissipation.
Also one last

Re: [drakelist] survey re: L7 tube failures

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
The original 3-500Z tubes are still in my L7, Amperex I think.  The
original owner gave it pretty good exercise on 80M at full power for
many years, but my use over the past few years has been very spotty
and only at the 400 to 500w level on 120V.  Pretty tough tubes in my
opinion.

On 6/19/06, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:



Fellow enthusiasts,

I'm trying to collect user experiences regarding 3-500Z tube failures with
the Drake L-7 linear amplifier.  Specifically, I'd like to know if you've
had a single tube failure, the one toward the centerline of the chassis NOT
the one in the corner.  Further, I'd like to know if the filament has
opened or if the lead from the envelope, to the socket pin, has become
desoldered; this pin is the one closest to the rear apron of the chassis.

Thanks and 73,

Evan

  
 Check out AOL.com today. Breaking news, video search, pictures, email and
IM. All on demand. Always Free.


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Re: [drakelist] shelf life of tubes

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I think it is a good idea to power up the filaments for a few hours
before putting full voltage on a transmitting tube.  I had the
experience of putting some 20 year old NOS 6146Bs into a TS-820 (800V
HV unloaded).  For the first two days of approx 2 hrs use each, I had
three occurances of brief single-shot HV shorts due to internal tube
arcing.  The arc only lasted milliseconds but was enough to dim the
panel lights.  Residual gas builds up over the years.  A HV
transmitting tube is highly dependent upon a good vacuum.  Just a few
hours of hot filament is enough to get the residual gas agitated and
then captured by a hot getter flashing.  After those several 6146 arc
events, the tubes settled down and worked just fine.  If I had given
them some light exercise prior to installation, I'll bet those arcs
never would have happened.

On 5/5/06, Garey Barrell [EMAIL PROTECTED] wrote:


Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang
--
Seems like I have seen something about storing transmitting tubes
upright to prevent the filament (or other elements) from sagging.
Also a recommendation to run with filament power only for several (?)
hours after long term storage before applying HV.

There WILL be some leakage past the glass-metal pin seals over time,
and when the tube is powered up the getter will absorb some gas.

I don't think this is much of a problem with small receiving tubes.
There are still plenty of two-digit tubes from the 1930's that are
running just fine, along with millions of tubes from the 40's - 60's.

73, Garey - K4OAH
Atlanta

Drake B  C-Line Service CDs
http://www.k4oah.com



[EMAIL PROTECTED] wrote:
  Im using WW2 vintage JAN tubes in some of my audio equipment and it
 works great. But, it just depends.

 Mark
 W0NCl

 -Original Message-
 From: Goss, Ed [EMAIL PROTECTED]
 To: Gary Poland [EMAIL PROTECTED]; [EMAIL PROTECTED];
 drakelist@www.zerobeat.net
 Sent: Fri, 5 May 2006 09:09:34 -0400
 Subject: RE: [drakelist] shelf life of tubes


 Goss, Ed [EMAIL PROTECTED] mailto:Ed.Goss%40jhuapl.edu made an 
utterance to the drakelist gang
 --
 There is no magic number; too many variables including design of the tube, how
 well the procedure for manufacturing was developed, how well the procedure was
 followed, quality control of fabrication equipment, handling of the tube after
 manufacture, and many others
 --Ed, N3CW--



 -Original Message-
 From: [EMAIL PROTECTED] mailto:owner-drakelist%40www.zerobeat.net
 [mailto:[EMAIL PROTECTED] mailto:owner-drakelist%40www.zerobeat.net%5dOn 
Behalf Of Gary Poland
 Sent: Thursday, May 04, 2006 7:44 PM
 To: [EMAIL PROTECTED] mailto:abqcooks%40aol.com; drakelist@www.zerobeat.net 
mailto:drakelist%40www.zerobeat.net
 Subject: Re: [drakelist] shelf life of tubes



 Gary Poland [EMAIL PROTECTED] mailto:gpoland1%40cinci.rr.com made an 
utterance to the drakelist gang
 --
 Jim,
   A fellow at Eimac once told me that  3-500Z's will get gassy if left
 stored for long periods of time. Other then that I dont know.

 73, Gary

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Re: [drakelist] L7 Voltage Sag

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
I'm going with the flow and say bad caps.  I have a recapped L7 here
in the shack running off 120V at the end of a long run thru the house.
 I typically load it to 400 or 500W on the CW (lower HV) setting with
at most 50W of drive.  While I haven't measured the line sag, I would
guess it runs 5 to 10V judging by the slight dimming of the lights.

BTW, a slow turning fan placed on top of the power supply cage does
wonders for drawing out heat and probably increasing longevity in the
process.

Dennis AE6C

On 3/27/06, Garey Barrell [EMAIL PROTECTED] wrote:

 Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 Evan -

 I think you have the right idea.  Sounds like one or more caps with a
 high ESR.  They charge up fine with just the bleeder load, but as soon
 as you draw any real current the voltage sags to about 1/2.   The
 other key, as I read the original question was that BOTH voltages drop
 to about 1000 V, or ~1300 and ~ 950?

 Add that the to fact that if they are original those caps are past their
 expected lifetime.  I bet an ESR meter would show the problem.

 73, Garey - K4OAH
 Atlanta

 Drake B  C-Line Service CDs
 http://www.k4oah.com



 [EMAIL PROTECTED] wrote:
  Based upon 30+ years of experience with L4, L4B, L7 amps, wired for
  110v and 220v, in multiple locations, I would bet a Starbuck's coffee
  that the problem with that great of a voltage sag is due to one or
  more electrolytic capacitors failing.  For the secondary to sag by
  40-50% due to a primary (line voltage) sag, that means the line
  voltage would go down to 55-60 VAC.  So, any bets?
 
  73,
 
  Evan
 
  -Original Message-
  From: [EMAIL PROTECTED]
  To: Neil Kutchera [EMAIL PROTECTED]; drakelist@www.zerobeat.net
  Sent: Mon, 27 Mar 2006 15:44:37 -0600
  Subject: RE: [drakelist] L7 Voltage Sag
 
 
   [EMAIL PROTECTED] mailto:pulsarxp%40earthlink.net made an utterance 
  to the drakelist gang
  --
  It probably means you have #14 house wiring!
  Lee
  w0vt
 
 
   [Original Message]
   From: Neil Kutchera [EMAIL PROTECTED] mailto:k4njk%40bellsouth.net
   To: drakelist@www.zerobeat.net mailto:drakelist%40www.zerobeat.net
   Date: 03/27/2006 12:26:21 PM
   Subject: [drakelist] L7 Voltage Sag
  
  
   Neil Kutchera [EMAIL PROTECTED] mailto:k4njk%40bellsouth.net made an 
   utterance to the drakelist
  gang
   --
   I'm working on repairing my Drake L7 amplifier before I put it up for
   sale.  It is set for 110 volts.  When I turn on the amp the plate
   voltage reads either 2600 in SSB or 1850 in CW.   Under load the it
   drops to 1000 volts regardless of the mode.  The amp will run between
   500 - 600 watts output with 120 watts of drive at this voltage.  I've
   tested this with two sets of tubes. Does this indicate the power
   supply caps are in need of replacement?  If so can anyone recommend a
   good source of parts?
  
   Thanks,
   Neil
   K4NJK
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Re: [drakelist] Interesting End: PS7 Voltage Regulation Problem

[Dennis Monticelli]

Dennis Monticelli [EMAIL PROTECTED] made an utterance to the drakelist gang
--
It appears to me that your PS has an undervoltage lockout feature. 
This is relatively common in today's supplies, but not so when the PS7
was built.  Undervoltage lockout turns off the output when the input
voltage is insufficient for the PS to work correctly.  An incorrectly
working supply is potentially dangerous to the load because the output
voltage may actually go to a high output state (excessive output
voltage) or oscillate.  During PS startup, there is special circuitry
to insure that the PS is able to ramp itself up rather than get
trapped in the undervoltage lockout state.  My guess is that the
startup circuity in the PS7 is rate sensitive.  When you apply full AC
instantly, it starts up.  When you apply AC input slowly, it does not.
 Rate sensitive startup (using a capacitor) is usually cheaper to
implement than using logic to govern startup.

I don't have a PS7 schematic so I admit to some speculation regarding
your problem.

Dennis AE6C

On 3/23/06, Ron Wagner [EMAIL PROTECTED] wrote:

 Ron Wagner [EMAIL PROTECTED] made an utterance to the drakelist gang
 --
 Kevin,
 If I understand you correctly, you were only feeding a percentage of the
 design voltage to the PS7 because of the variac.

 Let me make a guess as to your problem.  The regulator board needs a
 specified minimum voltage to run correctly.  If you were in fact
 starving the regulator of the correct operating voltage, anything is
 possible.  Anything including the distruction of various components within
 the regu;lator board, feedback loops in the regulator oscilating, and any
 number of other strange things.

 So my guess would be the 723 had its boxers in a bunch and did whatever
 it pleased and did not get reset until voltages got within specs for the
 design.

 73,
 Ron
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Re: [drakelist] Drakes wanted

[Dennis Monticelli]

I have an early L7 (serial 184) that does not have chimneys and uses
3-500Z's. If you don't block the airflow in the rear, the fan
doesn't hit high gear often. I replaced the caps in the PS and
placed a slow turning fan on top of it. That should go a long way
toward component lifetime.

Dennis AE6COn 1/11/06, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:

MyL-7 came with chimneys and the seller made a big deal
about telling me that they were included. After looking things
over, I realized that they were not helping anything due to the fan
placement and the heat from the amp dripped appreciably when I removed
them. They were almost touching eachother, too. I am really
surprised that I didn't melt the solder outof the
pins.Guess he didn't use it much and I didn't either before
removing the chimneys. At least I have a pair of spares in case I
get butterfingers when playing with the L-4B.

73,

John, W4AWM-Original Message-From: Ron Baker [EMAIL PROTECTED]
To: [EMAIL PROTECTED]Cc: 
drakelist@www.zerobeat.netSent: Wed, 11 Jan 2006 23:03:01 -0500Subject: RE: [drakelist] Drakes wanted


Ron Baker [EMAIL PROTECTED] made an utterance to the drakelist gang
--Are you sure the L7 had chimney's for the 3-500Z.   I have a later versionwhich did not have then because the rear mounted fan blew air directly
across the tubes.I Know the L4B had chimneys, but the L7,???Also, check out my TR7A article.  I have a later release on my website withlots of updated information.   I'm not sure if the other sites having my
article have the latest version.   Here is the link.http://www.wb4hfn.com/DRAKE/DrakeArticles/TR7_Comparison_Article/TR7_Idenity
-01.htm73, Ron / WB4HFN-Original Message-From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]] On Behalf Of 
[EMAIL PROTECTED]Sent: Wednesday, January 11, 2006 9:59 PMTo: [EMAIL PROTECTED]Cc: 
drakelist@www.zerobeat.netSubject: Re: [drakelist] Drakes wantedHi Richard,One thing you need to watch for when purchasing a TR-7A is that it is notactually a TR-7 in disguise. For a period of time, Drake sold spare face
plates for the A model to anyone who wanted one.  Many folks bought one toupgrade their TR-7.  Other than the face plate, there is no outwarddifference in appearence between the 2 models on the front panel.  There is
a small difference on the rear panel and several items were added insidewhich were accessories on the A model.  Here is a link to WB4HFNs page inthe Drake museum which will explain all this in detail:   Click here: Page 1
http://www.dproducts.be/DRAKE_MUSEUM/page_1.htm  Depending on where you get your TR-7A and the physical and electrical
coindition it is in, any additional filters and the PS-7 power supply, Youcan xpect to pay anywhere from $800.00 up. Obviously, a rig that is notpristine will sell for somewhat less, but frankly, a TR-7 is a much better
deal, especually if it has the NB-7 noise blanker installed. That and the AMfilter were the most expensive accessories.The L-7 is a fine little amplifier, but be sure to get one that has theoriginal power supply if you can.  The amps were shipped with either 3-400
or 3-500Z tubes.  If you can find one with 3-500, they are the betterchoice, but I would not turn down one with 3-400s at a slightly lower price.If it has been well cared for, the amp is pretty bullet proof, as long as
the finals are in good shape. The original caps in the PS should be replacedat some point for safety and the fusable resistor power rating shouldincreased.  A replacement capacitor kit may be available from The Heathkit
Shop. Be sure that the glass chimneys are present.  Here again, condition ofthe rig and tubes go a long way in determining the price, but a bottom lineof 800 and up is reasonable.If you find one and have it shipped, be prepared for sticker shock because
the PS weighs a ton! Have the seller remove the finals and chimneys andpackage them separately and do not have them shipped in the same box withthe amp.The tubes should preferably be shipped in a vertical configuration.
Hope this helps.73,  John,  W4AWM--Submissions:
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Re: [drakelist] R-4B bandswitch lubrication

[Dennis Monticelli]

I used 100% DeOxit from a needle applicator on my R4B wafer
switches. Being 100%, it did a good job even on the heavy oxide
buildup. I was careful not to get excess on the wafers themselves
even though previous wafer switch cleaings (of lesser rigs) with the 5%
spray turned out just fine.

Most folks use the 5% spray because it is commonly available and easy
to apply. But you have to soak components in the carrier fluid
just to get a decent amount of active ingredient on the contacts
themselves. One advantage to the spray is the washing effect of
the runoff. A further disadvantage is having that runoff coat
everything in the vicinityanother reason why I'm increasingly just
rifle shooting with the 100% stuff.

Denny AE6COn 1/8/06, Steve Berg [EMAIL PROTECTED] wrote:
Steve Berg [EMAIL PROTECTED] made an utterance to the drakelist gang--I have never had problems with de-oxit on switch wafers in my National,
Clegg, Gonset and Hallicrafters equipment.I think I may have even usedit on my 2B at one point or another.For general cleaning purposes oneither electronics or my smoking pipes collection, I use ethanol.I buy
the everclear variety from my local package goods store and use itsparingly with q-tips and pipe cleaners.I would steer clear of thede-natured stuff, especially if it contains methanol.It cleans wellwithout dissolving most things that I want to remain behind.For
lubrication, I use Kroil or Break Free sparingly.If it requiresgrease, I use the synthetic gun grease that comes in a plungerapplicator.I think it is sold as shooter's choice.Steve WA9JML--
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[drakelist] Electronic air cleaners damage rubber

[Dennis Monticelli]

FYI. There have been reports that the so-called electronic air
cleaners that emit negative ions damage rubber products in short
order. For example a pinch roller on a 6 mo old VCR that aged 20
years or a one-month-old drive belt that was crumbling. Other
reports are of rapidly failing rubber seals windows and disintegrating
carpet pads. What was in common with all these reports were various
models of negative-ion air cleaners that had been recently
installed. It seems that the ions penetrate every crevice and
will attack rubber.

Denny AE6C