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
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
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
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
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,
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
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
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
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
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
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
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
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
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
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.
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
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
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,
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
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:
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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.
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
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,
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
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
.
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
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
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
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
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
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
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
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
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
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,
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
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
___
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
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
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
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
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
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:
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
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
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
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,
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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