subject:"\[drakelist\] TR\-7"


Hi Guys,
Thanks for the replies. The first thing I thought to do was re-seat the 
boards and I did. Well, I didn't re-seat the ones that were hidden under
the display board (DR-7).  I'll take it apart and re-seat them if I have 
to, but, I think I have isolated the problem to the pre-driver board and it
doesn't plug into anything. It is bolted to a heatsink next to the PA. 
When it is in a failed condition, I have RF going into, but not out of, 
the pre-driver board.


Thanks for the offer, but I already have a set of extender boards.

I will find the problem eventually , I just need a schematic. I will 
take another look at Ron's site.


Thanks again,

Bob  K6GGO



Hi Bob:

Before jumping right to looking for a flaky component, have you done 
the requisite re-seating of the board?  Deoxit on the edge connector, 
and relay cleaning?


FWIW

Curt
KU8L


On 12/20/2011 3:15 PM, Robert Fish wrote:

Hi Guys,
I have a two part question. I noticed a few weeks ago that, on 
occasion, my TR-7 would not transmit when keyed. If I unkey and then 
key again, it would transmit.
I noticed when running digital modes, which I do using VOX for keying 
the transmitter. Well, the last few days it has become more frequent. 
It also happens in cw.
If I key the transmitter 10 times, maybe 3 or 4 times Ill get no RF 
out. I traced the problem to the pre-driver board. I always have RF 
in, but when it fails there is no RF going to the PA.
Even though I have an early TR-7, I have the later version of the 
driver board. Unfortunately, I only have the schematic for the early 
version in my service manual.


Where can I get a schematic for the later pre-driver board?

Any idea what is happening here? It shouldn't be too much trouble to 
figure out which component is going flakey, if I can get a print for 
the newer board.


Thanks in advance,

Bob  K6GGO

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Re: [Drakelist] TR-7 Transmit issues


I found the schematic on Ron's site. Thanks Lee.

Bob  K6GGO

Hi Guys,
Thanks for the replies. The first thing I thought to do was re-seat 
the boards and I did. Well, I didn't re-seat the ones that were hidden 
under
the display board (DR-7).  I'll take it apart and re-seat them if I 
have to, but, I think I have isolated the problem to the pre-driver 
board and it
doesn't plug into anything. It is bolted to a heatsink next to the PA. 
When it is in a failed condition, I have RF going into, but not out 
of, the pre-driver board.


Thanks for the offer, but I already have a set of extender boards.

I will find the problem eventually , I just need a schematic. I will 
take another look at Ron's site.


Thanks again,

Bob  K6GGO







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Re: [Drakelist] TR-7 Transmit issues

Well, it seems that the first transistor on the driver board is the 
culprit. Or, at least, when the transmitter fails, that is where the RF 
stops. It is a Motorola MPS-H20

I found the schematic on Ron's site. Thanks Lee.

Bob  K6GGO

Hi Guys,
Thanks for the replies. The first thing I thought to do was re-seat 
the boards and I did. Well, I didn't re-seat the ones that were 
hidden under
the display board (DR-7).  I'll take it apart and re-seat them if I 
have to, but, I think I have isolated the problem to the pre-driver 
board and it
doesn't plug into anything. It is bolted to a heatsink next to the 
PA. When it is in a failed condition, I have RF going into, but not 
out of, the pre-driver board.


Thanks for the offer, but I already have a set of extender boards.

I will find the problem eventually , I just need a schematic. I will 
take another look at Ron's site.


Thanks again,

Bob  K6GGO







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Re: [Drakelist] TR-7 Transmit issues

Sorry about that, I sent the e-mail before I was done typing. Does 
anyone have source for an MPS-H20. It looks like they aren't available. 
I found a reference to it on the Drake mods
document. The guy says he replaces them with MRF237 because it can 
handle a little extra power. Apparently, he thinks the TO-92 package was 
border line undersized for .3 watts.
Maybe that's why mine is going south (I've been running digital modes). 
I found these MRF237s on Ebay for 8 bucks (stick'em up). I'll pay it if 
I have to. Any thoughts?



Bob  K6GGO

Well, it seems that the first transistor on the driver board is the 
culprit. Or, at least, when the transmitter fails, that is where the 
RF stops. It is a Motorola MPS-H20

I found the schematic on Ron's site. Thanks Lee.

Bob  K6GGO

Hi Guys,
Thanks for the replies. The first thing I thought to do was re-seat 
the boards and I did. Well, I didn't re-seat the ones that were 
hidden under
the display board (DR-7).  I'll take it apart and re-seat them if I 
have to, but, I think I have isolated the problem to the pre-driver 
board and it
doesn't plug into anything. It is bolted to a heatsink next to the 
PA. When it is in a failed condition, I have RF going into, but not 
out of, the pre-driver board.


Thanks for the offer, but I already have a set of extender boards.

I will find the problem eventually , I just need a schematic. I will 
take another look at Ron's site.


Thanks again,

Bob  K6GGO







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Re: [Drakelist] TR-7 Transmit issues

2011-12-20 Thread Joe Pyles


I use NTE229 to replace the MPSH20 on the predriver board and they work fine.

73, Joe KC9LAD

At 06:57 PM 12/20/2011, you wrote:
Sorry about that, I sent the e-mail before I was done typing. Does 
anyone have source for an MPS-H20. It looks like they aren't 
available. I found a reference to it on the Drake mods
document. The guy says he replaces them with MRF237 because it can 
handle a little extra power. Apparently, he thinks the TO-92 package 
was border line undersized for .3 watts.
Maybe that's why mine is going south (I've been running digital 
modes). I found these MRF237s on Ebay for 8 bucks (stick'em up). 
I'll pay it if I have to. Any thoughts?



Bob  K6GGO

Well, it seems that the first transistor on the driver board is the 
culprit. Or, at least, when the transmitter fails, that is where 
the RF stops. It is a Motorola MPS-H20

I found the schematic on Ron's site. Thanks Lee.

Bob  K6GGO

Hi Guys,
Thanks for the replies. The first thing I thought to do was 
re-seat the boards and I did. Well, I didn't re-seat the ones 
that were hidden under
the display board (DR-7).  I'll take it apart and re-seat them if 
I have to, but, I think I have isolated the problem to the 
pre-driver board and it
doesn't plug into anything. It is bolted to a heatsink next to 
the PA. When it is in a failed condition, I have RF going into, 
but not out of, the pre-driver board.


Thanks for the offer, but I already have a set of extender boards.

I will find the problem eventually , I just need a schematic. I 
will take another look at Ron's site.


Thanks again,

Bob  K6GGO






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Re: [Drakelist] TR-7 Transmit issues

2011-12-20 Thread Bob Fish

Thanks Joe, 
Mouser has them for a buck and a half. That's more like it.

Bob K6GGO

Sent from my iPad

On Dec 20, 2011, at 4:15 PM, Joe Pyles epy...@indy.rr.com wrote:

 again, 

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[Drakelist] TR-7 Help!

2011-12-06 Thread RB

Hello from Australia.  I am new to this group so apologies if the format of 
this message is wrong

Just got a TR-7, and it the best traditions of on-line shopping it's arrived 
faulty.

When powered on, the panel lights come on but not other sign of activity.

It is drawing close to 5 amps at 13.8 Volts.

So far I have disconnected the PA power line, and taken every possible board 
out of its socket (incase of a shorted tantalum etc) with no luck.

The power supply board (the one near the front right of the radio) has a pair 
of transistors coming off it which get hot very quickly.

Anyone got any ideas ? Im hoping this is maybe a common fault.

I think the radio has been stored idle for many years, I dont know anymore of 
its history

Thanks

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Re: [Drakelist] TR-7 dial

2011-11-18 Thread Curt Nixon


I'm sure you are correct Jim...but I'm a short timer!

Curt

On 11/17/2011 8:46 PM, Jim Shorney wrote:

On Thu, 17 Nov 2011 09:48:33 -0500, Garey Barrell wrote:


I like the material of your CD washer, but the od is too big to fit through the 
front bezel of the 7
Line, and of course not nearly long enough.


The problem that I see with foam is that it tends to decay into goo after a
time. Given the orignal application, I can't imagine this type of foam is
designed for long lifetime.

I've used the automotive hose method, it works. And given the punishment this
type of hose is designed to take, I am quite sure it will last a lot longer
than I will.

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] TR-7 dial

2011-11-17 Thread Curt Nixon


Yes...

In the past I have use an O ring from the hardware store.

But the best is a white foam washer that is used in the packing of the 
cylinder packs of CD's and DVD blanks.  Approx ID is 9/16,  OD is approx 
1.2 and thickness approx 1/8.  Soft, high density foam.


Curt

On 11/16/2011 8:32 PM, Allen Bush wrote:
Does anyone have a recommendation for the little rubber piece that 
goes behind the dial skirt and allows the dial/knob to be slipped to 
calibrate the skirt?  Mine have turned hard and are cracking and 
turning to dust  Allen, W0OUU




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Re: [Drakelist] TR-7 dial

2011-11-17 Thread Curt Nixon


Isn't the clutch washer between the knob and the skirt?

Perhaps I'm thinking of the 3 and 4 series.

Curt

On 11/16/2011 10:17 PM, Garey Barrell wrote:

Allen -

There are several choices.  The original is surgical rubber tubing, 
which is a translucent amber colored rubber tubing.  It's very soft 
and flexible, and makes a great 'clutch' material.  Unfortunately 
after 30-40 years it gets hard and darkens in color.  It is difficult 
to find unless you have a friend who works in a hospital.  If you have 
a surgical supply store they will often cut off a foot or so for you, 
which is a lifetime supply.


Another possibility is automotive 'heater' hose, which is a black 
rubber, fabric reinforced tubing available at auto supply stores.  
Again they'll often cut off a piece, or sell you a foot cheaply.


Hardware stores also have poly tubing, the clear stuff on reels.  
Again, you need a foot or less!


ALL of the above are 3/8 id x 5/8 od.  You need to cut a piece about 
a half inch long.  More than the absolute length, the ends must be cut 
square and flat.  I use an X-Acto razor saw in the little aluminum 
'miter' box.  Various types of scissors and cutters will cut the 
tubing, but usually leave a poor end surface due to the tubing 
collapsing when cut.  But you've got a foot or so to experiment with, 
right?!?!


When you replace the MAIN TUNING knob, push in on it slightly to 
engage the clutch surfaces and then tighten the set screws.


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


Allen Bush wrote:
Does anyone have a recommendation for the little rubber piece that 
goes behind the dial skirt and allows the dial/knob to be slipped to 
calibrate the skirt?  Mine have turned hard and are cracking and 
turning to dust  Allen, W0OUU




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Re: [Drakelist] TR-7 dial

2011-11-17 Thread Steve Wedge

Apparently the 7's are different from the 3's and 4's.

While we're on the dial skirt topic, I've also found that, if you've busted 
that brittle circlip that's on the tuning shaft (or if it has moved; really - 
you do not want to try to spread it to move it back - DAMHIKT) of the B-Line 
that you can stack 1/4 x 20 washers on there until you get the proper spacing 
for the wave washer and dial skirt.  

That's also the way you can get a B knob and skirt onto a T-4X so it sorta 
matches an R-4B.

So now I'm curious: was the dial skirt assembly significantly different, or did 
Drake merely stop using the wave washers and switch to the tubing?

Enjoy Those Drakes...

Steve, W1ES/4

-Original Message-
From: Curt Nixon cptc...@flash.net
Sent: Nov 17, 2011 7:12 AM
To: drakelist@zerobeat.net
Subject: Re: [Drakelist] TR-7 dial

Isn't the clutch washer between the knob and the skirt?

Perhaps I'm thinking of the 3 and 4 series.

Curt

On 11/16/2011 10:17 PM, Garey Barrell wrote:
 Allen -

 There are several choices.  The original is surgical rubber tubing, 
 which is a translucent amber colored rubber tubing.  It's very soft 
 and flexible, and makes a great 'clutch' material.  Unfortunately 
 after 30-40 years it gets hard and darkens in color.  It is difficult 
 to find unless you have a friend who works in a hospital.  If you have 
 a surgical supply store they will often cut off a foot or so for you, 
 which is a lifetime supply.

 Another possibility is automotive 'heater' hose, which is a black 
 rubber, fabric reinforced tubing available at auto supply stores.  
 Again they'll often cut off a piece, or sell you a foot cheaply.

 Hardware stores also have poly tubing, the clear stuff on reels.  
 Again, you need a foot or less!

 ALL of the above are 3/8 id x 5/8 od.  You need to cut a piece about 
 a half inch long.  More than the absolute length, the ends must be cut 
 square and flat.  I use an X-Acto razor saw in the little aluminum 
 'miter' box.  Various types of scissors and cutters will cut the 
 tubing, but usually leave a poor end surface due to the tubing 
 collapsing when cut.  But you've got a foot or so to experiment with, 
 right?!?!

 When you replace the MAIN TUNING knob, push in on it slightly to 
 engage the clutch surfaces and then tighten the set screws.

 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


 Allen Bush wrote:
 Does anyone have a recommendation for the little rubber piece that 
 goes behind the dial skirt and allows the dial/knob to be slipped to 
 calibrate the skirt?  Mine have turned hard and are cracking and 
 turning to dust  Allen, W0OUU


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Re: [Drakelist] TR-7 dial

2011-11-17 Thread Nigel A. Gunn, W8IFF/G8IFF

I replaced mine with a felt disk.

On 17/11/11 13:00, drakelist-requ...@zerobeat.net wrote:

Message: 1
Date: Wed, 16 Nov 2011 17:32:43 -0800 (PST)
From: Allen Bushadb66...@yahoo.com
To:drakelist@zerobeat.net
Subject: [Drakelist] TR-7 dial
Message-ID:
1321493563.44233.yahoomailclas...@web161203.mail.bf1.yahoo.com
Content-Type: text/plain; charset=iso-8859-1

Does anyone have a recommendation for the little rubber piece that goes behind 
the dial skirt and allows the dial/knob to be slipped to calibrate the skirt?? 
Mine have turned hard and are cracking and turning to dust? Allen, W0OUU

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Re: [Drakelist] TR-7 dial

2011-11-17 Thread Garey Barrell

Curt -

No, they both go between the skirt and the washer in front of the C-clip. There are 'ears' in the
center hole of the skirt that fit into notches on the front of the larger brass shaft.

I like the material of your CD washer, but the od is too big to fit through the front bezel of the 7
Line, and of course not nearly long enough.

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

Curt Nixon wrote:

Isn't the clutch washer between the knob and the skirt?

Perhaps I'm thinking of the 3 and 4 series.

Curt

On 11/16/2011 10:17 PM, Garey Barrell wrote:

Allen -

There are several choices. The original is surgical rubber tubing, which is a translucent amber
colored rubber tubing. It's very soft and flexible, and makes a great 'clutch' material.
Unfortunately after 30-40 years it gets hard and darkens in color. It is difficult to find
unless you have a friend who works in a hospital. If you have a surgical supply store they will
often cut off a foot or so for you, which is a lifetime supply.

Another possibility is automotive 'heater' hose, which is a black rubber, fabric reinforced
tubing available at auto supply stores. Again they'll often cut off a piece, or sell you a foot
cheaply.

Hardware stores also have poly tubing, the clear stuff on reels. Again, you
need a foot or less!

ALL of the above are 3/8 id x 5/8 od. You need to cut a piece about a half inch long. More
than the absolute length, the ends must be cut square and flat. I use an X-Acto razor saw in the
little aluminum 'miter' box. Various types of scissors and cutters will cut the tubing, but
usually leave a poor end surface due to the tubing collapsing when cut. But you've got a foot or
so to experiment with, right?!?!

When you replace the MAIN TUNING knob, push in on it slightly to engage the clutch surfaces and
then tighten the set screws.

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

Allen Bush wrote:
Does anyone have a recommendation for the little rubber piece that goes behind the dial skirt
and allows the dial/knob to be slipped to calibrate the skirt? Mine have turned hard and are
cracking and turning to dust Allen, W0OUU

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Re: [Drakelist] TR-7 dial

2011-11-17 Thread Garey Barrell

The 7's are like the C-Line.  I've seen B-Lines with the wave washer and with the tubing.  I 'think' 
the B-Line was the same as the A from the factory, but the tubing method works.  The wave washer 
dug pretty deep grooves in the back of the dial skirt, and was 'gritty' to adjust.


The circlip IS a very brittle, HARD material.  I use circlip pliers, and all you have to do is take 
the pressure off (no visible gap between clip and shaft) just enough to allow you to slide it 
along.  I broke the first one many years ago by being too aggressive, and was never able to find a 
replacement.  There are plenty of the same size available, but not springy enough to hold against 
the dial pressure.


The B knob and skirt were a very popular item when they came out.  The slanted skirt is SOOO much 
better (easier to see!) in normal desk lighting.


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:

Apparently the 7's are different from the 3's and 4's.

While we're on the dial skirt topic, I've also found that, if you've busted 
that brittle circlip that's on the tuning shaft (or if it has moved; really - 
you do not want to try to spread it to move it back - DAMHIKT) of the B-Line 
that you can stack 1/4 x 20 washers on there until you get the proper spacing 
for the wave washer and dial skirt.

That's also the way you can get a B knob and skirt onto a T-4X so it sorta 
matches an R-4B.

So now I'm curious: was the dial skirt assembly significantly different, or did 
Drake merely stop using the wave washers and switch to the tubing?

Enjoy Those Drakes...

Steve, W1ES/4

-Original Message-

From: Curt Nixoncptc...@flash.net
Sent: Nov 17, 2011 7:12 AM
To: drakelist@zerobeat.net
Subject: Re: [Drakelist] TR-7 dial

Isn't the clutch washer between the knob and the skirt?

Perhaps I'm thinking of the 3 and 4 series.

Curt

On 11/16/2011 10:17 PM, Garey Barrell wrote:

Allen -

There are several choices.  The original is surgical rubber tubing,
which is a translucent amber colored rubber tubing.  It's very soft
and flexible, and makes a great 'clutch' material.  Unfortunately
after 30-40 years it gets hard and darkens in color.  It is difficult
to find unless you have a friend who works in a hospital.  If you have
a surgical supply store they will often cut off a foot or so for you,
which is a lifetime supply.

Another possibility is automotive 'heater' hose, which is a black
rubber, fabric reinforced tubing available at auto supply stores.
Again they'll often cut off a piece, or sell you a foot cheaply.

Hardware stores also have poly tubing, the clear stuff on reels.
Again, you need a foot or less!

ALL of the above are 3/8 id x 5/8 od.  You need to cut a piece about
a half inch long.  More than the absolute length, the ends must be cut
square and flat.  I use an X-Acto razor saw in the little aluminum
'miter' box.  Various types of scissors and cutters will cut the
tubing, but usually leave a poor end surface due to the tubing
collapsing when cut.  But you've got a foot or so to experiment with,
right?!?!

When you replace the MAIN TUNING knob, push in on it slightly to
engage the clutch surfaces and then tighten the set screws.

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


Allen Bush wrote:

Does anyone have a recommendation for the little rubber piece that
goes behind the dial skirt and allows the dial/knob to be slipped to
calibrate the skirt?  Mine have turned hard and are cracking and
turning to dust  Allen, W0OUU



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[Drakelist] TR-7

2011-11-17 Thread Billy Loyd

I have a Drake TR-7 and every now and then it will move 1000kc...In other words 
when on 3.700 it will change to 2.700...It does not last long but does it every 
so oftenAnyone have an idea where to start lookingThe voltege regulator 
pot is set at 10 voltsThats as far as I have checkedTnx in advance for 
the help.
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Re: [Drakelist] TR-7

2011-11-17 Thread Garey Barrell


Bill -

Does the radio move, or just the display?

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


Billy Loyd wrote:
I have a Drake TR-7 and every now and then it will move 1000kc...In other words when on 3.700 it 
will change to 2.700...It does not last long but does it every so oftenAnyone have an idea 
where to start lookingThe voltege regulator pot is set at 10 voltsThats as far as I have 
checkedTnx in advance for the help.

de BillKY4U


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Re: [Drakelist] TR-7 dial

2011-11-17 Thread Jim Shorney

On Thu, 17 Nov 2011 09:48:33 -0500, Garey Barrell wrote:

I like the material of your CD washer, but the od is too big to fit through 
the front bezel of the 7 
Line, and of course not nearly long enough.


The problem that I see with foam is that it tends to decay into goo after a
time. Given the orignal application, I can't imagine this type of foam is
designed for long lifetime.

I've used the automotive hose method, it works. And given the punishment this
type of hose is designed to take, I am quite sure it will last a lot longer
than I will.

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!

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will learn for a lifetime.

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[Drakelist] TR-7 dial

2011-11-16 Thread Allen Bush

Does anyone have a recommendation for the little rubber piece that goes behind 
the dial skirt and allows the dial/knob to be slipped to calibrate the skirt?  
Mine have turned hard and are cracking and turning to dust  Allen, W0OUU___
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Re: [Drakelist] TR-7 dial

2011-11-16 Thread Garey Barrell

Allen -

There are several choices. The original is surgical rubber tubing, which is a translucent amber
colored rubber tubing. It's very soft and flexible, and makes a great 'clutch' material.
Unfortunately after 30-40 years it gets hard and darkens in color. It is difficult to find unless
you have a friend who works in a hospital. If you have a surgical supply store they will often cut
off a foot or so for you, which is a lifetime supply.

Another possibility is automotive 'heater' hose, which is a black rubber, fabric reinforced tubing
available at auto supply stores. Again they'll often cut off a piece, or sell you a foot cheaply.

Hardware stores also have poly tubing, the clear stuff on reels. Again, you
need a foot or less!

ALL of the above are 3/8 id x 5/8 od. You need to cut a piece about a half inch long. More than
the absolute length, the ends must be cut square and flat. I use an X-Acto razor saw in the little
aluminum 'miter' box. Various types of scissors and cutters will cut the tubing, but usually leave
a poor end surface due to the tubing collapsing when cut. But you've got a foot or so to experiment
with, right?!?!

When you replace the MAIN TUNING knob, push in on it slightly to engage the clutch surfaces and then
tighten the set screws.

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

Allen Bush wrote:
Does anyone have a recommendation for the little rubber piece that goes behind the dial skirt and
allows the dial/knob to be slipped to calibrate the skirt? Mine have turned hard and are cracking
and turning to dust Allen, W0OUU

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Re: [Drakelist] TR-7 dial

2011-11-16 Thread K9sqg

My experience is that the independently owned hardware stores where I live 
actually sell surgical tubing in a few sizes.

-Original Message-
From: Garey Barrell k4...@mindspring.com
To: Allen Bush adb66...@yahoo.com
Cc: drakelist drakelist@zerobeat.net
Sent: Wed, Nov 16, 2011 5:18 pm
Subject: Re: [Drakelist] TR-7 dial

Allen -

There are several choices.  The original is surgical rubber tubing, which is a 
translucent amber 
colored rubber tubing.  It's very soft and flexible, and makes a great 'clutch' 
material.  
Unfortunately after 30-40 years it gets hard and darkens in color.  It is 
difficult to find unless 
you have a friend who works in a hospital.  If you have a surgical supply store 
they will often cut 
off a foot or so for you, which is a lifetime supply.

Another possibility is automotive 'heater' hose, which is a black rubber, 
fabric 
reinforced tubing 
available at auto supply stores.  Again they'll often cut off a piece, or sell 
you a foot cheaply.

Hardware stores also have poly tubing, the clear stuff on reels.  Again, you 
need a foot or less!

ALL of the above are 3/8 id x 5/8 od.  You need to cut a piece about a half 
inch long.  More than 
the absolute length, the ends must be cut square and flat.  I use an X-Acto 
razor saw in the little 
aluminum 'miter' box.  Various types of scissors and cutters will cut the 
tubing, but usually leave 
a poor end surface due to the tubing collapsing when cut.  But you've got a 
foot 
or so to experiment 
with, right?!?!

When you replace the MAIN TUNING knob, push in on it slightly to engage the 
clutch surfaces and then 
tighten the set screws.

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

Allen Bush wrote:
 Does anyone have a recommendation for the little rubber piece that goes 
 behind 
the dial skirt and 
 allows the dial/knob to be slipped to calibrate the skirt?  Mine have turned 
hard and are cracking 
 and turning to dust  Allen, W0OUU

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Re: [Drakelist] TR-7 Off Frequency (1Khz)

2011-07-05 Thread Jim Shorney

Hi Brian,

On Tue, 05 Jul 2011 13:26:33 -0400, bjon...@mindspring.com wrote:

Finally I
remembered my freq counter (keeps track of my 10Mhz frequency standard)
so I hooked the drake up to it directly and threw a 1W cw tone at it and
was off by 1Khz (i.e the DR7 displayed 14.2140, but the counter showed
14.2150)  (flipping over to the RV75 results in the same result)


A subtle, but important, distinction is that the TR-7 shifts the *transmit*
frequency from what the dial reads on CW. It seems that the majority of the
import rigs shift the recieve frequency. Thus, the DR-7 readout will be around
800 Hz off from your frequency counter in CW transmit. IIRC, this is not true
for AM, so try an carrier in AM mode.

So my first question is:
When trying to use WWV to determine receive frequency, what is the best
way to do so? Apparently how I have been doing it for years is
incorrect! 

What I usually do is set the PBT to center, RIT off, and adjust for zero beat
with WWV's carrier in SSB mode. This is easier if done during the periods when
WWV does not transmit audio tones. You will need to turn the volume up as you
approach zero beat in order to hear the beat note better. Use the strongest WWV
you can find. I'm curious as to how you were doing it that you think is
incorrect?

Question number two:
If both my transmit and receive frequency are off the same amount (1Khz)
is there an adjustment on the DR-7 that will allow it to display
correctly (My first glance through the service manual did not reveal any
way, but I thought I would ask the experts here) or is that something
that would have to be fixed through an alignment of the TR7?  (or at
1Khz off is it better to just tape a sticky note to the table reminding
me to add +1?)

The only adjustment that could possibly cause a TX/RX shift problem here is the
RIT center pot on the parent board. Otherwise, your RX and TX are the same as
the signals come from the same source. There is no seperate reference for the
DR-7. You rig may need to have the RIT center adjusted, and/or a frequency
alignment of the oscillators. This is not a hard thing to do, but you do need a
sensitive counter to read the oscillator signals. First, check the +10v
adjustment; if it's too far off, it will need to be set to 10V and you may need
to touch up the AGC/S-Meter adjustment. Then you will adjust the 40 MHz, 13.695
MHz, and 8.05 MHz, in that order. That should get you there, but it's a good
idea to check the fixed passband adjustments while you are at it. They are
almost always off a little. Follow the adjustment procedure in the service
manual, without skipping any steps, and you should be fine. I've found that
it's a good idea to isolate the counter probe from the signal under test with
an as high in value (carbon) resistor as you can use and still get a stable
reading, as the load of the counter can shift the oscillators a tiny but
(probably not enough to be concerned, but I'm picky). This seems to be most
apparent on the 40 MHz.

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] TR-7 HELP

2011-05-12 Thread Curt Nixon

On this page...down to restoration techniques...TR-7 Sticky Paint 
repair.  It works and is a lot easier to do than a repaint.


Lots of other great info also

http://www.wb4hfn.com/DRAKE/DrakeTechTips.htm

Curt
KU8L



Norman  Barbara Ray wrote:
I have a complete TR-7 which I am helping a silent key widow dispose 
of.  It has all the boxes made for it including a bunch of Drake log 
books. 
 
I know this has been covered so apologize ahead of time for posting 
this but I am concerned about the finish being what some call 
“sticky”.  It is in relatively good shape but has a few marks on it.  
It seems to me from previous discussions with Drake and Alpha that 
there may be a procedure short of stripping and re-painting with the 
Drake paint  to make it look some better.   I have a buyer for it and 
they have not expressed any problem with the finish but would like to 
pass on any information so they can make a decision if they end up 
buying it.
 
This is a well cared for TR-7 system and want to make sure it goes to 
someone who appreciates the heritage of Drake.  It is one of the few 
complete system I have seen even with the Drake mike and the dummy load.
 
Any help would be appreciated.
 
Norm W7LFA



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[Drakelist] TR-7 no transmit

2011-02-18 Thread

Power up, good receive on short 20' wire, s-3 steady, couple of jumps to s-5 on 
strong 20 meter signal.  S-meter drops to zero, and no movement on w-7 meter on 
transmit test, two differet 7077, A-104 mics.(300 watt drake dummy attached to 
W7)  mid 3k range, all late boards, including aux7, NB, 2nd IF, only early is 
on the PA, small board, have a late series pa brick, and several assorted 
boards as spares. Before start-up, carefully pulled, de-oxit pins, and several 
re-seatings all topside boards, and hit the band switches also first with kroil 
and then with de-oxit, as start. VFO now very smooth and easy turning.  Cured 
the aux7 of 3 bands changing displays routine.  Frequency rock solid stable, 
except .9/0. can flicker back and forth on a very small spot...LOL

Since my gear is very limited, any suggestions as to board swaps as a testing 
bed would be welcome, Starting as to whether the pa brick might be a good 
start? Probably missing several, but can try the ones I have.  I'd rather spend 
a few hours on this then merely send it out somewheres,..at least maybe narrow 
it down some. Maybe get lucky!

Last night, heard a signal out of Japan and Europe, S3, Boston boomed in S5.  
S-3 barely audible on speaker, but my hearing pretty poor, earphones help a 
lot. on 20' of #12 house wire up a floor and across the ceiling a ways.

Meanwhile, will spend some time in the service manual, read it carefully 
through, and bookmark starting points.  Time to see if the heatkit testing rig 
Vxxx works, and look over that manual, also. Fluke 87, screwdriver, and 
extender board set on hand. Not in a hurry.

Good break in weather today, 40's.  One of the pigs jumped? over the 18 of 
fence above the 2 1/2 ft of hardpack, and went shoulder deep in 3' unpacked 
snow. Poor piggy didn't go far, backed up after less than 15' and climbed back 
into the pen, urged on by the other pig happily slurping down alone the 2nd 
pail of warm feed and some hot boiled potatoes.  They do like to 
eat...Yorkshires, 18 months now, getting pretty big.  Ever see the cartoon 
movie, Pigs is Pigs  Disney, I think...digressing

73'a
ken
AB1JZ

p.s. some might be interested in this: Egypt Influence Network, from Egypt 
tweetgrid postings on tb2k, pg 105? of the series ofnear continuous coverage.

http://www.kovasboguta.com/uploads/4/7/9/5/4795292/egyptinfluencenetwork.pdf  

This is high res version, and is a small indication of what monitoring and 
computers can do. My biggest surprise this is in the open...

_
Netscape.  Just the Net You Need.

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Re: [Drakelist] TR-7 no transmit

2011-02-18 Thread Ron

Ken,
Have you tried CW mode to see if it is related to the audio chain vs more or 
less just the RF chain?  

73,
Ron WD8SBB

--- On Fri, 2/18/11, kendw...@netscape.com kendw...@netscape.com wrote:

 From: kendw...@netscape.com kendw...@netscape.com
 Subject: [Drakelist] TR-7 no transmit
 To: drakelist@zerobeat.net
 Date: Friday, February 18, 2011, 4:56 PM
 Power up, good receive on short 20'
 wire, s-3 steady, couple of jumps to s-5 on strong 20 meter
 signal.  S-meter drops to zero, and no movement on w-7
 meter on transmit test, two differet 7077, A-104 mics.(300
 watt drake dummy attached to W7)  mid 3k range, all
 late boards, including aux7, NB, 2nd IF, only early is on
 the PA, small board, have a late series pa brick, and
 several assorted boards as spares. Before start-up,
 carefully pulled, de-oxit pins, and several re-seatings all
 topside boards, and hit the band switches also first with
 kroil and then with de-oxit, as start. VFO now very smooth
 and easy turning.  Cured the aux7 of 3 bands changing
 displays routine.  Frequency rock solid stable, except
 .9/0. can flicker back and forth on a very small spot...LOL
 
 Since my gear is very limited, any suggestions as to board
 swaps as a testing bed would be welcome, Starting as to
 whether the pa brick might be a good start? Probably missing
 several, but can try the ones I have.  I'd rather spend
 a few hours on this then merely send it out somewheres,..at
 least maybe narrow it down some. Maybe get lucky!
 
 Last night, heard a signal out of Japan and Europe, S3,
 Boston boomed in S5.  S-3 barely audible on speaker,
 but my hearing pretty poor, earphones help a lot. on 20' of
 #12 house wire up a floor and across the ceiling a ways.
 
 Meanwhile, will spend some time in the service manual, read
 it carefully through, and bookmark starting points. 
 Time to see if the heatkit testing rig Vxxx works, and look
 over that manual, also. Fluke 87, screwdriver, and extender
 board set on hand. Not in a hurry.
 
 Good break in weather today, 40's.  One of the pigs
 jumped? over the 18 of fence above the 2 1/2 ft of
 hardpack, and went shoulder deep in 3' unpacked snow. Poor
 piggy didn't go far, backed up after less than 15' and
 climbed back into the pen, urged on by the other pig happily
 slurping down alone the 2nd pail of warm feed and some hot
 boiled potatoes.  They do like to eat...Yorkshires, 18
 months now, getting pretty big.  Ever see the cartoon
 movie, Pigs is Pigs  Disney, I think...digressing
 
 73'a
 ken
 AB1JZ
 
 p.s. some might be interested in this: Egypt Influence
 Network, from Egypt tweetgrid postings on tb2k, pg 105? of
 the series ofnear continuous coverage.
 
 http://www.kovasboguta.com/uploads/4/7/9/5/4795292/egyptinfluencenetwork.pdf 
 
 
 This is high res version, and is a small indication of what
 monitoring and computers can do. My biggest surprise this is
 in the open...
 
 _
 Netscape.  Just the Net You Need.
 
 ___
 Drakelist mailing list
 Drakelist@zerobeat.net
 http://mailman.zerobeat.net/mailman/listinfo/drakelist
 


  

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Re: [Drakelist] TR-7 no transmit

2011-02-18 Thread Jim Shorney

On Fri, 18 Feb 2011 13:56:25 -0800, kendw...@netscape.com wrote:

S-meter drops to zero, and no movement on w-7 meter on transmit test, two 
differet 7077, A-104 mics.

Any output in CW or AM?

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] TR-7 local oscillator

2011-02-02 Thread Al Ward

Garey
I appreciate your comments as well as others on their recommendations. Looks
like a weekend project.
73
Al W5LUA 

-Original Message-
From: drakelist-boun...@zerobeat.net [mailto:drakelist-boun...@zerobeat.net]
On Behalf Of Garey Barrell
Sent: Wednesday, February 02, 2011 3:33 AM
Cc: drakelist@zerobeat.net
Subject: Re: [Drakelist] TR-7 local oscillator

Al -

There are two PLL's in the TR-7, one for the bands below 20M and another for
bands above.  Your 'high band' VCO is not locking.  The 'wandering' 
frequency is just the free-running VCO going to it's 'idle' frequency 'or
so', which should be around 32 MHz.

First suspect is corrosion on the card connector pins, and of course all the
likely candidates are UNDER the DR-7 board.  Get a bottle of DeoxIT D100L,
and set aside an afternoon to remove, DeoxIT and replace all the boards.  It
doesn't hurt to twist each of the coax cables a bit at each termination.  If
you unplug one, be careful to get the center conductor (contact 'pin')
aligned carefully before pushing it home.  Careful also to get the DR-7 pins
nice and straight to ensure they go into the correct socket.

If that doesn't take care of it, (~95% probability that it WILL,) then check
the +24 VDC supply on the small power supply board just behind the front
panel logo.  Careful to not bump the trimpots, especially the right-most one
closest to the side panel.  If this voltage is low, verify that the top half
of the DC-DC converter transformer on that board is in place and firmly in
contact with the lower half.  Two 'E' 
shaped cores, 'face-to-face' and in firm contact.  The shorted loop of wire
around the transformer IS supposed to be there, not to hold the halves
together (wrong axis anyway!) but to minimize the external field from the
transformer.

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


Al Ward wrote:
 Hello to the group
 My TR-7 local oscillator for bands 20M and above will not lock. The 
 display shows it wondering up in frequency. The last band position 
 that works properly is the 7 MHz position and you can step the 
 frequency segments up to 10 MHz and that is as high as it will go and 
 stay locked.
 Does anyone have any advice on what and where to look for the problem? 
 I did buy some extender boards in preparation to work on this problem.
 Thanks and 73
 Al W5LUA


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[Drakelist] TR-7 local oscillator

2011-02-01 Thread Al Ward

Hello to the group
My TR-7 local oscillator for bands 20M and above will not lock. The display
shows it wondering up in frequency. The last band position that works
properly is the 7 MHz position and you can step the frequency segments up to
10 MHz and that is as high as it will go and stay locked.
Does anyone have any advice on what and where to look for the problem? I did
buy some extender boards in preparation to work on this problem.
Thanks and 73
Al W5LUA
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Re: [Drakelist] TR-7 local oscillator

2011-02-01 Thread Jim Shorney

First things to check are the +24v power supply and those pesky Molex pin
connectors between the DR-7 and the boards underneath it.

73

-Jim


On Wed, 2 Feb 2011 00:49:10 -, Al Ward wrote:

Hello to the group
My TR-7 local oscillator for bands 20M and above will not lock. The display
shows it wondering up in frequency. The last band position that works
properly is the 7 MHz position and you can step the frequency segments up to
10 MHz and that is as high as it will go and stay locked.
Does anyone have any advice on what and where to look for the problem? I did
buy some extender boards in preparation to work on this problem.
Thanks and 73
Al W5LUA



--
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] TR-7 local oscillator

2011-02-01 Thread Garey Barrell


Al -

There are two PLL's in the TR-7, one for the bands below 20M and another 
for bands above.  Your 'high band' VCO is not locking.  The 'wandering' 
frequency is just the free-running VCO going to it's 'idle' frequency 
'or so', which should be around 32 MHz.


First suspect is corrosion on the card connector pins, and of course all 
the likely candidates are UNDER the DR-7 board.  Get a bottle of DeoxIT 
D100L, and set aside an afternoon to remove, DeoxIT and replace all the 
boards.  It doesn't hurt to twist each of the coax cables a bit at each 
termination.  If you unplug one, be careful to get the center conductor 
(contact 'pin') aligned carefully before pushing it home.  Careful also 
to get the DR-7 pins nice and straight to ensure they go into the 
correct socket.


If that doesn't take care of it, (~95% probability that it WILL,) then 
check the +24 VDC supply on the small power supply board just behind the 
front panel logo.  Careful to not bump the trimpots, especially the 
right-most one closest to the side panel.  If this voltage is low, 
verify that the top half of the DC-DC converter transformer on that 
board is in place and firmly in contact with the lower half.  Two 'E' 
shaped cores, 'face-to-face' and in firm contact.  The shorted loop of 
wire around the transformer IS supposed to be there, not to hold the 
halves together (wrong axis anyway!) but to minimize the external field 
from the transformer.


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


Al Ward wrote:

Hello to the group
My TR-7 local oscillator for bands 20M and above will not lock. The 
display shows it wondering up in frequency. The last band position 
that works properly is the 7 MHz position and you can step the 
frequency segments up to 10 MHz and that is as high as it will go and 
stay locked.
Does anyone have any advice on what and where to look for the problem? 
I did buy some extender boards in preparation to work on this problem.

Thanks and 73
Al W5LUA
   


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[Drakelist] TR-7 28 MHz power falloff


Hi gang,

Here's an odd one. Fired up the trusty 7-Line this weekend for the 10 Meter
contest, and I noticed that I wasn't gettng any ALC action and power output was
low. Further investigation revealed that the power drops from about 95 Watts CW
at 28.0 to around 65 Watts at 28.4 MHz into a DL-1000 dummy load. The PA was
rebuilt a couple of years ago per the article on the WB4HFN web site, and has
been rock solid until now. My first inclination without cracking the manual is
a faulty component in the output lowpass filter, or perhaps some other filter
stage somewhere.

Any thoughts? I'm not going to bench the radio in the middle of a contest,
despite the fact that the propagation gods are ignoring me again, just trying
to formulate a plan of attack.

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
http://www.nebraskaghosts.org



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Re: [Drakelist] TR-7 28 MHz power falloff

Thanks, Bob. Yeah, I know that those PIN diodes get blamed for lots of stuff
that they don't really cause. :) I was getting a solid 90+ watts out on 10
Meters, with ALC, after I rebuilt the PA deck. Perhaps not the best it could
do, but certianly adequate. The power level drop does not concern me so much,
as we all know you can work 10 with a wet noodle when the band is open. Rather,
the lack of ALC makes it easier to overdrive something under these conditions.
I can level the output with my SP-75, and a check with a local indicated that I
was OK at that level, but it still needs to be fixed later.  And, of course,
I'll check the PIN diodes again...

73

-Jim

On Sat, 11 Dec 2010 09:51:48 -0800, Robert Fish wrote:

Hi Jim,
I think you are probably aware of the Pin Diode issues on the higher 
bands. I think that affects the whole band or bands (15 meters too).
Not just a portion of a band. It does seem like your LPF's are rolling 
off early.

I am using a TR-7 on the 10 meter contest right now as well. I am barely 
driving a linear amp (20 watts) to get me up to 150 watts with it.
Why not just run a KW. You ask? It brings the neighbors and the family  
out of the wood work if I run 1000 watts  on 28 MHZ.


Bob  K6GGO


 Hi gang,

 Here's an odd one. Fired up the trusty 7-Line this weekend for the 10 Meter
 contest, and I noticed that I wasn't gettng any ALC action and power output 
 was
 low. Further investigation revealed that the power drops from about 95 Watts 
 CW
 at 28.0 to around 65 Watts at 28.4 MHz into a DL-1000 dummy load. The PA was
 rebuilt a couple of years ago per the article on the WB4HFN web site, and has
 been rock solid until now. My first inclination without cracking the manual 
 is
 a faulty component in the output lowpass filter, or perhaps some other filter
 stage somewhere.

 Any thoughts? I'm not going to bench the radio in the middle of a contest,
 despite the fact that the propagation gods are ignoring me again, just trying
 to formulate a plan of attack.

 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!

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Re: [Drakelist] TR-7 28 MHz power falloff


I'm getting some great suggestions, thanks to everyone. 

However, just so we are all on the same page, I know about the PIN doides. I am
discounting them at this point since the power out is OK at 28.0, but falls off
by a good 35 watts by 28.4. This does not seem like PIN diode behaviour.

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!

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will learn for a lifetime.

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Re: [Drakelist] TR-7 28 MHz power falloff

2010-12-11 Thread Garey Barrell


Jim -

PIN diodes are kinda like PA tubes.  They get leaky, and start to fall 
off at the highest frequencies first.  They don't always short or open!


Perhaps this is why you're not hearing much on 10 either!  :-)

Yes, it could be a cap in the LP filter, but I'd say diodes are much 
more likely.


I think the Calibrator switching diodes are the primary culprit.

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


Jim Shorney wrote:

I'm getting some great suggestions, thanks to everyone.

However, just so we are all on the same page, I know about the PIN doides. I am
discounting them at this point since the power out is OK at 28.0, but falls off
by a good 35 watts by 28.4. This does not seem like PIN diode behaviour.

73

-Jim


   


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Re: [Drakelist] TR-7 28 MHz power falloff

Hi Gary,

On Sat, 11 Dec 2010 13:34:19 -0500, Garey Barrell wrote:

PIN diodes are kinda like PA tubes.  They get leaky, and start to fall 
off at the highest frequencies first.  They don't always short or open!

That may be true, but I wouldn't expect that much in just 400 KHz. I've been
tempted to remove that calibrator function anyway, on the 7-Line it just seems
to be enhanced uselessness. If it were a seperate 100 KHz crystal, maybe if
could be useful once in a while. But seeing as how it's derived from the same
master oscillator as the rest of the radio, if the radio is off, so is the
calibrator.


Perhaps this is why you're not hearing much on 10 either!  :-)

Seeing that the R-7 and the HR-2510 aren't hearing much either, I doubt it. I'm
also watching the DX-Sherlock prop maps, and they agree. Typical of Es in
December, Nebraska doesn't get much. It tends to favor the southern states and
the coast. Aside from that, I'm hearing plenty of spurs from digital stuff
across the band. :)

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/
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Re: [Drakelist] TR-7 Update

2010-10-17 Thread Jim Shorney

On Sat, 16 Oct 2010 20:19:54 -0400, K8JDC wrote:

I backed off the pot on the predriver board and it's happy so far.  I 
backed it off very slightly and it still oscillated on 40m so I had to 
go further.  I think I still have about the same output power and I 
think the ALC LED is still coming on correctly so I think it is okay.  I 
still have good power on 10m through 80m.

I was careful during the alignment to not set that pot too high.  Makes 
me wonder if something has drifted in value.


Proper alignment is a balance between the setting of the gain pot and the ALC
pot. Drake spec is to adjust the ALC for 140-150 watts on 20 Meters (CW,
carrier control fullly clockwise), then adjust the gain pot so you are *just*
into ALC on 10 Meters. The 10 Meter end of it can be a bit iffy, depending on
how your PA deck performs at the high end - sometimes you need more gain than
the circuit can handle, and 40 Meters takes off. There is an article on
WB4HFN's web site about rebuilding the PA deck with some more modern devices
that perform better at high frequencies. The gain of the transistors falls off
as you go up in frequency, so there is really too much gain in the circuit at
lower frequencies. The negative feedback circuit in the REV. 2 predriver board
is a RL network from collector to base of Q2201 which provides increasig
negative feedback as you go lower in frequency. My educated guess was that more
negative feedback was still needed, and reducing the value of R2203 achieved
this. There may or may not still be enough gain to get rated power on 10
Meters, results vary. It worked out well on my personal rig with the rebuilt PA
deck as per the aforementioned article, and another unit with a stock PA deck.
I'm still waiting for some engineer-dude to do the math on the feedback
thing... :)

I tried some other things, including adding extra grounding foil to the PA
board as described in an internet article from another ham, and nothing else
seemed to make a dent in the 40 Meter oscilation issue. Floyd's PIN diode
attenuator board is a neat idea, and I may give it a try someday just for fun,
but for now I'm sticking with the KISS principle - the simple fix is working
fine, and I'm happy.

--
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
http://www.nebraskaghosts.org



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[Drakelist] TR-7 Oscillating?


 Gents,

 My TR-7 started doing something unusual this morning.  I tried to 
check into a 40m phone net and I noticed my external VSWR meter going 
crazy.  It's a dual-needle type and I would start talking and things 
would be okay and then the reflected needle would instantly jump to 
infinity.  Unkey and try again and it would do the same...normal for a 
second or two and then a jump to infinity.  I think I saw the same 
behavior when I first got this radio and did the full alignment when 
adjusting the two big power output pots and it went into oscillation.  
(I don't recall the exact names of those pots but I recall one was in 
the PA section and one underneath the radio.)  My radio seemed to be a 
little touchy to those adjustments and wanted to oscillate but all has 
been well for the last 18 months or so until this morning.  As luck 
would have it, I recently rebuilt my microphone cable, re-arranged my 
ham desk, and adjusted my antenna slightly so I've touched about 
everything but I can't find any evidence that I have any kind of flaky 
connection in the antenna as that was my first thought given the 
reflected power indication.  The problem is that the reflected needle 
just goes from zero to infinity and I think that's exactly what it did 
when it went into oscillation.  My VSWR meter uses an inline directional 
coupler arrangement (Palstar WM-150)on the input to the tuner.  The 
receive strength is rock solid and we have no wind whatsoever on the 
antenna today.  I tried reducing mic gain and so on but the problem 
still happens.  It doesn't necessarily make sense to me that oscillating 
would cause the VSWR needle to jump but I'm pretty sure this is what it 
did when I adjusted those pots about 2 years ago.  Thought I would check 
with the experts before dragging it out of the operating position and 
trying to adjust those pots.


Thanks...

Dave
K8JDC

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Re: [Drakelist] TR-7 Oscillating?

2010-10-16 Thread Tom Evans, AG9X

Dave,

Does the built-in TR-7 reflected power meter jump to infinity?

A couple troubleshooting suggestions:

Disconnect the antenna and feed the TR-7 directly into a dummy load.

Disconnect the mic and see if this happens on CW.

Good luck with it.

Tom, AG9X



On Sat, Oct 16, 2010 at 9:19 AM, K8JDC k8...@sbcglobal.net wrote:
  Gents,

     My TR-7 started doing something unusual this morning.  I tried to check
 into a 40m phone net and I noticed my external VSWR meter going crazy.  It's
 a dual-needle type and I would start talking and things would be okay and
 then the reflected needle would instantly jump to infinity.  Unkey and try
 again and it would do the same...normal for a second or two and then a jump
 to infinity.  I think I saw the same behavior when I first got this radio
 and did the full alignment when adjusting the two big power output pots and
 it went into oscillation.  (I don't recall the exact names of those pots but
 I recall one was in the PA section and one underneath the radio.)  My radio
 seemed to be a little touchy to those adjustments and wanted to oscillate
 but all has been well for the last 18 months or so until this morning.  As
 luck would have it, I recently rebuilt my microphone cable, re-arranged my
 ham desk, and adjusted my antenna slightly so I've touched about everything
 but I can't find any evidence that I have any kind of flaky connection in
 the antenna as that was my first thought given the reflected power
 indication.  The problem is that the reflected needle just goes from zero to
 infinity and I think that's exactly what it did when it went into
 oscillation.  My VSWR meter uses an inline directional coupler arrangement
 (Palstar WM-150)on the input to the tuner.  The receive strength is rock
 solid and we have no wind whatsoever on the antenna today.  I tried reducing
 mic gain and so on but the problem still happens.  It doesn't necessarily
 make sense to me that oscillating would cause the VSWR needle to jump but
 I'm pretty sure this is what it did when I adjusted those pots about 2 years
 ago.  Thought I would check with the experts before dragging it out of the
 operating position and trying to adjust those pots.

 Thanks...

 Dave
 K8JDC

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[Drakelist] TR-7 - More Info


 Some more data points:

1.  I cannot get the radio to malfunction on a dummy load.  I have only 
seen the problem on 40m when connected to the antenna which is a 135-ft 
doublet fed with ladder line.  Tuner is a Tentec 238B and the tuner is 
right next to the TR-7.  That leads me to wonder if there's some RF from 
the balanced line that is part of the problem.


2.  I checked on 20m and don't see the problem on either a dummy load or 
my antenna which is a Steppir.  Output power is stable.


3.  The TR-7 forward meter goes to zero when the problem happens.  
Reflected indicator goes max scale.  So those readings are the same as 
my external meter.


4.  I hooked up my Tentec Orion to the same tuner/antenna and all is 
well.  No hint of anything wrong with the antenna.  Output power is 
totally stable.


5.  This problem happens on CW as well as SSB.  I have a toggle switch 
wired to key the radio for tuning and it will put out full power into 
the antenna for a few seconds and then the reflected power will go to 
infinity.  Power into the dummy load is fine.


6.  I did notice at least once that the problem occurred just as I 
unkeyed in CW mode.  So, just as I unkeyed, I saw the reflected power 
jump high.


So, the above leads me to wonder about the transmit relay.  I wondered 
if the contacts are somehow dirty but I don't see the problem on the 
dummy load so that leads me to wonder if the T/R relay is somehow being 
affected by some RF from the ladder line which is nearby.  It's not 
easily possible to separate the radio and tuner any more because of how 
my desk is laid out.  The ladder line comes out of the tuner and goes to 
the left to the outside world.  The TR-7 sits just to the right of the 
tuner so the ladder line does not go behind the radio although it's only 
about 10 inches away from the T/R relay when it exits the tuner.


??

Dave
K8JDC

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Re: [Drakelist] TR-7 - More Info

2010-10-16 Thread J. Steven Cochrane

Also check for a broken lead somewhere in the ladder line as well as the 
connections at the antenna. The breaks can be hard to see sometimes, so you 
have to check very closely.
I have basically the same set-up with one of my TR7s but I use an MN75. When 
one of the leads breaks on the ladder line, depending on where it is 
located, it can cause strange indications in the shack due to RF radiation.

Steve w7jsc


- Original Message - 
From: Don Cunningham wb5...@martineer.net
To: K8JDC k8...@sbcglobal.net; drakelist@zerobeat.net
Sent: Saturday, October 16, 2010 10:10 AM
Subject: Re: [Drakelist] TR-7 - More Info


 Dave,
 Do you have a good ground on your balanced line tuner??  I have those
 problems with my tuners and ladder line if I don't have a good ground 
 hooked
 up.
 73,
 Don, WB5HAK


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Re: [Drakelist] TR-7 - More Info

2010-10-16 Thread Garey Barrell


Dave -

If the external SWR meter goes to 'infinity' on reflected, then the 
problem is PAST that meter.  The fact that it is ok on a dummy load also 
indicates an antenna problem.


Sounds like an open feedline, - OR - balun, if used.

73, Garey - K4OAH
Glen Allen, VA

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


K8JDC wrote:

 Some more data points:

1.  I cannot get the radio to malfunction on a dummy load.  I have 
only seen the problem on 40m when connected to the antenna which is a 
135-ft doublet fed with ladder line.  Tuner is a Tentec 238B and the 
tuner is right next to the TR-7.  That leads me to wonder if there's 
some RF from the balanced line that is part of the problem.


2.  I checked on 20m and don't see the problem on either a dummy load 
or my antenna which is a Steppir.  Output power is stable.


3.  The TR-7 forward meter goes to zero when the problem happens.  
Reflected indicator goes max scale.  So those readings are the same as 
my external meter.


4.  I hooked up my Tentec Orion to the same tuner/antenna and all is 
well.  No hint of anything wrong with the antenna.  Output power is 
totally stable.


5.  This problem happens on CW as well as SSB.  I have a toggle switch 
wired to key the radio for tuning and it will put out full power into 
the antenna for a few seconds and then the reflected power will go to 
infinity.  Power into the dummy load is fine.


6.  I did notice at least once that the problem occurred just as I 
unkeyed in CW mode.  So, just as I unkeyed, I saw the reflected power 
jump high.


So, the above leads me to wonder about the transmit relay.  I wondered 
if the contacts are somehow dirty but I don't see the problem on the 
dummy load so that leads me to wonder if the T/R relay is somehow 
being affected by some RF from the ladder line which is nearby.  It's 
not easily possible to separate the radio and tuner any more because 
of how my desk is laid out.  The ladder line comes out of the tuner 
and goes to the left to the outside world.  The TR-7 sits just to the 
right of the tuner so the ladder line does not go behind the radio 
although it's only about 10 inches away from the T/R relay when it 
exits the tuner.


??

Dave
K8JDC




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Re: [Drakelist] TR-7 - More Info

2010-10-16 Thread Jim Shorney


That *almost* sounds like the 40 Meter oscillation problem - except for the
behaviour of the forward power meter. Some TR-7s are prone to PA deck
oscillation in the 40 meter band with a reactive load (antenna). The easy fix
for this is to reduce the gain of the predriver board by adjusting the provided
gain pot. The better fix that I have arrived at is to increase the negative
feedback in the predriver circuit, which reduces the overall gain of the
predriver and still allows full power output to be achieved. I've done this
only on REV. 2 predrivers, I haven't had a REV. 1 come across my bench yet.

73

-Jim


On Sat, 16 Oct 2010 13:00:30 -0400, Garey Barrell wrote:

Dave -

If the external SWR meter goes to 'infinity' on reflected, then the 
problem is PAST that meter.  The fact that it is ok on a dummy load also 
indicates an antenna problem.

Sounds like an open feedline, - OR - balun, if used.

73, Garey - K4OAH
Glen Allen, VA

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


K8JDC wrote:
  Some more data points:

 1.  I cannot get the radio to malfunction on a dummy load.  I have 
 only seen the problem on 40m when connected to the antenna which is a 
 135-ft doublet fed with ladder line.  Tuner is a Tentec 238B and the 
 tuner is right next to the TR-7.  That leads me to wonder if there's 
 some RF from the balanced line that is part of the problem.

 2.  I checked on 20m and don't see the problem on either a dummy load 
 or my antenna which is a Steppir.  Output power is stable.

 3.  The TR-7 forward meter goes to zero when the problem happens.  
 Reflected indicator goes max scale.  So those readings are the same as 
 my external meter.

 4.  I hooked up my Tentec Orion to the same tuner/antenna and all is 
 well.  No hint of anything wrong with the antenna.  Output power is 
 totally stable.

 5.  This problem happens on CW as well as SSB.  I have a toggle switch 
 wired to key the radio for tuning and it will put out full power into 
 the antenna for a few seconds and then the reflected power will go to 
 infinity.  Power into the dummy load is fine.

 6.  I did notice at least once that the problem occurred just as I 
 unkeyed in CW mode.  So, just as I unkeyed, I saw the reflected power 
 jump high.

 So, the above leads me to wonder about the transmit relay.  I wondered 
 if the contacts are somehow dirty but I don't see the problem on the 
 dummy load so that leads me to wonder if the T/R relay is somehow 
 being affected by some RF from the ladder line which is nearby.  It's 
 not easily possible to separate the radio and tuner any more because 
 of how my desk is laid out.  The ladder line comes out of the tuner 
 and goes to the left to the outside world.  The TR-7 sits just to the 
 right of the tuner so the ladder line does not go behind the radio 
 although it's only about 10 inches away from the T/R relay when it 
 exits the tuner.

 ??

 Dave
 K8JDC



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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
http://www.nebraskaghosts.org



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Re: [Drakelist] TR-7 - More Info

2010-10-16 Thread Douglas

 Date: Sat, 16 Oct 2010 12:03:18 -0400
 From: K8JDC k8...@sbcglobal.net
 To: drakelist@zerobeat.net
 Subject: [Drakelist] TR-7  - More Info
 Message-ID: 4cb9ccc6.7020...@sbcglobal.net
 Content-Type: text/plain; charset=ISO-8859-1;
 format=flowed

   Some more data points:

 1.  I cannot get the radio to malfunction on a dummy
 load.  I have only 
 seen the problem on 40m when connected to the antenna which
 is a 135-ft 
 doublet fed with ladder line.  Tuner is a Tentec 238B
 and the tuner is 
 right next to the TR-7.  That leads me to wonder if
 there's some RF from 
 the balanced line that is part of the problem.

 2.  I checked on 20m and don't see the problem on
 either a dummy load or 
 my antenna which is a Steppir.  Output power is
 stable.

 3.  The TR-7 forward meter goes to zero when the
 problem happens.  
 Reflected indicator goes max scale.  So those readings
 are the same as 
 my external meter.

 4.  I hooked up my Tentec Orion to the same
 tuner/antenna and all is 
 well.  No hint of anything wrong with the
 antenna.  Output power is 
 totally stable.

 5.  This problem happens on CW as well as SSB.  I
 have a toggle switch 
 wired to key the radio for tuning and it will put out full
 power into 
 the antenna for a few seconds and then the reflected power
 will go to 
 infinity.  Power into the dummy load is fine.

 6.  I did notice at least once that the problem
 occurred just as I 
 unkeyed in CW mode.  So, just as I unkeyed, I saw the
 reflected power 
 jump high.

 So, the above leads me to wonder about the transmit
 relay.  I wondered 
 if the contacts are somehow dirty but I don't see the
 problem on the 
 dummy load so that leads me to wonder if the T/R relay is
 somehow being 
 affected by some RF from the ladder line which is
 nearby.  It's not 
 easily possible to separate the radio and tuner any more
 because of how 
 my desk is laid out.  The ladder line comes out of the
 tuner and goes to 
 the left to the outside world.  The TR-7 sits just to
 the right of the 
 tuner so the ladder line does not go behind the radio
 although it's only 
 about 10 inches away from the T/R relay when it exits the
 tuner.

 ??

 Dave
 K8JDC

I've not found a 135 ft antenna feed with ladder line to be ideal on 40 meters. 
It presents a high impedance/high RF voltage load to your tuner, increasing the 
RF field around the ladder line and probably causing RF feedback within your 
TR7.

I'd attempt to lengthen the ladder line to find a combo that works better or 
better yet simply use another antenna on 40 mtrs. If you have enough room for 
135 ft, you have enough room for a 66 ft coax feed dipole for 40.

73,

Doug/WA1TUT

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Re: [Drakelist] TR-7 - More Info

2010-10-16 Thread Garey Barrell


Jim -

Is that a possibility?  If the antenna is tuned to 20M by the tuner, and 
the transmitter is putting out 40M RF, then the transmitter is seeing a 
mismatch and 'shuts down'.  Does it 'really' go to ZERO power or is it 
just rolled back to 20 or so Watts?


BUT, if you put 40M RF into a tuner set for 20M why would the external 
power meter show high reflected power?  Unless enough 40M RF is getting 
through the tuner to see the mismatched antenna


My head hurts   Worth looking into.

What's the serial number of the transceiver??

73, Garey - K4OAH
Glen Allen, VA

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


Jim Shorney wrote:

That *almost* sounds like the 40 Meter oscillation problem - except for the
behaviour of the forward power meter. Some TR-7s are prone to PA deck
oscillation in the 40 meter band with a reactive load (antenna). The easy fix
for this is to reduce the gain of the predriver board by adjusting the provided
gain pot. The better fix that I have arrived at is to increase the negative
feedback in the predriver circuit, which reduces the overall gain of the
predriver and still allows full power output to be achieved. I've done this
only on REV. 2 predrivers, I haven't had a REV. 1 come across my bench yet.

73

-Jim


On Sat, 16 Oct 2010 13:00:30 -0400, Garey Barrell wrote:

   

Dave -

If the external SWR meter goes to 'infinity' on reflected, then the
problem is PAST that meter.  The fact that it is ok on a dummy load also
indicates an antenna problem.

Sounds like an open feedline, - OR - balun, if used.

73, Garey - K4OAH
Glen Allen, VA

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


K8JDC wrote:
 

  Some more data points:

1.  I cannot get the radio to malfunction on a dummy load.  I have
only seen the problem on 40m when connected to the antenna which is a
135-ft doublet fed with ladder line.  Tuner is a Tentec 238B and the
tuner is right next to the TR-7.  That leads me to wonder if there's
some RF from the balanced line that is part of the problem.

2.  I checked on 20m and don't see the problem on either a dummy load
or my antenna which is a Steppir.  Output power is stable.

3.  The TR-7 forward meter goes to zero when the problem happens.
Reflected indicator goes max scale.  So those readings are the same as
my external meter.

4.  I hooked up my Tentec Orion to the same tuner/antenna and all is
well.  No hint of anything wrong with the antenna.  Output power is
totally stable.

5.  This problem happens on CW as well as SSB.  I have a toggle switch
wired to key the radio for tuning and it will put out full power into
the antenna for a few seconds and then the reflected power will go to
infinity.  Power into the dummy load is fine.

6.  I did notice at least once that the problem occurred just as I
unkeyed in CW mode.  So, just as I unkeyed, I saw the reflected power
jump high.

So, the above leads me to wonder about the transmit relay.  I wondered
if the contacts are somehow dirty but I don't see the problem on the
dummy load so that leads me to wonder if the T/R relay is somehow
being affected by some RF from the ladder line which is nearby.  It's
not easily possible to separate the radio and tuner any more because
of how my desk is laid out.  The ladder line comes out of the tuner
and goes to the left to the outside world.  The TR-7 sits just to the
right of the tuner so the ladder line does not go behind the radio
although it's only about 10 inches away from the T/R relay when it
exits the tuner.

??

Dave
K8JDC
   




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[Drakelist] TR-7 - More Info Cont'd

 To everybody who has written thus far, I thank you.  Still working on 
it...


- I have double-checked the ground connections on the tuner and radio.  
All is good there.


- To Gary who suggested that the external tuner indicated that the 
problem was past that point, I hooked my Tentec up to the same 
tuner/antenna and it is rock solid at full power output into the same 
configuration.  I also don't think I have a break in the ladder line for 
the same reason.  I have connected my MFJ-259 to the tuner input and the 
antenna is about 58+j7 in terms of impedance.  Looks rock solid on the 
259...no fluctuation.


- I can't induce the problem on 20m...only 40m.  I ran 20m CW into the 
same doublet/ladder line antenna and it's fine...at least through a 
short test.


- During testing, I notice that I can induce the problem by unkeying the 
radio a fairly high percentage of the time.  So, if I put it in CW and 
key up, all will be well until I unkey.  When I unkey, the reflected 
power will frequently jump.  Same on SSB if I key the mic with no input 
audio.  If I just key the mic with basically zero RF going out and then 
unkey, I will see the reflected needle jump when I let off the PTT 
switch.  This is what had me thinking about the T/R relay.  I tried this 
on 20m and didn't see the same thing.  It operated normally.


When I aligned this radio (I don't recall the exact S/N but I think it's 
around 4900), I had trouble keeping it from oscillating when I followed 
the instructions.  I tried to follow the service manual carefully but it 
wanted to oscillate.  I had to fiddle with it a fair amount going 
between the two adjustment pots to make it happy.  Maybe it's still too 
hot.  My meter says I'm getting about 125W out on 40m.


Dave
K8JD

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Re: [Drakelist] TR-7 - More Info Cont'd

2010-10-16 Thread Jim Shorney

On Sat, 16 Oct 2010 16:50:50 -0400, K8JDC wrote:

I had trouble keeping it from oscillating when I followed 
the instructions.  I tried to follow the service manual carefully but it 
wanted to oscillate.  I had to fiddle with it a fair amount going 
between the two adjustment pots to make it happy.  Maybe it's still too 
hot.  My meter says I'm getting about 125W out on 40m.



I would bet that if you had a frequency counter coupled to it, you would find
that it is oscillating somewhere in the 9 MHz area. That is the symptom of the
40 Meter oscillation problem that I found. 125 Watts is below the spec that
Drake says to align it to, so you should be able to get more out. I would have
to go back and look at my notes, but I think 330 Ohms paralleled across R2203
on the REV. 2 predriver board was what I used to increase the amount negative
feedback at lower frequencies. It may be possible or necessary to go even lower
in value, but this is what worked for me on two samples that I had. I was just
able to make rated output through adjustment of the predriver pot and ALC pot
without oscillation. It's hard to get it to oscillate into a dummy load, it
seems to need an antenna to take off.

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
http://www.nebraskaghosts.org



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Re: [Drakelist] TR-7 - More Info

2010-10-16 Thread Jim Shorney

On Sat, 16 Oct 2010 15:43:01 -0400, Garey Barrell wrote:


Is that a possibility?  If the antenna is tuned to 20M by the tuner, and 
the transmitter is putting out 40M RF, then the transmitter is seeing a 
mismatch and 'shuts down'.  Does it 'really' go to ZERO power or is it 
just rolled back to 20 or so Watts?


Actually, the oscillation seems to be inherent in the bandswitch segment that
covers 40 Meters. I was able to see it in any 500 KHz segment of that range,
and the actual frequency of the oscillation was in the area of 9 MHz,
regardless of which 500 KHz segment of that range that I was in. So, any
antenna resonant in a ham band would have high VSWR at the freqency of
oscillation. In power testing on a dummy load, I did seem to see a shallow peak
in output around 9 MHz, and for some reason this is what suggested to me that
the gain somewhere in the  predriver might be too high in that area. I ceased
further investigation once I found a fix that worked. Maybe somone who has the
proper software could model the REV. 2 predriver and see what crawls out.


BUT, if you put 40M RF into a tuner set for 20M why would the external 
power meter show high reflected power?  Unless enough 40M RF is getting 
through the tuner to see the mismatched antenna

My head hurts   Worth looking into.

What puzzles me is the behaviour of the forward power meter. IIRC, in the units
that I had here, the forward power was quite high when it was oscillating.
Almost like full power CW. Maybe it's some difference in the way the rigs were
adjusted.  WTF?

Interesting problem.

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
http://www.nebraskaghosts.org



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[Drakelist] TR-7 Update