If you have a general coverage receiver/transceiver, listen for the crystal on 21.5 MHz.? Take a wire from the receiver antenna input over to the TR4CW and place it near the crystal area. You should hear a strong signal. You can compare what you hear against one of the other bands that are working. You should have around the same signal level.?

Have you performed the procedure in sections 5-10 Injection Crystal Oscillator on page 5-2?? If the crystal is weak you can try swapping out the V1-6EA8 tube with a known good tube. You might be able to get more output with a stronger tube. You can swap the 6EA8 in V3 and see if the output is any better if you don't have a spare.?

Good luck,
Mark, WB0IQK

Both can still be found.







73

-Jim
NU0C

On Sat, 30 Mar 2024 01:46:08 -0700
"Glenn, OZ1HFT" <glenn.mh.dk@...> wrote:

Hi Mark

PIN diode inspiration:





Found via:


backup:


--

best regards,

Glenn, OZ1HFT

--

73

-Jim
NU0C

Glenn,

Thanks for the data. I will be looking out for PIN suitable for the TR-7 for my spares draw.

The three 1N4007 I substituted for the RX input / TX drive steering PIN on the HPF board are working OK, but I have made no measurements of the impact of their higher capacitance. A small relay might also make a good substitute for very expensive / unobtanium PIN. They are cheap enough, but parameters of particular interest to RF engineers are not usually specified, so it would be a case of suck it and see!

Regards,

Mark, G4FPH.

Jim,

Just put my later s/n (100xx) TR-7 on the bench, in place of the fixer-upper one, by way of a comparison. About time it saw some power!

Carrier suppression on the later one is -60 dB and no trace of any 1 kHz modulation spurs in the TX noise floor down as far as I can see.

With a normal amount of mic. gain, and replacing the mic. with a 600 R termination, the TX noise floor sits at around -85 dB, looks pretty flat across the SSB bandwidth, and does not sound 'crackly'. Winding the mic. gain flat out, the TX noise comes up to -70dB and again sounds 'smooth'.

So, I think I have answered the question I posed at the start of this thread: My early s/n radio could do a lot better!

Happy Easter to all!

Regards,

Mark, G4FPH.

Hi Mark

PIN diode inspiration:





Found via:


backup:


--

best regards,

Glenn, OZ1HFT

That could be. One thing that web browsers do is a lot of disk writes as they cache web pages.

73

-Jim
NU0C

On Fri, 29 Mar 2024 20:58:19 -0400
"Jeramy Thibodeaux" <kg4azt@...> wrote:

Tom,

My first thought was thinking a failing or undersized power supply.

40m is dead on my TR-4CW and suspect it may be the 21.5 overtone crystal. All other bands check okay.
Any suggestions on who could supply me one.?
Tnx.....Bill wa8bda

Tom,

My first thought was thinking a failing or undersized power supply.? Re-reading some of the responses I'm inclined to recommend trying these two things next (No Cost).

1. Hard drive defrag.


2. Open the PC.? Pull and Swap the memory sticks slots to see if the problem manifests in a different application.? Intent is to try and rule out a failing memory stick.

73,

JT
KG4AZT

Yes, I was part of the discussion. I also posted a link to W8JI's engineering analysis that shows why the indirectly grounded grid circuit was a bad idea. The idea did not originate with Drake and I have noted that amplifier manufacturers seem to have abandoned the idea more recently. Some never used it.

73

-Jim
NU0C

On Fri, 29 Mar 2024 20:46:27 -0700
"Richard Knoppow" <1oldlens1@...> wrote:

There was just some discussion about this, I think in this list.
Drake's idea was that the indirect grounding provided some negative feed
back which reduced the distortion. That may be desirable even at the
price of some reduction of power.

On 3/29/2024 6:53 PM, Jim Shorney wrote:

It is a PITA on an L7 due to the tight spaces. I just did a second one. Works nice.

73

-Jim
NU0C

--

73

-Jim
NU0C

There was just some discussion about this, I think in this list. Drake's idea was that the indirect grounding provided some negative feed back which reduced the distortion. That may be desirable even at the price of some reduction of power.

--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

It is a PITA on an L7 due to the tight spaces. I just did a second one. Works nice.

73

-Jim
NU0C

On Fri, 29 Mar 2024 15:37:30 -0700
"K6OXN Bob" <bobk6oxn@...> wrote:

I have had my L7 amplifier for about a year now, and it was working very well. I recently read and article about grounding the grids on the 3-500 tubes. I had not checked that with my L7. Today I had a chance to check and found that my tubes were wired just as Drake made them. With the RF chokes and the 1kv caps. Well I has some 16 gauge buss wire and decided to do the recommended grounding of the grids. Was not the most easy task, but taking my time about 2 hours or so.? I removed the RF chokes and caps and wired the grids pin 2,3, and 4 to ground with the buss wire. Firing up the L7 very gingerly and driving it with my TR7 at about 60 watts, I get about 600 watts out on CW and about 1200-1300 peak on SSB. So I guess the grounded grid is the way to go as it reduces the drive power and increases output power without the increase in plate current. I will keep this for now. I saved all the parts so it something happens, I can revert but it is working I think better will leave it.? Just some note on my L7, as it is a work horse.

On 3/29/24 17:37, K6OXN Bob wrote:

I have had my L7 amplifier for about a year now, and it was working
very well. I recently read and article about grounding the grids on
the 3-500 tubes. I had not checked that with my L7. Today I had a
chance to check and found that my tubes were wired just as Drake made
them. With the RF chokes and the 1kv caps. Well I has some 16 gauge
buss wire and decided to do the recommended grounding of the grids.
Was not the most easy task, but taking my time about 2 hours or so.? I
removed the RF chokes and caps and wired the grids pin 2,3, and 4 to
ground with the buss wire. Firing up the L7 very gingerly and driving
it with my TR7 at about 60 watts, I get about 600 watts out on CW and
about 1200-1300 peak on SSB. So I guess the grounded grid is the way
to go as it reduces the drive power and increases output power without
the increase in plate current. I will keep this for now. I saved all
the parts so it something happens, I can revert but it is working I
think better will leave it.? Just some note on my L7, as it is a work
horse.

When I grounded the grids on my L-4B; I used wide strips of copper cut
from a sheet of copper.? I don't recall the thickness of the sheet, but
it's one I got at a hobby shop.

73

Stan
KM4HQE

I have had my L7 amplifier for about a year now, and it was working very well. I recently read and article about grounding the grids on the 3-500 tubes. I had not checked that with my L7. Today I had a chance to check and found that my tubes were wired just as Drake made them. With the RF chokes and the 1kv caps. Well I has some 16 gauge buss wire and decided to do the recommended grounding of the grids. Was not the most easy task, but taking my time about 2 hours or so.? I removed the RF chokes and caps and wired the grids pin 2,3, and 4 to ground with the buss wire. Firing up the L7 very gingerly and driving it with my TR7 at about 60 watts, I get about 600 watts out on CW and about 1200-1300 peak on SSB. So I guess the grounded grid is the way to go as it reduces the drive power and increases output power without the increase in plate current. I will keep this for now. I saved all the parts so it something happens, I can revert but it is working I think better will leave it.? Just some note on my L7, as it is a work horse.

开云体育

Cache is clear. ? History cleaned. ? Used chrome Firefox edge. ?No diff. ?Ran 2complete virus Chk ?over 3 hrs. ? No diff. ? ?Nothing found. ? ? Tom

开云体育

I keep thinking that but insides are dust free. ? No warm parts. ? Using win10 win defender. ? Fans all work. ? Tom

Nice work Mark! You're making progress. It will be interesting to see where you end up.

73

-Jim
NU0C

On Fri, 29 Mar 2024 12:17:03 -0700
"atlasstuff" <g4fph@...> wrote:

Jim,

I found the article from Feb. 1989 by AE7K, entitled 'Zener Diode Noise'. I won't be undertaking 'carpet-bombing' bypassing all of the regulators in my radio!

I had previously added the additional bond to the corner of the HPF board to fend off the 40 m oscillation issue. I've now added a couple of additional bonds (well, there were empty holes, now filled with bolts and solder tags!), so that all three boards comprising the HPF assembly are bonded to nearby metalwork (the centre board having a bond at either end). Interestingly, even after doing this, by waggling the piece of metal around the HPF behind the S-meter lamp, I could still provoke the low-level spurs in the receiver to show themselves. At some point, I will replace the sheet metal screws that fix the HPF 'shield' to the sidewall with bolts and nuts, as these screws clearly do not clamp the two metal parts together sufficiently. I see more sheet metal screws holding the screen between HPF and LPF assemblies. I might do those to.

I played around with the 7805 regulator that feeds the display part of the DR7. I added a solder tag it's nearby bolt to give a more local ground. Installing capacitors between input and output pins of 7805 to this local ground has reduced the level of the spikes on the DC rails both sides of the regulator. Output-side fast spikes have dropped from 80 mV p-p (when I turned the brightness on the 'scope up!) to 20 mV p-p. Input-side now has no fast spikes, just a 50 mV p-p 1 kHz ripple. Capacitors used were a 470 uF electrolytic on the input side and a 100 uF tantalum, plus a 150 nF (probably not needed) on the output side. I'll play with these values some more, before deciding whether to keep the mod.

On TX, the effect of the additional bypassing has dropped the level of the 1 kHz modulation by 10 dB, or so, 2 kHz modulation is at about the same level as the 1k. I had another go at the carrier balance and achieved between -62 and -65 dB, so now in spec:-)

There's quite a few 0.22 uF capacitors on the Transmit Exciter board. I need to order some of these in.

Regards,

Mark, G4FPH.

--

73

-Jim
NU0C

Tom,

If you are using your PC mainly for email and internet browsing I would suggest installing Linux on for that purpose.? Pick your flavor (I have used OpenSuSE since about 2001) but if you're a Linux beginner, just go to and follow the simple directions.

Ubuntu (or )? is probably the easiest and most popular Linux for people familiar with Windows and has the most Ham Radio applications available (like FLDIGI, WSJT-X logging programs etc....and no, HRD doesn't run on any Linux AFAIK)

I actually have a Winblows10 laptop but I only use it for TurboTax and other programs that require win10.?

?My main Linux desktop and a MAC Book Pro (Mid2012)? runs OpenSuSE Linux Leap 15.5 X64 ?

I use it for all email (using Thunderbird) and all internet browsing using Firefox.?? I do all my banking and everything else using Linux. "Office Stuff" (word processing/spreadsheets etc)? is accomplished using LibreOffice (which is available for Linux, Winblows and the MAC (not the truck)

ymmv !
--

73/Rick

W4XA
*Every post is created using Linux

Jim,

I found the article from Feb. 1989 by AE7K, entitled 'Zener Diode Noise'. I won't be undertaking 'carpet-bombing' bypassing all of the regulators in my radio!

I had previously added the additional bond to the corner of the HPF board to fend off the 40 m oscillation issue. I've now added a couple of additional bonds (well, there were empty holes, now filled with bolts and solder tags!), so that all three boards comprising the HPF assembly are bonded to nearby metalwork (the centre board having a bond at either end). Interestingly, even after doing this, by waggling the piece of metal around the HPF behind the S-meter lamp, I could still provoke the low-level spurs in the receiver to show themselves. At some point, I will replace the sheet metal screws that fix the HPF 'shield' to the sidewall with bolts and nuts, as these screws clearly do not clamp the two metal parts together sufficiently. I see more sheet metal screws holding the screen between HPF and LPF assemblies. I might do those to.

I played around with the 7805 regulator that feeds the display part of the DR7. I added a solder tag it's nearby bolt to give a more local ground. Installing capacitors between input and output pins of 7805 to this local ground has reduced the level of the spikes on the DC rails both sides of the regulator. Output-side fast spikes have dropped from 80 mV p-p (when I turned the brightness on the 'scope up!) to 20 mV p-p. Input-side now has no fast spikes, just a 50 mV p-p 1 kHz ripple. Capacitors used were a 470 uF electrolytic on the input side and a 100 uF tantalum, plus a 150 nF (probably not needed) on the output side. I'll play with these values some more, before deciding whether to keep the mod.

On TX, the effect of the additional bypassing has dropped the level of the 1 kHz modulation by 10 dB, or so, 2 kHz modulation is at about the same level as the 1k. I had another go at the carrier balance and achieved between -62 and -65 dB, so now in spec:-)


There's quite a few 0.22 uF capacitors on the Transmit Exciter board. I need to order some of these in.

Regards,

Mark, G4FPH.