Okay: I'll measure D5 again.
 I think I'm getting it narrowed down and thanks to all as I've re-learned a bit since my novice and general days in the 1970's when I had ample time as a teenager to dig into things with big tubes, heavy wires, and hefty switches. 

When decent paychecks (and surface mounting) came along later, it became convenient to let someone else fix it.

Dave

I sincerely grateful for all the suggestions and handholding!  I want to give all the Elmers a status report at this mid-point in the process, as I'm sure it'll help others.

I now have a massive dummy load for power supply testing, by the way.

Here's what I've found from all of the helpful suggestions:

The voltage across D5 drops under load conditions. This is contrary to Tanakasan's  results if D5 was good.

The remainder of the testing below indicates the LM723, 1n1184a silicon rectifier diodes, and the filter caps ( two 32k filter capacitors) show to be good. Specifically: 

The voltage between pin 12 and pin 7 of the LM723 drops only a little when tested under load conditions. 

Moving the + lead to LM723 pin 10 shows voltage increase under load conditions vs no-load.

The 1n1184a silicon rectifier diodes are good.

There is no voltage sag at the + terminal of the filter caps: voltage is steady under load and no-load conditions.

I tried two LM743's and still get voltage drop under load testing.

The voltage at each pass transistor emitter is the same at 1.19 volts.

So, this eliminates some more of the components as being bad, and next on the list is to test the Q2  TIP29A and D5 1N4002.
Thanks for the help and the learning process support.

Dave

If it's is easy to run the ladderline, do it! 

I live in a HOA subdivision and have only two small palm trees on my lot, both of them in the front yard.  I have no decent option for an antenna except in the attic. 

My shack is on the second floor with no earth ground nearby.

I run ladderline from an external antenna tuner, to behind an entertainment center with all sorts of wires and cables back there, though the wall, and into the attic to a zig-zag wire "loop" (if you can call it a "loop") up about 20 feet.  There's just no way I can keep ladderline away from other objects, wires, or metal.

It works well.

It also solved an RFI problem that no counterpoise could.

Try it.

Dave

Regarding bulbs as RF indicators, I was testing my Galaxy 5 MK III transceiver one day in 1975 using a 75 w incandescent bulb connected to the output of my rig. The bulb was on the table next to me.

I was transmitting, "Hello, test. Testing. Testing. Helllllooooooo". When I released the mic button,  I was called by W4CMI (SK) who was about a mile away. We chatted for awhile, then I rode my bike to his house and we had a nice eyeball.

Dave

A nearby lightning strike made my Astron RS-35A inoperative.

I've replaced the 4 pass transistors, the SCR 2N681, and the LM723 voltage regulator chip. The power supply now comes to life with 13.8 volts output under no-load testing.

When I connect a Kenwood TS440s (in receive mode), the voltage output drops to about 7 volts, and of course, the transceiver barely energizes.

Similar low-voltage result with a Yaesu 2 m FM rig.

The Yaesu 2 M rig was not involved in the lightning strike.

I tried another LM723, but still get a big drop in output voltage.

What would be the likely culprit for this wimpy output under load and how should I proceed?

Thanks.

Dave

How to uninstall Multipsk :   

The directions to uninstall of Multipsk are found in the README file within Multipsk. The details are show below:

UNINSTALLATION OF THE MULTIPSK AND CLOCK APPLICATIONS
As there is no change in the Windows registers base, these applications
can be uninstalled manually (with Windows Explorer) by deleting the folder
containing the Multipsk and Clock files.
Since the registry base is not modified from MultiPSK installation, you will not find MultiPSK listed in the Windows "Add or Remove" section of the Control Panel.

I had the same trouble with my RS-35A blowing fuses after a lightning strike.  I found the technical hand-holding very helpful and the comments from experienced electronic techs were awesome. Thank you.

My Astron RS-35A is now working again: one of the 2N3055 pass transistors was bad. For the sake of clarity for those (like me) who haven't dissected their Astrons before, that the 4 pass transistors (on the back of the power supply, within the heat sink) can be replaced in 4 minutes without soldering as they unscrew and can be pried out. The new transistors plug in only one way. Easy.

Dave
n 4 e f

From the reference materials I have regarding the Cobra 138 CB rig conversion to 10 meters:

The Cobra 138 is a fine rig for conversion to 10 meters.  The original 7.8025 MHz crystal is the only crystal that needs changing.

Send me your email address and I'll scan and send you the article.

Dave n4ef ^(at) ATT _(dot) net

Brett, how were you able to remove the wax?

I have a TS440s with similar and well known problem, but I've not been successful removing the wax.

How did you do it?

Dave N4EF

My shack is on the second floor. I tried long ground wires (like you suggested). Too much RFI.

I tried counterpoises. Too much RFI.

I eliminated coax cable feedlines using ladderline instead. POOF! RFI GONE!

My set-up:
RIG-to-MFJ el cheapo antenna tuner-to-ladderline-to-antenna in attic

I have no ground to anything and my TS440s works great with all my computer and electronic equipment throughout the house.  XYL is happy.

Dude,balanced lines rule.

Dave N4EF

My shack is on the second floor. I tried long ground wires (like you suggested). Too much RFI.

I tried counterpoises. Too much RFI.

I eliminated coax cable feedlines using ladderline instead. POOF! RFI GONE!

My set-up:
RIG-to-MFJ el cheapo antenna tuner-to-ladderline-to-antenna in attic

I have no ground to anything and my TS440s works great with all my computer and electronic equipment throughout the house.  XYL is happy.

Dude,balanced lines rule.

Dave N4EF

I've heard those tones as well, and believe they are JT65, a slow MFSK.

Bingo! MICROPHONICS: That must be the reason for the goo!

There are few slugs within the goo, however, there are a whole bunch of well-mounted circuit board parts certainly wouldn't bounce around when mobile. BUT, preventing microphonic oscillation is a very logical.

Beeswax! Of course!  

PROBLEM SOLVED! Thanks for your help.

Dave N4EF

Most replies suggest moving your ham radio antenna.

Perhaps it's easier to move your TV antenna (at least to address the TVI!)




Also, consider changing your HF antenna feedline to 450 ohm balanced line; it cleared up a lot of my TVI and telephone problems. Re-evaluate your earth ground as well - review textbook and online articles on RF grouding. Simply cleaning some connections might make a big difference.


As others have said, reduce your power. I run no more than 25 watts most of the time with little problem getting QSOs.

Good luck with it.

My Kenwood TS440s transceiver has a known problem with a non-conductive circuit-board stabilizing "goo" that degrades into a conductive "goo".

I'm not exactly sure what to call this silver-dollar-sized blob of waxy-rubbery stuff that was poured onto the components on the RF circuit board, but eventually, the degradation causes the PLL to not lock. The fix is to scrape off the "goo" from the components which allows the PLL to lock again.

I'd like to completely remove this old degraded waxy-rubbery mess from the RF circuit board and put down a fresh blob of stabilizer, but....

Question: What is the purpose of this goo? Where can I get some commercial grade replacement goo?