Kenwood TS-430s: SSB RX with very low AF volume and S-meter stuck at S-0.

 Repair Brief – Kenwood TS-430s – bad SSB RX.

 

DISCLAIMER: the following instructions are provided only as a report of my hobby experience. In no way I am responsible of any damage you or your device can suffer by following this procedure. Lethal voltages are present in the device!! Qualified personnel only! You know what you are doing and you are proceeding at your own risk!

 

Symptoms (RX only):

• In USB and LSB low volume and no S-meter deviation.

• Strong (local) SSB station are demodulated OK and can be heard with very high volume setting. IF-Shift and RIT working OK as well as NOTCH.

• AM and CW are OK.

Findings:

• In USB and LSB, the ACG line (gate of Q13) stuck at 2.5V, no matter of signal strength.

• Q17 (what is it useful for?!) voltages: 2.6V all terminals as per schematics.

• SSB line goes high when USB or LSB are selected (as expected).

• On AM S-meter is well calibrated for S-0 and S-9.

• CAR signal present @305mV RMS in USB, CW (8.8314KHz) and LSB (8.8284KHz).
  It disappears in AM.
  

TOWER 5 Transistors Walkie talkies from the 60s - The ones that ignited my radio/electronics hobby.

Tale of my first transmission : 27.125MHz - CB Channel 14.

When I was young (late sixties, first seventies) I got a couple of black TOWER walkie talkies.
They were shiny and looked like rocket science objects.

My actual units

It wasn't long before I realized they weren't usable: communications with a friend were difficult, if not impossible, even between rooms.
On the other hand, however, one evening, I heard voices coming out of one of the radios. They were people who chatted about this and that using esoteric language...as well as coded words (CQ, QTH, QRZ, YL, 88, Roger, K, ...).
I tried to make myself heard, but no one could listen to me.
Suddenly, while I was desperately trying to make myself heard, (are you listening? Hello, ready, are you listening?...) one of those voices answered me. He greeted me, welcomed me and ... explained to me that I had a "super regenerative" radio in my hands and that it could simultaneously listen to many frequencies but only transmit on a single one. That's explained me why I was hearing many voices but I had difficulty make me listen.
After a few days I met that person: he was an OM with a shack that looked like a spaceship to me.
BINGO. Since then I have been CB for years and have become passionate about radio and electronics.
Eventually I also got an ham license.

A DIY bench RF step attenuator with Arduino and Aeroflex-Weinschel step attenuators

A while ago I made a bargain purchasing a couple of Aeroflex-Weinschel step attenuators (models 150T/11 and 150T/70) for 20EUR each.

The idea was to implement a bench step attenuator for my lab.

Here is the project.

Those attenuators offer serial and parallel digital interface. I choose to use the parallel interface protocol.

Each attenuator is controlled by 4 bits (a nibble), so, with the help of the following map, I built an Arduino sketch to drive the attenuators by a rotary encoder:

The table on the left simply lists all the wires coming out of the attenuators with color and function.