Converting old president grant SSB 5 pin to 4 pin

[nomadradio]

Well I'm at a bit of a stumbling point. I crossed pins 2 and 4 in to pin 1 of the cobra connector and hooked everything else up as I think it should be according to wire functions. Now I've tried 5 different 4 pin mics and they all seem to do something different. I tried a cobra ca73, a pierce Simpson from a lynx 23 base, a SBE powered base mic, and a procomm I just picked up at the local CB shop (NAPA). They had a new 5 pin mic in stock so I picked up one of those; a ProComm PSM5. MOST of the 4 pins I tried are still feeding audio through the Mic when keyed, one of the exceptions was a jc penny pinto SSB mic that would play audio through the speaker when keyed and through the Mic when un keyed. The sbe base mic worked on tx but but didn't divert audio to the speaker when un keyed.

I think I'm going to try re attaching the 5 pin plug and using the NAPA 5 pin mic. I'm really at a bit of a loss for why this thing is acting like this

Learned years ago to check the wires on a mike that's not from a standard supplier like Astatic or Turner. Colors will vary from one mike to the next.

A look inside the mike can simplify identifying which wire color is wired to which function inside the mike. Testing for continuity on transmit and receive will work, too. That may be simpler for a mike with an amplifier or echo pc board inside. A mike with the wires soldered directly to the switch can be interpreted by eye, to identify the audio, ground transmit and receive wire colors.

73

 

[Jim Dickey]

The 5 pin Mike works as it should, radio functions are restored. Just need to figure out why it's only modulating on SSB now, am had no mod.


Never mind, turned the Mike gain all the way off while I was fidgeting. Dk @ 4w, swinging to 10w. This appears to have a Mitsubishi 1969, is it worth trying to turn it up any more?

 

[nomadradio]

Hmmm. 10 Watts peak on what kind of meter?

Any wattmeter that's correct should show the same carrier power.

But as soon as you modulate an AM radio, they begin to disagree.

Could be that this is all you should see on that meter.

What kind is it?

73

 

[Jim Dickey]

This is on an old workman p5000. I've checked a lot of different units with the meter and even an amp pushing about 200w on SSB. It seems to be reasonably accurate from what I've been told to expect from various stock rigs and those that were modified with mosfet finals. Shows a dead solid 4 watt carrier and holds at about 10 w when the Mic gain is at about 80% and I'm making the "awwwww" sound.

I just replaced the junk mosfets and relay that I smoked on a kl203 with 4 new Fairchild 13n10s and a avicom relay. The old components were sanded and unidentifiable, as well as poorly soldered. I killed the old mosfets with a momentary input of about 8w AM. The heatsink was Damn near too hot to hold when this happened.

The new mosfets are taking 18w of sideband and turning out a tick over 200w. Even after a 5 minute periodI of 10 second transmissions (12 or so total), the heat sink has yet to exceed room temperature.

Everyone says to run these amps with low input power, did I fix the reason for the low power input suggestion by replacing the mosfets and relay? The relay was $2.63 and the fetz were$.68 at mouser. I bought a bunch for swapping finals on cobra 29s