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Ohhh, gotcha! I didn't catch that part... sorry! Yeah, you would need an SO-239 connector. If you have a junk/parts radio laying around, you can remove it and install in the 55HP and it will work fine, you won't have any installation issues with it, they are all universal. ~Cheers~

Nothing special, if you have a soldering iron, you can melt the solder on the connector and re-attach the wire to the connector. Nice and easy. :)(y) ~Cheers~

I wonder how unusual it is to have a final with a bias issue like that.... just seems odd to me. ~Cheers~

I checked the MV1Y diode on the 2nd final, checks as it should. It matches the other MV1Y diode. Just for giggles, I replaced the 2nd final.... everything is perfect now. Bias currents on both finals are stable, and adjust as they should. Was able to dial everything right up per the service...

Ok, from what I just tested, both finals have stable voltage on their respective bases, 1st final has .54V, while the 2nd final has .66V. However, if I turn both bias pots to minimum, then adjust the 2nd final bias pot up, the bias current starting running away, but the bias voltage stays...

Hiya Andy! I checked under the PCB, and everything looks clean under a magnifier, nothing bridged at all. Nothing heats up at all during testing, everything runs cool. ~Cheers~

Bob85, thanks for the info! I'll look into that tomorrow evening after work. I suppose that method could also tell me which one of the bias tracking diodes could be at fault as well. :) ~Cheers~

Hmm... I'll look into that Wavrider! I did shoot the pots with De-Oxit D5, and it didn't change anything. I can install a couple of new pots and see if that changes anything. I'll post an update with the results tomorrow, I gotta hit the flat side and get some sleep. 1 more day of the grind...

Hiya folks! I have a bit of an unusual problem, one I can say I've never really seen before... I have a President Grant DX, the dual final 3 band radio. I wanted to set the driver and final bias currents, and the final bias current wants to "float" upwards, by quite a bit. Driver bias current...

At least from my experimentation, I've noticed that cathode biasing provides more gain than grid biasing... but at a cost. You have to be careful of your input drive. Excessive drive can damage the tube, and can cause potential oscillation issues. For sweep tubes, this is generally a no-go...

Check to make sure the final bias current is properly set. If the bias on the final is way too high, it can cause this condition. It won't have this problem on AM because the final is not getting the full 13.8V at its collector. I've had this problem in the past where the someone had cranked the...

That's a swing mod. Just remove all the parts off the PCB on the back side near the B754, and replace TR32, and you should be good to go. Pretty much guarantee that is why you're squealing. ~Cheers~

I have a few good used pulls. You can also replace a C1307 with a C1969 or a C2312. ~Cheers~

The 138 used a C1307 final. In stock form, it was good for 4W AM and 12W SSB output. These did NOT tune very hot, so on AM, you could get 7-8W of swing and maybe 14-15W PEP output on SSB when tuned. ~Cheers~

Woid. ~Cheers~

Another problem that should be noted is the mode switch on the base station radios. This component tends to be the bottleneck. On most base stations, the power the the finals gets routed through the mode switch. Because of this, when modifying a base to run a MOSFET, you can damage the mode...

ASW, It's been a hot minute since I've owned that amp, sold that a long time ago to a buddy of mine. Wish I had it back, although these days I run a T/S 667V that's heavily modified by me. I use it maybe 1% of the time... :lol: ~Cheers~

Such a waste of money... but it is the customer's radio to do with as he pleases. So much bad thinking going into this whole mess that it makes my head hurt.... "A fool and his money are soon parted...." ~Cheers~

Welcome to the world of mis-aligned, drifty Galaxy radios. Sorry. :( That radio will need a proper TX/RX alignment to reach its full potential. ~Cheers~

Snake oil. Not impressed. Those kind of mosfets will not work properly in this application. I want to see one of these fully tested with a spectrum analyzer, and also see how they perform. I'd also bet they drop power significantly when they get hot from use, too. Not saying the T/S amps are...