Search results

Vacuum variables, vacuum contactor for HV, of course time delay, cover interlocks for your protection, variable tuned input, oil filled caps in HV supply, high temp and grid current shut off, just to name a few. Oh yeah, if you use a F7 tube instead of a A7 you won't need a socket. It just bolts...

The amp has automatic SSB delay. Sometimes it gets to be a pain when using on AM. You can lift the electrolytic cap by the relay (1000mfd?) and insert a switch in series so you can cut it in circuit and out for AM operation if you wish.

If it was driven real hard I would suspect a mica cap in the tuned input being toast. Switch your exciter and the amp to a different band and see if it will load into a dummy load then. If the bandswitch is burnt looking it might be a good thing to check it closely also.

It seems that when new it came with 4 gauge wire.............I might be wrong as that was many years ago. But one thing for sure, there is not a 1x4 anywhere that will bother that amp when it is working properly.

Texas Star website says 30 amps current draw on the 350.

Yeah, I think Firebird also. John Wayne used to sell a ton of those amps at the CB Breaks and such in the '70s.

Post a photo of what is bad, trimmer cap, air variable, whatever. Any numbers or markings will be helpful also.

Well that is pretty much where you are at the moment is having to check components. If do not know how to check the individual devices it might be best to find someone who is and let them check it for you. The keying circuit in that amp is pretty basic and someone with basic electronics...

I'd agree on a bad connection. You might want to check around C4, 1000 mfd cap by the relay. That is the cap which keeps the relay keyed while in the SSB mode. I've seen a lot of the cut out of circuit. You can change it to a higher value to hold the key longer also.

What does the voltage read when you key the mike? This is beginning to sound like a keying circuit problem. Do you know how to check the components that make it up?

More Marital Bliss

Glad it worked out.

Maco 300M One thing to remember is that thing is hungry. It will need at least 70 amps (or more) to make it work the way it should. When sold new they came with an high output alternator as part of the package.

If you turn the SSB switch to the "ON" position will the relay stay keyed? If is does you have a problem in the keying circuit. One other thing is does the radio talk ok when the amp is turned off? If I remember correctly there should be a 2N2905 keying transistor that could be bad.

Is there a possibility that the mike cartridge is bad? Make sure that the head off the D104 works on another mike.

A dummy load is a resistive load that will be a close to perfect match for the radio to operate into. You can use it to check and make sure that your antenna is not causing any problems. One question I have not seen asked (or maybe missed) is how big are the power wires going to the amp and...

It's over at the other site.:tt2:

If your radio is keying 1 1/2 watts try raising the dead key. Does the amp stay keyed if you modulate into the mike? If it stays keyed when you talk and not when you just dead key you need to raise the key of the radio in order to keep it keyed.

The relay could possibly have bad contacts causing this. Usually you can hear it arcing if so. Does the amp have a HV meter on it? If so does the reading drop when the wattage drops? It sounds like something is getting hot and it is losing drive maybe.

On an outside chance you do not have the antenna and transmitter reversed do you? This will cause the relay to chatter. Will the relay stay keyed while not saying anything or does it do it all the time?