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Varmint 400

nfsus

Yeah its turned off, touch it
May 9, 2011
126
61
38
45
Arkansas
I've a varmint 400 12v amp. It was in a lot i bought. It has both tube sockets, no tubes and 4 pills along the back. I could use some help with this. Is it tube is it pill? What the heck! The old guy said it was a talker back whene but didnt remember any tubes.
 

kc8mob

Active Member
Sep 26, 2017
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Yeah those TO-3 cased transistors are part of the "Vibrater" circuit. Basically a 60ish hz oscillator and power amp to convert 12Vdc to an AC signal a typical linear transformer can then use and step up. Exactly what frequency depends on transformer design though.

Then, it's onto normal rectification for high voltage.

Dangerous contraptions really. Make sure the amp chassis is tied to the vehicle ground and well..
 
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nomadradio

Analog Retentive
Apr 3, 2005
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Louisville, KY
www.nomadradio.com
TO-3 transistors? Or TO-36 "doorknob" types? They were germanium transistors, older than the silicon types that have been dominant since the Jurassic era.

They are hideously expensive and rare now. I've been hoping some genius would work out a way to use modern power MOSFETs in place of the original parts. The so-called "chopper" transistors were failure prone unless you treated them just right.

A tube-type mobile amplifier reminds me of restoring a 1905 steam tractor to mow your lawn. Sure, you could. But more-efficient solutions have been worked out since 1905.

When it was new, you didn't have many choices for putting more power into your mobile antenna. This kind of linear would draw more power and break down more often than a decent solid-state linear. Consider also that unless you stay on one channel, the need to peak the plate tune control goes along with going up or down more than ten or twenty channels. If you contemplate putting it on the air, EVERY single electrolytic cap must be changed. A shorted one can poof other parts. The two tubes should be a decent match so the power gets divided evenly between them.

Ah, the joys of an antique ride. At least you don't have to turn a crank handle to start it.

73
 

kc8mob

Active Member
Sep 26, 2017
42
49
48
39
I didn't see any picture. Units with vibrator circuits I've seen personally were TO-3

The case style really isn't relevant to the mans problem or exactly how 12Vdc becomes plate voltage, germanium or not.

He didn't know if he bought a tube amps or a "pill' amp. Sadly for him, it appears he bought neither.

These are dead end contraptions in the end.
 

nfsus

Yeah its turned off, touch it
May 9, 2011
126
61
38
45
Arkansas
It was part of a pile of stuff. Cobra2000 40ft tower, rotor, controller, 110v amp, d104, some other stuff. Just was part of the whole deal. I'll give it to a local guy that collects older stuff. Its beat up.
 

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