Bought a literal bushel basket full of old CB amps for near nothing. Many
are tube type mobiles that use inverter power supplies. I am trying to
figure out what frequency the power supply oscilates. My plan is to get some
of the power supplies up and running using a TL494 and Power FETS. What kind
of transistors were used in thes things. Some of them look lie they were
stud mounted and others are obviously TO3. Any help would be greatly
appreciated.

In article ,
Jimmy wrote:
Bought a literal bushel basket full of old CB amps for near nothing. Many
are tube type mobiles that use inverter power supplies. I am trying to
figure out what frequency the power supply oscilates. My plan is to get some
of the power supplies up and running using a TL494 and Power FETS. What kind
of transistors were used in thes things. Some of them look lie they were
stud mounted and others are obviously TO3. Any help would be greatly
appreciated.

If I were building such a thing, I'd use darlingtons myself. A frequency
counter will tell you what frequency the relaxation oscillator is running at,
though you should be generally aware that it will drop when the load is put
on. Probably in the 15-50 KC region to use cheap magnetics and semis.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Jimmy" wrote in message .com...
Bought a literal bushel basket full of old CB amps for near nothing. Many
are tube type mobiles that use inverter power supplies. I am trying to
figure out what frequency the power supply oscilates. My plan is to get some
of the power supplies up and running using a TL494 and Power FETS. What kind
of transistors were used in thes things. Some of them look lie they were
stud mounted and others are obviously TO3. Any help would be greatly
appreciated.

Most of the transistors with the stud mount were PNP germanium in the
TO36 case. These worked as a miltivibrator, with the HV transformer
primary as the load. It depended on a feedback winding for operation.
With circuit tricks you could have the collector (case) at ground
potential.

These would oscillate in the neighborhood of 3-10 kHz, and usually
emitted a soft squeal when operating.

most of those amps were built as cheaply as possible, and I'd
seriously question the value of any of the componenets. A good source
for T-powered HV supplies is surplus two-way radios, such as the GE
Matr Pro, or Motrac.

Gary Hildebrand WA7KKP

Gary hildebrand wrote:
"Jimmy" wrote in message .com...
Bought a literal bushel basket full of old CB amps for near nothing. Many
are tube type mobiles that use inverter power supplies. I am trying to
figure out what frequency the power supply oscilates. My plan is to get some
of the power supplies up and running using a TL494 and Power FETS. What kind
of transistors were used in thes things. Some of them look lie they were
stud mounted and others are obviously TO3. Any help would be greatly
appreciated.

Most of the transistors with the stud mount were PNP germanium in the
TO36 case. These worked as a miltivibrator, with the HV transformer
primary as the load. It depended on a feedback winding for operation.
With circuit tricks you could have the collector (case) at ground
potential.

Hmmm. There were (and still are) a lot of stud-mount SCRs. That might
seem a good choice for a cheap multivibrator circuit, if a little slow.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."