Vintage radios

Yes it can work. But if it hasn't been run in many years it could blow the caps.

 

what can you do to keep from blowing the caps? found dad an g'pa's old krako's from the 70s an wanta run one with a texas star 300 watt warmer in a 85 359!!!

 

with echo an talk back too!!

 

Try turning it on and just let it run for a few days. Do NOT talk on it. It should help.

 

Have seen it suggested to use a variable power supply and start voltage low and gradually increase it over a several day period to help recondition capacitors. You might try a search on qrz.com or arrl.org for more information on bringing vintage radios back to life. Your choice whether to mention it's a cb there are purists anywhere. Good luck with it. A friend gave me a beautiful transoceanic shortwave receiver I plugged it in not knowing any better it played about a hour then smoke started rising

 

Changing out the caps is fairly easy, there not expensive.

Caps dry out, just the way they are.

They can be purchased at your local Radio Shack.

Im in the middle of restoring a Robyn SX102D, Clean it with alcohol and a tooth brush (inside) before you power up a older set.

 

A lot of those older CBs were cast aside when people had the 40 channels approved for use in (IIRC) 1977. I've got a slew (about 45) of the Royce CBs here at the shop and in storage. Some of them were ill-suited for mobile use, as they tried going for a semi-modular approach for a couple of models. Individual circuits were relegated to their own "daughter boards", that were connected to the mother board via a bunch of fairly stiff bare wires as jumpers in a straight line array. The problem came when vibration would eventually break the solder joints at one end or the other of the soldered standoff/jumper wires. Some folks shotgunned the service on failed units by starting out with resoldering every single one of those jumpers; then, if it worked, they had no idea what specific circuit had failed.
Most of the Royces also used an interstage coupling method called "emitter follower", which isn't the greatest for producing gain. I ignore the jumpers except from the standpoint of metering each end for continuity.

If your rig has tubes, power it up with none of the tubes in place. (Note: for all the following steps, power the radio down before adding or removing tubes.) If no smoke comes curling out, plug in just the rectifier and power it up (preferable with a Variac transformer at about 50-60% of line voltage. Some tube rectifiers and regulators won't even conduct until you're up around 85-90% of rated input voltage, and the filter capacitors only filter DC. So you can test the big capacitors with the rectifier and regulator in-circuit.

If that holds at reduced voltage, crank it up to rated voltage (around 117 v.a.c., even though many radios were built when standard line voltage was about 110, and modern line voltage can be up upwards of 130. My house typically runs around 128 v.a.c. unless it's during a period of high grid demand, like all the air conditioners in the neighborhood and all the clothes dryers running at the same time. That's enough to blow lots of gear made in the 40s and 50s.)

If nothing goes Pop! after 2 hours at rated voltage, plug in all the tubes except the final(s). That will let the "lower high voltage", like around 275 VDC, do its job, and will stress the filter caps on that voltage bus and probably show up any shorted tubes. Be sure to key the transmitter; don't expect any output because the final(s) are out, but it will at least send signal to the other TX stages. (You should be able to hear the signal on a local CB, too.)

Finally, plug in the final and give the filament time to warm up. With a dummy load (PLEASE don't align you radio into a jenn-u-wine antenna) read your output on the wattmeter as you adjust the appropriate tuning adjustments for the final(s). You may find a trimmer cap or variable coil on the input, and a couple of variable caps on the output. One will increase the loading (coupling to the antenna circuit), and the other will tune for resonance. Those two will interact somewhat. If rhere is a "TVI trap" or "54 Mhz trap", DO NOT adjust it for maximum signal on the output. Doing so will only increase the amount of second harmonic signal coming out of the radio, which is all at or above the 6 Meter ham band, and does you no good on CB.

But I digress; I'm old, and I do that sometimes. Has nothing to do with Teaberry. In fact, the only Teaberry I have is a Model T Base, made by ECI and virtually identical to Lafayettes and many other similar CB boatanchors of its day. Works better than new, pure on the spectrum analyzer, and gets lots of compliments on the air.

Sorry, I digressed. But I'm old, and I do that. Too many years around RF, I guess.
But I digress; I'm old............

73

 

Will it work?

Of course it will.

BUT don't take a solid state radio and apply a low voltage to it, start with 11.5 volts and move up to 13.8 over a day or so.

 

Thanks for the clarification on solid state. I didn't recall that being mentioned in the article I read on subject.