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Added bias? Where? The center tap of the input transformer has a RF choke on it, with the other end grounded. Won't put any bias voltage on the transistor base leads that way. The resistors that burned appear to be in line with the radio drive power. A failed transistor tends to short internally...

Until I see a schematic that's all they are. Just another flavor of secret sauce. Ideally the radio's RMS power at full modulation should be the same regardless of carrier setting. It's all about the waveform. If you smoosh the positive peaks this raises the average power but hoses your audio...

By gum, it worked! The fix from TSB1232 and new caps did the trick. No more 32 MHz. Gotta love it when a plan comes together. 73

Excessive bias current leads to excessive heat and eventual breakdown. 73

Nine times out of ten, a brand-new final that pukes immediately is the victim of other faults in the final transistor's base circuit. Turning the bias trimpot to the zero-voltage end and placing that all-important current meter in line with the test jumper serves to provide a safe starting point...

So, ahh... What's the objective here? If more transmit power is the desire, you won't see enough increase for anyone on the other end to ever know. The receiver's S-meter doesn't respond at all like your wattmeter. You'll need to double your transmit wattage before the S-meter at the other end...

Much safer to use a diagonal cutter with sufficiently thin and sharp jaws to clip the pins at the shoulder, up against the plastic. Much less risk to the circuit board. Too easy for a Dremel to get away from you. 73

For decades radios with features not legal for 27 MHz CBs have entered the country as "10 meter" transceivers. Typically the Galaxy, RCI, Connex and such brands will be intentionally crippled on the inside before shipment, and get "un-crippled" to cover 40 CB channels once the radio is safely...

A weekend warrior whose work bench is the kitchen table. 73

TSB 1232 says the factory included this resistor/cap mod from serial number 83012001 and up. Says to me they caught this design booboo before the end of 1978, if that's really what the radio serial number's first digit '8' is supposed to indicate. I misspoke when I said I had never seen this...

In sideband modes and AM transmit (only) the carrier input frequency is subracted from the VCO frequency. The TMS1000 mcu was found in Texas Instruments pocket calculators of the era. This one has a different program than the calculators, but it's mask programmed. The optical mask used to expose...

Had some requests for an upgrade kit to replace the relay in the Browning 180 base linear. It was legal for Browning to sell, because their 1960s radios were type accepted for a business license. No joke. Had one customer in 1975 that was licensed for 27.320 MHz. Had a Browning Mark 2 base...

Sure it does, just with some added arithmetic. Discovered an odd quirk in the Galaxy FC-390 external 'display' a while back. Has two wires to select the IF offset, For AM, leave both wires alone. For USB, feed 8 Volts to the yellow wire. For LSB the orange wire. IF you feed both wires, the...

As an old technology fades away your range of options shrinks. And when there remains only one source for a needed part, it's too late to shop around for a better deal. 73

Lazarus! Arise from your back burner. A few years ago I posted a project that shrinks the 9/16-inch digits on the SanJian PLJ6-LED frequency display so it fits behind the dial window of a Siltronix 80/90 VFO or the VFO window of a Tram D201. And then reality set in. Removing the big digits...

Should. 73

This is where the 30-buck chinesium fleabay tranistor tester pays for itself. Odds are most of the four linear MOSFETs are croaked. No good way to test them with only a multimeter. Got in the habit of calling that linear stage the firestarter junior. But they can fail and still look okay on...

Yeah, cover up your peanut whistle with a silk top hat. 73

Sure enough. The VCO module is a "roach motel" for the tuning voltage coming from pin 7 of the MC145106. Tuning voltage goes into the module's pin 5, doesn't come out. More than once I'll get asked about some section of a radio that seldom breaks. I'll have to excuse my lack of knowledge, and...

If I read the schemo right, that network serves to reduce the control voltage driving the track-tune varactors. The tuning voltage that drives the VCO also controls track-tune varactors in the receiver's 2nd RF and the transmitter's mixer output. The track-tuning varactors D18/D19, D99,100 and...