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This is dictated by the type of PLL chip connected to the channel selector. That radio has a chip that just won't do this trick. The 2816 chip is a later design that's intended to lock you out of adding frequencies the simple way. Also locks you out of going up one channel. 73

Well, that's a horse of a different color. That one sets the bias voltage on the final transistors. It's set by breaking the DC circuit to the final drain circuit and inserting a current meter. Old rule was 60 mA per transistor. I've been told that 20 mA is safer. 73

VR10 is fed from D89 and D90, set up as a half-wave voltage doubler, fed from C218, a one-half pf cap that is fed from the output of the final transistors. Don't have the 2950DX schemo handy, but the 2995DX uses the same circuit board...

Probably. No need to turn on the preamp. It's a receive-only feature, not part of the transmit side at all. Once the bias is hooked up, subtract that 60 mA from the current draw to see what the RF transistors' idle current is. 73

Makes me wonder if we should come up with a miniaturized version of the Keyboard. The 5-Amp power relay we use looks like a tight fit in that radio. 73

This collection should be legible enough to use. A diagram for a Maco product is just a list of suggestions. The one with the hand-scribbled notes has specifics from units we saw here. Better than nothing.

The 5 MHz is meant for the Browning Mark 3 SSB transmitter. It takes the place of a 5 MHz crystal that's always selected and moves the coverage of the radio's 23-channel selector up and down in frequency. Just one problem. The circuit where it feeds in is narrow-banded and the power tends to...

You're not setting voltage, really. Yes, it will be in the ballpark of 6/10th of a Volt. The exact voltage is affected by temperature, power-supply voltage and the manufacturing variation of one transistor to the next. Your target is the zero-signal DC current through the RF transistors with NO...

220 ohm 2 Watt. 73

Does this one say "27.300" on the rear panel? The yellow wire is a keying wire. That VFO is meant for a radio that uses one crystal for each transmit channel. The transmit crystal operates on the frequency that you're receiving. Can't have the VFO pushing out a carrier while you're trying to...

Those caps should do just fine. They won't see voltages anywhere near 50 Volts DC. There's nothing sacred about the 40-ohm value of the power resistor. I would put a 5k ohm trimpot in series with the 1k resistor in line with the transistor's base lead. You need to have a way to set the actual...

The hyperlinks above to the software are dead. Might try the wayback machine. See if those links got archived in 2016. 73

Almost. The center pin (collector) of the TIP42 needs to be feeding the 40 ohm 10 Watt. The emitter should connect to the fat red wire. The 1k resistor will have about 12 Volts across it. The power it will dissipate is the voltage squared divided by the resistance. 144 divided by 1000 is just...

I'll guess that "other web site" would refer to another radio web forum that closed down long ago. Maybe. 73

Biggest single hint is the driven element. It's a folded dipole. The 300-ohm twinlead wrapped around it is a proper impedance match for this type driven element. And the most-popular feedline for rooftop TV antennas in the analog era. 73

First thing to try is a substitute mike. Mikes break far more frequently than radios. Or just unplug the mike. If you can hear any receiver audio that way, the problem is in the radio. And if the radio is dead silent with no mike plugged in, this points to the mike as being the source of your...

Any chance you can see a resistor with one leg clipped open? Especially around the mike amplifier section. Clipping a resistor is one way to open up the AM modulation limit. But clipping the wrong one can shut down the AM audio altogether. 73

BAN DIHYDROGEN MONOXIDE! Most deadly substance on the planet. Kills more people every year than any other toxin! 73

No such thing as too much air. 73

Not the best quality pic, but we had tiny teflon sleeve on hand, and this is the least-labor fix for us. 73