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Every single toggle switch had its own trimmer pot. Each scale had to be calibrated separately. Does rather create the possibility the separate scales won't agree without being really methodical with the calibration. 73

I would have a look at R258. It's a 2.2k resistor, three red bands. It's located about a half inch forward of TP9. If C44 were to fail as a dead short, this voltage won't get past a half Volt with a strong receiver signal. Here's where a signal generator pays for itself. If you can turn up a...

Are there any good panda jokes? 73

A look at the schematic reveals that the echo and the transmit input from the mike are not connected. Likewise the echo switch has no connection whatever to the counter display. The only way that switch can make a difference to the those functions is for something to connect them together...

Looks like a receiver preamp relay. You'd expect the type number and manufacturer logo to be printed on the top. Here's how we fix a preamp relay problem. The preamp is mostly a waste of time, so replacing the relay just doesn't seem justified to me. This method is appealing for a mobile...

Just provided my best guess where to start in the private "conversation" section. Just where did the directions for this procedure come from? Are they available online anywhere? Might shed some light on where to find this fault. Did have one other thought. TR51, the fat modulator transistor...

Simpler on the 959. Just break the connection between the channel selector and the PLL chip on two wires. https://cbtricks.org/radios/galaxy/dx959/dx959_freq-mod_1.htm Channel chart is https://cbtricks.org/radios/galaxy/dx959/dx959_ch-chart_after_mod.htm 73

Emitter voltage on the AM-modulator transistor should never be more than about 6/10 of a Volt lower than the base voltage. The base-to-emitter drop shown above is over two and a half Volts. That just screams bad power transistor. We adopted the habit of using a TIP41 to replace that part. And...

The guy making this amplifier is responding to market incentives, just like anyone else building a product to sell. The incentive is to show the highest wattmeter reading with the lowest-possible production cost. Any feature or function that doesn't serve to push the wattmeter reading higher is...

Dern shame nobody came up with a surface-mount version of the PLL Viagra board. Woulda made it cheap to produce. 73

I remember years ago reading a book about television servicing. It was written in the 1950s. The advice was about working without a schematic diagram. He suggested that probabilities are a good guide if you lack a fault chart or proper diagram. Said the most-likely part to fail in a 1950s TV was...

I wouldn't be disappointed with 900W PEP. That's 120-plus per tube overall. Not gonna see a lot more than that. I would be more concerned about each Plate Tune control. If both of them are peaking well between the max and min extremes, you're usually good to go. And a Tune cap that is all the...

Any chance the power cord is wired for a different radio that uses the same 12-pin plug? 73

To the best of my knowledge, Carl never came up with one. Sold the last one from our junk pile on fleabay. Had the usual Bulldog fatal flaw, a seized needle. Would run into an obstacle halfway up the scale and stay there until you slapped it. The meter movements were military surplus, sealed...

If you use 20LF6 for the two driver tubes it will scream, kinda like an unlimited fuel dragster. The 20-Volt heater will have 28 Volts or more on it. Kinda like a nitrous bottle with no off switch. The unlimiteds only race one thousand feet for a reason. The motor won't stay in one piece the...

If they replaced D15 and D16 with Schottky parts that could cause trouble. Those two are PIN diodes. They act as a voltage-controlled attenuator, cutting down the signal coming in from the antenna in step with the receiver's AGC. I have seen those two replaced with the wrong diode, and the usual...

Not a symptom I remember seeing. 73

Or just swap tubes. I have looked down into the top mica insulator on the tubes in more than one linear only to see the screen grid begin to glow red, then darken when it goes back to receive mode. Typically the result of the Load control being too loose, maybe? Tubes that got this kind of...

A capacitor marked ".006" is microfarads. Yeah, it's also six nanofarads, but it seems only geeks use that unit in the USA. It's also 6000 picofarads. Here's what I would recommend. The RF current is pretty high in that spot, and a capacitor's RF resistance is a big deal. Simple rule. More...

All good advice, but I'd be looking for a heat-related fault. As in, a capacitor that gets hot and stops performing. The blocking cap between the plate choke where the tube-cap clips all connect on one side, and the Plate Tune control on the other side can do this. Too much voltage there to...