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*WARNING:? I am a hobbyist and I am learning vintage radios. I can usually find my way around schematics to some degree, but not well. I do better with service manuals and I've not found any for

Let's make this easy. Pull the board and out it on your bench. Connect 10 volts to pin 11/38 and ground to 11/11. Make your measurements with and without the transistor on the board. Verify the pinout

There is no Zener in the PTO schematic you posted. :D "VE7PS via groups.io" <ve7ps@...> wrote: -- 73 -Jim NU0C

US Patent 4237521, conveniently stored in the group Files section for your viewing pleasure. /g/DRAKE-RADIO/files/TR-7/US4237521.pdf I proved experimentally some years ago that the

Check the 50 kHz LO injection into the product detector and the second mixer. This is not a typical failure. Rob, NC0B

Measured exactly 10 volts out of the variable power supply that I just got to red and black on the PTO. I have so many ways to get the signal from the PTO that I simply placed my spectrum analyzer

Yes, either sideband is valid for tune-up; however, with the UPPER lamp on, I presume I will also transmit on USB which, of course, is backwards from normal 40M operation. That's what's confusing me.

You can tune up on either sideband using TUNE, which is an audio tone. X is always used for CW which offsets the carrier oscillator to put its signal inside the passband of the filter (LSB filter I

*** I've used code for I/O on a few projects. Well, mostly for O. Once upon a time, I was working on a project at work that had a CPU that talked to another CPU. They communicated via a shared memory

Perhaps a switch that responds to commands spoken in Morse code. Barry - N4BUQ

Steve, I sent the chart as space-delimited with a fixed-width font but I suppose something transformed them. Sorry about that. What I'm trying to understand is how to tune up for, say, 40M SSB. If I

*** Or you could get a "clapper" :). https://www.youtube.com/watch?v=TBPVJtGBf8Y&t=537s - Jerry, KF6VB

I seem to remember that many of those very small-value caps that are in parallel with transformer windings were put there to increase bandwidth. Steve Wedge, W1ES Time flies like an arrow. Fruit flies

Another day without a solution. ?I methodically went through all band switch wafers and found no issues. ?Verified the 18.1 MHz crystal is making connection in the socket. ?Did some continuity

20 & 80 are the oddballs because they're only single conversion. 80 is the difference between CO and PTO and 20 is 9 MHz the sum. Other bands with difference frequencies. Also, the sideband filter

X is needed for CW, so the switch will select the carrier to be on LSB for all but 20m. At least I think that's what you're showing because when I replied my email app changed the tab formatting :-)

I'm trying to get my head wrapped around the sideband schemes for the TR-4 and have a question. Below is a table of how the sideband lamps react with the various BAND and SIDEBAND switch positions in

That capacitor is DC shorted directly to ground on one end, and also to ground on the other end through T11 and then through T5. Not very likely to be bad. Gary w0DVN

I have discovered that the failure mechanism of every Oak switch (the AC power switch on the backs of pots) are mechanical failure of the bronze spring and not due to scorched contacts. These switches

The heatsink and internals of the TR-7 series were designed for the fan to pull heat out of the rig. ?Some prefer to push air into the rig thus driving heat toward the PTO and increasing drift and