[Milsurplus] Working 80 & 40 simultaneously with the TRC-77A!

[Richard Arland, W3OSS]

OK, now I have done it!!

I was re-aligning my 77A last night. I was having problems getting chnl 3 oscillator to fire up on 3570 kc. I put the 3570 rock into chnl 2 (originally aligned on 3565 kc) and it fired right up, indicating that the xtal was working. Again I tried it on chnl 3. FINALLY, I ended up taking the chnl 2 OSC coil all the way down to the stop while counting the turns, then bringing it back out to the original position and rechecked that chnl 2 OSC still fired up. With this info, I ran the chnl 3 OSC coil slug all the way down to the stop and backed it out the same number of turns that I had on chnl 2. This should put things "in the ballpark". 

Chnl 3 started oscillating and I peaked things up with the OSC Cap and coil, and proceeded to align the TX PA circuitry. I had a small Sony battery operated SW receiver handy and was using that on 80 M to listen for the TRC-77A osc to fire up. For some reason, I ended up checking the 2nd harmonic of 3570 (7140 kc) and found a louder signal on the air there than on 3570! 

This brings up my question: Given that (according to the TM) the OSC coil/cap values are the same on all 6 chnls, AND the TM says that you can put any xtal between 3 & 8 mc in ANY xtal slot in the transmitter and obtain an output, why did chnl 3 decided to be a freq doubler? 

This brings up another thought: It might be wise to put a "converted for ham use" TRC-77A on a spec analyzer after alignment just to be sure things were working as advertised and you don't have an output somewhere you don't want one. 

Anybody have thoughts on this doubling problem? OR...is it a problem?? Happen to anyone else??

73 Rich W3OSS