Realistic 457 USB frequency fluctuates during alignment

[Lkaskel]

Ok Men,
Here is the update.

I re-aligned it based on the 458 manual (which has some errors) and confirming with the President Washington (1st edition). That has me checking frequency values at TP8. This would give me a stable frequency on all bands. I have no way of explaining the 100hz drop on SSB when aligning on TP6. I would love to spend more time with it but the owner wants it back so he can sell it and recoup his money. He was hoping for a gem but got a very well used radio. The clock and channel display have segments out as well. I have on the shelf a President Washington and Robyn SB-520 for a recap and alignment so I may play with them to see if I can reproduce the same challenge and maybe learn something as well.

One last question. When doing the alignment I am able to get the frequencies in spec (I have an 11 digit freq counter calibrated). On this radio, when I complete synthesizer portion I can get LSB to transmit on frequency but USB is 200Hz high. If I align the xmit to USB then the LSB is 200Hz low. That is with all alignment points in spec. has anyone seen that? The 2 separate alignments for SSB are CT4 and CT5 for the 34MHz and CT2 and CT3 for 7.**MHz.

What process do you use to balance out the alignment?

Thanks as always everyone for your input!!!

 

[vswr]

The TRC-449 and TRC-458 Factory service manuals show the carrier oscillator alignments to be set at 34.xxxx Mhz not 33.xxxx Mhz per your video.

The Sams manual for the TRC-457 does indicate 33.xxxx Mhz. I believe it is a misprint since it is the same basic chassis as the 449 and 458.

The Sams manual for the Cobra 139/138 (#127) does show the carrier oscillator alignment at 34.xxxx same as the factory manual for the 449 and 458.

Might start there?

73
David

Geebus! Maybe thsts why mine shows 1k up on USB and 1k down on LSB! All alignments are spot on but when I'm on 38LSB I'm told I'm off freq. 3 counters measure 27.384 and USB its 27.386. AM is rock solid. This was driving me nuts! Could it be something other than this? I only just saw this thread because of my 457 issue but not sure if I can even tune it up to 34.xxxx. seems that i can vary it by about 20 or 30 hz by either varicap direction but a full mhz??