PRC-74 Again

 I saw this LSB:

and this USB filter on Ebay:

USB source: https://www.ebay.com/itm/326058586882

LSB source: https://www.ebay.com/itm/226549486681 

I've mentioned the PRC-74 before:

https://wb9kzy.blogspot.com/2022/09/just-dream-prc-74-transceiver.html 

46 crystals, 4 rotating switches - it would be "easy" to replace those crystals with a Si5351.  The 4 rotary switches would also be easy to simulate using the same technique as the Morse Dial timer:

https://wb9kzy.blogspot.com/2025/05/inspiration-for-kit.html 

But the fly in the ointment may be seen in this:

There is a LOT of ripple although the skirts are steep.  Hopefully the ripple is due to improper termination at the spectrum analyzer I/O ?  Also the price isn't super cheap for either filter.  And in these crazy times, how much tariff tax would be applied ?  Probably only one filter is needed since the Si5351 offers the builder an easily agile BFO.

I suspect that the LSB filter is meant for the CP-34 or CP-44 only ?  The resistors look to be too modern for a radio like the PRC-74.  Also, the PRC-74 was a true single sideband radio: upper sideband only !

see the stock USB board in the CP-34 circled in red:

that variable inductor is unique with the brass "drill bit" machining    

bottom view makes the opening clearer for the 2nd optional filter:

the open space at the upper right

picture source: https://www.greenradio.de/b_cp34.htm 

Anyhow, just a daydream for now, but it's fun to dream :)

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm