On Sep 30, 2026, at 12:41 PM, ac2eu--- via Milsurplus <[email protected]> wrote:

This a bit out of context , but generally:

Assuming that the IF is 455 KHZ , the Xtal would need to be 10.455 Mhz for a 10 Mhz station. The oscillator plate and the preceding circuits  would have to be tuned according to the frequency selected..

If that doesn't work , maybe the IF isn't 455 Khz?

On Wednesday, September 30, 2026 at 11:15:27 AM EDT, Charlie L. via Milsurplus <[email protected]> wrote:

I don't think they are overtone or the circuit is a multiplier based  on the schematic shown below.  I have tried doubling and tripling the freq and adding 455 KC and it still does not end up in the HF aviation band of the day.  Triple it and you end up in the 75 meter band.  The manual on Nick's site is a 1965 school book from the FAA academy, and while it does include a schematic and an explanation of how the RX works, it has no details or relevant info on how to change ranges, or even a list of available coil sets in that era.  Interesting to note, that the RUP, and RCQ style receivers,  similar to the National NC100, plus 51J4's at some stations, were used into the late 1990's for listening to WWV to set station clocks, and things like the time code generator in voice recorder systems. .  They got replaced by a GPS based RX that fed time data directly into the systems that required it.   Some field offices in the 1970's bought the Heathkit 'Most Accurate Clock', that picked the best signal on 5, 10, or 15 MC WWV and displayed the station time.

Charlie

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