[Oldmadham]

After submitting the previous post, a bit of information came back to me.
It may not be useful, but here it is, for what it's worth.

The normal method of operation with "Wadley loop" radios like this one, is to:-
(1) Set the MHz control to the required band.

(2) Adjust the peaking knob for maximum noise.

(3) Tune across the band with the kHz knob.

It is, thus, a bit more "structured" than a conventional superhet, where the bands are changed with switches, so each range change presents you with virtually a separate radio for that band.
With such radios the "peaking"control just tweaks the aerial input tuning.

With the SSR-1 & the FRG-7, the MHz control tunes to each of the harmonics of 1MHz, "which one", depending on the required band.

The SSR1 MHz control was always a "bit off" the markings.
You would move it to the "MHz" marking, then a little bit off, & up would come the noise.

The Drake used, from memory, a 10 MHz crystal, which was then divided down to 1MHz, a popular modification being to change the oscillator to 1MHz directly.
I think this was because Drake, or the Japanese OEM were miserly, & 10 MHz crystals were cheaper.
I dunno if Yaesu did the same.