[SiriusHardware]

I was surprised by the ingenuity employed by some people to get the largely intentionally 'immovable' UK spec radios to shift upwards by 2Mhz or so given that the PLL ICs had been expressly designed to make exactly that sort of thing impossible.

There were two main approaches weren't there, one being to mix the output of the VCO with an oscillator and then feed the resulting (VCO minus oscillator) frequency to the input of the PLL so that the actual VCO frequency was shifted up by 2 Mhz.

The one which really impressed me was the pulse-stealing method which would digitally remove one in every n pulses from the output of the VCO before feeding it back into the PLL, so that the VCO frequency seemed lower than it really was and was duly accordingly raised. That must have been a real light bulb moment on someone's part.

All of this was also complicated by the fact that the VCO frequency had to be 1/2 TX frequency on TX, as well.

There were a few very rare UK models which used unrestricted PLLs, among them the JWR M2, the nearly identical ICOM ICB 1050 and the early version (only) of the Binatone Route 66. Later versions of that used the UK-specific LC713x PLLs.

I acquired a Rotel RVC 220 which had been converted to 10FM using the 'digital' method but, finding no activity on 10FM, restored it to as-new working order on its original frequencies.