UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - 10M FM

SiriusHardware · 27th Nov 2018, 2:23 pm

I take it there must be at least one more crystal in addition to the 10.240Mhz reference crystal, i.e, the 'loop mixer' crystal. A refinement would be to insert an eprom between the channel switch and PLL, programmed such that either:

(Repeater shift = off)
-All channel switch codes are passed through unaltered

or

(Repeater shift = on)
-Channel codes 31-40 are shifted down by 100Khz / 10 channels in TX
-Channel codes 21-30 are shifted up by 100Khz / 10 channels in TX.

(This assumes that channel 21=29.500Mhz and channel 40 = 29.690MHz).

Unfortunately there is only one operational 'classic' 10FM repeater in the UK that I know of, near Northampton. Another looks to be coming online soon near Norwich. Both are likely to prefer CTCSS for access.

27th Nov 2018, 2:23 pm	#43
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: 10M FM - any activity these days? I take it there must be at least one more crystal in addition to the 10.240Mhz reference crystal, i.e, the 'loop mixer' crystal. A refinement would be to insert an eprom between the channel switch and PLL, programmed such that either: (Repeater shift = off) -All channel switch codes are passed through unaltered or (Repeater shift = on) -Channel codes 31-40 are shifted down by 100Khz / 10 channels in TX -Channel codes 21-30 are shifted up by 100Khz / 10 channels in TX. (This assumes that channel 21=29.500Mhz and channel 40 = 29.690MHz). Unfortunately there is only one operational 'classic' 10FM repeater in the UK that I know of, near Northampton. Another looks to be coming online soon near Norwich. Both are likely to prefer CTCSS for access.