4 Metre activity. - UK Vintage Radio Repair and Restoration Discussion Forum

G8BBZ · 3rd Feb 2026, 5:12 pm

Hi All,
I recently acquired an ancient AM Pye Reporter and was surprised to discover that it is crystalled for 70.65MHz transmit and receive. This was not the original frequency setting, which was a more normal split frequency simplex allocation, so a previous owner has tuned it to the new frequency.
This frequency does lie within the extended 4m allocation but I was not aware of any AM activity in this area. Has anybody else come across this?
cheers
Peter G8BBZ

G6Tanuki · 3rd Feb 2026, 5:50 pm

From memory, in ancient history (the nineteen fifties) the 4M band was 70 to 72MHz. It was later cut back to 70.0-70.5MHz and the space reclaimed from amateurs was generally then occupied by the likes of fire brigade.

4M has always been an oddity, not part of the traditional worldwide ham radio allocations, indeed it was in the middle of what the Eastern European communist bloc used for FM broadcasting.

Not sure when the UK 4M band got downsized though.

70.26 and 70.45 were the usual fixed frequencies for 4M from the mid sixties onwards.

Jon_G4MDC · 4th Feb 2026, 9:52 am

That is presumably the early Pye Reporter AM5D and not the MF6AM that came along in the late 1970s?

It would be interesting to know what frequency crystals are fitted for 70.65MHz please.

G8BBZ · 4th Feb 2026, 7:03 pm

Hi Jon,
Yes the early one PTC118.
Crystal frequencies are Tx 11775kHz Rx 10507kHz. Both crystals are by Cathodeon - hardly the amateur choice of supplier I would have thought, but then I don't know when they were procured. From (fading) memory the likes of Quartslab didn't arrive until the 70's but the set dates from mid-50's.
IF is 2.9MHz.
cheers
Peter G8BBZ

Jon_G4MDC · 5th Feb 2026, 9:30 am

Very interesting Peter. So the TX is x6 multiplication.

The RX is effectively x7 - 2.9 which is Pye's old trick of mixing the Xtal x6 to produce first IF 10.507+2.9=13.407 then mixing that with Xtal fundamental frequency again to get the 2nd IF 2.9MHz.

Nice to know thank you. I realise I had one of these in the 1970s but never did anything with it. Long gone.

Cathodeon were the crystal supply part of the Pye empire so I wonder if this set was actually a homer by one of the staff...

Actually another theory has come to mind. In the 70s and 80s Pye operated the returned equipment scheme where employees could buy ex rental sets for their own use.
I had several turns around that - I think you were allowed to buy 1x Mobile 1x Portable 1x Base each year. That might explain it. In the 1960s Cathodeon were probably Hobson's choice for obtaining crystals in the Cambridge & Newmarket area.

3rd Feb 2026, 5:12 pm	#1
G8BBZ Pentode Join Date: Oct 2005 Location: Huddersfield, West Yorkshire, UK. Posts: 211	4 Metre activity. Hi All, I recently acquired an ancient AM Pye Reporter and was surprised to discover that it is crystalled for 70.65MHz transmit and receive. This was not the original frequency setting, which was a more normal split frequency simplex allocation, so a previous owner has tuned it to the new frequency. This frequency does lie within the extended 4m allocation but I was not aware of any AM activity in this area. Has anybody else come across this? cheers Peter G8BBZ __________________ Peter G8BBZ

3rd Feb 2026, 5:50 pm	#2
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 15,892	Re: 4 Metre activity. From memory, in ancient history (the nineteen fifties) the 4M band was 70 to 72MHz. It was later cut back to 70.0-70.5MHz and the space reclaimed from amateurs was generally then occupied by the likes of fire brigade. 4M has always been an oddity, not part of the traditional worldwide ham radio allocations, indeed it was in the middle of what the Eastern European communist bloc used for FM broadcasting. Not sure when the UK 4M band got downsized though. 70.26 and 70.45 were the usual fixed frequencies for 4M from the mid sixties onwards. __________________ Let's Degauss.

4th Feb 2026, 9:52 am	#3
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,364	Re: 4 Metre activity. That is presumably the early Pye Reporter AM5D and not the MF6AM that came along in the late 1970s? It would be interesting to know what frequency crystals are fitted for 70.65MHz please.

4th Feb 2026, 7:03 pm	#4
G8BBZ Pentode Join Date: Oct 2005 Location: Huddersfield, West Yorkshire, UK. Posts: 211	Re: 4 Metre activity. Hi Jon, Yes the early one PTC118. Crystal frequencies are Tx 11775kHz Rx 10507kHz. Both crystals are by Cathodeon - hardly the amateur choice of supplier I would have thought, but then I don't know when they were procured. From (fading) memory the likes of Quartslab didn't arrive until the 70's but the set dates from mid-50's. IF is 2.9MHz. cheers Peter G8BBZ __________________ Peter G8BBZ

5th Feb 2026, 9:30 am	#5
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,364	Re: 4 Metre activity. Very interesting Peter. So the TX is x6 multiplication. The RX is effectively x7 - 2.9 which is Pye's old trick of mixing the Xtal x6 to produce first IF 10.507+2.9=13.407 then mixing that with Xtal fundamental frequency again to get the 2nd IF 2.9MHz. Nice to know thank you. I realise I had one of these in the 1970s but never did anything with it. Long gone. Cathodeon were the crystal supply part of the Pye empire so I wonder if this set was actually a homer by one of the staff... Actually another theory has come to mind. In the 70s and 80s Pye operated the returned equipment scheme where employees could buy ex rental sets for their own use. I had several turns around that - I think you were allowed to buy 1x Mobile 1x Portable 1x Base each year. That might explain it. In the 1960s Cathodeon were probably Hobson's choice for obtaining crystals in the Cambridge & Newmarket area. Last edited by Jon_G4MDC; 5th Feb 2026 at 9:48 am.