Pye base station identification - UK Vintage Radio Repair and Restoration Discussion Forum

NottsIan · 28th Mar 2018, 9:59 am

Hello all,
I've just dug out the mortal remains of a Pye base station. I've had this for about thirty years and it's time I did something with it. It's a rack mounted system from the Cambridge/Vanguard era. The transmitter is missing (but there's another partly dismantled receiver chassis in its place) and the receiver has many boards in common with the AM10B/D radios. I could do with knowing what it is before looking for circuit diagrams etc.

I'd be grateful for any information about this.

Best wishes

Ian.

SiriusHardware · 28th Mar 2018, 10:40 am

Ian, welcome, but we could do with a little more information.

Could you post a couple of pictures, and let us know if there are any manufacturer identification plates on any of the items.

Pye were fond of using small rectangular (aluminium?) plates with the model numbers and other pertinent details engraved on them.

G6Tanuki · 28th Mar 2018, 10:43 am

Have a look here:

http://www.pmrconversion.info/PYEBASEbroc.htm

Whst you're describing sounds rather like an AM27 or FM27. I used to have its big brother the F60FM as my 2-metre home station in the 1980s: with a bit of tweaking its QQV06/40A could put out about 75 Watts!

NottsIan · 28th Mar 2018, 12:28 pm

Thanks for the remarkably quick responses.

Yes, it has to be an AM27 from that brochure. Mine has an extra switch on the lower panel but it's clearly the same rack and receiver. Should I be looking for AM27 or AM10FRX diagrams?

Best wishes

Ian.

G6Tanuki · 28th Mar 2018, 1:31 pm

I'd look for both: I've always heard them referred to as the AM27 or FM27 receiver.

Sparky67 · 28th Mar 2018, 4:58 pm

To be totally pedantic, they were / are designated F27AM and F27FM. They sound much better with the audio filter choke bypassed and the parallel caps removed

G6Tanuki · 28th Mar 2018, 5:14 pm

One thing to remember if trying to fire one of these receivers up: they used Mullard OC170-type transistors in the RF amps, local-oscillator and 10.7MHz IF-strip (the 455KHz IF strip generally uses "GET" series transistors made by GEC, which are reliable).

The OC-transistors are of course prone to tin-whiskering. Expect to have to replace them all!

Also, the IF filtering is a bit 'wide' - some of these were designed for 50KHz channel-spacing and somewhat more FM deviation than is common today - so the received audio can sound a bit quiet.

The RX and TX crystals are the same as used in Cambridges/Vanguards and even the later all-transistor Westminster: you can often pick sets of them up cheaply at radio rallies.

Finally: on some of them there's a strange behaviour in the squelch where at certain signal-levels even with a constant carrier the squelch relay chatters at about 2Hz - the fault is due to a leaky capacitor and/one of the OC201 transistors in the squelch circuit which is *supposed* to provide a sort-of "Schmitt trigger" hysteresis effect having gone low-gain.

Sparky67 · 28th Mar 2018, 5:35 pm

... and all the coil cores will by now be very reluctant to move if you need to realign it Ian. Probably to the point of cracking and having to be drilled out. Been there etc.

Trying to remember the Pye designation from my youth....was that receiver called the AM10F / FM10F?

Martin

NottsIan · 29th Mar 2018, 1:07 pm

Thanks for all the information. Searching for the service information has been fruitless so far. Most of the relevant results point back to this thread!! I'll see what a "wanted" post brings.

With a bit of luck I'll get a chance to put some power on it over the weekend. Looking around today for OC170 substitutes and some isopropyl alcohol.

By the way, it's crystalled for 145.500 so shouldn't be too long before I can hear something on it

Best wishes

Ian.

28th Mar 2018, 9:59 am	#1
NottsIan Tetrode Join Date: Mar 2018 Location: Nottingham, Nottinghamshire, UK. Posts: 88	Pye base station identification Hello all, I've just dug out the mortal remains of a Pye base station. I've had this for about thirty years and it's time I did something with it. It's a rack mounted system from the Cambridge/Vanguard era. The transmitter is missing (but there's another partly dismantled receiver chassis in its place) and the receiver has many boards in common with the AM10B/D radios. I could do with knowing what it is before looking for circuit diagrams etc. I'd be grateful for any information about this. Best wishes Ian.

28th Mar 2018, 10:40 am	#2
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,558	Re: Pye base station identification Ian, welcome, but we could do with a little more information. Could you post a couple of pictures, and let us know if there are any manufacturer identification plates on any of the items. Pye were fond of using small rectangular (aluminium?) plates with the model numbers and other pertinent details engraved on them.

28th Mar 2018, 10:43 am	#3
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Pye base station identification Have a look here: http://www.pmrconversion.info/PYEBASEbroc.htm Whst you're describing sounds rather like an AM27 or FM27. I used to have its big brother the F60FM as my 2-metre home station in the 1980s: with a bit of tweaking its QQV06/40A could put out about 75 Watts!

28th Mar 2018, 12:28 pm	#4
NottsIan Tetrode Join Date: Mar 2018 Location: Nottingham, Nottinghamshire, UK. Posts: 88	Re: Pye base station identification Thanks for the remarkably quick responses. Yes, it has to be an AM27 from that brochure. Mine has an extra switch on the lower panel but it's clearly the same rack and receiver. Should I be looking for AM27 or AM10FRX diagrams? Best wishes Ian.

28th Mar 2018, 1:31 pm	#5
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Pye base station identification I'd look for both: I've always heard them referred to as the AM27 or FM27 receiver.

28th Mar 2018, 4:58 pm	#6
Sparky67 Heptode Join Date: Feb 2008 Location: Great Barr, Sandwell, West Midlands, UK. Posts: 589	Re: Pye base station identification To be totally pedantic, they were / are designated F27AM and F27FM. They sound much better with the audio filter choke bypassed and the parallel caps removed

28th Mar 2018, 5:14 pm	#7
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Pye base station identification One thing to remember if trying to fire one of these receivers up: they used Mullard OC170-type transistors in the RF amps, local-oscillator and 10.7MHz IF-strip (the 455KHz IF strip generally uses "GET" series transistors made by GEC, which are reliable). The OC-transistors are of course prone to tin-whiskering. Expect to have to replace them all! Also, the IF filtering is a bit 'wide' - some of these were designed for 50KHz channel-spacing and somewhat more FM deviation than is common today - so the received audio can sound a bit quiet. The RX and TX crystals are the same as used in Cambridges/Vanguards and even the later all-transistor Westminster: you can often pick sets of them up cheaply at radio rallies. Finally: on some of them there's a strange behaviour in the squelch where at certain signal-levels even with a constant carrier the squelch relay chatters at about 2Hz - the fault is due to a leaky capacitor and/one of the OC201 transistors in the squelch circuit which is supposed to provide a sort-of "Schmitt trigger" hysteresis effect having gone low-gain.

28th Mar 2018, 5:35 pm	#8
Sparky67 Heptode Join Date: Feb 2008 Location: Great Barr, Sandwell, West Midlands, UK. Posts: 589	Re: Pye base station identification ... and all the coil cores will by now be very reluctant to move if you need to realign it Ian. Probably to the point of cracking and having to be drilled out. Been there etc. Trying to remember the Pye designation from my youth....was that receiver called the AM10F / FM10F? Martin

29th Mar 2018, 1:07 pm	#9
NottsIan Tetrode Join Date: Mar 2018 Location: Nottingham, Nottinghamshire, UK. Posts: 88	Re: Pye base station identification Thanks for all the information. Searching for the service information has been fruitless so far. Most of the relevant results point back to this thread!! I'll see what a "wanted" post brings. With a bit of luck I'll get a chance to put some power on it over the weekend. Looking around today for OC170 substitutes and some isopropyl alcohol. By the way, it's crystalled for 145.500 so shouldn't be too long before I can hear something on it Best wishes Ian.