Pye T30FM transmitter and R17/R18 receivers

[G8BBZ]

Hi All,
I have recently acquired two Pye base station systems, one being T30FM and R17 and the other T30FM and R18. Old stuff but it in excellent condition and I am determined to do something useful with it.
I find I have no manuals for any of these equipments in my collection and hope somebody can help.
The two T30FM's appear to have different PA stages, one has a single large PA module, the other a two smaller PA modules.
The R17 and R18 appear to be identical apart from the RF/Mixer module. The R17 appears to be a standard Westminster receiver module, the R18 has a more complex RF module.
I am sure everybody else had these units years ago and replaced them with something smaller and more modern.
Any circuit diagram and alignment info would be gratefully received - any cost incurred will, of course, be reimbursed.
cheers
Peter G8BBZ

[G6Tanuki]

From memory, the crystalling and alignment of these are discussed in the first version of the Chris Lorek PMR conversions book. My copy's *somewhere* in the attic but it would probably take me an afternoon to find.

[Jon_G4MDC]

You don't say whether they are High band (148-174 mostly) or Low Band (68-88MHz) or could be P Band 79/101MHz?

I know a fair bit about these and have some info - but it is well buried.

T30FM IIRC had a low power PA Box - single output device about 10W-ish to a second square box usually containing a pair of devices to reach 30W. I have seen 45W or more from them.

They had a bit of an issue with power supply dissipation on high duty cycles. The 2N3055 on the heatsink at the rear gets a hard time. Regulator PCBs are often quite crunchy around the driver TR and resistors.

I forget the R17/18 but I think you might be right that one had a front end box with nice helical resonators while the other only had a front end PCB - pretty much stolen from a Westminster.

[G8BBZ]

Hi Jon,
All are hi band and currently tuned around 154MHz so I presume came out of a home office system somewhere - though having said that i would have thought all of the home office police, fire and ambulance service systems would have disappeared long since when they all converted to Airwave.
Thanks for the tip on the psu issues - i will investigate
cheers
Peter G8BBZ

[Jon_G4MDC]

Very good Peter. I think you will find that FM Westminster crystals will suit them.
Double check by reverse calculating the ones already fitted if there are any.

TX will be 4MHz for 2m, Fc/36, 30pF Parallel will usually be fine.
RX will be 45MHz for 2m, (Fc-10.7)/3, Series resonant 3rd Overtone.

Most Japanese rice box crystals are fine for the RX but their TX ones are more often
12,16 or 18MHz.

I too like that front end box. Tip is to inspect the copper sheet inside the lid.
It needs to be clean and mate well with the dividers in the main chassis.
I have increased sensitivity by 6dB just by rocking the lid on these!

[CambridgeWorks]

Hi Peter, for old times sake I wish I could help but am certain all my manuals went about 10 years ago, just keeping a few of very rare ones. I will look just in case. Btw it is 50 years since we worked in Cambridge!
As Jon says, the lid fitting is critical as helical resonators are contained within. A fibre tip burnishing brush was a handy tool to polish up the mating surfaces.
In service I found the T30fm the most reliable gear of that era. Fit and forget, unlike the AM tx, frequent replacement of QQV03-10.
Basic R17 alignment is same as W15fm, the R18 only has the selective front end as a difference afaik. The cascode fets sometimes failed with near lightning strikes.
Before any alignment, dribble some ipa or similar in the coils to free up the slugs. NOT the beer IPA or even "Dark Tolly and Mild" from 1968!
Rob

[Jon_G4MDC]

Who wants to use Tolly Cobblers to free up front end slugs?
You guys beat me to Cambridge by about 10years by the sound of it.

In 1978 BBC/PYE....interviewed at both.

The ceilings were falling down at the BBC so ended up in CB3 1DW.
(before it became CB3 1DP - and there is a story there but it is only for the pub)
Good recall about the fibre brush - quite essential kit.

I did more with that box on the R150/R470/R460 - the exact same principles applied though.

We can discuss T30AMs a plenty. I like them.

[Biggles]

If you can give me a couple of days to find them I think I may have the genuine Pye manuals for these. I'm pretty sure they were used as site links before the Home Office main schemes went high band and they were replaced by microwave. It's a long time since I worked on that stuff. I will have a rummage round in my stock of manuals and get back to you.
Alan.

[Jon_G4MDC]

You are right Alan. R150 and R470 were link receivers.

Please don't go to any trouble on my account to look handbooks for those out.
I have them but they are well buried in the pile.

It could be Peter would appreciate any R17/R18 or T30FM stuff you can find though!

[Biggles]

Peter, I have found all three Pye manuals you need. Luckily I had seen them fairly recently. If you still require them send me a PM. Yours for the cost of postage.
Alan.

[Jon_G4MDC]

Well done Alan!

If Peter doesn't want them I might ....

I know I have T30AM already, but it could be the others are missing from my collection. I didn't encounter many of those in the day.

I did have a T30FM/R18(17?) pair running on 70.45MHz at one point.
That ran 45W out quite easily. They could usually hear me when using it but I had no where to QSY...only one set of crystals.
Later I used an FM914 which managed almost as much output on a decent 12V supply. That is still around here somewhere.

Just remembered another T30FM of mine. It was used as an AX25 Packet-banger when I lived in Cambridge and the nearest packet node was the RSGB in Potters Bar. 144.650 I think. Kerrrr-chiiiiick

[Biggles]

I seem to remember the link transmitters were pretty reliable. I think they used to auto shut down the remote TX if the receive path was lost. They did suffer when there was a lift on. I remember being on a site near Kendal and every link was chattering on and off due to long range interference. I think the links ran about ten watts into either a three or five ele yagi on horizontal polarisation. They were all replaced with Philips L700 microwave or those orange Plessey jobs when the main Tx went onto 154/155 MHz sometime in the eighties. The main Rx's were more of a problem to set up. Who remembers trying to align the tones on a Pye ASSORT voting system? Hours of frustration. Happy days.
Alan.

[SiriusHardware]

These units are briefly covered in the earlier of Chris Lorek G4HCL's two books about PMR conversions to amateur use - 'Surplus 2-way Radio Conversion Handbook' (Argus). The information given amounts to crystal calculation / specifications and alignment points.