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Old 1st Jul 2011, 12:21 am   #21
Herald1360
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Default Re: Pye Westminster

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Originally Posted by Junk Box Nick View Post
"INS 4/11/74" and "CODE" and the same number that is on the plug on the PCB. I would guess that 4/11/74 was the date some work was done. As you say this is over ten years before cellphones started to appear.
INS for "INSTALLED" perhaps?

It's got bugs in it- any of them got a convenient date code visible?
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Old 1st Jul 2011, 11:59 am   #22
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Default Re: Pye Westminster

Some of the bugs are still alive - I'm sure they've not been there since 1974.
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Old 16th Jul 2011, 8:19 pm   #23
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Default Re: Pye Westminster

I have a copy of the manual for a Westminster. any use to you?
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Old 11th Aug 2013, 6:07 pm   #24
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Default Re: Pye Westminster

I have just acquired a Pye Westminster W30FM and W15U - does anybody have the circuit diagrams/user manual for either? If not the W30FM then the W15FM circuit will do to get me going... I last worked on these 20+ years ago!

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Old 11th Aug 2013, 9:11 pm   #25
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Default Re: Pye Westminster

I've got W15FM docs somewhere - If I can find them I'll happily photocopy them for you.

(It's a long time since I played with Wessies too: at one time I had *five* of the things boot-mounted in my car. Then we got issued with the AM/FM Whitehall which made the control-box-fitment issue a bit easier...)
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Old 15th Aug 2013, 5:56 pm   #26
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Default Re: Pye Westminster

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Their main problem is that they need a pair of crystals for each frequency of interest, and I think each pair made to order will knock you back about £20 now. I think it used to be about £11 per pair.
We surely must be approaching the point now where fairly compact Direct Digital Synthesiser circuits must be available virtually off the shelf - most of these old units used a relatively low frequency crystal (one for transmit, one for receive as you say) followed by a multiplier to get to the required frequency.

A lot of these old crystal-controlled antique transceivers would be much more useful if there was a handy general purpose programmable synthesiser block available - has there not been any progress along that road?
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Old 15th Aug 2013, 6:07 pm   #27
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Default Re: Pye Westminster

Further to the last post, this is the kind of thing I was talking about, although the example linked to here would be most useful as the VFO for a direct-conversion receiver and / or companion transmitter. But if you were handy with microprocessors you could also persuade it to generate the transmit / receive frequency pairs required by an old crystal controlled transceiver with virtually no limit to the number of channels possible, within legal limits and the physical capability of the transceiver in question of course.

http://www.pongrance.com/super-dds.html
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Old 17th Aug 2013, 6:42 pm   #28
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Default Re: Pye Westminster

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Originally Posted by SiriusHardware View Post
A lot of these old crystal-controlled antique transceivers would be much more useful if there was a handy general purpose programmable synthesiser block available - has there not been any progress along that road?
There is the Multi-Rock 2 which I built and works well, the kit is available from the S9 Plus website for £30.

I am still using my W15FM wessie on 4 metres.

Very interesting thread!
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Old 19th Aug 2013, 9:24 pm   #29
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Default Re: Pye Westminster

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A lot of these old crystal-controlled antique transceivers would be much more useful if there was a handy general purpose programmable synthesiser block available - has there not been any progress along that road?
Since asking my question (re: Direct Digital synthesisers) I have discovered that there is a small DDS module available all over internet auction sites - about £6 from a UK source, or even less if you are prepared to risk an order from the far east. (Search on 'DDS AD9850')

The module as it comes doesn't do anything - the user would need to be a little bit conversant with microcontrollers such as PIC, AVR, Arduino, etc - for the latter I have already found some open source sketches which have been written to control these modules.

I don't see an easy way to frequency-modulate them through direct application of an audio signal, so they are best used as steady VFOs for tunable rigs or as a multi-crystal substitute in an AM radio such as the AM Westminster.

To achieve FM TX I think you would have to mix a real crystal oscillator and the output of the DDS operating at frequencies which, when mixed, produced the desired 'crystal' frequency. You could then FM the crystal oscillator in the usual way, and the mixed output would then also be FMed.

To act as a multi-crystal substitute the microcontroller would need about 5 I/O pins to serially control the DDS synthesiser, 6 pins (minimum) to drive an LCD display, a single pin to read the state of RX/TX in order to know when to generate the receive or transmit crystal frequency for any given channel, and four or eight input bits to read one or two BCD switches for channel selection. That's potentially ten or a hundred channels from one DDS module, or, since the step resolution seems to be optionally as small as 1Hz, a continuously tunable VFO tuning across the whole of the AM portion of any amateur band such as 4m.
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Old 19th Aug 2013, 11:21 pm   #30
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Too late to edit the above: The universal DDS synthesiser module I was talking about is the very same one used at the heart of your Multi-Rock 2: I have to say that for what you get (including ready made PCBs, a display and a couple of rotary encoders and a preprogrammed microprocessor with a good generic set of features) I think it seems remarkably good value - I doubt that I could produce a finished one-off project like that for myself for anything less.
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Old 21st Aug 2013, 12:00 am   #31
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Default Re: Pye Westminster

Yes, and by building as a stand-alone unit you can use it for any number of applications.
But if you still want crystals, I recommend IQ Design for price and speed.
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Old 21st Aug 2013, 9:04 am   #32
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Default Re: Pye Westminster

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Originally Posted by SiriusHardware View Post
To achieve FM TX I think you would have to mix a real crystal oscillator and the output of the DDS operating at frequencies which, when mixed, produced the desired 'crystal' frequency. You could then FM the crystal oscillator in the usual way, and the mixed output would then also be FMed.
Much "FM" private-mobile-radio gear actually used phase-modulation rather than directly FMing the xtal. Back in the 1960s and 1970s it was easier to do this [basically connecting a variable reactance across a coil somewhere after the xtal oscillator] than trying to direct-FM the xtal.

It's hard enough to get a straight xtal oscillator multiplied up from low-HF to 450MHz or so to stay reliably on-channel for ambient temperatures ranging anywhere between -20 and +50 centigrade. Hooking extra components across the xtal to do direct-FM wouldn't help stability. You'd be amazed how hot the inside of a black car's boot can get on a summer's day.
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Old 21st Aug 2013, 12:49 pm   #33
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Default Re: Pye Westminster

ISTR that phase mod with either pre- or de- emphasis of the input audio (can't remember which) comes out as FM anyway. At any rate for NBFM maybe.

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Old 21st Aug 2013, 2:36 pm   #34
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I can only speak from experience with the later Pye M290, but the FM versions of that radio did apply their FM or PM to the TX crystal oscillator - only a little bit of FMing was actually needed, because when you multiplied the crystal frequency by *2 or *4 to get the final TX frequency, you also, happily, multiplied the deviation by 2 or 4 as well.

So, in theory, you could take out the original TX crystal and replace it with one with (say) 1/3rd of the original crystal frequency, but leave the system to modulate it still in place. Get the DDS to generate the other 2/3 of the original frequency, mix it with the output from the new 1/3rd crystal and one of the resulting new frequencies will be the original crystal frequency, frequency modulated. This can then be passed up through the original multiplier chain to the transmitter.

By changing the DDS frequency up or down in carefully worked out steps, multiple FM TX channels could be generated just with the one FMed 1/3rd frequency crystal.

On the receive side, depending on how high the frequency of the original RX crystals was, the same crystal + DDS mix trick might have to be used to get the fairly high 'crystal' frequency needed, minus the modulation of course.

Interestingly the AD9850 DDS does have the facility for 5 bit's worth of Phase Modulation but that seems too crude for PM representation of complex audio waveforms.

The AD9850 frequency programming interface (in parallel mode) is extremely fast, so you could, again in theory, continually read audio in from a high-speed ADC and continually modify the DDS frequency plus and minus from centre by an amount corresponding to the value read in from the ADC.

Yes, things can and do drift. I believe (I could be wrong) that the M290s could have heated, temperature stabilised crystal compartments as an option, although I never saw one.

Last edited by SiriusHardware; 21st Aug 2013 at 2:57 pm.
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Old 22nd Sep 2013, 8:36 pm   #35
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Default Re: Pye Westminster

Here in the USA in the 1960's one of the PYE Cambridge series mobiles was imported and made into a car telephone. The one with the Ledex relays inside. An external decoder by Western Electric was added and a "Princess" style home telephone was used as the control box. It is shown on my Bell System car telephone history web pages near the bottom of this page:

http://www.wb6nvh.com/MTSfiles/Carphone3.htm
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Old 23rd Sep 2013, 12:08 am   #36
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Default Re: Pye Westminster

Hi Geoff,
The Cambridge is (was) the predecessor to the Westminster. Valve transmitter but transistorised receiver.
I'm intrigued by the link-up with ARC, whose Avionics products I used to service.
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Old 24th Sep 2013, 9:54 am   #37
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Even some Westminsters used valves for the PA, the F30 base station has one and so does the 30W mobile version with an inverter for the HT. I used Cambridges and Westminsters for PMR from 1966 until the use of mobile phones became cheaper than the license.

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Old 24th Sep 2013, 6:59 pm   #38
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Default Re: Pye Westminster

I still have a modified 2m westminster with about 4 sets of crystals. Best / clearest set I have.

I have a book about modifying them by a guy called Chris

I used to come across them in air sea rescue in the 80's. they mounted them in wessex helicopters to talk to the coastguard. Trouble is they shook themselves to bits / off tune and went US on a regular basis.
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Old 24th Sep 2013, 8:06 pm   #39
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Default Re: Pye Westminster

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Even some Westminsters used valves for the PA Peter
Yes, the high power ones. The Pye evolutionary trail goes backwards too, there was a Vanguard with essentially the Cambridge receiver, the AM25T, but we're digressing.
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Old 24th Sep 2013, 8:25 pm   #40
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Default Re: Pye Westminster

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I have a book about modifying them by a guy called Chris
That'll be Chris Lorek's "The PMR Conversion Handbook".
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