Pye Europa MF25 Information

[Medic6955]

Greetings from Canada

Looking for info on the Pye MF25, this is for a antique ambulance i'm restoring, looking for a confirmation of the crystal frequencies

These were popular where I live back in the 70's but seems nearly impossible to track down any info on them over here

I can clearly see the 10.7 MHz receiver IF, so i'm fairly confident the formula is:
(frequency - 10.7) / 3

Does the transmitter use 16 MHz (frequency/ 16)?

Would love to see a copy of a service manual or the pages from Chris Loreks book

Thanks in advance
Nick

[Medic6955]

After many hours of searching I did find the info I needed:

https://www.americanradiohistory.com...RT-1989-03.pdf

but i'd still love to see any schematics, info, ect you guys may have on the MF25

[G6Tanuki]

There were various Europas, MF5FM (5-Watt), MF25FM (25-Watt) and MF5U (5-watt UHF)..
http://www.pyetelecomhistory.org/pro...F25FMMF5U_1971

There is a writeup on crystallising and aligning them in the first Chris Lorek book. If you want to PM me an email-address I can photo the relevant pages and email them to you.

[There was even a pilot-carrier SSB Europa produced experimentally by Pye but despite showing some promise the concept never achieved type-acceptance in the UK]

[Medic6955]

Thank you, I sent a PM

The only major thing I'm lacking right now for my MF25FM is the load capacitance in pF or series so I can order the crystals...

[dodgy-dxer]

Originally Posted by Medic6955

Would love to see a copy of a service manual...

Nick

There was never a "service manual" for the MF25 which was pretty unusual at Pye

There is a 4 folded A4 or foolscap sheet with the circuit and alignement instructions

I will have a rummage for mine but haven't seen it in years!

If I find it I'll scan it

NB Be very careful when testing. The audio out chip must be balanced and if you earth one side of the speaker connection the chip dies instantly

Fred

[dodgy-dxer]

Originally Posted by G6Tanuki

[There was even a pilot-carrier SSB Europa produced experimentally by Pye but despite showing some promise the concept never achieved type-acceptance in the UK]

Wasn't the HF SSB170 made in the same case?

Fred

[Biggles]

I used to maintain and repair the Europa sets a few years back, for the Ambulance Service in the UK. I think I still have a lot of crystals for them somewhere, so if you know what frequencies you need, I could check my stock, assuming the frequency bands were the same in Canada as the UK. Ours were around 166/171MHz. I probably have a few spares for them too if you need some.
Alan.

[Medic6955]

Ours were all on 148-150 MHz, I don't mind ordering some crystals but I really need to find out what the load capacitance is if you have any idea?

[Biggles]

In the UK quite often I found that the crystal manufacturers would have the correct data spec for the crystal if you just gave them the radio type it for which it was required. The only other suggestion is to take it from the service sheet but I haven't seen my copy for quite a while now, and it may take some time to find it. I seem to remember that in Pye equipment the transmit frequency trimmer was quite often a capacitor, while the receiver trim was an inductor. It's a long time since I did anything with Europas so my memory may be clouded though.
Alan.

[dodgy-dxer]

For Crystals

quartslab@aol.com

UK company run by a ham

They may well have the Pye specs

Fred

[CambridgeWorks]

Be very careful with the audio o/p stage. Loudspeaker is 12 ohm impedance. The TO3 cased o/p ic (6 or 8 pin, M5102Y IIRC) is very rare! DO NOT earth the speaker pins !
I used to have a spare, but no idea where if it is not in my main IC box.
Sometimes the relay contacts could be intermittent, usually on rx. In all, a rig I liked. Our local ambulance service had about 100 total I maintained.
We had an additional channel I had to install on all over a weekend. 10.7MHz was the tx crystal for 171.2MHz. RX was 166.4MHz. Image being 145MHz. I often had fun with the local crews if stuck behind them in traffic. Using my 2M rig (Pye W15fm of course) on 145MHz with commands like "blue lights on" or "horns please" which they often obliged with.
The SSB170 is indeed the same box, 2-10MHz IIRC, it is fixed sideband, lower I think. I do own one.
Rob

[Medic6955]

Thanks for all the info guys

They are neat radio and formed the basis of our first provincial ambulance radio system

[VT FUSE]

The load capacitance was 30pF. SURPLUS 2-WAY RADIO CONVERSION HANDBOOK, Chris Lorek, ARGUS BOOKS had info and I had one for a couple of years Xtal'd on Ambulance service frequencies for the BASICS scheme.
Many on here will have the familiar yellow jacketed book sat on a shelf.
I just cannot bring to memory the Xtal multiplication factor.
I seem to recall that the ssb?? radio was built into the same rugged Pegasus/Beaver cast case as used by the military MOULD (insertion) and mobile installations etc,never saw one in the Europa style case (but then,I never was a Telecom's Engineer!)
Quartslab would have no problem calculating the Xtals out for you if you simply told them the TX/RX freq's required and specified they are for the high band FM radio.

Cheers

Mike

[AC/HL]

Europa crystal data

[Sparky67]

Was it the MF25 which suffered from the loose-antenna-connector-syndrome and intermittent high VSWR-generated issues due to it being riveted on rather than bolted? Or am I thinking of another Pye radio?

Martin
G4NCE

[M3VUV51]

didnt these put out lots of sproggs if i remember?

[Jon_G4MDC]

The RX crystal multiplications of the Europa series were always a puzzle to me.
For years the VHF Westminster had used 3rd Overtone (tuned by an inductor) doubled for low band, tripled for high band. High side or low side injection whatever suited.
(Interesting that UHF Europa followed the Westminster in multiplier choices)

On TX the FM modulators needed a low crystal frequency and high multiplication to get enough deviation.
The RX needed none of that. So why did they make the Europa RX use fundamental crystals and more multiplication....
Some of the worst spurs were caused by +/- crystal...

Come the M290 series and they were back to using 3rd overtone RX crystals...

[CambridgeWorks]

Never seen riveted connectors on these. Maybe the MF5AM I think. Can't say ever had spurious problems, but as a Pye service engineer always aligned correctly as per service instructions. Maybe if amateurs "tweaked" for maximum output, could have been a different matter. Certainly, the UHF and VHF 25W versions needed greater attention to detail when aligning. Also, the crystals could only be netted when the hinged PCB was in final position.
Rob

[dodgy-dxer]

A case for a "thumbs up" symbol if there ever was!!

Fred

[VT FUSE]

Medic6955

You have a PM