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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 29th May 2018, 10:05 pm   #1
chaz007
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Default Eddystone Receiver.

I’ve acquired this radio recently and am trying to track down the model, looking at google it seems to be possibly an 840 but there are differences. It's also been ‘got at’ works to a point but won’t receive anything other than random static and whistles. Has a non standard mains transformer fitted, some strange modifications to various things and the smoothing cap just loose inside, it reformed OK on my limiter though. Anyone got any ideas what it is so I can find the right schematics?
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Old 29th May 2018, 11:39 pm   #2
turretslug
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Default Re: Eddystone Receiver.

It does indeed give all the appearance of being an 840C, with its late model case, the linearised frequency scaling resulting from the 'C's variable ratio tuning drive and 480kHz to 30MHz coverage split into 5 bands. If so, the mains transformer would have been an addition to this originally AC/DC set- maybe fitting the transformer displaced the smoothing capacitor and they then lost interest in finishing things off properly, it's not unusual to encounter modified sets that started off as "nice idea" and ended in "but...."!

Hopefully, the 840C circuit will at least be a starter.
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Old 30th May 2018, 8:57 am   #3
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Default Re: Eddystone Receiver.

Have a look at the Eddystone User Group website, where you'll find a vast amount of information.
http://eddystoneusergroup.org.uk/

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Old 30th May 2018, 7:34 pm   #4
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Default Re: Eddystone Receiver.

I might recognise that one. Does it have a circular patch of rust on the case bottom?
Please may we see the transformer?
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Old 31st May 2018, 5:35 pm   #5
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Default Re: Eddystone Receiver.

Here’s some more pics of the radio. It does seem that it started life as an 840c but the knobs at the front are different, a sensitivity control has been added as well as other mods. Don’t know what the other things are on the back panel. Mr bodger has had a good go! The radio below is completely homebrew so the guy who had these must of knew a bit about it!
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Old 31st May 2018, 6:22 pm   #6
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Default Re: Eddystone Receiver.

Thanks for the pics. No it is not the same one I knew. Blooming great transformer that is!

I put one of the RS kit transformers in mine where the primary was 230-240V prewound, you make your own secondaries. The object was to change from U series to E series valves with lesser requirement on heater cathode insulation. I had the idea that was why it had hum on the LO when working at high frequencies. It didn't seem to be HT related. Everybody on CW @ 14MHz and above had a T3 note - worse on 28MHz. Interesting on SSB...

I also reckoned that isolation from the mains was no bad thing. I could see no need to run it on DC - ever.

At the time, when I was an SWL, I hoped it would be a step up from the Trio 9R59-DS I already had. The truth of it - not much different except that the construction was much more rigid.

I hope you enjoy putting it to rights. I would keep a transformer, just maybe not that one. It looks good for something else needing many more Watts.

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Old 31st May 2018, 6:38 pm   #7
chaz007
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Default Re: Eddystone Receiver.

It is a dirty great transformer! I think it’s going to take me a while to try and decipher what mods have been done and why/where they are connected with this one. Be nice to make it work as it should
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Old 31st May 2018, 7:03 pm   #8
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Default Re: Eddystone Receiver.

Good luck. I might have some info stored away somewhere...

I used to have the 840C instructions and circuit as a paper copy.
It seems my Eddystone folder of "gen" has nothing on the 840C so in the short term it is of no help.
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Old 31st May 2018, 7:30 pm   #9
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Default Re: Eddystone Receiver.

Looks like a transformer from old Marconi test gear maybe? They certainly used good build quality and often unusually high ht windings. That is in my opinion.
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Old 31st May 2018, 9:41 pm   #10
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Default Re: Eddystone Receiver.

That transformer looks to be a high quality vacuum-impregnated type, but of monster proportions for the job in hand.

It looks like rather a lot of the Eddystone circuitry has been replaced, but what with? I suspect there is no circuit for what it's become floating around anywhere.

It may be easiest to either use this set as a parts donor for restoring another, or to just treat it as a cabinet with a nice tuning drive and use it as the basis of something of your own (making a better job of it than the last guy)

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Old 31st May 2018, 10:00 pm   #11
chaz007
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Default Re: Eddystone Receiver.

I’ve included a couple of under chassis pics, it’s just a mess!
I think I’ll just add it to the to be fixed pile and try and get it working better than it does by replacing knackered components and hoping for the best! It must of worked at some point in its current configuration
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Old 31st May 2018, 10:56 pm   #12
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Default Re: Eddystone Receiver.

There's no accounting for what some folk do with things.... Is the tuning cord really scraping around what appears to be a meter casing fixed in place of the magic eye holder? Yes, that is a huge mains tranformer, and a rather nice one too- it certainly is reminiscent of ones found in Marconi stuff. The 840C doesn't really need anything bigger than the sort of thing that would be found in a mid 'fifties AM/FM set to run its valve complement.
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Old 31st May 2018, 11:09 pm   #13
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Default Re: Eddystone Receiver.

If you were to restore it to the original 840C configuration, you'd need to be very careful to get all the mountings and isolating components right

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Old 1st Jun 2018, 11:44 am   #14
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Arrow Re: Eddystone Receiver.

Although I've never owned nor worked on the 840C, I have owned and worked on many Eddystone receivers of the 'communications' type. Looking at the under-chassis wiring, I find it difficult to believe that that construction is original. If the set were mine, I'd retain it as an A.C. mains only model (perhaps replacing that mains xfmr.) and a complete re-do of the under chassis wiring - aiming at something comparable to the excellent standards one usually associates with such Eddystone kit.
So yes, a lot of work involved in all that - but the resulting sense of satisfaction would make it all worthwhile!

Al.
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Old 1st Jun 2018, 11:51 am   #15
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Arrow Re: Eddystone Receiver.

Quote:
Originally Posted by Jon_G4MDC View Post
I had the idea that was why it had hum on the LO when working at high frequencies. It didn't seem to be HT related. Everybody on CW @ 14MHz and above had a T3 note - worse on 28MHz. Interesting on SSB...
Probably due to lack of decoupling of the heater wiring plus a poor layout of that wiring.

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Old 1st Jun 2018, 7:26 pm   #16
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Default Re: Eddystone Receiver.

If you need a picture of layout then I have 2 sets here.Just PM me.
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