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 Post subject: Eddystone 850/2
PostPosted: Sep Tue 14, 2021 1:45 am 
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Joined: Jan Fri 20, 2012 10:25 pm
Posts: 345
Location: Warminster, PA
Starting to work on my Eddystone 850/2. Can get the IF stage to align but the sensitivity is very low. Tubes all "check" ok but wouldn't rule out a soft one in circuit.

Poking around looking for flaky components and I'm noticing that on most of the soldered connections the component lead is not physically wrapped to the connections and then soldered, they look like they were just tacked on. Is this how the Brits assembled these radios?

This particular radio is identified as a development unit so maybe "production" wiring is better?

Oh, and any suggestions as to where to hunt to find the reason for the low sensitivity is appreciated.

Tom
W3TA


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 Post subject: Re: Eddystone 850/2
PostPosted: Sep Fri 17, 2021 2:36 am 
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Joined: Apr Sun 08, 2007 6:47 am
Posts: 4987
Location: British Columbia
I see a Plessey axial lead electrolytic, the one with the two tone plastic shell, that is likely to be dried out, however they are easily restuffed with a new cap if that's your thing. The rest look like either oil caps, or mil spec paper ones, could be TCC brand, but they are all 60+ years old so not trustworthy. Low volume could be something simple like the plate load resistor on the 1st Audio tube, or a leaky coupling cap in the audio section. I like Eddystone sets, they are rather nicely built, I'm not sure why they would tack solder stuff from the factory, that was not normal practice in British manufacture, though it does look like some repair work was done near the rear apron.
Regards
Arran


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 Post subject: Re: Eddystone 850/2
PostPosted: Sep Fri 17, 2021 1:18 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 18807
Location: Utica, NY 13502 (USA)
I have the VHF version of your radio, model 770/R. It is a complicated radio with 19 tubes! All of the paper and electrolytic caps were bad as well as some resistors that had been stressed and had changed value due to leaky caps. It also has several tubes with grid emission which caused some plate resistors to overheat.

The caps and resistors were not "tack soldered" but the wires were not mechanically twisted around the tube socket and other terminals (such as IF transformers) after inserting them through the holes. I assumed this was done to avoid damage to those components in the event that replacement would eventually become necessary. Forward-thinking Britts.

It's a fun radio once restored.

Dave


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