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Old 26th Mar 2018, 9:44 pm   #1
poppydog
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Default Jamistor transistor 2

I recently repaired this French LW/MW radio and it's looking and sounding so good I thought I would post on here with it as its something a little different. The sound was very quiet and a little distorted and the current was a bit high, a visual check revealed a 500uf electrolytic smoothing cap that had started to reveal its contents and a 100uf output coupling cap that didn’t look much better. The 100uf output coupler measured 29pf according to my tester, I decided to replace all the electrolytics, there was only 4 in total anyway so it made sense to do them all, the current came down the distortion disappeared and the radio now had good volume.

The speaker is quite odd on this in that the magnet is on the cone side, a little research revealed that the French have done this on 1 or 2 other radios, I'm assuming it’s a space saving thing. I did have a bit of an issue with the coil starting to rub whilst it was out of the radio after checking that everything was ok after the cap replacement but since its back in the case it seems to be ok (fingers crossed).

The board layout is nice and simple, ideal for me, and the components are all easily accessible. It now sounds fantastic and picks up everything on both wavebands, it’s the most sensitive am radio I own.

The cabinet was not in too bad a condition apart from a fair bit of the vinyl had come unstuck. That was a bit of a pain to stick back, someone had already had a go at sticking the bottom of the front, there was a load of pva an inch thick that took some getting off before I could start. That front piece didn’t turn out as good as I wanted it to but its as good as its going to get, it needs a new piece really. I think its supposed to take a pair of 1289 4.5v batteries but the battery connector is not in good condition so an aa 9v holder is attached with some snaps, a pp9 was just a little too big.

Some information and schematic is available from here https://www.doctsf.com/grandlivre/fiche.php?ref=28494 (I hope I'm allowed to post this link on here).

One thing that was not nice was that it was full of either dandruff/dead skin or something just as nasty that ended up getting everywhere , I initially thought it was dried glue but the dried glue was in fact orange in colour.

I know this was only a cap changing exercise but it was worth it as this radio is a belter.

Here are some 'before' pics, will post some 'after' pics in a bit.

Regards
Poppydog
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Old 26th Mar 2018, 9:52 pm   #2
poppydog
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Default Re: Jamistor transistor 2

Some more pics in state of dis-repair.
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Old 26th Mar 2018, 9:57 pm   #3
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Default Re: Jamistor transistor 2

Final pics - the 'after' pics...

Regards
Poppydog
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Old 26th Mar 2018, 10:07 pm   #4
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Default Re: Jamistor transistor 2

Nice job, as you say its an interesting design, I do like the rivet/tagboard assembly, when does this set date from?

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Old 26th Mar 2018, 10:10 pm   #5
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Default Re: Jamistor transistor 2

Elegant on the outside, neat on the inside, plus the added interest iof being unusual.
GO, PO, and a large speaker, so it's a competitor to the Hacker Herald.
A very attractive set, nicely restored.

You'll have to take it on a beach holiday to the South of France.

David
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Old 27th Mar 2018, 5:46 pm   #6
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Default Re: Jamistor transistor 2

Designed to be either a portable or slide into a car dashboard, a matching auxiliary amplifier can be fitted to the car for higher power output to an additional speaker. The label in the picture dates it to 1968, curious that it is all hand made when printed circuits where the norm by then, similar to the earlier Bush TR90 car/portable in that respect.
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Old 27th Mar 2018, 9:38 pm   #7
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Nice job !!
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Old 27th Mar 2018, 10:31 pm   #8
poppydog
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Default Re: Jamistor transistor 2

Thanks for all the replies, I am not sure what year this model was in production from as there is very little information on it however the guarantee card that came with this has a1968 stamp on it, the serial number on the card matches the one on the case. The rivet/tagboard is the first one I have ever worked on, one thing I was surprised at was the amount of solder inside those rivets, the joint must have stayed hot for a very long time after.

No need to travel to the South of France Radio Wrangler as I can get to the beach in just 2 minutes from where I live in my French van (Citroen Dispatch) with my French radio and some snails I collected on the way .

Yes Geoff I think you are right about it being for use in a car etc. as there is a separate button on top that needs to be pressed if you want to use an external aerial i.e. car etc.

Its certainly turned out better than I expected, even the missus said she liked it

Regards
Poppydog
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