2nd Apr 2020, 11:19 pm | #1 |
Heptode
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Barker 88
Would anyone have or be able to take a photo of the underside of the chassis of a Barkers 88.
I've downloaded the schematic and I seem to have an extra wax capacitor but can't find it. Mark |
3rd Apr 2020, 12:10 am | #2 |
Dekatron
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Re: Barker 88
Does this help: https://vintage-radio.net/forum/show...4&postcount=11
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3rd Apr 2020, 9:06 am | #3 |
Heptode
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Re: Barker 88
Thanks for that bill just found out that there is 2 sets of the same model 88 a early one and a late one. The one I need is a early one. The schematic I have is the trader service sheet. Sheet says there are 6 x 0.02uf capacitors but I've got 7. Judging by the mains colours I would say somebody has been in there.
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3rd Apr 2020, 10:07 am | #4 |
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Re: Barker 88
Someone's definitely been in there as the smoothing caps have been replaced.
Where is the extra capacitor wired into the circuit? If it's the one you're pointing to, one end appears to go to chassis and the other to a pin on a valve holder. Which valve and which pin?
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3rd Apr 2020, 11:15 am | #5 |
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Re: Barker 88
One end is on valve 2 and chassis the other end goes to a tag and then goes to r2, then to valve2 via r10 I think and green cable goes to magic eye
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3rd Apr 2020, 11:30 am | #6 |
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Re: Barker 88
C8 ?
Lawrence. |
3rd Apr 2020, 11:45 am | #7 |
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Re: Barker 88
Agreed.
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3rd Apr 2020, 11:53 am | #8 |
Heptode
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Re: Barker 88
Ok if that's C8 then it would look at a glance I have a extra one here somewhere.
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3rd Apr 2020, 12:21 pm | #9 | |
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Re: Barker 88
Quote:
Lawrence. Last edited by ms660; 3rd Apr 2020 at 12:30 pm. |
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3rd Apr 2020, 1:50 pm | #10 |
Heptode
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Re: Barker 88
Thanks for that Lawrence me not reading probably. why would they do a alternative output stage? I was given this set ages ago wasn't planning on doing it up as I think the output transformer has gone the person I got it from said he had it on all the time the one it stopped working that's about a year ago. But isolation has changed that so I thought let's have a quick look at it. I have a output transformer that is not to far off so could use that
Mark |
3rd Apr 2020, 1:57 pm | #11 |
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Re: Barker 88
You say you think the output transformer has "gone". Have you tested it? Wound components are one of the first things to check when restoring a radio.
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3rd Apr 2020, 2:21 pm | #12 |
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Re: Barker 88
I've just been working on a barker 88 (about 2-3 weeks ago) my version was the modified output stage. This one had an extra 0.1 near the HT+ to ground by the output transformer connector. It was not on any of the circuits i could find.
My problem was that the one output valve had been forced in the holder and made t's own 'key' for the pin. I never noticed the first time i put it back together, and yes, got the valve wrong. It burned out the 100ohm g2 resistor. It was very smokey! It's ok now, if you need any info i can probably get it on the bench next week some ime. Derek |
3rd Apr 2020, 3:41 pm | #13 |
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Re: Barker 88
Graham, yeah I did check the output transformer and not getting any ohms or continuity on the green so I was presuming it would need a replacement ,that's one of the reasons I left it, but as I have more time on my hands why not. I have got some with a primary of 470.0 ohms and a secondary 0.40ohms i thought it would do.
Thank you Derek i should be ok, but if I need me help I will let you know Mark |
3rd Apr 2020, 9:16 pm | #14 |
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Re: Barker 88
I have a Barker 88 and so far have not found an exact circuit for it. Mine uses a 6J6 as a phase splitter....the circuit I have shows the 6Q7 being used as phase splitter. Extra components are used around the 6J6 so in the end I 'reverse engineered' the circuit.
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3rd Apr 2020, 9:50 pm | #15 | |
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Re: Barker 88
Quote:
The set also uses an energised speaker, so check the continuity of all the speaker windings.
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3rd Apr 2020, 10:25 pm | #16 |
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Re: Barker 88
The speaker winding is ok I will take the speaker out in morning to have a better look at the transformer. Can you still get one like that Graham
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4th Apr 2020, 8:35 am | #17 |
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Re: Barker 88
What could I use as a replacement I dont think rewinding would be worth the cost
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4th Apr 2020, 8:55 am | #18 |
Nonode
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Re: Barker 88
If you want to hear some sound from this receiver you could use a mains transformer as a temporary audio output transformer.
You will need a transformer with a split primary (120 V + 120 V) and a 3 Volt output. That should be a reasonable match for a 6V6 push pull output stage. |
14th Apr 2020, 3:39 pm | #19 |
Heptode
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Re: Barker 88
Hi what can I use to replace c13 its valve 3 cathode by-pass 25.0uf dont know the voltage is. Would this be a important one to change everything else I have from my stock but not sure about this one
Mark |
14th Apr 2020, 3:51 pm | #20 |
Hexode
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Re: Barker 88
I would use something like 22uf at 25volt(or higher)
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