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Old 26th February 2003, 07:16 PM   #21
JDeV is offline JDeV  South Africa
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Thanx to all for all Just hope I get it running now.
I start to like this tube valve bussiness, will have to try some more.
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Old 26th February 2003, 07:17 PM   #22
EC8010 is offline EC8010  United Kingdom
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Case proven, it has permeability tuning for FM, or at least, it will have when some string is added.
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Old 26th February 2003, 07:21 PM   #23
JDeV is offline JDeV  South Africa
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Quote:
Originally posted by EC8010
Case proven, it has permeability tuning for FM, or at least, it will have when some string is added.
When I add the string , must the cap and other tuner thing (what do you call it) both be turned all the way to the 1 side or must they actually be "tuned" for too other?
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Old 26th February 2003, 07:22 PM   #24
EC8010 is offline EC8010  United Kingdom
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I've just been looking harder, and realised that very few valve radios had ferrite rod aerials, and that the IF transformers are remarkably small. I think this must be quite a late valve radio. My Mullard ECL86 data sheet is dated 1963, so it could be late 60s.
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Old 26th February 2003, 07:26 PM   #25
dhaen is offline dhaen  Europe
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They each do different things: The air-spaced tuning capacitor is for AM (MW), the tuning coil is for FM.
Re-stringing a tuning cord (without a diagram) used to be every service engineers nightmare. There can be many permutations, and there is usually a spring somewhere to maintain tension.
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Old 26th February 2003, 07:28 PM   #26
EC8010 is offline EC8010  United Kingdom
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Quote:
Originally posted by JDeV

When I add the string , must the cap and other tuner thing (what do you call it) both be turned all the way to the 1 side or must they actually be "tuned" for too other?
It would be nice to think that the string just goes in a large pentagon, but designers were often a bit imaginative here. You'll need to set both the variable capacitor and the variable permeability tuner to their clockwise endstops before adding the string. The larger pulley probably has room for the spring that holds the "string" in tension. When I was a kid, I had a lot of trouble putting the string back on and making it work afterwards.

It's not really string, you need fine non-stretchy nylon cord. The proper stuff is probably available on the web if you do a "vintage radio" search.

There's a very good book on restoring radios, "Electronic Classics" by Emmerson. He deals with all the problems, together with a very sneaky wheeze for replacing tuning scales.
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Old 26th February 2003, 07:31 PM   #27
dhaen is offline dhaen  Europe
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Yes, I agree. An oddity is the size of the output transformer; It's too small for a good quality output stage. If they were economising, I would have thought they'd have used ECL82 which was cheaper at the time.

Conspiracy theory:
It used to have an ECL82.....

Has anyone searched for a schematic?
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Old 26th February 2003, 07:34 PM   #28
EC8010 is offline EC8010  United Kingdom
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Default Search for a schematic?

Good grief, no! It's far more fun guessing.
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Old 26th February 2003, 07:36 PM   #29
JDeV is offline JDeV  South Africa
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Earlier today when I got this radio I thought, "ah a nice tube radio, must be great working with this", it seems like it is going to be more then just "great" more like a "great challenge" to repair it. But, got time - got diyaudio.com - will work.
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Old 26th February 2003, 08:02 PM   #30
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Quote:
Originally posted by JDeV
Tube ECH81 broke when I touched it, it was all white inside.
I should have a bunch of those in one of my junk tube boxes... but it would need to be mailed half-way round the world -- might still be cheaper than buying one..

dave
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