Help - tube radio - Page 3

JDeV · 26th February 2003, 07:16 PM

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.

EC8010 · 26th February 2003, 07:17 PM

Case proven, it has permeability tuning for FM, or at least, it will have when some string is added.

JDeV · 26th February 2003, 07:21 PM

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?

EC8010 · 26th February 2003, 07:22 PM

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.

dhaen · 26th February 2003, 07:26 PM

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.

EC8010 · 26th February 2003, 07:28 PM

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.

dhaen · 26th February 2003, 07:31 PM

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?

EC8010 · 26th February 2003, 07:34 PM

Good grief, no! It's far more fun guessing.

JDeV · 26th February 2003, 07:36 PM

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.

planet10 · 26th February 2003, 08:02 PM

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

26th February 2003, 07:16 PM	#21
JDeV diyAudio Member Join Date: Oct 2002 Location: Cape Town	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. __________________ "Be carefull who's advice you buy, but be patient with those who supply it." From Baz Luhrmann's - Everybody’s Free (To Wear Sunscreen)

26th February 2003, 07:17 PM	#22
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Case proven, it has permeability tuning for FM, or at least, it will have when some string is added. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

26th February 2003, 07:22 PM	#24
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Date? 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. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

26th February 2003, 07:31 PM	#27
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	Date question 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?

26th February 2003, 07:34 PM	#28
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Search for a schematic? Good grief, no! It's far more fun guessing. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...


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26th February 2003, 07:26 PM	#25
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	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.

26th February 2003, 07:36 PM	#29
JDeV diyAudio Member Join Date: Oct 2002 Location: Cape Town	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. __________________ "Be carefull who's advice you buy, but be patient with those who supply it." From Baz Luhrmann's - Everybody’s Free (To Wear Sunscreen)

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