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Old 27th April 2007, 12:01 AM   #1
bulgin is offline bulgin  South Africa
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Hi All

Although I run tube equipment (Mostly Leak) and can do repairs and upgrades to a limited extent, my knowledge of tube circuits are shamefully inadequate. This situation will change as I bought a bundle of vintage tube literature last night for the equivalent of about US$8. The books and catalogues are old - some older than me - and here are some titles: Radio Engineer's Pocket Book (FJ Camm) 1944, Technical Manual - Sylvania Radio Tubes (1946), Sylvania Tube Compliment Book (1944), RCA Receiving Tube Manual (1940), Osram Valve Manual Part 1 (1951), The Superhet Manual, F J Camm (1946), Thermionic Valves in Modern Radio Receivers - Witts (1945), RCA Rec eiving Tube Manual (1940), Technical Manual - Sylvania Set-Tested Radio Tubes (1936), Marconi Valves (Undated) RCA Receiving Tube Manual (1956).

Cheers. It's cold and raining here in Cape Town and I've got a lot of reading to catch up on

bulgin
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Old 27th April 2007, 12:25 AM   #2
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In Pick'n'pay, or in Hyperama?
You are very lucky! Enjoy!
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Old 27th April 2007, 08:37 AM   #3
EC8010 is offline EC8010  United Kingdom
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You did very well there. F J Camm was a well-known author in the UK (lots of articles in Practical Wireless). Was it really the "Sylvania Tube Compliment Book (1944)" - a book of nice things being said about Sylvania tubes? (Thinking about it, it probably was.)
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Old 27th April 2007, 11:15 AM   #4
bulgin is offline bulgin  South Africa
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Hello Wavebourne & EC8010

How do you guys know about Pick 'n Pay or the Hyperama:

No, it wasn't there. I am a member of the Cape Town Society of Model and Experimental Engineers (Centenary Year now, 2007) and when members pass on to that great workshop in the sky, their tools, machines and libraries are often sold on our premises in aid of their widows or families left behind. During the last few weeks, I was absent from our Wednesday meets due to commitments and a member kept the books for me until last Wednesday. Both myself and the keeper of the books now may have a price on our heads. A mutual friend of both of us (living just around the corner from the keeper) is a valve collector...in fact his entire house is like a museum of vintage valve gear.

@EC8010 I have other books of F J Camm which I regularly read as they are so interesting. And piles of vintage audio mags with Mr Camm's writings.

Regards

bulgin
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Old 28th April 2007, 12:26 AM   #5
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Hi Bulgin (A),

So that's where our rain goes - Clouds up here and nothing else!

Regards
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Old 28th April 2007, 03:17 AM   #6
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Quote:
Originally posted by Johan Potgieter
Hi Bulgin (A),

So that's where our rain goes - Clouds up here and nothing else!

I remember going on N1 freeway near Randburg when the first rain started... People honked, laughed, they were happy! Radio started the song, "It is raining, man, Alleluia!" ...the next day hailstones of a chicken egg size were hitting my car.


You are lucky Johan! You may take half of our winter rains and give us half of your summer rains, I miss them here in California!


Bulgin, I can buy and ship you a scanner, also to buy and install additional 120 GB drive into my server, if you promise to scan all your books!
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Old 28th April 2007, 11:10 AM   #7
bulgin is offline bulgin  South Africa
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Hello Johan, Wavebourne

Errr...I have a scanner I'll have to ask the boss for 3 months off work though Oh hell, here comes the job jar

It's supposed to rain until Monday but right now there's a bit of sun.

While here oh Wise Ones, I recently saw a re-furbed Leak Stereo 20 which looked condition-wise, straight 'out of the box'. Mine too, is electronically in good condition with new capsets, binding posts and all the rest but it looks a bit rough compared to the best I've seen.

I'm planning a 'valet' service after considering a total strip and repaint (which I can easily do). The problem is those fragile bits of white lettering on the chassis. I suppose there are ways to reproduce them for re-application after painting but this could be risky.

I have been thinking, as an alternative - to remove fragile bits and carefully clean the chassis from dust and apply some Turtle Wax Color Magic (colour enriched car polish) in gold - very carefully, to enhance the gold-coloured chassis again. Obviously ensuring that this polish is safe for the white lettering. The black bits on the transformers should be no problem to restore to real black.

Do you think this will work?

regards

bulgin
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Old 28th April 2007, 12:41 PM   #8
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Bulgin,

Regarding the polish, y-e-e-e-e-s, but that will start to remove the lettering at some stage. The lettering is cleaning-resistant, but as the amplifier is old, this can be unpredictable. Water and soap, yes, then you will to carefully experiment. Coloured wax? that might also colour the white lettering. You will conclude that I did this before, but just washing and not so much colour restoration, except in small spots.

But, oh dear! I have bad news in other rerspects. Don't ask me why, but the Leak Stereo 20 has overcompensated NFB plus a less that optimal operating point for the first triode! This checks out in a rather nasty square wave response as well as linearity tests. I found this consistently on 6 amplifiers (3 stereos), so not a once off. It can be corrected with a few component value changes. In this respect you can either have a poor original h.f. response, or optimal with different values - not both.

Not wanting to high-jack the thread, you could mail me privately, or if others are interested or had similar experiences, start a new thread.

Regards.
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Old 28th April 2007, 06:52 PM   #9
bulgin is offline bulgin  South Africa
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Hello Johan

I will start a new thread if that's OK? "Leak Stereo 20..."

Regards

bulgin (AJH)
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