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-   -   Hickok 752A calibration? (http://www.diyaudio.com/forums/tubes-valves/203124-hickok-752a-calibration.html)

dgta 25th December 2011 04:57 AM

Hickok 752A calibration?
 
Does anyone have a calibration writeup for this tube tester? I do have the manual but it has nothing about calibration. A web search yielded nothing. Was there a separate service manual with this info? Thanks.

HollowState 25th December 2011 06:38 PM

1 Attachment(s)
To my knowledge there is no written calibration procedure by Hickok for the 752A. Calibration was set during manufacture by the use of mostly fixed resistors just like the 539 series. A "standard test tube", usually a 6L6, is used to verify accuracy.

However, a fellow named Daniel Schoo has written articals about calibrating Hickok tube testers. You can find them on line by searching his name. A good write-up was made available through Audioxpress on their website as a free download. It was for the 539C, but the basic principals can be applied to yours.

Also see:
http://bellsouthpwp.net/p/a/padgett46/cal539c.htm

http://books.google.com/books?id=FaF...0schoo&f=false

http://www.desmith.net/NMdS/Electron...ion%20V4.1.pdf

dgta 26th December 2011 03:04 PM

Thanks Hollow. Good reading.

It looks like Daniel Schoo wrote an article in Audio Xpress about calibration of Hickok testers, somewhere around July-August 2007. Can't find it for download on their website. Does anyone have a copy or link to it?

EDIT: The article IS listed (8/07) but won't download. Anybody have a copy?

http://www.audioamateur.com/ax-supplemental.html

HollowState 26th December 2011 04:25 PM

The PDF attachment that I posted was from AudioXpress.
Untitled Document Scroll down to 8/07 area

Joshua_G 26th December 2011 05:39 PM

There is a calibration manual offered at ePay: HICKOK 752 752A TUBE TESTER CALIBRATION MANUAL. VERY RARE! FIRST TIME AVAILABLE! | eBay .

dgta 26th December 2011 10:19 PM

Thanks Hollow, I didn't realize your pdf was the actual article. I did scroll down to it on their site but it wouldn't download. Just took me to a useless page when I clicked on it.

Joshua, did you actually get that manual? Looks suspicious. Hard to believe he's the only person in the world with a copy of the manual and then he "re-typed it" ???? Why? Why not just sell copies of the real thing? Sounds fake.

HollowState 26th December 2011 11:39 PM

Quote:

Originally Posted by dgta (Post 2835086)
Hard to believe he's the only person in the world with a copy of the manual and then he "re-typed it" ???? Why? Why not just sell copies of the real thing? Sounds fake.

It may be a legal thing. If it's a Government document perhaps reproducing it directly may not be a good idea, even if they don't really care. I've never heard of it until now. But I don't need it either. The Schoo artical is enough. And yes, the AudioXpress website isn't working right now. The PDF I posted I had saved in "my documents" some time ago.

dgta 27th December 2011 02:50 AM

I can buy the legal theory, not sure I'm ready to buy the idea that he's the only one in the world with a 752 calibration manual. I'd want to see proof that there actually is such thing as a calibration manual from Hickok, not something written by someone else.

And yes, with Schoo's article and a little tracing through the schematic I think we have enough to make sense of it. Thanks. But I wouldn't mind paying for a factory manual if I knew it was genuine.

GloBug 27th December 2011 03:12 AM

That eBayer has sold a few copies with good feedback. Might be worth a shot.
For $30, I can see why your hesitant.

tonekwest 27th December 2011 10:33 AM

New member to DIY, and thought I might comment about the post. I personally know that Hickok did make certain manuals for the 752/752A that contained the above mentioned calibration/troubleshooting info. Since the 752/752A was used by the FAA, Hickok did supply the Feds with the info. I would also agree with HollowState about copying Government documents and offering them for sale. As far as the only one in the world with a copy, not likely!


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