SV: SV: [AMPS] Re: High voltage tester 0-30kV for sale or swap

[sm5ki]

>My instrument can actually hear the first ions travelling over on voltages 
>much lower than flash-over. Great when testing transmitting tubes. I 
>remember making an experiment with a 40uF/2500V metal paper cap used in hi 
>voltage photo-flash units and some copying machines. I could actually hear 
>the self-healing process and could increase the voltage til the flash-over 
>point when the cap became permanentely shorted at abt 5kV.
>
>Yes, the ceramics piezo effect is heard with this kind of commercial 
>instrument. Hard to do with a 15 mm plastic tube,hi!
>
>A similar instrument has been made by AIRMEC around 1957 if I remember right?
>
>I remember also that in 1947 we used to listen on our labs long-wave 
>receiver for corona effects in shipborne transformers.
>
>I am glad to report also I got response from different parts of the world 
>to my mail.
>
>Be careful Rich - hard plastic tubes  no good for those  DX ears, hi!
>
>Prosit de Hans SM5KI
>----------
>>Från: measures <2@vc.net>
>>Till: "sm5ki" <sm5ki@algonet.se>, "Martin Ellis" <jmellis@ihug.co.nz>, 
>"amps" <amps@contesting.com>
>>Ämne: [AMPS] Re: High voltage tester 0-30kV for sale or swap
>>Datum: mån 20 mar 2000 15.26
>>
>
>>
>>>I am the owner of what I think you call a " high pot". It is made by Danish
>>>firm Danbridge and goes fro 0  up to 30 kV. Basically it is, I think, a
>>>variable high impedance DC voltage source with an audio amplifier and a
>>>microammeter in series. As you turn up the voltage  you can hear every ion
>>>travelling across your test object and at the same time read the microampere
>>>current. If you increase voltage, you get a cracking noise that just before
>>>flash-over turns into a hissing sound. The flash-over should not harm your
>>>test object as the generatosr inherent resistance is high.
>>>
>>>Great for testing tubes, transformers, isolation and transmitters. However,
>>>I believe piezoelectric effects in ceramics may disturb the measurments?
>>>
>>I  have not observed this.
>>
>>>Weight is 12.5 kgs
>>>Dimensions 16 1/2W x 10 1/4H x 11 3/4D
>>>And is for sale or a swap deal?
>>>
>>>This instrument must be similar to yours Rich?
>>>
>>It is similar to my largest high-pot, except mine has no speaker.  I use
>>a 15mm plastic tube to listen for corona.  .
>>>
>>>
>>>
>>>>FrÂn: measures <2@vc.net>
>>>>Till: "Martin Ellis" <jmellis@ihug.co.nz>, "amps" <amps@contesting.com>
>>>>Ÿmne: Re: [AMPS] 2 x 3-500z amplifiers
>>>>Datum: mÂn 20 mar 2000 07.21
>>>>
>>>
>>>>
>>>>>
>>>>>Good morning,
>>>>>While activity is quiet on the reflector, I would like to raise
>>>>>a question about the TL922 amplifier:
>>>>>
>>>>>How can we assess the performance of individual tubes in a TL922?
>>>>
>>>>The most accurate way is to high-pot. the grid/fil.   Normal withstanding
>>>>potential @2uA is 8 to 9 kV.  With a withstanding potential of under 5kV,
>>>>the filament/grid may short when the tube is very hot.  The second most
>>>>accurate way is to measure the grid/fil. C with a digital C meter.
>>>>Anything over 10pF indicates that the filament grid clearance is
>>>>abnormal.
>>>>
>>>>>For example, after a major event is one tube faulty or do we need to
>>>>>replace both tubes?
>>>>
>>>>Only tubes with low withstanding potential need to be replaced.  922s
>>>>typically short one tube per ''main event''. .
>>>>
>>>>>Or if output is slowly going down, is one tube carrying the work load,
>>>>>or are both tubes getting "soft".
>>>>>
>>>>no info on such
>>>>
>>>>>
>>>>>It does not help to view the anode color, as one tube seems
>>>>>to get more cooling air than the other.
>>>>
>>>>I measured the temp of the filament pins during operation.  The 922
>>>>cooling is Way better than it looks.  The baffle with holes appears to be
>>>>the key.
>>>>
>>>>>As the filaments are in series, you cannot pull one tube,and all
>>>>>metering is of course for both tubes.  Is it permitted to lift
>>>>>one plate cap and operate the amp?
>>>>
>>>>No
>>>>>
>>>>cheers, Martin
>>>>
>>>>-  Rich..., 805.386.3734, www.vcnet.com/measures.
>>>>end
>>>>
>>>>
>>>>--
>>>>FAQ on WWW:               http://www.contesting.com/ampsfaq.html
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>>>>
>>>>
>>>
>>
>>
>>-  Rich..., 805.386.3734, www.vcnet.com/measures.
>>end
>>
>>
>>--
>>FAQ on WWW:               http://www.contesting.com/ampsfaq.html
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>>
>>

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