[Amps] gs35b on hf problem .

[Alek Petkovic]

No, nor have I.

But.....

At our club, we have 4 x Codan 500 Watt hf ssb transmitters which run a 
pair of 4cx250 tubes in the pa. We have a box of used pulls for the 
transmitters. Each and every one of those tubes was put into one of the 
transmitters and fired up. Without exception, we had flashovers on all 
tubes occurring as soon as plate voltage was applied. Lucky the protection 
is very effective in these transmitters.

We decided to try burning the tubes in for a day each on just heater volts 
and air cooling applied.
We did this to all the tubes.

Once that was done, we fired up the transmitters in earnest and tested each 
of the tubes again.

Guess what? No flashovers. Not a single one.

I ain't no scientist but I know that by doing a burn in on those used tubes 
we solved all our flashover problems. I dunno why and I don't care why. I 
just care that it worked.

73 from sunny Perth,
Alek
VK6APK

At 09:33 AM 11/11/2005, R.Measures wrote:

>On Nov 10, 2005, at 2:57 PM, Alek Petkovic wrote:
>
>>Do you think you may have actually had a glitch? Hopefully, you cooked the
>>tube as recommended before you applied hv.
>
>I have read nothing about cooking the gas out of tubes in the Eimac 
>literature.
>>
>>73, Alek
>>VK6APK
>>
>>At 05:43 AM 11/11/2005, Carlo Houben wrote:
>>>Hi , i am building a hf amp around a gs35b (new old stock ) in a GG
>>>configuration
>>>g3sek triodeboard for control .
>>>HV 3300V no load .
>>>The following is my problem :
>>>1/  My glitch resistor  33 ohm  17 w passed out by measuring  zero signal
>>>anode current .
>>>first it was 20Ma and after i put the bias voltage to around 29 V it was
>>>100 Ma .
>>>but after 3 times ptt the glitch resitor past out .
>>>annyone an idea where i have to look for .
>>>Thanks in advance .
>>>73
>>>ON4BR
>>>
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>>
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>>
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>
>Richard L. Measures, AG6K, 805.386.3734.  www.somis.org

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