[Amps] TL-922A - Loud Pop, Blown Fuses

[R.Measures]

On Dec 5, 2004, at 6:32 PM, Clay Curtiss W7CE wrote:

> Thanks to everyone for all of the suggestions.  I put both tubes back 
> in the
> sockets and hooked up the anode connector to only one tube at a time.  
> The
> first tube is fine, but when I connected the second tube (first tube 
> now
> unconnected), the fuses blew promptly.

Was the connected tube in the inboard socket?

>  It seems the mystery is solved.
> I've already tracked down a new pair of 3-500Z's at a good price and 
> they
> should arrive sometime late next week.

Would you sell me the old tubes?
>
> Thanks again for all of the really helpful ideas.
>
> 73,
> Clay  W7CE
>
> ----- Original Message -----
> From: <gdaught6 at stanford.edu>
> To: <amps at contesting.com>
> Sent: Sunday, December 05, 2004 6:10 PM
> Subject: Re: [Amps] TL-922A - Loud Pop, Blown Fuses
>
>
>> On 5 Dec 2004 at 18:03, Clay Curtiss  W7CE wrote:
>>
>>> Hi Rich,
>>> I didn't remove the tubes, but I did remove the anode connection to
>>> both of them for the quick HV test.  The fuses don't blow when the
>>> anodes aren't connected.
>>>
>>> I figured the sound wasn't inside the tube for the reason you 
>>> mention.
>>>  Any idea what could be causing the loud pop?  The first time I heard
>>> it, I figured it was the spark gap on the T/R relay, but after
>>> thinking about it that doesn't make sense since I wasn't transmitting
>>> and the amp was in standby.
>>
>> I'll respond to this via reflector; I've already posted to Clay.
>>
>> I repaired an LK-550 (three 3-500z's) that sounded like a .22 caliber
>> going off.  It was the fuses.  I removed all 3 tubes, and put them
>> back, one at a time, trying each socket.  I found two tubes that were
>> fine in any socket, and one tube that ate fuses.  In fact, sometimes
>> the fuses exploded... literally... like blown to smithereens.
>> Replaced the bad tube, and everything was fine.
>>
>> 73,
>>
>> George T. Daughters, K6GT
>>
>>
>>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org