[Amps] 3-500Z tube problems

[Alek Petkovic]

Hey, did the 4-1000A have a similar problem?

My mate had one and the anode structure was on the piss. The tube and 
box must have been dropped at some time.

We just held the tube and using the laws of inertia, gave the tube a few 
thumps, in the appropriate places, until the anode looked straight. it 
was then plugged into his amp and it would still be working today, if we 
hadn't transplanted a YC156 into the deck.

73, Alek.
VK6APK

On 15/06/2016 1:30 AM, Carl wrote:
> The weld problem was due to a cheapened down assembly where the 
> original anode to top assembly was fully welded to just 3 spot welds. 
> This was at the SLC plant which was known for several other dumb moves.
>
> I have one of those leaning top tubes here on display.
>
> Carl
> KM1H
>
>
>
> ----- Original Message ----- From: "Vic Rosenthal" <k2vco.vic at gmail.com>
> To: "Jack C. Shutt" <w9gt at frontier.com>; <amps at contesting.com>
> Sent: Monday, June 13, 2016 9:39 AM
> Subject: Re: [Amps] 3-500Z tube problems
>
>
>> I have seen a few of these in genuine Eimacs from a specific period. 
>> I don't recall the date codes, but I'm sure someone here knows. The 
>> problem was bad welds which allowed the grid assembly to move and 
>> touch the filament.
>>
>> In the cases that I had, the short only appeared when the filament 
>> was hot. I doubt that this could be cleared by an electrical 
>> procedure, but maybe a slap on the tube in the right place would 
>> work, at least temporarily.
>> -- 
>> Vic 4X6GP
>>
>> On June 11, 2016 7:55:55 PM GMT+03:00, "Jack C. Shutt" 
>> <w9gt at frontier.com> wrote:
>>> Hello all. I don't post here very often, but always enjoy reading the
>>> posts and comments about the experiences of others.I'm looking for some
>>> info and advice on 3-500Z tubes. I have used these tubes for many
>>> years in several home brew amps, as well as in a few commercially-built
>>> units. I recently have had some bad experiences with bad tubes (fil to
>>> grid shorts?) resulting in the loss of some expensive components such
>>> as the fil/bias transformer, grid meter, and bias circuitry consisting
>>> of hard-to-find high power zener diodes, etc. I'm wondering if anyone
>>> has had any success in reviving bad tubes with shorts. Is there a
>>> procedure that can be used for clearing these shorts? Also wondering
>>> about design additions that you may have included in amps to protect
>>> the circuitry from catastrophic failures. I have experienced failures
>>> of Eimac tubes and Chinese versions. Looking forward to your comments.
>>> 73, Jack, W9GT
>>> _______________________________________________
>>> Amps mailing list
>>> Amps at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
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