[Amps] 3-500z - intermittent filament

[John E. Cleeve]

I would advise caution in resoldering the sleeved pins of the 3-500 et al 
tubes, for the Eimac spec. and the late Bill Orr, warned that the melting 
point of the solder used,  could be very close to the temperature which 
would destroy the glass to metal seal of the filament pins..........more 
effective electrical contact, between the tube filament pin sleeves and 
sockets, with more effective directed forced air cooling of the tube base 
sockets are the routes to follow.....but this has all be said 
before.....regards, John G3JVC.


----- Original Message ----- 
From: "Steve Thompson" <g8gsq at eltac.co.uk>
To: <amps at contesting.com>
Sent: Thursday, February 08, 2007 12:15 PM
Subject: Re: [Amps] 3-500z - intermittent filament


>
>
> terry at g4amt.com wrote:
>
>> The pins are riveted over on the tube side of the `former` so they cannot
>> (?) be removed; they are of `split` construction. The only way  I could
>> re-solder them was to use a solder sucker to extract the old solder - put 
>> a
>> couple of drips of flux in the hole and re-solder with silver solder;
>> heating the pin with a mini-blowlamp ...
>
> A question as to what should be used here? There's 'silver solder' as
> used with a torch for brazing. There's also standard pcb solders with
> added silver content to give them a lower melting point than straight
> tin/lead.
>
> Steve
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