[Amps] 8877 Longetivity

[David C. Hallam]

At the risk of starting another long thread, I will ask a question.

Given the relative low accuracy of normal AC panel meters, how can you be
sure that you are actually within the filament voltage tolerance specified
by the manufacturer?  A high accuracy AC meter is a rather large and
somewhat expensive animal.

David
KC2JD/4

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]On
> Behalf Of Nelson Wittstock
> Sent: Sunday, January 28, 2007 2:36 PM
> To: Amps at contesting.com
> Subject: [Amps] 8877 Longetivity
>
>
> FWIW I am using an 8877 in my amp that I built back in 1977. It
> is still the
> original tube.  My filament transformer is run off a Variac and I have a
> panel meter to monitor and see that it is five volts.  I also have a timer
> interlock so that the HV cannot be turned on until the tube has had three
> minutes to warm up.  When I shut down I run the Variac back down
> to zero and
> leave the blower on for a few minutes for cool down.  The amp was
> built from
> a QST article in the September 1971 issue.  It has seen a lot if use.  I
> added 160 meters to it and it has served me well.
>
> Nelson, K8DJC
>
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