[Amps] High filament current on the 8877 amplifier tube

[Steve Thompson]

Assuming they are Eimac manufacture, try asking CPI/Eimac for advice.

The only hazardous material in them is going to be the cathode coating
(Typ. Barium and Strontium oxides); radio and TV tubes containing the
same aren't normally considered hazardous.

Some years ago I used to get ceramic tubes cheap from the local scrap
metal dealer, where they were sent for the copper value in the anode.

Steve G8GSQ

On 16/10/2023 07:46, Tim Duffy wrote:
> I am still testing 8877s here. Two or three every day. They warm up with
> filament only for 4 hours before HV.
>
> What I have learned is that 8877's drawing 15 amps of filament current are
> bad tubes. They draw zero plate current.
>
> So the five tubes that are high filament current ones, are "duds"
>
>
>
> So what is the proper way to dispose of these bad tubes?
>
>
>
> 73
>
> Tim K3LR
>
>
>
> From: Tim Duffy [mailto:k3lr at k3lr.com]
> Sent: Sunday, October 8, 2023 2:48 PM
> To: 'ham-amplifiers at groups.io'; 'amps at contesting.com'
> Subject: High filament current on the 8877 amplifier tube
>
>
>
> Most 8877 tubes that I test draw 11 amps of filament current at 5 volts.
>
> I have tested three recently that draw 15 amps of filament current. All of
> these tubes are used and have little "dings".
>
>
>
> Is 15 amps an indication of a problem tube? Or should I apply HV to the
> plate and see what happens?
>
>
>
> 73
>
> Tim K3LR
>
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