Perhaps I used a wrong choice of words with "concentrated at" "Concentrated
from and upwards" would be mo betta.
Since the 8877 is normally cooled from the base up, the socket and pins will
run cool. This is not the case with some other tubes which require filament
seal cooling.
Also the 8877 original question requires grid dissapation to be included in
the total. This can be up to 25W. Filament and grid power are included in
published air flow specs.
Carl
KM1H
----- Original Message -----
From: "mikea" <mikea@mikea.ath.cx>
To: <amps@contesting.com>
Sent: Tuesday, February 23, 2010 10:15 AM
Subject: Re: [Amps] Resting plate watts with An 8877
> On Tue, Feb 23, 2010 at 10:03:46AM -0500, Carl wrote:
>> With the 50W concentrated at the socket pins.
>>
>> Carl
>>
>>
>> >
>> > Dr. Gary, How are you? In the case of the AL-1500
>> >
>> >
>> > Filament 5v X10A= 50 watts
>
> Why would the filament heat be concentrated at the socket pins? If that
> were the case, then the filament itself wouldn't be getting hot, which
> would mean that there would be no electron emission and the tube wouldn't
> work.
>
> If you're thinking that the socket pins will get hot from ohmic heating,
> then you're postulating high-resistance connections between the pins and
> the socket contacts, which would be A Very Bad Thing.
>
> I think that the filament is going to heat the grid and plate the most, by
> radiation, because it's closest to them, while there will be less heating
> by conduction down the filament connections to the tube base and through
> it
> to other parts of the tube.
>
> --
> Mike Andrews, W5EGO
> mikea@mikea.ath.cx
> Tired old sysadmin
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