[Amps] Heat Dissapating 8877 HV Plate Caps

Tom Rauch w8ji at contesting.com
Sun Aug 26 00:05:34 EDT 2007


>    For crying out loud! Which way are the plates on all of 
> the other plate dissipating caps oriented? Look at those 
> for 813's, 4-400's, 4-1000's.....they'e all with 
> horizontal fins>>

Tubes with large stems through  glass or ceramic envelope 
often need heat dissipation from the seal area. The better 
heatsinks have vertical fins or fins oriented in line with 
the airflow, although anything will work with enough air and 
area.

External anode tubes aren't helped a bit by a "heatsink" 
although it is sometimes a way to get a connection (although 
often not the best way).

. I don't recall seeing any of them with vertical plates 
anywheres.  >>

I certainly remember vertical fins on 3-400 and 3-500 tubes 
with chimneys. While the cooling is more effective when fins 
line up with the airflow, a large enough dissipating cap 
with improperly aligned fins could and often does work just 
fine.

Personally I wouldn't waste my time adding a heat 
dissipating cap on an external anode tube but for some of us 
it can be convenient way to get an attachment point for the 
anode connection. We just shouldn't pretend it is doing 
anything meaningful for keeping seals cool.

73 Tom 




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