[Amps] Fw: Fan for SB220

[Pete Smith]

Just one minor quibble - the first two inches of the top rear portion of 
my SB-220's RF cage is not open, presumably to make sure that the air 
from the fan at least starts out in the right direction.  The only 
thermal problems I have had with my amp was the melting of the solder in 
the filament pins of the  tubes.  The explanation I have heard for this 
has nothing to do with cooling air or the lack, but rather to resistive 
heating due to a slightly resistive connection between the pins and the 
socket clips.  After re-soldering the pins, I polished their outer 
surface and then swapped the clips for those on two of the three grid 
pins.  No problems since.


73, Pete N4ZR

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On 12/18/2010 1:20 PM, Mitch Cox wrote:
> The cooling on a standard SB-220 is a hit or miss proposition at best. You have a large fan blowing at 2 tubes without anything directing or channeling airflow with a completely open top letting the purposed airflow from the fan escape right through the roof of the amplifier before it even reaches the tubes.