Date: Sat, 18 Dec 2010 14:37:59 EST
From: K8MLM@aol.com
Subject: Re: [Amps] Fan for SB220
Paint the inside and outside black. The black inside will absorb the heat
more effectively and the black outside will radiate it more effectively.
Bob
K8MLM
## I own 4 x drake L4B's. Guess what ? They paint both the inside and
outside
of the cabinets.... FLAT BLACK ! Having said that, the top lid, just above
the tubes
gets very hot. The vertical side walls run stone cold. I doubt very much if
the sidewalls
absorb IR radiation or not. The small vent holes on top lid restrict the air
flow too much.
## What would work better, imo, is to whack 2 x big holes, one above each
tube, and install
a chrome 'hamburger grille' [finger guard] above each tube. Then the hot
air from the 2 x chimney's
could escape better. Both top and bottom lids on the L4B's are steel, not al.
## To kill the heat, I used 10 x 6A10's in series...and reduced the idloe
current..from 230 ma...
down to 100 ma. [ ssb/2650 vdc mode] Idle is 40 ma on cw/1900 vdc mode.
I can adjust the
bias in 3 x steps....with a SPDT- center off miniature toggle on the real apron.
later.. Jim VE7RF
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