I installed a pair of 4" fans on a RF Concepts 170W brick (30 watt in) and
it runs stone cold for almost a year of JT44 and FSK441 activity now. Even
some EME contacts on it to some bigger stations to inspire any readers
interested in trying it out. Initially used a 12ft Cushcraft 10 element
beam, though most are done now with a pair of 21ft (3WL) 10 element long
boom yagis and an Az El rotor system.
I recently converted a stock AM-6154 to 2M and am running over 300 watts for
EME and except for one day when the shack was at 85 degrees, it has been
running fine for me. It does help heat up the shack, so when temps in
Seattle reach over 90 (as recently it has), and the amp adds more heat (lots
of it), things can be rough. We do not have air conditioning up here :-).
On the 90+ degree day it started to make clicking/buzzing noises like
something in the cavity was loose and vibrating a bit. Now that things are
cooler I have not heard that noise anymore, though I noticed my tuning is
now different. Still investigating what is up with that. Not sure that is
very inspiring or not :-).
> Date: Tue, 17 Jun 2003 14:24:29 -0400
> From: "Andrew T. Flowers, K0SM" <flowersa@...>
>Subject: Re: Duty Cycle
>I have a Mirage 2516 (25 in for 160 out) that I run at 100% with a four
>inch fan blowing into the fins, and it stays *cold*. I've been using it
>on WSJT, which is 30sec on/30sec off. Been doing that for 2 years now.
> I'm not saying that every amp will do this, but so far so good. I know
>some of the older bricks tend to trip the temp sensor really easily, so
>you can give it a try. If it's uncomfortable to the touch it's probably
> >My 2m RF brick (150W) has a stated duty cycle of < 50%...not good.
> >There is a small fan that cuts in when the amp gets warm. If it gets
> >too hot (never so far in regular operation) the amp will shut down
> >until it cools. My question is...how much of an improvement in duty
> >cycle might I reasonably expect if I blow the large top plate heatsink
> >with a big squirrel cage blower?
> >Also...does anyone use a converted AM-6154/55 for WSJT. I have no idea
> >what its duty cycle might be.
> >Steve / VE7SL
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