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Re: Duty Cycle

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  • Mike Lewis
    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
    Message 1 of 7 , Jun 18, 2003
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      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 :-).

      Mike, K7MDL


      > 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
      >too much.
      >
      >Andy K0SM/2
      >
      >cqer01 wrote:
      >
      > >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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    • Steve McDonald
      Thanks for all the info Mike...sounds encouraging. We have the same brick amp. Not sure what I will do with the AM6155; it is unconverted so far. I take it
      Message 2 of 7 , Jun 18, 2003
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        Thanks for all the info Mike...sounds encouraging. We have the same brick
        amp. Not sure what I will do with the AM6155; it is unconverted so far. I
        take it that you do not use yours on WSJT then?

        Steve / VE7SL
      • Charles Plunk
        My 2m amp is an RF concepts 2-315 40in-170out. I run it with 50 watts drive for between 180-200 out (no element for my bird in that range yet) I have a 220v
        Message 3 of 7 , Jun 20, 2003
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          My 2m amp is an RF concepts 2-315 40in-170out.

          I run it with 50 watts drive for between 180-200 out (no element for my bird in that range yet)

          I have a 220v  5" muffin fan running on 110volts on top of it at a 45 degree angle with a bracked I fashioned. The fan runs very quiet.

          Have been running it this way for over a year on WSJT and other modes. I gets only a bit warm during a 30+ minute attempt.

          My Astron RS-50m very warm during this time but can still hold a finger on the fins without much pain hihi.

          I run 2  220v  5" muffin fans on my ft-847 at different angles. Also it has an internal fan. It stays rather cool.

          Much rather burn a brick up than the rig.

          Chuck
          AF4O



          At 01:10 PM 6/17/03, you wrote:
          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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