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[Amps] Extra Fan Mod for 87A

To: <>
Subject: [Amps] Extra Fan Mod for 87A
From: "Jim Thomson" <>
Date: Wed, 25 Oct 2017 00:58:15 -0700
List-post: <>
Date: Sun, 22 Oct 2017 20:40:00 -0400
From: "Carl" <>
To: <>, <>
Subject: Re: [Amps] Extra Fan Mod for 87A

<My 76PA (3 tubes) already had that fan when it arrived here from a Carribean 
contest station. It didnt save the amp from a blown transformer, tubes, 
bandswitch, and more, thanks to very non technical and inexperienced 

It has been running fine here for about 12-15 years with that fan as it 
often gets used on AM wih a rewound transformer.


##  One day, Art Bell, W6OBB, had his alpha  89 or 87A tuned up for
10M 1500 watts out into a flat swr.  He takes off in the car for a 
few hours to do errands.  Comes back several hours later to find the alpha
turned into molten glop.  His cat had fallen asleep on the footswitch. Amp had 
running 1.5 kw FM cxr for hrs on 10M band.   Art phones Alpha and asks about 
no time limit drivel.   Head tech tells him... dont believe the advertising 
hype.  The tank coils
had cooked their little brains out.  .1875 tubing is not big enough on the high 
Xfmr was just about on fire. I believe he had the optional rear mounted fan on 
there as well. 

##  eff at top end of 10M is barely 50%.    Toss in a 1.5 kw  CCS cxr, and 
thats a worse case scenario.  
The fan install require longer screws, plus the finger guard.... aka... 
hamburger grille. 

Jim   VE7RF
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