[Amps] Extra Fan Mod for 87A

[Jim Thomson]

Date: Sun, 22 Oct 2017 20:40:00 -0400
From: "Carl" <km1h at jeremy.qozzy.com>
To: <gudguyham at aol.com>, <amps at contesting.com>
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 
operators.

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.

Carl

##  One day, Art Bell, W6OBB, had his alpha  89 or 87A tuned up for
10M FM..at 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 been
running 1.5 kw FM cxr for hrs on 10M band.   Art phones Alpha and asks about the...
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 bands. 
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