[Premium-Rx] Harris 110A 1 kwatt rf Amplifier question

[Steve Sykes]

The RF-110 amplifier usually comes with a baffle similar to what Berndt 
has installed to reduce the fan noise. These amplifiers are not designed 
to be in the same room as the operator so the fan noise was not usually 
an issue.  The only way to get the air flow required in the space 
allowed was to use a 400 Hz fan. As one list member stated the bearing 
could be noisy, they are high quality parts but who knows how long they 
have been running.  Another thing to watch for on these amplifiers is 
the sound deadening foam on the inner surfaces air passages gets dried 
out and little bits of it end up in the cooling fins of the tubes 
causing them to overheat. You need to inspect the tubes and the air 
passages every once in awhile.
I would not try to change the fan for a quieter one.  It has been tried, 
even at Harris, but there usually problems.

73
Steve KD2OM

On 02/11/2011 01:30 AM, Blair Batty wrote:
> Gentlemen:
>
> I have a Harris 590 receiver.  I know a few of you have
> built premium Harris systems, using the 110a amplifier.
>
> Because I live in an apartment, I use the Harris 590 receiver
> and planned for a remote transmitter.  I eBayed a Harris, 1 kwatt,
> transceiver, mounted in a standard 6' rack (surplus USA
> Airbase). I also ebayed the remote control for it.
>
> RF-270-5A Transceiver, 1 kiloWatt SSB, CW, AM consisting of:
>       *  RF 2305 receiver/exciter,
>       * with all the cables and interface boxes.
>       * Harris RF551a Preselector
>       * Harris 110a Power Amplifier and power supply
>       * Harris 7401 remote control
>
> My rural friend let me install it in his shack, (for providing
> the site,  my friend gets local use of it). When I'll want to use
> it remotely, I'll phone and tell him to throw on the
> master power switch.
>
> The remote control give complete control of the transceiver;
> frequency, mode, etc. It communicates via rs232, or with
> the builtin modems over phone lines. We will use rs232 to
> TCP/IP adaptors. I have a static ip. For audio, we'll probably
> use a uhf link.
>
> So far, we have the receiver/exciter working, and the Power
> Amplifier and have talked all over North America with it
> on 80 meters. We have an issue to fix in the Harris RF551a
> Preselector. Then will get the remote control working.
>
> My Question: Does anyone have any experiance quieting down
> the fan in the Harris 110a Power Amplifier? I seem to remember
> someone warning not to fool with it, or I'll melt the tubes...
>
> Sincerely
> /blair
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