[AMRadio] RE:Finaly got the "Dream Rig"

Bill Fondren bill.fondren at sbcglobal.net
Fri Jul 25 17:13:38 EDT 2008

Hey, thanks for the idea of the fan noise problem.   I have  a Gates BC 500 T and fan noise is the only complaint I have.   I babyset a BC 1T back in the 60's and well remember the 
  mod reactor talking to u.  My 500 T does not seem to do that.  No one has ever complained abt the fan noise but it bothers me in the shack.  U are correct abt the transmiter being made to operate 24/7 and in ham service they are just floating along.  thanks  again   Bill  K5PML

"D. Chester" <k4kyv at charter.net> wrote:
  > From: "Todd, KA1KAQ" 
> One thing to keep in mind with running a converted BC transmitter is
> that it is intermittent service, not full-strap 24/7. Cooling
> shouldn't be a problem, though proper ventilation and a decent blower
> or two are always a plus. Was working on the 300G last night and is
> amazes me how much air the two-squirrel blower moves.

And probably how much noise it makes.

My Gates BC1-T was far too noisy to use in the shack near the operating 
position when I first got it converted and on the air. The mod reactor 
talked back like a PA speaker, the blowers sounded like a vacuum cleaner 
running and the a.c. contactor relays sounded like a chain saw.

I replaced the mod reactor with a potted unit that I had on hand, and it is 
very quiet. I converted the relay circuitry so that all the control relays 
run off DC. There are two blower fans in the transmitter, each with 110v 
motors, connected in series to run off 220. I moved the wire to the motors 
to a 110v tap, so that each motor now is running on 55 volts. They work 
very well at half voltage and are whisper quiet (although still audible), 
but still move plenty of air. I mounted a toggle switch to fill an extra 
hole that was on the front panel, which allows me to cut the blowers 
completely off. I have never had any problem with anything overheating with 
the fans turned off, but in warm weather or when I operate the rig for an 
extended period I usually run them, but in winter for one short QSO I 
usually turn the fans off.

With the mods, the Gates is almost as quiet as my homebrew transmitters, 
none of which even have any blower fans.

There are few things I find more annoying over the air than to hear someone 
transmitting on phone, and the blower noise in the background is almost as 
loud as their voice. "Big Guns" on SSB are notorious for that.

Don k4kyv 

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