[AMRadio] replacing fans in BC rigs

John Lyles jtml at losalamos.com
Sat Jul 26 23:50:45 EDT 2008

My Continental 314R1 1 kW had a noisy cabinet fan from Grainger in it. Sounded like a jet taking off. It also has a squirrel cage blower for the 3-500Zs that pressurizes them from underneath.  I replaced the  cabinet flushing fan with a Rotron Caravel fan. It is a lot less noisy, but still too loud. I like your idea of running them off 110 V, as they have 220 VAC motors in the 314R1. 


> Date: Fri, 25 Jul 2008 14:29:07 -0500
> From: "D. Chester" <k4kyv at charter.net>
> Subject: Re: [AMRadio] RE:Finaly got the "Dream Rig"

> 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.

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