I bought my 425 used, I think through someone who advertised it on the
Ten-Tec reflector. When I first tried it out the fan (blower) noise was
objectionably loud. I opened the 425 up, removed the blower, and took it
apart as far as I could. I cleaned all of the old lubricating grease/oil
off of the bushings and washers, and cleaned the built up dust from the
squirrel cage. I re-lubed it (don't remember what I used, here is a good
starting point for a discussion that could go on for days about what to
use or not use) and put it all back together. I did not change any of
the neoprene bushings that are used as vibration dampening mounts for
the motor, though it occurs to me that these could get old and stiff (as
many of us do) and some improvement in the noise level could be made by
putting new ones in. When I got it all back together it still made more
noise than I wish it did, however there was a marked improvement.The
power supply I have is the one with the voltage high/low and fan speed
fast/slow switches. I leave the fan speed in the slow position except
when operating in a contest.
The motor used for the blower is very similar to the ones I used to
rebuild in Tektronix 544 and 547 oldsillyscopes. Also reminiscent of
phonograph motors and SB-200, SB-220 fans.
I use the kind of headphones that completely cover the ears, and the
noise does not bother me. Without the headphones the vacuum relay noise
is more annoying to me than the blower. Someday I will change the
mounting bushings on the vacuum relay and replace the stiff solid wire
leads to the relay with flexible braid. I think this will reduce the
mechanical vibration coupling from the vacuum relay to the chassis, and
reduce the noise I hope.
I have a 425 Titan which works nicely, but the fan noise drives me crazy. I
would rather run barefoot than listen to it. I tried to remount it once, but
to no avail.
DE N6KB
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