[Amps] Protecting Blowers

[Harold B. Mandel]

Many of us use fans and blowers whose exhaust ports
are open into the amplifier under-chassis plenum and even
into the Anode compartment where their airflow cools
the tank circuitry, and worry about RF fields damaging
the blower.

In one of AG6K's articles mention is made how an
RF "event" welds the squirrel-cage shaft with the
RF amperage absorbed by the blower.

A simple yet effective protective measure is to 
attach a section of aluminum window screening across
the fan ports leading to the RF compartments, with care taken
to see that it's well grounded.

Running an additional heavy conductor such as a tinned
braid to the fan enclosure also helps keep the RF on the 
skin of the fan instead of on and in the armature and
bearing surfaces.

Lastly, bypassing the fan motor leads with some disc
capacitors can't hurt.

Respectfully,

Hal Mandel
W4HBM