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YAESU G5400 Lessons Learned



Ladies and Gents:

In several private discussions on these things, I've been asked to
publicly post the following:

The G5400 system suffers from some design problems.  Specifically, a
"stall" of the elevation rotor can take out the motor, power
transformer, and THEN the fuse.  It happened to me, and to 2 others that
I personally know of.

Here's why it happens:  The control box is over fused.  The elevation
rotor has no overload protection.  The limit switches prevent it from
grinding into a stop, but if it is overtorqued because a pine tree grows
into the path of your 2m antenna, there is no protection.

Here's what I did to prevent the catastrophic failure from ever
happening again:  I replaced the 2AMP fuse the controller has with a
progressively smaller SLOW BLOW fuse until the fuse blows.  I wound up
with a 1 1/4 amp  slow blow.  The slow blow allows for starting current,
the smaller rating makes the fuse protect the transformer.  (I've had 2
subsequent rotor failures for various reasons with no transformer
failure.)

New subject:  The azimuth rotor is protected by a thermal overload in
series with one of the motor windings.  On overload, the motor heats up,
the switch opens, and power is removed until things cool.  Have stalled
the azimuth rotor, but never had one fail.  HOWEVER!  When I was inside
to replace the position indicator pot, I learned that the sensor is
attached to the motor windings with cellophane tape.  Which had dried
out, rendering the sensor an air temperature sensor.  I solved this with
some good tape, backed up by a tie-wrap.

Hope this info is useful.

73,
Jim
wb4gcs@amsat.org

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