[Amps] repair of older Command Tech VHF-2000 amp

[Louis Parascondola]

I performed what seemed to be a rather odd repair on an older Command Tech VHF-2000.  I thought I would share this since it could possibly affect the HF models.  This particular amp like most has a piece of coax that comes off the output of the tank circuit and goes over to the antenna relay. In this case a harmonic filter.  The coax was affixed to the side of the wall and dove down to the bottom and over to the relay. Filter in this case.   There was what seemed to be a soft arc to the coax as it bent over the edge and down.  The amp exhibited no output whatsoever and acted like there was not antenna connected.  I tracked down the problem to that coax being internally shorted.  An autopsy of the piece of coax was amazing.  Apparently the owner of this amp operated digital modes like JT65 so I would think there were many  periods of heavy duty cycles.  Apparently over time the dielectric center conductor heated up and little by little the wire migrated to the outer edge and eventually broke through at the "arc" strain point and shorted to the braid.  Several inches of the center wire was way far away from the center of the dielectric.  Go figure.