[Elecraft] K2 PA Failures and Remote Antenna Switch System

Josh Fiden josh at voodoolab.com
Sat May 21 16:59:50 EDT 2016


Reviewing the schematic on Ameritron.com for RCS-4 there is a 220uF 
electrolytic across each relay coil. There are also a pair of diodes 
which will clamp the coil voltage, although it might not be immediately 
apparent since they're not directly across the coils. Unlikely that 
these parts are missing since they're not just clamps, but necessary for 
the selector to function.

This does not look like any design flaw of the RCS-4. If I had to guess 
without seeing the hardware, it seems more likely that a failure 
occurred to cause hot switching of the antenna... if that was happening 
repeatedly, the finals wouldn't be happy!

73,
Josh W6XU

> Inside the relay box I found no diodes and no capacitors across the relays that might have been used in the design to avoid this kind of problem.



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