My Herc II came with the 10/12m option board installed. A replacement
option board was fitted (by me) about a year ago, after I had repeated
"overdrive" trip-outs on 10/12m. The new option board fixed that for a
year or so, but now its come back to haunt me. All other bands are
normal; no problem getting 500w into a dummy load or into an antenna
(via tuner).
The symtoms are variable. Sometimes the Herc II works normally when I
fire it up on 10/12m. More usually, it goes into overdrive at around
100-120 watts out. But even if it works normally, it is a temporary
thing. It works OK for several minutes, then bingo. The overdrive trip
fires again.
Getting my Herc II out of the rack is not a trivial job. Testing it
out of the rack is very hard work because it requires almost the
complete station to be torn apart and re-located to the kitchen table.
That could start WW 3.
It looks like there are relatively few possible causes. (1) the
relay contacts which enable 10/12m are dirty or the relays are
working intermittently. (2) One or more of the caps on the option
board is breaking down (but why is it sometimes OK ??)
(3) I have suddenly acquired a bad joint from somewhere. Again, why is
it sometimes OK ?? And why has it taken a year to show up ??
I should say that I have had some bad joint problems; all major
interconnections were carefully re-soldered the last go around.
Somebody out there may have seen this one before. All suggestions
gratefully received, so I can figure if I need to plan my XYL's next
vacation and free up the kitchen for serious soldering.
John G3JAG
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