- Diodes at input blown up because of extremely strong signals
near-frequency. Bandfilters may help, as does careful frequency planning
and some antenna distance. (ages ago I used a FT747 which uses a light
bulb as protection - after a heavy radio weekend I had the lightbulb
open and one of the input coils fused!)
73,
Geert Jan PE1HZG
I own 3x K3, one a pure "S" and 2 which are pimped to be a "S" (almost..).
Blown diodes at the input (both Main and Sub RX) are the most common
failures I'm struggling with for several years with each of my K3's.
None of them blown by strong nearby signals but all of them by lightning
in summer. I've never been faced by a direct hit - luckily - but a
strike say some 500 meters or even a kilometer away will send these
diodes to the great Mannitou Of Radio. I have to admit that this is a
hilltop QTH and sometimes I forget to disconnect the whole stuff when
I'm in a QRL hurry or something similar (XYL hurry i.e......).
Fun fact: during our DU-DXpedition on Panglao Isl. we were in the very
heart of all thunderstorms years ago when strong linghtning apperaed
every evening and night for hours. We had two K3 with us and none of
them struggled with dead diodes at the input. Just because I had a box
with several spare with me? Only Murphy knows.
BTW, several broken knobs along the years too, thats another common
failure.
73 Udo, DK5YA
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