The FT-990 has notoriously poor QSK performance, clipping every element. It
also clips the first element in VOX mode. The scope pictures in the original
QST review confirm this. I've scoped one of the latest models manufactured,
and the design flaw still exists. As I recall, there's something like a 10ms
delay after key closure before RF starts (i.e., 10ms of the element is cut
off.) Unfortunately, there's a 7ms delay after key closure before the amp
relay or solid state keying output is enabled, leaving only 3ms between
keying the amp and the start of RF. No problem for pin-diode based amps like
the 86/87/89, but not enough margin for some vacuum relay based amps. Like
Dick, I found the only solution was to program an external keyer (the Heath
MemoryMatic in my case) to lengthen the elements. It sounds good on the air,
but the sidetone has an annoying amount of weight.
73, Dick WC1M
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