[GreenKeys] Getting stuff on the air

[Harold Hallikainen]

> One thing I noticed when feeding through the microphone jack on a newer
> radio (mine is a TS-570S) is that it’s very easy to overdrive the radio.
> The Kenwood is set at 50 mic gain as default, I could not get a good
> signal out until I dropped it to 5.  The splatter is probably a result of
> that same issue with your radio.
>
> Daniel
>
>
> K6YIC
> http://K6YIC.com

Thanks! My radio ( https://w6iwi.org/SEA245/ ) has a 600 ohm "tri-state"
audio bus between the transceiver and the control head(s). It looks like
it lies about 0 dBm on the bus. I messed with it today and as I increased
the drive on the level much above that, the mark to space power ratio
moved away from 1.0. So I set it where the radio APPEARS to be linear. It
looks very nice on the waterfall if I slowly switch from mark to space (my
model 15 does not have a break key, so I unplugged the printer from the
TU-170 and used a clip lead to short the loop jack tip and ring, then open
it). Something that just occurred to me is, I wonder if the selector
magnet ringing ( see scope photo at https://w6iwi.org/rtty/ ) is getting
into the FM oscillator. I'll try transmitting (holding down space bar)
with the selector magnets shorted and see if that looks cleaner. I can
also look at the AFSK keying input on the ITU-170 and see if there's
ringing there. I MIGHT also add a clamp zener (maybe 275 V) across C40 or
maybe in place of C40 to minimize ringing. Maybe also add a capacitor
across the AFSK keying input to slow down the edges a bit.

Again, THANKS for the comments!

Harold
https://w6iwi.org







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