The filter upgrade helps to kill off some of the high end hiss. I did mine, but
for the life of me can’t say I can tell a big difference. Is there a change?
Sure, but I don’t know if the time/labor/money was worth it.
The audio filter is analog and based on op amps. They do sound odd, and it’s
the nature of the beast. At the time this was sold, it had (still does) an
amazing amount of filtering. It’s all in the audio chain, remember this is
still a direct conversion receiver.
because the filtering is analog, bandwidth is set via the C/R combinations
within the filters. Dig out the necessary look up charts and plug in different
values to suit your needs.
Remember, this is an old radio. Don’t try and make it into something it isn’t.
The optional keyer was a KR5 for all practical means. It’s not a great keyer!
It makes dots and dashes. There’s no dot/dash memory, and while the dashes are
self completing, you can’t insert a element until the one being produced is
finished. It certainly is NOT IMABIC. If you use it long enough, you’ll send
damn good code. If not, then you’re like me and the code I send using one
simply sucks.
The PA in this rig has always been know for issues. One is they changed
designed throughout production. It doesn’t matter what the schematic shows,
replacement if necessary, use the ones in the radio. The last time I did a PA
transistor replacement, the parts were hard to come by and expensive. RF parts
is your friend in this case.
The bias needs to be checked after you replace the drivers or PA transistors.
The manual tells you how to do that.
If you don’t like the QSK, most likely a capacitor can be changed in the T/R
circuit to slow/ease it down. I don’t have information about that off hand.
Personally, I’d enjoy the radio as it, warts and all, and know that’s how it
worked way back then.
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
J e e p
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