Thank you, Mike. The radio without filtering, but with my LP filter,
sounds quite nice. But I do need the added filtering for operating and am
attempting to make it sound better than it does. Perhaps components have
aged and it is not operating at spec. I'm slowly looking into all this.
Thought I'd ask other aficionados so as to not reinvent the wheel!
72,
Garry
On Sun, Aug 22, 2021 at 1:52 PM Mike Bryce <prosolar@sssnet.com> wrote:
> 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
> o|||||||o
>
>
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