Re: AM RF Signal Generation

Joerg <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:

Hello Mike,

100Hz is about 0.7ppm. Pretty good, but you don't say if that was
close to the band edge where the crystal was mostly in control, or at
the other edge where the LC circuit was dominating. BTW, do you
happen to know how they managed to pull it that far?

Ok, took a break from stair case fixing. I do not like wood frame
construction at all but what can I do? My arm seems to fall off now.
Anyhow, one source for a free schematic of the old IC202 seems to be:

http://www.schematicsonline.com/item.php?item=381

This one is kind of hard to read but you can see the concept in the
south-west corner of the first page:

http://www.radioamateur.eu/schemi/IC202s_sch.pdf

OK, thanks very much. The pdf was cramped but quite a bit easier to follow.

There seems to be only two crystals, with inductors in series. Other
bandswitched sections seem to be a straight LC oscillator.

Also, there seems to be a varactor in a pi connection with what looks like
a variable tuning cap. The varactor lead goes way off to the right - maybe
part of a PLL?

So that helped me understand it a bit better. Thanks. Nice to know the
schematics are still available.

Regards,

Mike Monett
.

Quantcast