Sorry for being such a RX newbie here. I guess I shoulda stayed awake
more during signals class. My expertise is very large switching and
resonant power supplies and transmitters.

So the multipath distortion causes fading of the carrier only?? This
makes some sense to me. A small set of the lower sideband frequencies
would also cause phase cancellation, but since the audio spectrum is
moving around so fast no one notices. I think I'm on the right track
here. So use another carrier slaved to the received carrier and you
get better reception during fade. Even if it wanders a few cycles
during fade you probably don't hear anyway. I guess that is how a sync
detector works.

I Imagine it would be a chore to build a sync detector from the ground
up, but I would also think it must have already been put into an ic
chip, no???

I like the link R2000swl posted to AmWindow for the precision full-wave
rectifier. I think I'll stick it on a pc board and give it a try. If
anybody wants a board let me know. They are very inexpensive.

bm, or anyone else, if you have good link to ELPAF or alternative RX
circuits then maybe I could throw that down on same board if not too
much room.

Details of board size at www.expresspcb.com I do the small one double
side and no silkscreen 3 boiards 60bucks.

You can contact me off board at

73
Bob
N9NEO





bm wrote:
Well, it works.

I have been playing with the ELPAF since last autumn; first on my
R-390A, which, despite having done the AF Deck mod, does have its
quirks with regard to audio quality. The ELPAF cleaned up audio
admirably. Mostly doing MW DX then. Then, this summer together with a
modified IC-703 mostly on SW. It practically eliminates the distortion
caused by fades, as well as high-frequency hiss and noise giving an
audibly better signal to noise ratio. The trade-off is of course a
more limited audio response. Personally I can live with that - I never
use bandwidths wider than 6-7 kHz anyway. My ELPAF has a bypass switch
so it is easy to compare audio quality.

I used to have an SE-3 as well, and enjoyed the excellent audio it
produced. The ELPAF does little less with regard to audio recovery. I
am thinking about doing an A-B comparison between the two later on.

BM