--- Ben K8DIT <benk8dit@serv.net> wrote:
> Not there. We are lead to believe that the swept BDR
> and IMD are half that
> of the Main Rx on the Orion! There must be a 'rest
> of the story' there.
Yes there is, the
Pegasus/Jupiter/RX320/RX350/516/Orion sub RX all
suffer the same malady as all other radio designs do
that use up conversion and wide roofing filters do.
That is they are prone to less that stellar BDR specs
within the bandwidth of the first IF roofing filter.
> I have both the Omni 6+ and the Jupiter and have to
> think that there's more
> going on with the Jupiter than what is being
> reported.
> Also, there is a move by some to increase the IF
> gain by turning an internal
> pot in the Jupiter. This cant be a good thing for
> BDR and IMD readings but
> noone is postulating on its negative potential. In
> an analog reciver, if you
> indiscriminately raise the IF gain, results will
> result in more noise w/o
> benefit to s/n ration. Is this the case with
> digitally capable IFs?
Yes there is a down side, the strong signal handling
capability does degrade, and is in fact quite
dramatic. The good news is that with proper setting of
the RF gain control the negatives can be managed. On
HF the Pegasus/Jupiter do not have any problems with
S/N ratio, they are very sensitive. Arguably though
they may be a bit shy for overall gain for the higher
HF bands. So tweaking IF gain pot will improve the
overall gain but does makes it easier to overload the
D to A stage and generate distortion products.
I experimented with the IF gain pot in the Pegasus
(Jupiter is identical) last January and here's a
thread that discusses what I found.
http://lists.contesting.com/archives/html/TenTec/2003-01/msg00641.html
Duane
N9DG
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