Bob,
I know you addressed this question to George but I hope you
don't mind if I respond also.
I run a rig here I call the "SuperJupe". I thought of calling it
Parater or Jupiton but I liked SuperJupe better. :-)
OK........enough nonsense. What I did is connect the Jupiter to
the output bus of the 6.3 Mhz filter bank on my Paragon. This
results in a rig that is similar to what George describes. The
Paragon has a very robust front end as demonstrated by the
ARRL lab tests. The connection was a simple matter of tacking a
47 pF capacitor to the filter output bus on the passband tuning
board. I then ran a length of RG-174 to the antenna input of the
Jupiter. Tune the Jupiter to either 6.3000 Mhz or 6.297 Mhz
[more on this in a minute] and you are good to go.
The result is a receiver with five stages of good crystal
selectivity prior to the signal arriving at the DSP analog to
digital converter in the Jup. Tuning and transmitting is done
with the Paragon. When receiving LSB on the Paragon, set the
Jupiter to 6.297 USB. When receiving USB, set Jupiter to
6.300 LSB. Works like a champ!
I did this primarily to see how much improvement the Orion will
be over the Pegasus/Jupiter. I realize the Paragon front end is
not quite up to the Orion but it is a very strong front end never-
the-less and it enables me to put narrow filtering in front of the
DSP section of the Jup. Something you cannot do with the
Jupiter alone.
The results are just what I expected. In most cases, there is
no difference in performance of the SuperJup and just a plain
old Jupiter. BUT.............on CW when there is a strong signal
close to a very weak signal I am trying to copy, the difference is
quite noticeable.
My back woods analysis of the matter is that to prevent
overloading the DSP A/D converter, the Jupiter applies
hardware AGC to the front end, reducing gain when signals in the
front end passband exceed a certain level. If you happen to be
listening to a very weak signal, it may disappear or at least be
greatly reduced in strength when the gain is reduced. This is all
necessary because of the fixed bandwidth of the front end.
Since I can switch in various filters down to 250 Hz in the
Paragon, any signal more than 300 or 400 hz away simply cannot
be heard by the Jupiter front end, therefore not causing the
hardware AGC to reduce gain. Turn the Paragon AGC off, and
there will be no loss of signal strength on desired signals because
of strong signals off to the side.
When transmitting on the Paragon, the 6.3 Mhz filter board is
powered down, resulting in no transmit signal feed through to
the Jupiter.
As George said, (this is the ) "Best of two worlds: the almost
bullet-proof K2 front end and all the IF DSP capabilities of the
PRO, including the Spectrum Scope", substituting Paragon for K2
and Jupiter or Pegasus for PRO.
!!!!!!CAUTION!!!!!!! If you try this........DO NOT TRANSMIT with
the Jupiter. I don't think the Paragon filter board would like it
too well! :-) Of course, if you keep the Jupiter on 6.3 Mhz, it
won't transmit. I also enable the TX Loop but leave the TX
jacks open so it won't transmit on any frequency.
Please note that I did this as an experiment, not because there
is anything wrong with the Jupiter. In fact, for my type of
operating, I really don't need this kind of performance 99+% of
the time. It was just something I wanted to try.
On 8 Nov 2002 at 7:19, robert k stephens wrote:
> Hi George
>
> I'm wondering... Could the same thing be done using a K2 for the front
> end of a Jup/Peg? Would that make a significant improvement?
>
> 73 & tnx
> Bob KB1CIW
> Scout
> T-4
>
> At 07:40 AM 11/5/02 -0600, George, W5YR wrote:
>
> [snip]
> >
> >I use my K2 as another front end for my Icom PRO by taking an IF
> >signal out of the K2 and into the PRO. Best of two worlds: the almost
> >bullet-proof K2 front end and all the IF DSP capabilities of the PRO,
> >including the Spectrum Scope.
> >
> >If I ever make time, I will prepare an article on this for the
> >Elecraft list and their web site.
> >
> >73/72, George
> >Amateur Radio W5YR - the Yellow Rose of Texas
> >In the 57th year and it just keeps getting better!
> >Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> >K2 #489 Icom IC-765 #2349 Icom IC-756 PRO #2121
> >
> >
> >robert k stephens wrote:
> >>
> >> George,
> >> Could you summarize/highlight that article for those of us who
> >> don't get
> QEX?
> >> tnx
> >> Bob KB1CIW
> >
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