Re: [amsat-bb] AO40 QRP zone?

["John Wilcox" <ns1z@xxxxxxxx>]

I also tried the cascaded pre-amps but I then took the 2.4 gHz to my VR-5000
receiver. I thought it worked great there..

----- Original Message -----
From: Al Lawler <alawler@us.oracle.com>
To: Edward R. Cole <al7eb@ptialaska.net>; <amsat-bb@AMSAT.Org>
Sent: Thursday, August 09, 2001 5:16 PM
Subject: Re: [amsat-bb] AO40 QRP zone?


>
>
> [A further comment on Ed Cole's comments]
>
> > Al has got a pretty good receiving set
> > up by the look of it.
>
>   Thanks, ed!  I'll believe it when I work alaska on ao-40... :^)
>
>
> > The DEM has only about 15 dB gain and thus
> > will not do quite so well in getting the best system NF [BTW there is a
> > cheap $35 way to fix this].  So the combination of his antenna and DEM
> > preamp may be limiting Al's hearing over others a little bit.
>
>
>   The Excel link performance spread sheet shows a miniescule
> increase in performance with a few more db of preamp gain,
> so yes, indeed a bit more gain there would help, but getting
> even a few fractional db more out of the antenna pays even
> bigger dividends in my case.
>
>   I proved this, by running 2 DEM preamps cascaded ahead of my
> drake converter.  I knew it was a dumb idea before I tried
> it, but as they say in the movies, "I just had to know"...
>
> The noise level was a solid s9, but recieve
> performance wasn't noticably improved.   (BTW, the 2nd
> preamp is for an eventual second antenna array.
>
> My qth is such that one antenna  can only see about half the
> southern sky, but 2 could cover it nicely from descreet
> locations not visible from the road... :^)
>
>   I guess the only last point I want to make is that the
> BBQ grill has been  FINE for everyday use with other well equipped
> stations at good squint angles, particularly  with the S1 Transponder.
>
>   My quest for extra gain is to be able to work the bird when
> my squint angle is bad (but good for dx statons I'm trying
> to talk to), or when  it's snowing/raining etc.
>
>
>   -al
>
>
>
>
>
>
>
> "Edward R. Cole" wrote:
> >
> > >From: Estes Wayne-W10191 <W10191@motorola.com>
> > >Al Lawler wrote:
> > >
> > >I'm using the Phillips-tech 24dbi(Linear) bbq dish with a DEM preamp
and a
> > >drake 'easy-mod' converter
> > >with great success.  I can definately hear as well as the vast majority
of
> > >people on the birds (and quite
> > >obviously better than many.)...I STILL don't hear as well as the people
> > >using 1-meter circular dishes.
> > >...I've caught myself on one or 2 occasions accidently cq'ing on top of
a
> > >very weak QSO.  (There is a LOT of activity on ao-40 at very low signal
> > >levels.)
> > >
> > >Wayne replies:
> > >
> > >A good solution to this problem is to designate a "QRP zone" on AO40.
> > >People with marginal receive setups should avoid this zone completely.
> > >People with "average" receive setups should avoid calling CQ in this
zone.
> > >Everybody should avoid this zone when initially finding their downlink
> > >signal.
> > >
> > >Wayne Estes W9AE
> > >temporarily in Beijing
> >
> > How's the chinese food, Wayne?
> >
> > Regarding Al Lawyer's earlier post, Al has got a pretty good receiving
set
> > up by the look of it.  I may have a 4.5 dB advantage as far as antenna
due
> > to the 33-inch offset dishe's higher efficiency [no feed blockage may
get
> > up to 65%] and circular pol.  I notice Al is using the DEM preamp which
has
> > excellent NF into a Drake [freq only mod I'd guess].  I chose a higher
gain
> > preamp to use with my Drake because it can better overcome the high NF
of
> > the std Drake [est 6 to 8 dB].  The DEM has only about 15 dB gain and
thus
> > will not do quite so well in getting the best system NF [BTW there is a
> > cheap $35 way to fix this].  So the combination of his antenna and DEM
> > preamp may be limiting Al's hearing over others a little bit.
> >
> > I don't think there are too many out there using 1m and larger
> > dishes...seems I see mainly up to 36-inch.  In fairness there are so
many
> > local factors that can affect overall performance...local microwave RFI,
> > trees, elevation angle...plus the usual: squint, range, satellite agc.
> >
> > Now, regarding Wayne's proposal to segregate operators with excellent
> > receiving systems...no! no! no!  Wrong idea...probably wouldn't work
> > anyway.  The right approach is if you KNOW that you can't hear
well...then
> > don't call CQ.  Look for stations you CAN hear and call them!   ...and
> > think about how you can improve your 2.4G system to better hear.
> >
> > If anyone is to be segregated, it is the "alligator"!  But that is not
> > necessary, either...just move up band a ways and call CQ there...most
> > activity has been within 50 KHz of the beacon [on S2]...so less
likelyhood
> > you will QRM someone.
> >
> > I like the approach of educating folks how to improve their stations vs.
> > some segregational process.
> >
> > 2-cents ;-)
> > Ed
> >
> > ----
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