Re: [amsat-bb] AO40 QRP zone?

[Al Lawler <alawler@xxxxxxxxxxxxx>]

[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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