[amsat-bb] Follow-up: DH 80cm dish and helix feedhorn

[Kc2hax@xxxxxxx]

Hi Folks!
Had a beautiful Sunday afternoon/evening here in central Jersey paired with 
an excellent AO-40 orbit. Ideal outdoors antenna testing conditions to check 
the the 80 cm dish and helix feedhorn antenna with the TSI converter.
Signals were great and had real "armchair" copy. I guess conditions were in 
general very good because most of the comments heard in the downlink were 
about having very good reception. I was a bit surprised because of this very 
good signals because I usually have better AO-40 reception when it is over 
the Pacific than over the Atlantic, and this was an Atlantic orbit.
As said in my previous message I could not make a head to head comparison 
with the BBQ, however I was able to compare the DH dish and feedhorn with my 
small DSS dish (next project is helix cup for the DSS dish). Signals were 
exactly and consistently 2 S units better with the 80 cm dish. At around 
MA100, the beacon was S8 (Noise floor is S 0/1) with the DH dish and S6 with 
the smaller DSS dish.

Here are the photos of the testing setup: 
http://www.qsl.net/kc2hax/ant/deckrx.htm

Best 73 de antonio, kc2hax/ea4le


In a message dated 10/15/01 7:08:34 PM Eastern Daylight Time, Kc2hax writes:

> Hi Jerry et al.,
>  
>  Thanks for the kind comments. One of the best things of AO-40 is that it 
is 
> an
>  excellent experimenting platform. It is giving us a lot of opportunities
>  for continuos hands-on learning, the only problem is lack of spare time (or
>  should I say that the spare time is the one we use in our other live
>  ventures outside satellites) to address all that can be experimented.
>  
>  The other great thing with AO-40 is S band: 2.4 GHz is the ideal microwave
>  entry level frequency, wavelength is small enough to really enjoy quick
>  antenna experiments and big enough so accuracy is not a killer. Very well
>  balanced indeed. And yeah... I have a large inventory of mode S spare
>  antennas in the garage here in W2 and also in my EA  QTH from the AO-13 
days
>  (Yes, I even did mode S patches also -with no succes at all- in the AO-13
>  days)
>  Re your proposal on additional testing requiered (btw, I was somewhat
>  expecting this ;-)), It is going to be a bit difficult to make a fair
>  comparison because it is not easy to mechanically setup the UEK on the
>  Connifer focus in a way that could be properly compared with the TSI (the 
> UEK
>  has a very bad form factor to be in the focus of any dish). Testing the TSI
>  with the 80cm dish and helix-cup feed is easy -this will be my  next try-
>  altough I will not have the side by side subjective comparison...
>  In any case, next weekend time permitting (we are in the middle of the
>  soccer and fall baseball season ;-)) will try it. Stay tuned.
>  BTW, I received some requests for more detailed pictures and prepared a 
>  page with more graphic details here
>  http://www.qsl.net/kc2hax/ant/feedhorn.htm
>  
>  Best 73 de antonio, kc2hax/ea4le
>  
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