[amsat-bb] Re: S-band on Eagle

Edward R. Cole al7eb at acsalaska.net
Fri Sep 8 21:39:35 PDT 2006

Quite so, Dom.

Pre-launch predictions were way-off on AO-40 ground station requirements.
We were told all one needed was a 16-turn helix and a downconvertor such as
the "Drake".  I found that the 24-inch BBQ with bare Drake was deaf.  

But when I used a 33-inch offset feed dish (solen from my ku-band sat-TV)
coupled with a good preamp before my unmodified Drake...I could copy the
beacon out to squints of 49-degrees.  That tranlates as nearly 5 s-units
SNR for low squint angles (<10).  I did spend a little more than the
average BBQ dish user (I purchased the MKU-232 from db6nt for ~ $245, but
made the system).  I bought three Drakes in 1998 for $100 and modified one
to 435 MHz IF.  The other I received at 123 MHz totally unmodified.  I gave
the third as a door prize at a local hamfest.

My dish cost me $159 (for the 1-meter dish I had to buy for my TV system
since I stold the 33-inch for ham radio).  I built my own 5-turn helix for
under $20.  Everything else was left over from AO-10/13: FT-847, M2 UHF
yagi, 2m yagi.

For mode-L, I bought a 45-element loop-yagi ($125) and DEMI 144/1268 Tx
conv. ($450).  There is the Yaesu B5400 and coax cables, etc. etc. ...but
not counting that.  You should guess what my 2m-eme station cost?  So I
have a lot of cash tied up in eme/sat ham radio (~ $10K), but not everyone
need duplicate what I do.

To summarize, my mode-US station came real close to performing like my
AO-10 mode-B station (in many ways it was superior).

Well I am glad that Amsat-DL chose to keep mode-L and S on P3E.  You know
my opinion regarding Eagle...disappointment.  But I will reserve judgement
till the day it is in orbit and operational...then ask me!

73's Ed - KL7UW

At 11:43 AM 9/8/2006 +0200, i8cvs wrote:
>----- Original Message -----
>From: "Jim Sanford" <wb4gcs at amsat.org>
>To: <amsat-bb at amsat.org>
>Sent: Friday, September 08, 2006 3:40 AM
>Subject: [amsat-bb] S-band on Eagle
>> Ladies and gentlemen:
>> As one of you commented this evening, AO-40 wasn't exactly a rock
>> crusher on S-band.  It worked, and adequately, at least on CW, but was
>> not great.
>Hi James, WB4GCS
>Not true !
>If one of us commented that AO40 was not great and only was usable at least
>on CW it means that his own station was not adeguate for it and not the
>satellite was responsible and one non able to fly swallow does not make a
>By the experience of  users majority the S-band downlink of AO40 was great
>and the best ever made by AMSAT
>>As I reflect on my personal AO-40 experiences, I now
>> understand that there are 2 reasons for my disappointment.  Local noise
>> was one, and transponder distortion was another --
>If local noise was a problem for you it was not a problem for the world wide
>majority of  S-downlink users
>Distorsion is not completely true !
>Warbling and not distorsion was only present when RUDAK was operating
>so another swallow that not make a summer.
>> Thanks again and very 73,
>> Jim
>> James A. Sanford, PE
>> Eagle Project Manager
>> wb4gcs at amsat.org
>Best 73" de
>i8CVS Domenico
>Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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Ed - KL7UW  
http://www.qsl.net/al7eb - BP40iq 
144-EME: FT-847, mgf-1801/1402, 4xM2-xpol-20, 170w
432-EME: FT-847, mgf-1402, 1x21-ele (18.6 dBi), 60w

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