[amsat-bb] Re: AO-51 L band requirements

Gould Smith gouldsmi at bellsouth.net
Tue Apr 27 12:40:43 PDT 2010

Hi Bob,

As noted in the book, Mike Seguin, N1JEZ did those measurements during the 
first few months after launch. They proved to be pretty close as I remember. 
Mike noted that he was able to hold the L band uplink with 50W EIRPc, after 
he had fine tuned his antenna and carefully adjusted his Doppler to the 
center of the capture window.  Once people found the uplink frequency sweet 
spot for their TX and used auto Doppler, things also improved.
We also tweaked the audio level into the trasmitter over time to improve the 
transmit audio from the satellite.

But in year six, it is probably a good time to get some new measurements.

Gould, WA4SXM

----- Original Message ----- 
From: "Bob- W7LRD" <w7lrd at comcast.net>
To: <amsat-bb at amsat.org>
Sent: Tuesday, April 27, 2010 2:40 PM
Subject: [amsat-bb] AO-51 L band requirements

> Reading the AO-51 book by Gould where he discuses the L band requirements. 
> For occasional contact 150 W EIRP is needed. For superior performance 1 Kw 
> EIRP needed. Assuming I start out with 10W to a 16 turn helix 40 feet 
> away. Guesstimating- 5-8 W at the antenna, helix gain 8-12db. Guestimated 
> EIRP about 40W (worst case). Am I figuring this correct? If so then AO-51 
> is performing better than what the book says. I am trying to "fine tune" 
> what I have.
> Thanks 73 Bob W7LRD
> Seattle
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