[amsat-bb] Re: Opinions on ICOM 1271 1.2 ghz rig for satellite use?

[Greg D.]

Hi Ed,

Ah, these are the sorts of real data and numbers I was looking for.  Thanks!

Even presuming Eagle is better at hearing my uplink than AO-40 was, I'm 
still quite a few dB short of a QSO.  My Az/El assembly is not strong enough 
for any sort of large antenna - the 30" BBQ grill for AO-40 put it about at 
the limit, so adding another is out of the question.  So it looks like a 
power amp of some sort would be needed...

Thanks again,

Greg  KO6TH



----Original Message Follows----
From: "Edward R. Cole" <al7eb at acsalaska.net>
To: "Greg D." <ko6th_greg at hotmail.com>, amsat-bb at amsat.org
Subject: Re: [amsat-bb]  Opinions on ICOM 1271 1.2 ghz rig for  satellite 
use?
Date: Fri, 17 Nov 2006 23:03:34 -0900

At 08:39 PM 11/17/2006 -0800, Greg D. wrote:
 >
 >Hi folks,
 >
 >Not owning a 1.2 ghz rig, and it apparently being a strong preference for
 >Eagle, I've been on the lookout for a way to get on that band.  A
 >more-or-less local ham has an ICOM 1271 rig for sale.  How would this rig 
be
 >for satellite work?  What would be a reasonable price?
 >
 >With 10 watts out, and about a 60' run to the roof (about 50' of that 
would
 >probably be hardline), would I need a massive antenna to get any kind of
 >signal into the bird?
 >
 >The alternative is probably to find a one of those rare 1.2 ghz modules 
for
 >my Yaesu FT-737R, or some sort of transverter driven from my Yaesu FT-736R
 >or FT-767 (50/144/430 modules installed).  What do you think?
 >
 >Thanks,
 >
 >Greg  KO6TH

Greg,

Thew IC 1271 is fine for mode-L.

50-foot of 1/2-inch hardline has 1.4 dB loss at 1296 MHz (about 72% of your
power reaches the antenna).  So say you get 7w at the antenna.

It has been said that the min EIRP one needs for mode-L with a HEO like
Eagle is 1000w.  You would need 23 dBi of antenna gain with 7w to produce
1000w EIRP.  Two 45-element loop-yagis would do it, or a 4-foot dish.  A
4-foot dish is theoretically too small to work correctly at 1296, but for
transmitting-only it probably would suffice (it will have large sidelobes).

For better mode-L operation one should try for 2000-4000w EIRP and that
usually implies more power to the antenna or much bigger antennas.

On AO-40 I ran 9w into a single 45-element loop-yagi with very marginal
performance (one s-unit above noise floor on 2401 MHz)...really not
adequate for anything other than CW.
73's,
Ed - KL7UW
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