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" [email protected] To: "Greg D." [email protected], [email protected] 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 ========================================= BP40iq, Nikiski, AK http://www.qsl.net/al7eb Amsat #3212 Modes: V - U - L - S USA Rep. for Dubus Magazine: [email protected] =========================================
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