[amsat-bb] Fwd: Mode-L, etc.

["Edward R. Cole" <al7eb@xxxxxxxxxxxxx>]

>Date: Tue, 17 Dec 2002 10:21:24 -0900
>To: "Luc Leblanc (VE2DWE)" <luclebla@sorel-tracy.qc.ca>
>From: "Edward R. Cole" <al7eb@ptialaska.net>
>Subject: Mode-L, etc.
>
>Hi Luc,
>
>I changed the subject line...because I'm mostly going to reply about mode-L.
>
>At 11:36 AM 12/17/02 -0500, you wrote:
>>
>>I'm still working on my received set up on ao-40. I stopped using ao-40
until i can hear the transponder 
>>noise. From that point i can be sure that i can use just the right amount
of power needed to be within the 
>>LEILA and passband rules.
>
>A goal I think any serious AO-40 operator should shoot for.  When last I
had my system running, my 85cm offset feed (helix) dish could hear the
noise floor when squint-angle was under 10-degrees, so anyone should be
able to acheive this with a 3-foot dish and good low-noise receiving
system.  I think those two parameters are most significant for good
reception: >24 dBic antenna gain and NF < 1 dB.
>
>>As soon as i will be able to rotate my new 2.2 meters dish in azimuth i
planned to return on AO-40 with a 
>>more adequate receiving setup and i will also be able to monitor the MB
at the same time and visualized 
>>what is going on from L band.
>
>A large dish like 2.2m will definitley not hurt reception!  Ironically, I
am going to go to a 2.4m dish myself.  Not because the 85cm dish is bad,
but because I will use it for mode-L uplink.  My DEM 144/1268 Tx convertor
only puts out 15w-ssb, so the 45-elem loop yagi I used to use was really
marginal on mode-L2.  Then last spring a micro-burst of wind toppled the
whole AO-40 array, breaking the loop-yagi beyond repair.
>
>So finding the benefit from that event, I re-built the non-penetrating
roof mount (from angle-iron instead of 2x4's) and the 85cm dish/M2-436CP42
are back up sans the loop yagi, 1268 unit, or the 2401/435 (Drake)
downconvertor.
>
>Why?  Well, I have this perfectly good 8-foot dish mounted on a
computerized az-el mount sitting in the backyard doing SETI on 1420 MHz!
So I reasoned I will borrow it for ham radio.  Well, truthfully that was
always the goal!   I do have to figure out how to get the motors running
either with the existing electronics or bypassed by relays.
>
>At first I was just thinking of installing the mode-L uplink, but then I
thought why not use a dual-band feed and install the second downconvertor
on the big dish?  I'm now looking into a dual-band patch for this.  My
guess is the old 85cm mode-US equipment will not get much use after I get
things going on the big dish!  But I will use it until then.
>
>73, Have a good Holiday!
>
>Ed - AL7EB
>BP40iq
>50 MHz - 24 GHz
>eme: 144-QRV, 1296 & 10G under construction
>AO-40, AO-7
> 

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