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Re: 6 Buck S-band Downconverter results and question

I have not worked S band yet, but when I did work the recent L/U mode, I 
noted the same that you did about the signal.  When the bird came in 
view the noise modulated level came up on the S meter as with an open/no 
squelch control.  My guess is we are spoiled by our planet bound 
repeaters that have COR, TAIL TIMER, PL and other options to make 
monitoring easy for the control ops.   L/U mode did not require the 67 
Hz CTCSS and a suspect the S band mode does not either.

ps:  Hoping Santa has an S-band goodie for me.

Bruce Robertson wrote:

>Quoting Steve Holly <sgholly@optonline.net>:
>>First the question: Has anyone successfully used their 6 buck
>>downconverter with a simple low gain antenna like a patch or corner
>>reflector to work AO-51?
>>I converted my CalAmp 130215 by changing the crystal and tuning the
>>filter using a low level 2.4GHz signal source but so far have only
>>achieved marginal results. Using a preamp ahead of the downconverter
>>signals are Q5 and I made several contacts. Without the preamp I can
>>pick out an occasional word or two out of the noise but QSO's are
>>impossible. Comments and/or suggestions welcome.
>>Steve WI2W
>I've had my unit working for a month or so, and worked a couple of people
>on AO-51, including a WI2W :-) 
>A description of the work in progress is at
>and I produced some notes on my work at:
>In particular, I describe what I found tuning the thing by ear. I'd be
>interested in others' experiences. Before P3E goes up, I'd like to send the
>unit to someone with proper test gear to tune expertly and compare to
>high-grade equipment. A two-figure donation to one of the HEO campaigns
>would perhaps make appropriate recompense.
>It hasn't been perfect readability, but I think I'm getting better results
>than you. With only a few feet of cheap catv cable, I was getting S9+20
>full quieting. Now that the unit is in a tupperware container on the
>rotating beam and with 50' of equally cheap catv cable, I'm finding the
>signals more choppy: sometimes full quieting, sometimes quite difficult to
>work out. (I don't *think* this is the fault of cable loss, since I still
>have an S1 noise floor.) I recently discovered that my computer was spewing
>a few S-units of noise on S-band. The last pass I listened to was better
>once I'd turned it off (but that meant tuning by hand.)
>A note for full scientific honesty: between my first observations and
>latter one I twice transmitted 2m signals of about 4w up to the thing. It
>seems that the horrific losses in the catv cable did their stuff for me,
>because I can still hear my test signal at about the same level. I assume
>that a busted front end would result in a deaf downconverter.
>I find there are deep fades, and I look forward to building a RHCP helix
>antenna to see if the circular polarization and/or the increased gain will
>help. Long-term the goal is something that will work for HEO, so narrowing
>my beamwidth will help develop a system with HEO-style accuracy. And if it
>can track a LEO, it certainly can track a HEO.
>I found a reasonable guide to how well I was improving the system could be
>measured with the distance from it that the signal source (ref. above)
>could be heard. Tuning increased this remarkably, as did the antenna.
>An additional note, which I didn't include in my letter direct to Steve:
>the letter above claims that the s-meter on my if rig didn't change in the
>presence of the s-band signal unless someone transmitted. I now realize
>this is incorrect: even though the static sounds the same, one's s-meter
>will indicate the signal. Why doesn't the s-band transmitter on AO-51
>produce a silent FM signal as does the one in mode V/U?
>73, Bruce
>Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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