[amsat-bb] Re: Ridge Test Results
rogerkola at aol.com
Tue Apr 22 05:27:23 PDT 2008
Now that you have made some progress and secured some successful
communication, it might be time to optimize your base (control) station.
You mentioned in your first post that you were using "RG-8" coax but not how
long a run of it you had. At 435 mHz, RG-8/U is no where near optimal and
connectors do matter. Type "N" connectors would be best and a less lossy
coax might help you find those "missing" dB.
How long is your coax run and is it continuous or does it have splices?
----- Original Message -----
From: "Nathaniel S. Parsons" <nsp25 at cornell.edu>
To: "Amateur Radio Club" <hamradio-l at list.cornell.edu>;
<amsat-bb at amsat.org>; <gs at cusat.cornell.edu>; <tc at cusat.cornell.edu>; "Dan
Oltrogge" <Oltrogge at 1earthresearch.com>
Sent: Monday, April 21, 2008 11:43 PM
Subject: [amsat-bb] Re: Ridge Test Results
> I'm sorry we didn't get in touch, but my cell phone died while we were out
> Were were listening on 146.610, but didn't hear anything except the time.
> Maybe we weren't using it correctly?
> If you could get all of that material tomorrow, that would be excellent.
> do have access to sanding paper, a file, and a grinding wheel, though.
> On Mon, Apr 21, 2008 at 11:26 PM, F. Kevin Feeney <fkf1 at cornell.edu>
> > Were you transmitting in just one direction or from TS to D7 and then
> > D7 to TS?
> Via packet, only TS to D7 (some were sent the other way, but we were told
> having attenuators on the RX side would give us unreliable data). By
> both directions, and while that signal was fuzzy at higher attenuation, it
> never completely cut out. For the packets, we always received them on the
> radio, but the number recorded was the amount passed on to the computer.
> > Why list the power settings in each radio if you are only transmitting
> > from the TS2000 to the D7? That confused me.
> Just for completeness.
> > How successful have you been at running the radios in 9600 baud mode in
> > previous testing? If you don't have many weeks of positive results in
> > mode at this point with whatever antennas, I'd be very wary of
> > a launch.
> Not very. We could complete the mission at 1200 baud, though, it would
> take longer to move data back and forth.
> > so what are the power listings for each radio telling us? To me I think
> > I'm seeing that your circularly polarized antenna isn't quite as good in
> > horizontal mode as in vertical? You have to have less attenuation in
> > to get two good packets per two tries for the same power settings in
> > horizontal as for vertical. looks like about a 15 db difference? (30 vs
> > That says your circular antenna "circularity" is suspect. Is it a helix?
> > Crossed yagis with phasing harness? Is it up in the air off the support
> > structure? Are the feedlines trailed out the back of the antenna, or do
> > come down through the elements to the mast?
> I'm sorry that I wasn't clear, but all our rotations were in the direction
> of the other station. So, if an observer were looking at us from the side,
> "satellite" |
> XXXXX- Ground
> "satellite" --
> 45 deg:
> "satellite" /
> So we didn't really test the circularity of the ground antenna, but the
> pattern of the rubber duck.
> > Wait - were you testing the loop during any of this? I thought all of
> > measurements were made with the rubber duck only in three orientations,
> > vertical, horizonatal and 45 degree. Where is the loop data shown?
> The loop data is the 10 dB figure mentioned in my first email. Under these
> same conditions on Friday, the loop only worked up to 10dB.
> Also, I can use a network analyzer tomorrow at 2PM. Is it worth analyzing
> the square loop antenna at this point?
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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