[amsat-bb] armstrong az/el adjustment

["Wayne Estes W9AE" <w9ae@xxxxxxxxxxxxx>]

NX7U wrote:

Of course, this is all quite a bit trickier if your rotator is made by the
ArmStrong company (like mine).  It would be nice to get the sun to stay
still for about 30min (hey, that could be a SciFi story!).  Also, I am
doomed to continuous compass-and-inclinometer work.  I'm getting pretty good
at eyeballing azimuth now :-)


W9AE replies:

A compass and inclinometer may be necessary for setting the initial az/el to
start an operating session.  But it's not necessary after that.  I highly
recommend using either a long headphone extension cord or 900 MHz cordless
headphones.  That allows you to adjust the az/el for best audible beacon
reception.  It's always best to adjust for the ACTUAL best reception rather
than the PREDICTED best reception.  To minimize the trips, adjust the
antennas slightly "ahead" of the actual best reception, based on the
direction that you know AO40 is moving.

I use a 40-foot headphone extension cord and a spare set of cheap headphones
with my portable AO40 antenna setup.  There is no need to drag the long
extension cord back and forth.  I run the headphone extension cord along
with the coax cables, and leave the spare headphones connected to the
outside end of the headphone extension.  Then the manual az/el adjustment
process is very quick and easy:

1. Tune to the AO40 beacon
2. Unplug the "inside" headphones
3. Plug in the headphone extension
4. Run outside and put on the "outside" headphones
5. Tweak the az/el by ear
6. Run back inside
7. Unplug the headphone extension
8. Plug in the "inside" headphones
9. Re-tune to your operating frequency

It looks like a lot of steps, but it's much faster and easier than using a
compass and inclinometer.  A few trivial steps could be eliminated if you
used 900 MHz cordless headphones, or if you have a headphone "Y" adapter.
But wireless headphones cost a lot more than two 20-foot headphone extension
cables.  And then you need batteries.

Wayne Estes W9AE
Mundelein, IL, USA


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