[Moon-Net] SUN NOISE ON 144MHZ

Bob Atkins ka1gt at hotmail.com
Mon Sep 16 22:31:00 CEST 2019


"It looks to me my beam  width must be to large Probably 7 degrees so I do not see a peak of Sun noise"

I'm not sure what this means.  4x17 el yagis on 144 should have a beamwidth of around 12 degrees and you should plenty of sun noise according to EMECalc.  Under those conditions you should certainly be able to peak on sun noise. The peak may not be sharp, but just take the peak reading, rotate the array one direction until you are, say, 3dB down, then rotate in the other direction until you are 3dB down. The 3dB points will be sharper than the peak. Half way between those two numbers you will be pointing right at the sun (assuming a symmetrical beam pattern).

You can certainly try sighting up the antenna boom(s) at the sun (or moon), but that makes the assumption all 4 antennas are perfectly aligned and your beam isn't skewed off boresight by the array. That may or may not be true.

If you have no trees you must have something you can use as an alignment point. A hill, a building, a fence, streetlight or some other landmark. Using google maps you can calculate the bearing of that landmark from your array location.

On 1296 I use a laser pointer system - see http://bobatkins.com/radio/EME_antenna_aiming.html. With it I can quickly recalibrate Azimuth and Elevation indication to within 0.1 degrees, any time, any weather. It's an invaluable tool for me.

73
Bob, KA1GT
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From: Moon-net <moon-net-bounces at mailman.pe1itr.com> on behalf of ve1kg--- via Moon-net <moon-net at mailman.pe1itr.com>
Sent: Monday, September 16, 2019 1:15 PM
To: moon-net at mailman.pe1itr.com <moon-net at mailman.pe1itr.com>
Subject: [Moon-Net] SUN NOISE ON 144MHZ


Hi folks I am back on the air with a small SWR on the TX line which I never had before. 30 watts reflected for 1kw.Must have gotten rain from Dorian somewhere in the system!!!!



Now how do you measure sun noise when you have 4X17??? It looks to me my beam  width must be to large

Probably 7 degrees so I do not see a peak of Sun noise. I was trying to recalibrate my AZ before my MR last night & when I got MR I was off over 4 degrees. Not good even on 144mhz.

In the past I used a tree as a reference point after calibrating my AZ on the moon went it was visible & used the tree as reference point when I could not see the moon. No more tree after dorian.

So what do you guys do to recalibrate your AZ with no moon available???

Dying to know!!!!

Serge VE1KG
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