[Moon-Net] SUN NOISE ON 144MHZ

Courtney Duncan courtney.duncan.n5bf at gmail.com
Tue Sep 17 04:52:14 CEST 2019


Hi Serge, all,

My preferred method is sun shadows.  Pointing where the numbers say the sun
should be, I adjust for feed shadow right in the middle of the dish.  On
yagis I look for all the element shadows on the ground (or wall or roof or
whatever) right on top of each other so it's just one line for linear and
an 'X' for crossed.

At night, moon shadow can sometimes be used.

Second choice is to slew back and forth across the sun trying to find the
middle of the broad noise peak.  These usually agree within a degree or
so.  If you can't find sun noise it won't work, obviously.

Third choice is to slew back and forth across the moon looking for the
echoes peak.  This takes a long time because the echoes are only ten per
minute and the returns are highly variable for reasons not related to
antenna pointing.  A more precise way is to park where the moon will be and
do echoes while it slews through (for your beamwidth this could take an
hour) then make a plot and see how far off it looks.  That's also a noisy
measurement for the same variability reasons.  And it only gets you one
dimension.  But sometimes that's all you have.

73 Courtney N5BF DM04vf

On Mon, Sep 16, 2019 at 4:45 PM Peter Sumner via Moon-net <
moon-net at mailman.pe1itr.com> wrote:

> Hello Serge,
>  if you have a small hand held GPS (like the very cheap GARMIN I have
> here) you can set a way point at the bottom of your tower then walk to your
> most prominent landmark, hill, light pole tree in a property near you and
> then set another way point on the GPS, now the further away the reference
> point is, the more accurate the final angle value you will get.
>
> While at the land mark in the GPS select 'navigate to way point' and
> select the one you created for your tower and you will have a true north
> angle you can then use some math to reverse it to be the azimuth from your
> tower to the location.
>
> I now realize while writing this I could have walked back to my tower and
> did the opposite and selected the navigate to way point and select the
> remote point but hey that's too easy : -)
>
> Of course this does not help with elevation calibration but works a treat
> the get the AZ rotator calibrated.
>
> Regards,
> Peter, vk5pj
>
> On Tue, Sep 17, 2019 at 2:49 AM ve1kg--- via Moon-net <
> moon-net at mailman.pe1itr.com> wrote:
>
>> 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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