[TowerTalk] Calibrating antenna direction and using chokes witha beam

[Pete Raymond]

 The Operating Manual has a great chapter called Antenna Orientation, that 
tells you how to figure when the sun is directly due South at your qth. 
Then you can use your towers shadow as described below.  The math and a 
chart that is provided in this article is called "True corrections for 
Various Dates of the Year".  If you do not have this manual I would check 
with the ARRL web page and you might be able to access  that section of the 
manual, I'm not sure if the "Operating Manual" is available there or not.
It's all about using the sun.  I have used this method many times.   Good 
luck
73 Pete N4KW

----- Original Message ----- 
From: "Dan Hearn" <n5ardxcc at gmail.com>
To: "Mike" <noddy1211 at sbcglobal.net>
Cc: <towertalk at contesting.com>; "Rick Kiessig" <kiessig at gmail.com>
Sent: Thursday, October 25, 2012 9:46 PM
Subject: Re: [TowerTalk] Calibrating antenna direction and using chokes 
witha beam


> Here is a system which works for me and others in our ham club.
> Look in the newspaper for the times of sun up and sun down. Calculate the
> hours and minutes between. Divide this by 2 and that is the time of exact
> noon. At that time, look at the shadow of your tower or a vertical post 
> and
> the shadow points to true north. Hopefully your newspaper has 
> sunup/sundown
> times as ours does.
> 73, Dan, N5AR
>
> On Thu, Oct 25, 2012 at 5:58 PM, Mike <noddy1211 at sbcglobal.net> wrote:
>
>> There is going to be a website that will give your declination relative 
>> to
>> Magnetic North in ZL, I would go with that.  In California here finding a
>> strong station and adjusting the beam would be futile as the signal maybe
>> following a crooked path.  In California we are pretty much at 18 degrees
>> off Magnetic north, so it would make a difference to make the adjustment
>> for
>> True North.
>>
>> You government is sure to have a website, but if not any serious 
>> navigation
>> website in ZL will have True north relative to your position.  Even my 
>> car
>> manual shows true north so you can set the car compass.
>>
>> Mike
>>
>> -----Original Message-----
>> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
>> Rick
>> Kiessig
>> Sent: Thursday, October 25, 2012 5:04 PM
>> To: towertalk at contesting.com
>> Subject: [TowerTalk] Calibrating antenna direction and using chokes with 
>> a
>> beam
>>
>> I finished building my antenna (UltraBeam UB-50) and installing it on the
>> tower yesterday. Everything went reasonably smoothly.
>>
>>
>>
>> I tried to align the boom with true north before bolting it to the mast,
>> but
>> the result seems to be off by at least 10 degrees or so. I'm familiar 
>> with
>> the techniques for determining true north (although Polaris isn't visible
>> in
>> ZL), but I'm wondering if it's possible to do a more accurate calibration
>> by
>> measuring signal strength from a strong broadcaster with a known location
>> and a near-constant signal strength, over a range of azimuths. Then use 
>> the
>> center azimuth between two equal near-nulls on either side of the peak as
>> the calibration point. If this is viable, any suggestions for good 
>> station
>> to use as a target? Does frequency matter?
>>
>>
>>
>> What's the Best Practice with regard to using common mode chokes on the
>> feedline coming from a beam? I grounded the shield at the tower and again
>> outside the shack, with a lightning arrestor as well at the latter.
>>
>>
>>
>> Can't say I'm too happy with the way my rotator loop came out. I wrapped 
>> it
>> around the mast on top of the thrust bearing, but the TB has some bolts
>> that
>> stick out. Hopefully they won't grab or scrape the coax too much.
>>
>>
>>
>> I also have a UHF connector on one segment of LMR-600 that didn't seem to
>> go
>> onto a barrel connector as well as it should have. They are odd 
>> connectors
>> that have a very snug rotating collar, rather than the kind I'm used to
>> that
>> have a little up-and-down give in the direction of the cable. The center
>> pin
>> went in roughly 4 or 5 mm, but the collar hung up after only about two
>> turns. It's very snug (too snug), so I think the threads may have 
>> crossed.
>> I'm reluctant to take it apart now, though, since if the threads are
>> crossed, I may never get it together again, and it's a long segment of
>> LMR-600, which I don't have the tools or skills to replace connectors
>> myself. TDR on the line looks OK, and I did some TX tests at low, medium
>> and
>> high power, and didn't see any problems. I imagine I'm just asking for
>> trouble if I don't fix it, though, right?
>>
>>
>>
>> 73, Rick ZL2HAM
>>
>>
>>
>>
>>
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>
>
>
> -- 
> Dan Hearn
> N5AR
> _______________________________________________
>
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>
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