[TowerTalk] Calibrating antenna direction and using chokes with a beam

[Dan Hearn]

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