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

[Ron W8RJL]

A solution for your rotor loop is to buy a traffic cone, slit vertically, 
wrap around mast so the wide end covers the thrust bearing bolts, secure 
cone to mast with a hose clamp.

Regarding setting the rotor/antenna north, just use a compass and factor in 
the magnetic offset for you area. The lobe off the front of most HF yagi 
antennas is so big being off 10 degrees usually doesn't make a difference.

See attached photo.

73 and good luck,

Ron W8RJL

----- Original Message ----- 
From: "Rick Kiessig" <kiessig at gmail.com>
To: <towertalk at contesting.com>
Sent: Thursday, October 25, 2012 8:03 PM
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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