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Re: [TowerTalk] Beam problems A3S

To: "'David Calder'" <>, "'Artmouton'" <>, <>
Subject: Re: [TowerTalk] Beam problems A3S
From: "Roger N0VR" <>
Date: Sun, 3 Aug 2008 08:40:10 -0600
List-post: <">>
>From personal experience with the ATB-34 (an old Cushcraft which was a
predecessor to the A4) back in the early 80's, I had a trap installed 180
out with similar swr results. Your traps may be much better marked as to
which end goes toward the boom, but mine were not. Consequently, Murphy
prevailed and allowed me to place a trap with the "boom end" facing towards
the tip. Anyway, just one more thing to check.

Roger, N0VR

-----Original Message-----
From: David Calder [] 
Sent: Sunday, August 03, 2008 5:00 AM
To: 'Artmouton';
Subject: Re: [TowerTalk] Beam problems A3S

I assume you have the 40 Meter kit since you mentioned it.

If your VSWR is nuts on one band here is what could be the causes.
One is that a trap is bad or mis-tuned (wrong spot). Another is
that the antenna is too close to metal or another antenna. The
third is that it needs the length re-adjusted.

I assume all element lengths are correct and make sure that the
element spacing is correct.  
Make sure the reflector and director spacing are not swapped.

Check the traps ON the antenna with a grid dip meter or the
MFJ grid dip attachment for the their analyzer.

 73 Dave n4zkf

-----Original Message-----
[] On Behalf Of Artmouton
Sent: Saturday, August 02, 2008 10:33 PM
Subject: [TowerTalk] Beam problems A3S

Well, finally got the Cushcraft A3S cleaned and together.
Got it on the roof with stands.
I can find resonant point on 40 and 20 and will adjust for that.
10 also seems good.
But 15 is bad, real bad.
5:1 SWR and not even close to change at either end of the band.

Any suggestions?
Bad trap?
I will, recheck traps in the morning to be sure I have the right ones in the
right place but pretty sure that they are correct.
I checked measurement but it is so far off that could not be the problem

So, any way to "check" the 15M trap?
Swap it with another?
What tool or equipment do I need?
I had a crew coming tomorrow to put it on the tower but cancelled because of
the problem 73, Art K5FNQ


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