A3S Biting Partial Dust

n0dh at comtch.iea.com n0dh at comtch.iea.com
Tue Aug 15 19:29:06 EDT 1995

>Anybody have an email address for CushCraft Cushtomer Service or secret
>knowledge of how to check the traps on an A3S?  I apparently damaged it
>during Field Day (see, it IS contest related) and now have a lossy, wide
>bandwidth SWR curve on 20 (too wide, too quiet), SWR greater than 2 on 15
>over the whole band, but 10 seems OK.  Sounds to me like the outer trap or
>traps are shot on one of the elements.  Tips on resonant frequency, etc.
>would be most appreciated.

>73, Ward N0AX


Methods I have used in the past to check traps on my A4

1) Crank up the amp to 1200 watts hold the key down and look for smoke or 
sparks (no lie). In this case since it looks like 15 meter trap is the culprit 
do this on 15 meters.

2) Use a grid dip meter on the "outboard" end of the trap. This works best 
when trap is removed from the antenna in my experience. Not as exciting as 
number 1 above but usually workable. The dip is not real sharp so try a couple 
of traps till you know you have a good one and you can see what you are 
looking for which is probably one trap of the 6 for 15 meters that doesnt dip 
(if at all) like the others.

Usually what happens is a spider or a wasp crawls in there and gets fried 
leaving a carbon path on one of the little round plastic spacers. In the past 
you could get replacement spacers from Cushcraft. I  havent bought any in a 
few years so dont know if they still sell just the spacer. If they wont sell 
you a spacer then frabicating a new spacer is not exactly rocket science as 
you will see. 

Another hint for keeping the bugs out of the trap in the future is to glue 
little pieces of screen wire over the "weep" holes in the bottom of the trap. 
And make sure that the end caps are in good condx and not cracked. I'm pretty 
sure that Cushcraft will sell you new end caps.

>What do I need 15 for, anyway?

Good question for that matter why arent you out working on your 80 and 160 
arrays instaed of that 20 and 15 meter stuff anyway.


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