A3S TRAPS ID

Well I bought a CushCraft A3S a couple of years ago and I am wanting to put it up and use it. The problem is that when the ham took it down he didn't mark any of the traps as to which they were or where they went. I called MFJ/CUSHCRAFT and didn't get much help. I sent an email this morning requesting more help. I have tried to use my Heath GD-1B and I am not having any luck finding the resonant frequency of the traps. I am assuming that the longest traps are for 15M and the shorter are for 10M but I have been known to be WRONG.

I can't figure out why CUSHCRAFT didn't mark these traps with some type of marking that would last. The book says that they have a arrow on them and I guess CC just stuck a paper tape on and run it on out the door.

Does anybody out there have a idea of what frequency that the traps will resonate at or an idea of how to ID the traps for sure?

You can bet on 2 things, The Sun will come up in the morning and if and when I ID these traps they will be engraved with the trap model and the arrow.
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73's


Bill W4BD
Donalsonville, Ga.

I don't know if this is any help or not, but on most commercial ant's that I'm aware of, the traps aren't resonant inside the ham bands, so a GDO may not have the range to be useful here.

Have you seen this site?

http://www.iol.ie/~bravo/Troubleshooting%20Traps.htm

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My own favourite method of measuring trap resonance I got from the Towertalk reflector..

Using an Antenna analyser..MFJ, Autek etc....

Put a 50 ohm non-reactive resistor in parallel with the trap and use the frequency button to scan it. Look for the zero reactance points. This will be fairly broad, but will show you where the resonance is.

If you have a higher end analyzer like the AIM 4170, which can measure higher values more accurately, use a 450 ohm resistor, run a scan over the 20-10 bands and watch the reactance crossovers, which should be at the peak R points.

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Originally Posted by W4BD

< snip > I can't figure out why CUSHCRAFT didn't mark these traps with some type of marking that would last. The book says that they have a arrow on them and I guess CC just stuck a paper tape on and run it on out the door. < snip >__________________
73's

Bill W4BD Donalsonville, Ga.

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Sometimes the manufacturers just don't think things through.

Last July, a ham gave me an old Mosley TA-33jr beam that he's had stored since he came back East. The traps had all been color-coded. Unfortunatley, over time (in the air at the original owner's QTH and then at his before he moved) the color codes have all faded.

Just what I needed... another project. :doh:

Your best bet might be to find someone who has that same antenna down on the ground for maintenance or storage, and see if they can let you take measurements on their traps.

Bill, did you ever get a reply to your post. the cushcraft traps are fairly straightforward on what goes where!! The traps withthe taper on one end go on the outside and the traps with the same size ends goe to the inside with the end with th screw terminal under the black cap on the boom side. Below is the turns cheat sheet for their traps!

Cushcraft p/n designator
TA...............................10m trap has 18 turns
TB...............................15m trap has 31 turns
TC...............................15m trap has 31 turns

TA traps go on the inside (boom side) on all three elements.
TB traps go on the outside on the front (director) element.
TC traps go on the outside on the driven and reflector elements.

Good luck with your project if you are still doing it!!!

Tyrone - N5XES

N5XES

My hat off to you!
I am building a two element 3 band beam from traps from a A3S
There are no director traps and wight is an issue because I got a ship for MSWE 2013