I refurbished my A3 a number of years ago. The link will take you to a
compilation of notes I either developed from my own experience or notes
received from others.
As to the reference to using the MFJ dip coil on a 259, my experience was
that it was completely worthless and a waste of time and money (the coil,
not the 259). But, then I was using a REAL grid dip meter that actually
showed pronounced and definite dips at resonant points.
You said the arrows are pointing in toward the boom. That's good. But,
verify that you have traps TB on the director and traps TC on the Driven
element and on the reflector. If TB is on the DE or Ref, that could be the
>From your description, though, it sounds like there is a serious connection
problem with one or both DE 15m traps. I would disassemble them, verify the
coil connections are clean and working, and verify the capacitor (shield)
screw attachment is clean and working.
10m = good = it's traps are good.
15m = bad = it's trap/traps are bad, consequently, 20 and 40 are going to be
affected, too (it sounds like you have to readjust 40 and 20 to MAKE them
resonant). If 20 and 40m resonance is far from the mfr's specified
dimensions, then I'd certainly look at the 15m trap and verify they are good
before doing anything else.
If the driven element traps are good, but SWR is wacko, I'd then check the
corresponding traps on the reflector and director.
73 and good luck,
> 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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