The only comment I have is that it is an MFJ product now. I wonder if
those traps have the same issues as the coils on the new XM240 ie the
screw coming loose and bad connections.
J6/W0MU November 21 - December 1 2011 CQ WW DX CW
W0MU-1 CC Cluster w0mu.net
On 10/23/2011 4:08 PM, John Crovelli wrote:
> John KK9A et al.
> Some additional information. This is a brand new A4 antenna right out of the
> box from Cushcraft. The direction of the traps was clearly marked with
> stickers and all traps were properly installed in the right direction. And
> npne of the traps from the A4 had drain holes (an obvious mfgr error) but the
> TK traps for the 40M addon kit did have the holes drilled.
> Further, in shipment, over half of the SS hoseclamps were deformed/crushed.
> Had to buy six new ones to replace clamps that were not salvageable.
> The antenna is mounted in the clear at least 35 feet above a roof on an HDBX
> 48 foot tower. There are no other antennas nearby.....so we can pretty much
> eliminate interactions of any kind.
> Using the factory dimensions for tuning the DE for either 'center' or 'CW'
> that come with the A744 40M addon kit, the bandwidth was only about 180 khz
> on 20M, 350 khz on 15M, and maybe 500 khz on 10m, but in no case could I get
> the minimum SWR where I wanted it so the antenna would provide both cw and
> phone coverage.
> On 40 meters there was 120 khz of bandwidth, what I expected, and it had a
> minimum at 7055 which was what I was looking for.
> There are four possible points of adjustment on each element half. The
> maximum adjustment on each element half (between the 'center' and 'CW'
> options per the manual ) is 14 inches.
> Since I could not hit the desired sweet spot frequencies on any of the bands
> using the factory settings, I strongly suspect the traps are not tuned to the
> proper frequency for the dimensions provided. One or both of the TC and TD
> traps are potentially defective from the factory. This would account for the
> inability to hit the desired mid-point frequencies in the SWR curves, and the
> lack of overall bandwidth on 15 and 20, etc. where there should be nearly 500
> I have assembled and installed more than a dozen A3/A4 + A744 addon antennas
> so I'm very familiar with their assembly and installation.
> I'm looking for info from anyone who might have had this same experience
> and/or opinions of others what might be wrong. I have received several off
> line resonses so far, one of which confirmed the antenna should have nearly
> 500 khz of bandwidth, particularly on 20 and 10 meters.
> And no, I don't have the traps in my possession. They are still on the
> antenna which is currently mistuned in the air at 50'.
> John Crovelli W2GD/P40W
> TowerTalk mailing list
TowerTalk mailing list