[TowerTalk] Cushcraft/MFJ Traps

[Glenn Pritchard]

Scott,
That looks a lot like the Hy-Gain trap design they used years ago that MFJ
is now using. They had that plastic trap form that cracked easily under
pressure. I had an old 18AVT that used those, meh.
Why on earth they went cheap is beyond anyones guess.

Glenn, VA7UO

On Thu, Sep 12, 2019 at 2:44 PM K9MA <k9ma at sdellington.us> wrote:

> Here are links to photos of the A3 TC 15m trap, the original Cushcraft
> version circa 1992 and the recent MFJ one:
>
> sdellington.us/hr/TC_CC1.jpg
>
> sdellington.us/hr/TC_MFJ1.jpg
>
> Note the two pop rivets in the CC trap, missing from the MFJ one. There
> are two more rivets on the other side. The extra screw in the CC trap is
> one I added.  Note also that the wire on one end of the MFJ coil is
> wrapped the wrong way. Originally, both terminations looked much worse.
> Later, I wrapped both the right way, and added SS flat washers. I also
> fixed that almost shorted turn.
>
> The MFJ trap has 4 fewer turns than the CC trap, though the resonance is
> about the same. It looks like the MFJ coil form is slightly larger.
>
> I don't like to bash MFJ, as I think they provide a useful service to
> the ham radio community, but I do wish they paid more attention to QC,
> especially for antennas, installation of which involves a lot of work
> and expense.
>
> 73,
>
> Scott K9MA
>
>
> On 9/12/2019 13:22, K9MA wrote:
> > I recently ordered some replacement traps for my old A3S. One was
> > defective, so I took it apart. I was appalled at the poor quality.
> > While the original traps had several pop rivets, in addition to the
> > coil screws, connecting the tubing to the plastic insulator, the MFJ
> > version had only the two screws in the very end of the tubing. The
> > coil wires were sometimes wrapped the wrong way around the screws, and
> > some of the screws weren't even tight. Where the original coil was
> > coated with some kind of thick lacquer, the MFJ ones were bare.
> >
> > The moral of the story is don't even think about going to the trouble
> > of putting up an MFJ/Cushcraft beam without taking apart all the traps
> > and fixing the above problems.
> >
> > 73,
> >
> > Scott K9MA
> >
>
> --
> Scott  K9MA
>
> k9ma at sdellington.us
>
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