[Antennas] Mosley Classic 33 Balun?

Sat Dec 11 17:14:09 EST 2004

I'm sure this was meant for the group, Wish we could get the qth.net to
change the default mail settings for reply-to the group only.
> Consider using a RadioWorks Line isolator... go to:
> http://www.radioworks.com/PDFLineIsolator.htm for full information. I've
> found that Line Isolators provide better RF isolation than a coaxial
choke.
>> 73, Larry - W1GOR
>>>> ----- Original Message ----- 
> From: "Jack Painter" <223bthp at cox.net>
> To: "Don Boyer" <don.boyer at gte.net>; <antennas at mailman.qth.net>
> Sent: Saturday, December 11, 2004 3:54 PM
> Subject: Re: [Antennas] Mosley Classic 33 Balun?
>>> > Don Boyer wrote:
> >> I recently obtained a Mosley Classic 33 antenna that appears to be in
> >> excellent shape. It has an SO-239 coax connector to the antenna's
> > "Classic
> >> Match". The Mosley website indicates that for The Classic System: "To
> >> isolate the outer coax conductor from ground, the coax line is coiled
for
> > a
> >> few turns near the antenna end. This is designed to prevent the very
> >> unlikely effect of Feed Line Radiation". I have also heard that with
the
> >> Classic 33, you can connect your coax directly to the SO-239.
> >>
> >> Is this coiled coax actually needed and if so, how many turns, what
> > diameter
> >> is the coil and where is the coil located? (I typically use RG-8 coax)
> > Any
> >> comments regarding this interface would be greatly appreciated. The
> > coiled
> >> coax may not even be required. This is unclear to me.
> >>
> >> Also, any repair / maintenance pointers would be helpful before I put
the
> >> antenna on my tower. Thank you.
> >>
> >> Don - WB0AIN
> >>
> >
> > Hi Don, any coax-choke employed will always be right at the base of the
> > antenna, just prior to the antenna connector. This in not very practical
> > with RG-8 as it would require very large diameter turns (3 or 4 turns
are
> > fine for any choke). If you think its important, then do so. But a
> > balanced
> > antenna is not going to cause feedline radiation to any degree that
> > matters.
> > Should you drive it well outside its intended bandwidth, that's another
> > matter. Shield-grounding the coax to the tower ground at point of
antenna
> > attachment and at ground level of the tower, and at entrance to the
> > station
> > are critical for lightning protection if you are in an area subject to
> > lightning. This also serves to decouple feedline radiation on the outer
> > shield of course.
> > Best regards,
> >
> > Jack Painter
> > Virginia Beach Virginia