[Mobile-Portable] antenna

[Jay Eimer]

I'm not sure that's the issue, but if it is, we'll just have to live with
it.

The vehicle is a Jeep Grand Cherokee, so it's pretty tall.  The antenna is
about 4' of mast (wire-wound on fiberglass) with the loading coil near the
top, then a "stinger" (whip) that's another 4' or so.  Pretty tall to be
putting on a roof, especially on a high vehicle.

But the SWR isn't actually high (at least I don't think it is)- it's just
not stable.  On an MFJ-259 analyzer, it "swings" from 1.5:1 up to infinity
and back.  No idea how reliable the 1.5:1 is, since it won't settle on any
particular reading on any particular freq.  And changing the length of the
stinger has a minimal, and only somewhat, related affect on the low point.

On the other hand, the mount is on a trailer hitch (receiver type) so it
sticks out 8 or 10" behind the bumper (that's about as far as we're gonna
get).  As such, grounding between the receiver insert and the hitch itself
is through a fairly "loose" mating and one surface is painted, so it's
definitely suspect.  Some antennas evidently don't care (the Outbacker seems
to work) and others (especially the Iron Horse) do.

Jay

-----Original Message-----
From: mobile-portable-bounces at mailman.qth.net
[mailto:mobile-portable-bounces at mailman.qth.net]On Behalf Of JV
Sent: Monday, July 26, 2004 07:38
To: Z Mobile Portable
Subject: [Mobile-Portable] antenna


Hi Jay
    How close is the antenna to the car body? This will cause high SWR. Not
very practical for us mobilers. Can the antenna be mounted on top of the
vehicle? Can you borrow a mag mount just to try?
    Also, for anyone using the roof rack, check the rack for grounding. A
lot of racks using a mount that is nonconductive. I found that out on my
Cherokee. I also ran a #12 insulated wire from my four foot mag mount's
frame to the body using a screw that attached the trunk lid to the roof of
the car and don't use the roof rack.
JV
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Subject: RE: [Mobile-Portable] Iron Horse 40m Ground?



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