[Mobile-Portable] Question about HF mobile

[Rick Markey, KN3C]

Do you have a choke on the RF feedline?  A couple of ferrite beads
slipped over the coax will work, or you can form the coax into a coil by
wrapping it around a 1 liter soda bottle to form the coil.

The reason for the choke is to keep RF from traveling down the outside
of the coax shield and back to your radio.  RF will always take the path
of least resistance.  If your ground is not adequate at the antenna, the
RF will try to use the outside of the coax as the other "half" of your
antenna.

VSWR measuring devices are notorious for giving erroneous readings when
faced with RF on the outside of the coax shield.  On my mobile installs,
I use hash chokes in series with the DC leads to the screwdriver motor,
and ferrite beads over the coax to form a choke.  Mouser Electronics has
ferrite chokes in several different sizes to accommodate most coax.

de Rick, KN3C


-----Original Message-----
From: mobile-portable-bounces at mailman.qth.net
[mailto:mobile-portable-bounces at mailman.qth.net] On Behalf Of Arthur F.
Clemons
Sent: Wednesday, July 18, 2007 18:29
To: Mobile-Portable Reflector
Subject: Re: [Mobile-Portable] Question about HF mobile




> Ok all I have another question abt my HF mobile setup.
> 
> I'm about to run out of ideas.
> 
> I put a MFJ-269 analyzer on my 40m Hustler antenna the other day, the 
> analyzer shows 1.1:1 at 7277, flat SWR but yet I go to transmit and 
> might be getting 70 watts PEP out.
> 
> If I had known HF was this tricky, never would have even attempted to 
> try.
> 
> I'm open to suggestions, cause its got me baffled.
> 
> If I don't get it going with lower SWR, there will soon be a 706MKII 
> up for sale and I'll give up on my idea of HF mobile.


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