[GreenKeys] Coax type for simple vertical

[Ralph Irish]

Tony, et al

It seems to me that the 'natural impedance' of most quarter wave verticals is below 50 ohms.  I
remember reading in one of the ham magazines that putting a "Tee" fitting on the back of a mobile
rig and feeding the antenna with  TWO  pieces of RG-59 coax (resulting in a 37.5 ohm impedance)
seemed to do quite well in many mobile installations.  I tried this once with a borrowed SWAN-240
that I hurriedly installed in my Ford Mustang convertible.  (1966?)  

I was planning a trip to Milwaukee to attend the wedding of a cousin.  I ran the two pieces of coax
in the 'tunnels' on either side of the car, under the plates that sat on top of the 'tunnels'** and
into the trunk.  I used a clamp type mount on the front edge of the trunk.  The antenna was a 40M
Mark Mobile 'heliwhip' antenna, already tuned for the middle of 40M phone.  I had great QSOs all
the way to and from Milwaukee, and really impressed a brother of the bride, when I showed him the
rig and made a handful of contacts from his driveway.  Didn't plant seeds for a new ham, but he 
thought that the concept of talking to people all over was 'pretty neat'.

Ralph - W8ROI

**   The 'tunnels' were under the bottom of the closed door.  There was a decorative and 
     functional cover which enclosed some wiring from under the hood to the tail lights, turn
     signals, etc.  The coax was pushed 'parallel' to the small bundle of car wires and followed
     the same path into the trunk.  One of the easiest mobile antenna install jobs I can remember.

ROI

- - - - - - - -

On Oct 13, 2017, at 8:45 PM, tony.podrasky wrote:

> GA OMs;
> 
> I'm going to try using a 28' telescoping fiberglass pole
> with a wire taped to the top, running down the length
> of the pole, to an SO-293. The pole will be attached
> to my upstairs balcony - so I can take it down when I'm
> done (CC&R stuff).
> 
> Should I be using 52 or 75 Ohm coax to feed it?
> 
> UE,
> K2EAA - TONY
> NNNN
> ZCZC
> 
> -- 
> Sure, we can do it - just select any TWO:
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