[Fourlanders] FW: [Mw] Terminating Coax Runs in Rover Vehicles

[Jim Worsham]

FYI.  It looks like we will not be hearing N8UM on the air for a while.  We
have just about lost all of the rovers that we used to be able to count on
working from the mountain.  This doesn't bode well, especially for
microwaves, but I don't know what we can do about it.  Anyone want to go
roving in June and/or September?

73
Jim, W4KXY

It doesn't matter how beautiful your theory is, it doesn't matter how smart
you are.  If it doesn't agree with experiment, it's wrong.
Richard P. Feynman
-----Original Message-----
From: microwave-bounces at lists.valinet.com
[mailto:microwave-bounces at lists.valinet.com] On Behalf Of N8UM
Sent: Friday, April 17, 2009 12:59 PM
To: VHFcontesting at contesting.com; VHF REFLECTOR
Cc: microwave at lists.valinet.com
Subject: [Mw] Terminating Coax Runs in Rover Vehicles

The final connection from the rig/amp to the feedline in a rover situation
can be messy and subject to shifting or even pulling the rig out the window
if you hit a tree limb


The other issue is knowing if you are putting out power and your swr is
stable.  There were many contests that I discovered after returning home
that I was CQing without any power out.

 

One solution is to use Bird 43 meters, but separate the sensor element (line
section) from the meter.

 

Bird once sold a nice mounting bracket that fits over the ugly and ungainly
line section.  I had access to a number of line sections, so I just mounted
them all on a 3 x 36 x ½ in board behind the rigs in a vertical position (QC
connector to antenna pointing up, QC connector to rig/amp pointing down.).
Using QC adapters, I could select my coax termination type (N, uhf, 5/16
DIN) and easily calculate the exact cable length I would need from the
outside antenna to the line section board.  If any of the antennas ever came
loose and dragged down the highway, the tension was on the line section
connector that is a lot cheaper to replace than a TS-2000 or FT-290MkIII.
You can route the output from the line sections to one meter and switch
between bands or use multiple meters.  I chose to take the meters out of the
Bird cases and stack them vertically in 3 inch long cylinders of sch 40 PVC
plumbing pipe.  You could probably also use the W1GHZ bargraph meter sold by
DEMI in lieu of a 30 uA Bird meter movement.

 

By having all the line sections in one place, selecting and matching the
right length of coax from the rig/amp to the line section location is a
piece of cake.   It allowed use of 18 inch jumpers of Andrew ½ inch hardline
with right angle N connector on one end to go from the rig to the line
section/feedline.   If you are caught in a thunderstorm, disconnecting all
the coax feeds can be accomplished rapidly since they are all in one place
and accessible.

 

I used a Chevy Astro that had a flip out side window that popped open about
3 inches at the bottom.   That was enough room to route all my feedlines and
rotator control cable into the vehicle.  I them cut pieces of closed cell
foam like the kind sold as kneeling pads for gardening and sealed up the 3
sides of the swing out window.  A nice dressing of duct tape (replaced
several times a season due to UV degradation) provided a weather tight seal.
I never worried about security.  I figured if someone wanted to break into
the van they would find a way regardless of my security plans.

 

Why am I telling this story?  The line sections I used are excess to my
needs.  I just had my second knee totally replaced and will be out of rover
action for at least a season or two.  I am selling the line section,
mounting frame/bracket, and Bird connecting cable/adaptor (you select 3, 10
or 20 ft length), and 2 QC connectors (you specify N, uhf or 5/15 DIN) as a
package for $120 and I will pay cost of shipping in the CONUS.  All items
are in like new condition and I am the original owner.  Look at my ads
posted at QTH.com swaplist for pictures.



John B.  N8UM  Oak Ridge, Tennessee

 

 
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