On 09/19/2011 08:50 PM, Scott Dorsey wrote:
Kenneth wrote:
I was told I could use parallel runs of coax with the shields connected
to each other (and nothing else). 93 ohm coax would be best if I can
find some!

That gives you something like 150 ohms for RG-11, or 200 ohms for the
93 ohm stuff (which your Belden rep can sell you). Not 450 ohms.
Whether this is a problem or not depends on your antenna system.

A remote tuner is an option and there was an article in QST this month
on building one. But the differential cap (in a "T" network) and roller
coil driven by motors seems a bit "Rube Goldberg" to me. I'm also not
too sure how to build an end of limit switch for the coil.
(you don't want to leave that out!!!).

How does a remote tuner help you? You still have to run a 50 ohm
feedline and then transform to 450 ohms at the transmitter.

What's wrong with having a local tuner at the radio? I mean, besides
the feedline losses.
--scott


Nothing wrong with a tuner at the rig. The issue is running 450 ohm
twin lead (nothing magic about that impedance, just what is available in
a "open wire" balanced transmission line with low lose that will fit
though a 1.5" plastic pipe) from the shack to the attic next to coax
cable. I can't run the feed line "in the clear" which makes for more
loss. Putting the tuner in the attic allows running coax to the tuner
and the balance line to the antenna, the run from that point on is
'cleaner'.