RadioBanter - View Single Post - For the Longwire {Random Wire} Antenna to Coax Cable "Connection" - -

September 21st 05, 07:21 PM

On 20 Sep 2005 14:04:54 -0700, wrote:

The links are groovy and all, but actually in the real
world, it's fairly rare to need impedance matching
for a random or long wire, to a coax center pin.
Only with very short wires, might it really be worthwhile.
But with any wire say, 50 ft or longer, the use of
impedance matching is usually totally unneeded for
any decent HF radio. The chance of a mismatch
lowering the actual s/n ratio is slim. I almost never use
matching on random wires to any of my radios. It's just
not needed. You have such a high overall signal level
that losing a bit won't hurt you. For sure on the lower
bands. If I were to wanna match a random wire, I would
use a random wire tuner. IE: MFJ 16010, or whatever it
is... "I have owned one since the late 70's". Using a tuner
can reduce image problems in cheaper radios.
On the high bands, sometimes a tuner can help to peak
things up, but even still it's unlikely to actually increase
the s/n ratio much when using a random wire to the center
pin only. Test it and see. Only when the atmo noise level doesn't
drop when unhooking the antenna is there a problem.
If you hook up the antenna, and the noise increases, even
slightly, it's really as good as it's gonna get, unless you just
want to pump up the S meter. If you end up actually needing
matching on many bands, you gotta really dead front end.
Just mentioning this in case some read the title, and think it's
actually required for good reception. I've run a jillion random
wires of various length with nothing more than sticking it in
the center pin of the radio. Never had a problem with lack of
signal, unless the wire was super short.
MK

You're not matching the wire to the radio. You're matching the wire to
the coaxial cable. It makes a huge difference.