"Steveo" wrote in message
...
Vinnie S. wrote:
On Tue, 28 Jun 2005 01:11:31 -0400, Scott in Baltimore
wrote:

So ... I have an older CB - Cobra 21 LTD Classic with weather stns
etc. ... a 102" Shakespeare Antenna - 18' of cable - and this


What makes you think 18 feet of coax is even a half wave?

At 27.185 MHz (ch 19) a half wave is 17.21 feet.

At 66% velocity factor, an electrical half wave is 11.36 feet.

At 77% velocity factor, an electrical half wave is 13.25 feet.

What's so special about a half wavelength of coax?

The Mobile antenna websites practically tell you to keep the coax at 18
feet, or else. I thought that was true, until numerous people at this
group and several websites said that is nonsense.

Have you ever heard from the coax length police? Real sticklers when it
comes to that.

Hello, Mopar

Fact is that as long as the feedline is not lossy, SWR doesn't really
matter - so long as you present a proper 50 ohms to the rig via a tuner.

I used a long wire years ago from 1.8 MHz to 30 MHz and have no idea what
the SWR was on any frequencies. The pi network took care of that. The
thing was good for thousands of miles on milliwatts and anywhere at all on
50 watts or so )

Coax, however, can get lossy with high SWR, especially at the higher HF
frequencies (and virtually any frequency if the SWR is *really* high).

One possible warning - if the SWR is caused by a faulty connection or a bad
antenna, you can match the thing to your rig, but most of the power will
disappear as heat in the fault.


Best regards from Rochester, NY
Jim