Frank, That is true but a 1/2 wavelenght at 160 meters is quite long, about 260 feet; shorter with the velocity factor.
Mike N2MS ----- Original Message ----- From: donov...@starpower.net To: topband@contesting.com Cc: j...@audiosystemsgroup.com Sent: Fri, 13 Jun 2014 20:01:13 -0000 (UTC) Subject: Re: Topband: 50 ohm direct burial coax cable You can easily make the 75 ohm coax essentially "invisible" in a monoband application by using some RG-11 to extend the total length of the 75 ohm feedline to any multiple of 1/2 wavelength. 73 Frank W3LPL ----- Original Message ----- From: "Jim Brown" <j...@audiosystemsgroup.com> To: topband@contesting.com Sent: Friday, June 13, 2014 8:33:35 PM Subject: Re: Topband: 50 ohm direct burial coax cable On 6/13/2014 12:17 PM, Donald Chester wrote: > I think you're being overly picky. The 75-ohm cable would be at worst a 1.5:1 > mismatch. Probably a fraction of a dB loss at most, particularly with foam > type hard line. If you have a source of good, low-loss 75-ohm coax that will > safely handle the power you intend to run, and which will hold up for an > extended period under direct burial, use it. Yes. Assuming a suitable matching network at the transmitter, worst case excess loss due to a 1.5:1 mismatch is 0.18 dB, no matter how long the line. Curves showing this have been in every edition of the ARRL Handbook since I've been a ham (59 years). 73, Jim K9YC _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband