Do tell!
-----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of ZR Sent: Saturday, February 15, 2014 11:05 AM To: j...@audiosystemsgroup.com; 'TopBand' Subject: Re: Topband: Palomar R-X Noise Bridge ----- Original Message ----- From: "Jim Brown" <j...@audiosystemsgroup.com> To: "'TopBand'" <topband@contesting.com> Sent: Saturday, February 15, 2014 12:15 AM Subject: Re: Topband: Palomar R-X Noise Bridge > On 2/14/2014 7:00 PM, Charlie Cunningham wrote: >> All generally true, I expect, but I also believe that dielectric constant >> and dielectric losses also figure in and the lowest loss lines would be >> filled with air, dry nitrogen or evacuated. I expect those would likely >> be >> the lowest loss AND highest velocity factor cases. > > If you run the equations, you find that below about 1 GHz, the losses are > all copper losses. Dielectric loss is a few percent of the total loss in > the 500 MHz range. The benefit of a foam dielectric at HF and VHF is that > it allows the center conductor to be larger for a given shield diameter. > But the improvement in loss of a foam dielectric coax below 1 GHz is > entirely due to the center conductor being larger. > > BTW -- the relevant equation is on each Times data sheet. > > 73, Jim K9YC Dielectric losses become evident at 2M with 1500W and at 432 400W of steady carrier will heat up even the best N connectors and RG-213. For that reason many are switching to the 7/16 DIN. Carl KM1H _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband