TELEDYNMCS@aol.com wrote:
> I wrote:
>>If using RG-400 coax or equivalent as one should, 9 ft. will be about 8%
>>lossier than 6 feet.
> I've tested this arrangement using an Anritsu-Wiltron 251S Sweep Generator
> with RG-58C/U and RG-400 at 1090Mhz and the cable loss difference between
> the two was negligible at this frequency. Keep in mind this is a serious
> piece of test gear, not a $50 SWR meter from Radio Shack, so I'm confident
> and pleased with the results.
John, you didn't say the measured cable loss for the xpondr coax. I'm curious
because relatively lossy RG-58C, if it takes 12' of cable to an antenna back
near the tail, should result in a 50% loss. See, e.g., a coax loss calculator
at http://www.ocarc.ca/coax.htm
The original post ref'd Microair saying keep the cable to 6' or less, and let
you
thus get away with RG-58A/U. Both King and Narco supply low-loss cable, to
be limited to 9-10 feet, and Narco (even at 250W) says keep coax loss to 2db
(37%). With the Microair, 50% coax loss can put you only 15 watts to the good
under the TSO and the biennial test, which can result in dropouts if the
radiation
pattern isn't real good.
Regards,
Fred F.
|