I guess I differ with Greg KO6TH on what I consider "reasonable loss". I do a lot of VHF thru mw frequencies and hate to loose more than 1-dB in loss. I consider 25-foot of RG-213 at 144-MHz as max, then go to LMR-400 for longer runs (up to 150-foot). If longer runs needed then I use LDF or equivalent hardline.
My 2m eme antennas are 214 foot from the PA and measured total loss is 1.67 dB, but my preamps are mounted on the tower and only see about 0.4 dB loss. On 1296 my dish is about 100-foot from the shack and I have 6-dB loss in the LMR-600 transmission line. Fortunately my high power PA's are located at the dish and only need 2w drive from my 20w transverter in the shack. On 1296 receive the preamp is mounted directly to the dish feed and have about 125 foot of LMR-400 to transverter (7-dB loss). But preamp has 37-dB gain so easily overcomes the loss with about 30-dB residual gain to the transverter to result in 0.3 dBNF. This is all for eme where losses will kill your ability so see weak signals.
73, Ed - KL7UW http://www.kl7uw.com Dubus-NA Business mail: dubususa@gmail.com
...and is exactly why I have never been successful at EME or much with longer-distance weak signal stuff. Nice work, Ed!
Fortunately, most satellite work is not considered weak signal, so I can be a bit more frugal with the coax and still be successful in making contacts. But, yes, I really should tighten things up a bit when I get the chance. I honestly put up with sucking water out of the the wet 9913 years ago way too long before landing the hardline. Life's too short for bad coax.
Greg KO6TH
Edward R Cole wrote:
I guess I differ with Greg KO6TH on what I consider "reasonable loss". I do a lot of VHF thru mw frequencies and hate to loose more than 1-dB in loss. I consider 25-foot of RG-213 at 144-MHz as max, then go to LMR-400 for longer runs (up to 150-foot). If longer runs needed then I use LDF or equivalent hardline.
My 2m eme antennas are 214 foot from the PA and measured total loss is 1.67 dB, but my preamps are mounted on the tower and only see about 0.4 dB loss. On 1296 my dish is about 100-foot from the shack and I have 6-dB loss in the LMR-600 transmission line. Fortunately my high power PA's are located at the dish and only need 2w drive from my 20w transverter in the shack. On 1296 receive the preamp is mounted directly to the dish feed and have about 125 foot of LMR-400 to transverter (7-dB loss). But preamp has 37-dB gain so easily overcomes the loss with about 30-dB residual gain to the transverter to result in 0.3 dBNF. This is all for eme where losses will kill your ability so see weak signals.
73, Ed - KL7UW http://www.kl7uw.com Dubus-NA Business mail: dubususa@gmail.com _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
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Edward R Cole -
Greg D