[amsat-bb] Exciting Coax
ko6th.greg at gmail.com
Thu Jan 25 19:18:35 UTC 2018
...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.
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
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