I can support what Greg stated.

I have ten foot of LMR-400UF to go around my az-el system between my Relay/Preamp box and the 4-way divider that feeds my four 2m-eme yagis (21-foot long booms). There is another 18-foot of LMR-400 to each yagi so plenty of coax loss even in an eme array. I figure my loss from antenna to preamp at 0.45 dB.

I get away with that much loss because my preamps are 0.1 dB NF vs the typical satellite preamp that has 0.5dB NF. My overall Rx system NF is est. 0.57 dB.

on my 6m long-boom yagi I have about 2 turns of LMR-400 that wind around the mast before connecting to my relay/preamp box. This allows enough flex not to break the LMR-400. Ten foot of LMR-400UF would not be significantly more loss so up to 2m it should work fine. The real key to getting good Reception is the preamp at tower top. Most 2m radios have NF of 6 to 10 dB. Transverters are better at about 1.5-2 dB NF. But both benefit with a preamp close to the antenna.

I think there is a recent version of Belden 9913 which has solid foam core vs the polyethyline spiral bead with air core that was so susceptible to moisture. I think its called 9913F.

But I use LMR-400 as its about the same cost and much better with moisture if you do good sealing at the connectors.

73, Ed - KL7UW

------------ From: Greg D ko6th.greg@gmail.com To: w4upd updwrb@bristor-assoc.com, amsat-bb@amsat.org Subject: Re: [amsat-bb] LMR-400 direct to antenna or no?

Hi Reid,

I understand the desire for minimal use of connectors, but the coupling between the rigid cable coming from the shack to the rotor, and the flex cable going to the antenna, is a good place to put a nice little preamp. Think of it as a barrel connector with attitude. Yes, putting it at the antenna feed point is better, but unless you're working EME, the practical difference is pretty small.

Your luck with 9913 and water ingress is significantly better than mine ever was. I had one 60' run that kept getting worse over time. It got so bad that I drilled a hole in the lower end connector so I could suck out the water until I could find some hardline to replace it. Never used the stuff ever again.

Greg KO6TH

73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: dubususa@gmail.com