Vance posted that the FOAM coax has 25% less loss. Coax loss is specified in dB per 100 feet. We are not wiring a C5 galaxy here, my KR coax length was probably about 10 feet. The numbers for loss/100feet I found were from 3db/100feet to 6db/100feet (3db is bad, that is 50% of the power lost).
So I found a website that will calculate the loss for RG58. Go to http://www.timesmicrowave.com/cgi-bin/calculate.pl And you can calulate the db loss of various cable types. I plugged in 10' and 121.5Mhz for RG58 and got 0.5dB loss. Not too much loss. After having said this, using expensive cable is like buying a more powerful transmitter and reciever as it imporves your efficiency and weighs the same... can you notice the difference of 0.5dB loss vs 0.0dBloss. (I don't know if Vance's 25% more efficient for foam cable applies to the dB loss, or the transmitted power. (3dB is 50%) I think I purchased my *cheap* 50 ohm coax at Frys electronics (non foam insulated). When we are talking about 25% less loss, I'm thinking what is the loss per foot, and how many feet are we talking about.xI did a google search on cable loss... My antenna is a RST kit type, (Jim Weir?[sp]) Based on the type of testing I have done... I don't think it will be worth the $$. Antenna placement and other factors might contribute to loss more than cable selection. On the other hand... if you can throw money at a problem to make things better... it's easier than fussing with it. I think the only "critical" thing is to get 50 ohm instead of 75 ohm cable. ----- Original Message ----- From: "JIM VANCE" <va...@claflinwildcats.com> List-Post: krnet@list.krnet.org Date: Thu, 16 Oct 2003 19:03:00 -0500 To: "krnet" <kr...@mylist.net> Subject: KR>Coaxial cable > All aircraft radios use 50 ohm cable. Be sure to use RG58 FOAM. The foam > coax has about 1/4 the loss of the regular RG58. You can buy it at any > two-way communications shop or in the internet. The Radio Shack stuff may > cost 20% less, but it is almost as bad as hooking up the antenna using the > zip cord used on table lamps. > > Jim Vance > > Vance@ClaflinWildcats.com_______________________________________________ > see KRnet list details at http://www.krnet.org/instructions.html -- ___________________________________________________ OperaMail free e-mail - http://www.operamail.com OperaMail Premium - 28MB, POP3, more! US$29.99/year Powered by Outblaze
