After a couple of bad experiences with foamed polyethylene that got contaminated and solid polyethylene where heat had allowed the center conductor to shift, I have stuck with RG-142 and RG-400 style coax for short patch cables.
For little stuff that gets soldered into place, I use add RG-316 and RG-178. Teflon makes all of these cables easy to solder without damage. On Sun, 3 Mar 2013 14:08:15 -0500 (EST), johncr...@aol.com wrote: >I could not agree more, having been burned once or twice. > >One batch of "50 Ohm" cables was clearly marked 75 Ohms when received. These >used some form of >relatively high resistance foil shield and a drain wire for the outer >conductor. The high resistance permitted >a ground loop with hum on my 10 MHz reference thus FMing my signal generator. > >A couple of things to note: > >Measure the DC resistance between the connector bodies it should be way less >than 1 Ohm, perhaps >0.1 ohm above what you see with the probes shorted. > >The previous regarding RG-58 apply unless the cable is labeled with a >manufacturers part number and that is stated in the vendors spec - > >Such as > >BELDEN 8262 RG-58U Coaxial BNC M/M Patch Cable 10FT. > >RG58 C/U MIL C17 50 OHMS stamped on the cable. > >These were from - Digital Connections - cablesellforl...@yahoo.com and >purchased via eBay. The price was very reasonable. > >Testing with a HP ANA showed very low VSWR and the expected insertion loss up >to 1 GHz. Shield resistance was very low, as expected. I have used these in >lengths from 3 ft to 20 ft with no difficulty. > >The key here is the Belden part number in the vendors ad that can be checked >to see what you are getting. The MIL SPEC and RG58 etc was stamped on the >cables when received. > >For outstanding performance use RG-223 which is slightly larger than RG-58 and >is a 50 Ohm cable >having a very dense double sliver plated braid shield. > >You can buy these made up for a small fortune or buy an odd lot of RG-223 on >eBay and make your own. Pasternak has the connectors with the appropriate >diameter nuts and collars. The connectors for Rg-58 >are had to make work on RG-223. Connectors for Type N and SMA are also >available. > >Installing clamp style connectors on RG-223 requires a certain amount of >passion (and a stainless steel welders tooth brush to comb the braid) but hey, >no pain no gain. > >-73 john k6iql _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
