Hi Wayne, >From memory the suggestion was to use 50 ohm double screened cable for the phasing harness and intercavity cables. RG-142 (not to be confused with the far more popular RG-214) has two layers of braid and there are other types from various other manufacturers. You may be able to pick up similar cable at hamfests in the form of commercially made jumper cables that come out of mobile phone base stations and the likes...
Some double screened cables has a layer of aluminium tape covered with braid (like that used commonly for TV antennas). Probably should be avoided in this application due to potential problems with dissimilar metals and corrosion. If fact, some commercial guys recommend using nothing less than double shielded cables that have all conductors silver plated, and use silver plated N-type connectors all around. By the way, I've seen quite a few people say the QST cavities aren't the best and many have published improvements on the Internet (to improve performance and ease of construction) - it may be worth a quick search around the net! 73, Mark VK3BYY > -----Original Message----- > From: [email protected] > [mailto:[EMAIL PROTECTED] On Behalf Of vk4cya > Sent: Thursday, 10 January 2008 8:22 PM > To: [email protected] > Subject: [Repeater-Builder] cavity duplexer > > Hello to the group, > > I have just joined the group.The local radio club that i'm in it > putting together a cavity duplexer alot like the one in the july 1972 > issue of qst.We are going ahead leaps and bounds but we have came > across a problem it is suggested that we use rg55/u coax on the > cavity's but the problem is that i can't find anyone in australia > selling that type of coax.So is there anyone that could help me in > suggesting what else could be used.I have found a couple of sites on > the net that have rg55/u but in roll form.We are looking for around 2 > metres of it only. > > Any help would be most great > Thamks Wayne vk4cya >
