I just tuned a set of these T1500s Sunday night, I've seen them before but never had a need to tune a set till now. Adjusting the notches wasn't fun. I had seen Eric's note regarding sealing the holes and considered putting some silver/ aluminum duct tape used in HVAC over those slots when done but I didn't. Mark, you can get plain foil tape at Home Depot/Lowes.
What I did notice was that I was getting some leakage from somewhere during the notch settings depending on my cable positioning. Normally I would suspect a bad cable but I have very good test cables and pads reserved for tuning cavities and haven't seen this recently on other duplexers. I think Eric is right about some leakage through those slots. How much? Who knows depending on your specific cable routing and quality. Just don't route over those slots eh? 73 Don Kirchner W5DK From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of n9wys Sent: Tuesday, August 26, 2008 11:38 AM To: [email protected] Subject: RE: [Repeater-Builder] De-Sense and Circulator Question OK, I found the message. now the question: what aluminum tape is best for this? Or is there a "best" tape? I just got a Motorola duplexer for a 462 repeater I'm building, and it has the holes/slots in it. (And yes, it *IS* a MICOR.) Of the various types of tape available, does the adhesive need to be conductive? Or is it "good enough" for the foil to merely cover the openings? For example, I was browsing Mouser's choices of tape HERE <http://www.mouser.com/catalog/635/2090.pdf> ... http://www.mouser.com/catalog/635/2090.pdf I am interested in these tapes: 3M 425 or 427 (adhesive conductivity not listed) 3M 1170 (listed: "conductive adhesive") Although I'm thinking at these costs, they must ALL have conductive adhesives... 425 (1" wide) costs $20.93/roll; 427 is $61.95/roll; and 1170 is $46.07. If anybody has insights, I'd be interested to hear! Thanks, Mark - N9WYS -----Original Message----- From: [email protected] On Behalf Of Eric Lemmon snip Even if your T-1500-series duplexer is optimally tuned, you can possibly improve its performance a bit by using adhesive-backed aluminum tape to cover the slots where the loop and probe adjustments penetrate the side walls of the cavities. The metal tape will eliminate a possible leakage path through the slots. Your jumper cables should be made of RG-400/U or RG-214/U cable with the proper connectors on each end- no adapters. Crimped-on, silver-plated connectors are more reliable than those that are soldered or clamped. . <http://geo.yahoo.com/serv?s=97359714/grpId=104168/grpspId=1705063108/msgId= 84772/stime=1219768712/nc1=5028925/nc2=5191954/nc3=4025373>
