Norm, Whenever I install an antenna that uses molded "Y" joints, I take the time to seal them with 3M Scotchkote electrical sealant. I also ensure that all nuts are tight- a few new antennas had loose terminals, right out of the box. When applying the Scotchkote, I first do all upward-facing joints and allow the sealant to set, then invert the antenna and do the remaining joints. If I have the time, I give each joint a second coat. I use a small stiff brush to apply the sealant only where the cable jacket enters the splice block.
This is a messy job, so I do it at the shop a few days before making the trip to the site. I have several Scotchkote-treated exposed-dipole antennas in service, both VHF and UHF, and none of them has suffered a leaky harness. I have a mixture of Andrew (Decibel Products), Celwave, Sinclair, Comprod, and Telewave antennas, and I believe that the Scotchkote routine has prevented any water ingress problems. Disclaimer: I have no association with 3M; I am simply a satisfied customer. More info is here: <http://tinyurl.com/2cdrdnm> 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of NORM KNAPP Sent: Sunday, May 09, 2010 4:34 AM To: [email protected] Subject: Re: [Repeater-Builder] Commercial VHF antenna on 2m Not to throw a monkey wrench into things, but... Is that 4 dipole array antenna an Andrew db-224a? If so, and it was made in Mexico in the last 6 or 7 years the harness may leak... The leaks seem to be happening where the coax of the harness enters the molded "Y" where 3 coaxes are joined. There are at least 3 of these on each harness and some have 4 if you have an open stub factory installed in the harness near where the top and bottom halves come together. Andrew (now part of Commscope) has changed the harnesses to address this problem... I have gotten free replacement harnesses from them, but I have had to send the old harness back to them first. I sent one to them just over a month ago, but haven't gotten a new one back for it yet... Good luck. Norm ----- Original Message ----- From: [email protected] <mailto:Repeater-Builder%40yahoogroups.com> <[email protected] <mailto:Repeater-Builder%40yahoogroups.com> > To: [email protected] <mailto:Repeater-Builder%40yahoogroups.com> <[email protected] <mailto:Repeater-Builder%40yahoogroups.com> > Sent: Sat May 08 23:13:40 2010 Subject: [Repeater-Builder] Commercial VHF antenna on 2m Hi folks, Several weeks ago I posed the question of using a Commercial VHF antenna that was resonant on 154Mhz on 146.745Mhz. We tried it today. The SWR was a bit over 2:1 on the repeater freq. We installed a T connector after the cans and used an open stub to try to match the line...got it down to 1.5:1, wouldn't go any lower. We think the height of the antenna makes up for what we suspect is a lot of loss in the antenna. The previous location of the repeater antenna was 100ft ASL and this location is 525ft ASL. Maybe one day we'll get a chance to retune the four dipole antenna. Thanks to all that provided ideas for this project. 73, dave wa3gin
