Tom, Thanks for the information. This gives us an idea of what to expect when we tear it down. We might find a combination of these things that is giving us the problem.
73 JIM KA2AJH From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tom W2MN Sent: Monday, August 31, 2009 4:32 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Tram 1481 Dual Band UHF/VHF Antenna JIM KA2AJH, I use the TRAM 1480 (also Workman version) in several installations and they all work well. I have not had any problems or failures. The 1481 has additional collinear sections on top (making it about 6 ft taller). The TRAM and WORKMAN antennas are ELECTRICALLY similar to DIAMOND and COMET (I've had some completely apart). There are some mechanical differences which might make the D and C brands a little more durable in severe weather areas. I don't think they are worth the extra price. Now, they all are DC ground but not in the way we all think when compared to a J Pole. The antenna element is internally grounded through the coil in the base but capacitively coupled to the coax center conductor. So, if you look for a DC connection between center conductor and ground, you will think it is open circuit (but is not). Now, all of these very tall antennas tend to be very whippy. With the very low launch angle (particularly on 440) any strong wind will cause the signal strength to vary considerably with the wind. You might consider taking it completely apart (easy job) and examining for water (moisture) and any evidence of bad solder, broken connections or burn marks from lightning discharge. I have rebuilt a DIAMOND X500 that failed after many years. The problem was that the fiberglass wore thin and allowed moist air to condense onto the internal foam rattle insulators. They all seem to use common pieces of soft packing foam that acts like a small sponge. Replacing these and repainting the fiberglass (white or light gray PLASTIC spray paint) fixed the problem. The point is, all 4 brands are at risk of the same long term problem. Tom
