Eric Lemmon wrote: Nice info on the HS vs P lightning arrestors, Eric.
One of the local UHF ham repeater owners noticed a high SWR on his properly-lightning-protected (P, not HS, but still...) MSF-5000 a few weeks ago. They turned the power back quite a bit (SWR was about 1.5:1) and left it until weekend #2. Weekend #2, they went up and tested everything... at each place they could, they removed the connectors, inspected them, and put a good stable 50 ohm dummy load on the PA, and tested for reflectivity. None. Okay, problem's at the antenna. The antenna was a DB 8-element folded-dipole array... we've all seen 'em. Weekend #3, last weekend, they had a spare antenna, so they go get the local guys that know how to climb properly and go swap 'em... After they got the original antenna down, they could finally see what had happened. Thor had come for a visit. Melt-through, two holes near the top of the mounting mast, and when they tried to pull the two sections apart, they were arc welded together. Two strong guys couldn't pull the sections apart. It'll be interesting when they get around to doing the internal autopsy and looking at the harness to see what else is cooked. If I can, I'll get some photos. The antenna was mounted UNDERNEATH the platform on an old-style AT&T microwave tower. The big thing with the large walk-around platform on the top? Yep... lightning can still get you, even hiding under the tower's large steel platform. (Hmm, that reminds me... here's a photo of the site after a wildfire got a little too close for comfort in July of last summer... ) http://www.natetech.com/?p=185 -- or www.rmham.org has it too. The MSF-5000 is fine, and much happier now with an antenna that's not crispy. Nate WY0X Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
