[TowerTalk] N or UHF?

[Clint Talmadge]

I will echo what Dan Hearn has said with a little more detail.  In an N connector the center pin is positioned in the connector by the center conductor.  When the cable gets cold the copper contracts and draws the center pin out of the mating connector.   While working at a small company in New Hampshire, we ran a cable to the roof for an antenna to provide clock signals for a system we were developing.  Every morning the clock would not see the antenna.  We would trouble shoot it to the cable, take it out and replace it and everything would work fine.  Next morning, same thing!  Someone noticed we had been "fixing" it using "yesterday's" cable.  When we tried to figure out how a cable could heal itself overnight, we came upon the temperature difference of the cable run outside the wall in the New Hampshire winter and one that had spent the night coiled up in the warm shop on the floor.
If memory serves me, NO1V, Ernie Cote was the one who finally deduced the problem.


PL-259's center pin is fixed to the shell so cannot move in and out. Go with PL-259's

Clint - W5CPT
  ----- Original Message ----- 
  From: K8RI on TowerTalk 
  To: TOWERTALK at contesting.com 
  Sent: Monday, October 16, 2006 3:24 PM
  Subject: [TowerTalk] N or UHF?


  It's just a small thing, but I'm running some LMR-600 and 5/8 Heliax up the 
  tower for six and two. From the rig to the antennas is roughly 228 feet. 
  The pigtails from the entrance bulkhead are LMR-400 UF.  I grounded the 
  LMR-400 cable jacket at the base of the tower using UHF bulkhead connectors 
  through a bracket bolted to the tower legs (waterproofed with flooded heat 
  shrink).

  I can ground the two new cables the same way, or I can use a double female N 
  connector clamped to a leg of the tower. I'll be doing the same thing at the 
  top of the tower where the pigtails hook to the LMR-600 and Heliax.

  The only drawback I can see with the N connectors is the lower voltage break 
  down and although they are inherently water proof/resistant that is placing 
  a lot of faith in a little gasket. Of course I can do the flooded heat 
  shrink treatment on those as well. OTOH clamping directly to a tower leg 
  probably gives the best angle for diverting lightning off the coax.

  At six and two meters I doubt the extra loss for either type of connector is 
  worth taking into consideration. Due to RF exposure levels I'm limited to 
  380 watts key down (continuous) into the 2-meter array but at the 20% SSB 
  duty cycle I can still run the legal limit (when I get the amp).  I can run 
  the legal limit, any mode, on six.

  Any one have any good reasons/thoughts for going one way or the other?

   BTW IF for some reason, some where along the line a message gets tagged as 
  spam *Please* remove that tag before replying as the message will get dumped 
  at my ISP and I'll never see it. The same is true for answering anything 
  with the word "Digest" in the subject. They will not come through. I haven't 
  received any messages with the word digest in the subject line since early 
  last spring.

  Roger Halstead (K8RI and ARRL 40 year Life Member)
  N833R - World's oldest Debonair CD-2
  www.rogerhalstead.com 

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