Roger:
Instead of installing a couple of additional connector sets to effect
grounding on my coax runs up the tower, I fabricated my own shield connectors
from copper flashing. I posted a description on TT at:
http://lists.contesting.com/archives//html/Towertalk/2002-07/msg00698.html .
You should be able to use this technique directly on the smooth shield of
LMR-XXX, and possibly adapt it to the corrugated shield of heliax. FWIW.
73 de
Gene Smar AD3F
-------------- Original message ----------------------
From: "Dan Hearn" <dhearn@air-pipe.com>
> Roger, I have heard of problems with N connectors on the end of long cables.
> There is reportedly a different thermal expansion between shield and center
> conductor which tends to pull the center pin out of the socket. Apparently
> the UHF jobs are more tolerent of this. 73, Dan, N5AR
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com]On Behalf Of K8RI on TowerTalk
> Sent: Monday, October 16, 2006 1:25 PM
> To: TOWERTALK@contesting.com
> 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
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.408 / Virus Database: 268.13.4/477 - Release Date: 10/16/2006
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|