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Re: [TowerTalk] DAVIS RF response: Alternatives & Comscope SFX-500 data

To: "Steve Davis -Davis RF Co." <>
Subject: Re: [TowerTalk] DAVIS RF response: Alternatives & Comscope SFX-500 data vs. LMR & LDF4
From: "Roger (K8RI)" <>
Date: Sun, 07 Jun 2009 13:41:10 -0400
List-post: <">>

Steve Davis -Davis RF Co. wrote:
> Hi Joe and others,
> Here is your loss data (below).  Not sure how this will reproduce on TT, so, 
> for ref.,  the .5 MHz = .065,   the 10 MHz = .293;      30  = .512, etc.
>  Although Commscope is a well built cable, Andrew and LMR are also very well 
> built as likely you know.  Often, for various reasons, Heliax (LDF, etc) is 
> overkill for hams and more costly.  By overkill, I am not referring to 
> attenuation, as often the alternative choices are very close to same 
> attenua.  Overkill is as to the extra strength (and cost vs. comparable LMR) 
> of Heliax (for hauling up very high commercial towers) and crush resistance 
> (if you plan to drive your car over it day in day out... HI).
I always thought that LDF-4 was a lot more fragile than the LMR series 
with the exception of the small stuff like the 240 series. I found it 
kinked much easier with normal handling around the shop or hauling up 
the tower. 7/8" OTOH was pretty rugged ...and heavy. I use the LMR-600 
for almost everything, not because I need it on HF, but as  I use it on 
VHF and UHF I decided to use it where ever I could.   This means I only 
need a couple of connectors types and when purchasing there is usually a 
substantial difference in price when purchasing 1000'. 

I use the LMR-600 from the rigs to the tower and up the tower. I use the 
Davis BuryFlex for pigtails and feed lines to the slopers although I do 
use CNT240 to the 40 meter slopers, but that is probably going to get 
changed to a good quality RG-8X with braid plus foil shield, at least 
for a trial. I'm using BuryFlex to the 75 meter slopers and may end up 
using it to those on 75 as well. 

I had two runs of LDF-4 and gave them away. Had it been 7/8" I'd have 
used it.

The station(s) here in a constant state of change, so there's no 
guarantee as to what I'll end up with out there.

Roger (K8RI)

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