[TowerTalk] Repairing/replacing a damaged feedline

[Gene Smar]

You don't need to worry about matching impedances if you make the 75 Ohm cable a multiple of one-half wavelength long, taking VF into consideration.  Impedances repeat every 1/2 WL.


73 de
Gene Smar  AD3F


-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Stan Stockton
Sent: Monday, March 25, 2019 11:02 AM
To: Bob Shohet, KQ2M <kq2m at kq2m.com>
Cc: TowerTalk at contesting.com
Subject: Re: [TowerTalk] Repairing/replacing a damaged feedline

I would make a trip to the CATV providers in the area and see if I could get free hardline, replace it with something less likely to ever have a problem, match the antenna to 75 ohms at antenna feed point and back to 50 ohms on the shack end if you believe necessary.

Less loss, less likely to get damaged by critters and free!

They gave given me dozens of reels of 3/4" hardline with 300 or more feet on each reel.  A little sweet talk is all that was required.

73...Stan, K5GO

On Sun, Mar 24, 2019, 8:00 PM Bob Shohet, KQ2M <kq2m at kq2m.com> wrote:

> Hi,
>
> Today I noticed that my 160 feedline which is a ~ 325’ feet long run 
> of Buryflex, had lots of critter teeth marks in two main areas.  
> Clearly the coax in these areas is damaged beyond repair.
>
> Starting at the feedpoint of the 160 Inverted L, the first 25’ runs 
> downhill and is pristine with no critter teeth holes.  Then they start 
> to appear and run off and on for the next 100’ or so.  The is enormous 
> damage at the 100’ mark – about 75’ from where they start appearing, 
> and from start to finish, the length of critter damaged cable is ~ 
> 100’.  This entire area is on flat ground.
>
> My understanding is that foam tends to wick up moisture but for how 
> far on flat ground?  Can it wick 25’?  50’? 100’? The entire length of 
> the buryflex?  I don’t want to wind up using and damaged or 
> deteriorated cable but I don’t want to needlessly waste 150’ – 200’ of 
> potentially good coax
>
> The coax run is ~ 6 years old so aside from the critter damage and any 
> possibly wicked up moisture, the rest of the cable still has many 
> potential years of life left.
>
> So my question is – should I just replace the entire 325’ Buryflex 
> feedline?  Or does it make sense to replace the the 100’ damaged area 
> plus an additional “safety” area of ~ 50’ for a total of 150’?
>
> Tnx & 73
>
> Bob KQ2M
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