[BC] RG-8

[Gregory Muir]

Sorry for the previous email.  My "send" finger twitched.

I can appreciate the possibility of possible intermod due to the metallic 
differences between the tinned copper braid and the aluminum foil shield. 
As to how much intermod coupling finally makes it through the foil would be 
a good investigation exercise in the lab.  Unfortunately I don't have a TEM 
cell within my grasp.

Times actually was thinking ahead of us on this subject, though.  See 
http://www.timesmicrowave.com/content/pdf/lmr/04-07.pdf .  They recommend 
their T-COM series cable for overall good performance if intermod is a 
concern.

As for jumpers, if I require a Heliax product, the Superflex line (FSJ 
series cable) works very well.  FSJ1 has a minimum bending radius of 1 inch.

Greg


----- Original Message ----- 
From: "Mike McCarthy" <Towers at mre.com>
To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
Sent: Friday, April 04, 2008 7:39 AM
Subject: Re: [BC] RG-8


> What Times doesn't say is LMR series cables introduce IM between the braid 
> and foil.  Thus artificially raising the noise floor.  In very sensitive 
> applications, the raising of the floor 3-6 dB could be unacceptable.
>
> Andrew makes a LDF-1, a 1/4" cable for last foot applications.
>
> MM
>
> At 11:07 PM 4/3/2008 -0600, Gregory Muir wrote
>>Choice of cabling is often found out to be inadequate after the job has 
>>been completed.  It tales careful consideration before you start to choose 
>>the cable for your application.  If you look closely at cellular sites you 
>>will often find 214 in use within the building.  Then it is Heliax up the 
>>tower. The same applies to trunking sites.  But there I have even seen RG8 
>>in use.
>>
>>LMR400 is effectively solid.  It's a foil tape covered with a tinned 
>>copper braid.  Times touts shielding effectiveness 50 dB greater than 
>>single layer braid.  In the past I have had 100% success of its use at

<snip>