Re: [BULK] - [TowerTalk] RG-11 Source?

[Gary Schafer <garyschafer@comcast.net>]

Tom Rauch wrote:
 If someone thinks
> increasing something that doesn't set the limit is
> important, that's fine. Let's just not pretend it is good
> engineering or good science.
>
> 73 Tom



Just saying it doesn't matter isn't good science either.

Years ago I worked for a cable tv company for a short time. All their 
drops were single shield cable. It was in a small town with no tv 
stations near. That cable generally worked fine. I now live in the Ft. 
Lauderdale area. Some places rg59 will work ok and in other places it 
will not. I have seen the difference in my own house.

The relevance to duplexers and cable tv is they share the same problems. 
Cable shielding.

I can't speak for your equipment but I do know that all the major 
duplexer manufacturers use double shielded cable. It would seem that 
because they are all in competition with one another that cost would be 
a concern. If single shield worked as well it would be used to save 
cost. Double shielded cable was never a marketing gimmick for them.

Over the years I have had a direct association with 3 different leading 
duplexer manufacturers. I have seen first hand in their labs why double 
shielded cable is necessary. Yes sometimes you can get away without it.

You will not see companies like Motorola use single shielded cable on a 
large antenna site or on duplexers. Maybe they know something.

Also at -130 db things get a little difficult to know what is real and 
what is not. Isolation over 120 db is very difficult to attain and 
measure with any kind of certainty.

Most reputable cable companies put a lot of time and money into 
selecting the cable they use. I know that they don't use multi shielded 
cable just because it costs more.

Multi shielding is not always needed. But most companies use it on 
everything to insure things always work as intended. The enviroment is 
not always known.

73
Gary  K4FMX


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