[TowerTalk] [Bulk] Coax cable economics. (was Mosley Antenna Question)

[Don]

The ham with the finest antennas and feedlines, and big power still won't 
stand a chance against the A-1 operator who knows savy operating techniques 
(usually will pull in contacts from under the former's nose).

Don W7WLL

-----Original Message----- 
From: Grant Saviers
Sent: Wednesday, February 18, 2015 2:32 PM
To: kz8e at wt.net ; towertalk at contesting.com
Subject: Re: [TowerTalk] [Bulk] Coax cable economics. (was Mosley Antenna 
Question)

Add Davis RF Buryflex to your list - loss almost the same as
LMR400/9913.  500' is $0.85/ft.  The polyethylene jacket is far better
than 9913's and LMR400.  Sorry I ever bought the 9913!

re hardline: LDF4 is frequently available on ebay at around $1/ft and
has half the db loss and very long life, and real Andrew connectors also
around $12 ea too.  LDF5 (7/8") is a bit pricey and rare on ebay, but
0.195db/100ft at 30MHz.  I'm looking for a few hundred feet.

Grant KZ1W
a few tenths of a db here and there and pretty soon there is 3db.


On 2/18/2015 1:38 PM, Earl Morse wrote:
> Coaxial cable here is bought in quantities of 500'.  Scraps less than 100' 
> get hauled off to the hamfest.
>
> Looking at price per foot of 3 popular types of 1/2" coax we have:
>
> LMR400  $1.18/ft  or  $589.99/500 ft roll
> RG213   $0.83/ft  or  $412.99/500 ft roll
> 9913    $1.12/ft  or  $559.99/500 ft roll
>
>
> Loss/100 ft of these @ 30MHz is:
>
> LMR400  0.7 dB
> RG213   1.2 dB
> 9913    0.7 dB
>
> At this frequency the loss in a 500' run (@30 MHz) would be:
>
> LMR400 3.5 dB
> RG213  6.0 dB
> 9913   3.5 dB
>
> Crunching these numbers, 2.5 dB can be gained from spending either an 
> extra $177 for the LMR400 or $147 for the 9913 over the RG213.  This is 
> just for 30 MHz and a 500 foot run.  Losses would be lower at lower 
> frequencies and higher at higher frequencies especially when the 
> dielectric loss properties of the cable kick in.  Your run may be shorter, 
> hopefully not longer.  It starts to add up and an amplifier starts to look 
> like a good deal where you can get 10 dB on all bands for the same price.
>
> These cables can all use the same cheap (but not too cheap) PL259 
> connector.  You might get a chunk of free 50 ohm 7/8" Heliax and spend 
> $150 for connectors.
>
> There are tons of other cables available.  They all have different 
> properties.  They all have advantages and disadvantages.  Your application 
> may need direct burial or need to be very flexible.  You may be phasing 
> something and require something that needs a specific phase velocity.  I 
> have seen guys use aluminum jacketed 75 ohm CATV hard line where 
> connectors are soldered to it with a pigtail and the shield is clamped to 
> the aluminum jacket with a hose clamp then the whole thing gets a milk jug 
> or bleach bottle shoved over the top of it.  Hey, the cable is free.
>
> As with everything in life.  Check the fine print.  Figure out your 
> cost/Bel.  Take into account the frequency you are using and what exactly 
> it is you want to do.
>
> If price/Bel is no object, then get your bank book out, give me a call, 
> and I will build you a dream station.  Heck, if we are talking contract I 
> will even come over and operate it for you.
>
> Oh yeah, someday you will probably have to replace all that coax, probably 
> around 10-15 years when the rest of the station starts breaking down. 
> (I'm at 12 years now and over due especially after a well meaning neighbor 
> hit the coax bundle going to the tower with a mower.)  Then start saving 
> up again for the rebuild as soon as you complete the station.  (Are they 
> ever really completed?)
>
> Earl
> N8SS
>
>
>
>
>
>> ----------------------------
>>
>> Message: 1
>> Date: Tue, 17 Feb 2015 18:37:51 -0800
>> From: Jim Brown <jim at audiosystemsgroup.com>
>> To: towertalk at contesting.com
>> Subject: Re: [TowerTalk] Mosley Antenna Question
>> Message-ID: <54E3FAFF.8020406 at audiosystemsgroup.com>
>> Content-Type: text/plain; charset=windows-1252; format=flowed
>>
>> On Tue,2/17/2015 1:30 PM, Ed Sawyer wrote:
>> I can tell you one reason to spec RG213 over LMR400 to feed your Mosley
>> tribander, or any other tribander for that matter.
>>
>> There are some misconceptions here that are the result of advertising.
>> Loss below about 500 MHz is entirely due to the resistance of the
>> conductors at the frequency of interest. The dielectric does not
>> contribute to loss below that frequency unless it's wet, and if it's
>> been wet, the braid is probably degraded, increasing copper loss. :)
>>
>> If you really want low loss, use hard line. I'm feeding my SteppIR with
>> 350 ft of 7/8-in. :)
>>
>> 73, Jim K9YC
>>
>>
>> ------------------------------
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