[TowerTalk] Coax choice for crank-up - looking for TT experience/recommendations

[David Aslin G3WGN]

Hi Rich,
Thanks for the thought.  I developed an Excel spreadsheet for our 6Gs DXpeditions (TX6G, E6GG, ZL7G) that does the same as the arrg calculator but allows multiple segments each with selectable coax types to give a transceiver-to-antenna loss figure, so I can see the effect of cable selection on overall and segment loss; in addition to all the types of cable available in the US, it includes many European cables like Ecoflex, Aircell and the Messi & Paolini products.  For DXpedition use it also includes cable weights so we can trade off loss versus weight for shipping.
For my home station I set a goal of maximum overall cable loss on 10/12m of 1dB and that's why LDF5-50A came into the picture (we use a 2dB target for our DXpeditions as it's more realistic for lightweight cables and we factor in antenna gain/loss too).  I have a very quiet QTH so 1dB is worth aiming for. I agree that for 30 and 80m hardline is overkill for 150feet.
73, David G3WGN  M6O


-----Original Message-----
From: Richard Thorne [mailto:rthorne at rthorne.net] 
Sent: 10 July 2017 22:43
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Coax choice for crank-up - looking for TT experience/recommendations

David,

Have you run the coax loss numbers on the intended frequencies?  You may find that going to hard line from the base of the tower is not worth it.

Try http://www.arrg.us/pages/Loss-Calc.htm I just used it to determine that RG-213 is plenty of coax to go up a rotating tower for a new 80m dipole and a 30m yagi.  While there is a difference between 7/8 hard line and rg-213 at those frequencies, the difference in loss is not worth worrying about.

Rich - N5ZC

On 7/10/2017 11:15 AM, David Aslin G3WGN wrote:
> I'm putting together a new contest station and have already decided on/obtained LDF5-50A for the 150ft runs to the bases of the two crank-up towers.
> Looking for real-life experiences with cable choices for going up the telescopic crank-up towers.  Seems to me LDF Heliax (either 4-50 or 5-50) won't have sufficient flexibility for the job - the towers are likely to be up/down frequently for neighbour and passing storm reasons. Am I too cautious on that score or is a low-loss coax with stranded core like the Messi & Paolini Hyperflex/Ultraflex series or LMR 400/600UF a better bet?
> 73, David G3WGN  M6O
>
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