[TowerTalk] [Bulk] FW: Coax lengths for phasing a stack

[Markku Oksanen]

>From a systems design perspective I still hold that it is best to make sure that you will CERTAINLY have the same current on each driven element by cutting to odd number of wavelengths.
It may not really make too much cable since even on 20 m 1/4 wave in RG-213 type cable is 3.5 meters and you have thus 3.5, 10.5, 17.5 and 24.5 meters to use.  And if desired, one can have a feed to lower antenna with say 3.5 meters ( if the driven element is close to the tower) and then run a longer cable, say 17.5 meters to the top antenna.The phase relationship between antennas will be slightly frequency dependant this way but quick calculation between 14.2 and say 14 MHz, shows 1.4% frequency difference but because there is a one full wavelengths worth of electrical distance, this translates to 5 degree phase error.  Totally nothing to worry about.
What I want to point out here is that it is good engineering practice to make sure that every individual element of the design is done to best available knowledge, then, and perhaps only then, the system altogether will work as was planned.
MarkkuOH2RA/OG2A/WW1C

> From: gm3sek at ifwtech.co.uk
> To: towertalk at contesting.com
> Date: Mon, 9 Feb 2015 08:45:57 +0000
> Subject: Re: [TowerTalk] [Bulk]  FW:  Coax lengths for phasing a stack
> 
> KZ1W wrote:
> >"a few tenths of a db here and a few tenths there and pretty soon there
> >is -3db"
> >
> 
> Or: "Take care of the millibels and the decibels will take care of
> themselves."
> 
> 
> 73 from Ian GM3SEK
> 
> 
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