[Moon-net] Phasing lines

[G1OGY (Dave)]

> ------------------------------
>
> Message: 5
> Date: Sun, 19 Nov 2006 20:04:14 -0800
> From: KA6AMD <ka6amd at earthlink.net>
> Subject: Re: [Moon-net] Phasing lines
> To: moon-net at list-serv.davidv.net
> Message-ID: <4561293E.4010602 at earthlink.net
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> I'm not exactly sure how you measured the cables, but from what you 
> describe, there could be a lot of interactions going on during the 
> measurement.  As long as the cable is from the same lot, you should be 
> able to get very close by cutting exactly the same length of cables.  If 
> you ended up with different lengths, something was wrong with your 
> measurement.  Remember, everything repeats at half wavelength 
> intervals.  Nulls are a quarter wavelength from an open and a half 
> wavelength from a short.  The wavelength is 70cm times the velocity 
> factor of the cable.  Did you use a short or open to measure your null?
> 
> Erich, KA6AMD
> DM15do

>> F. Veitch wrote:
>> I would be interested in the groups comments on whether it is worth the
>> expense of having precision phasing lines fabricated for a small 70cm eme
>> array (4 x K2RIW x 19)  I had tried to make up some precision length LMR-400
>> cable assemblies using an isolated source, Tee, and 50 Ohm load with an RF
>> Voltmeter, but while things trimmed to a very nice null, the lengths were
>> extremely erratic, and I am loath to spend any more in connectors and cables
>> without understanding what I have done wrong.  I really do not believe that
>> Velocity factor varies that much in the same cable length.  Assuming the
>> antennas are correctly matched, will equal lengths of LMR to the 4WPSD be
>> adequate?  Should I spend the money for commercially fabricated lines?  
>>  
>> Thanks in advance
>> Fletch
>> K3JYD
>> FM18pl



This is the method Diode Communications (UK)
used for my 10 x 5M Ecoflex-15 for 432MHz.

<http://www.gm4jjj.co.uk/cutting_phasing_lines.htm>


-- 
Dave Gilligan, G1OGY
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