[TowerTalk] M2 20M5 SWR measurements

[Stan Stockton]

Jorge,

Unless you have 50 ohms and no reactance at the driven element terminals at both frequencies (which you do not have) your coax will provide some transformation at the other end.  I assume your coax is .66 velocity factor.  Try another test.  If you can, add a jumper that is about 14.5 feet long to your 8.35 long one for a total of about 22.5-23 feet or replace the 8.35 one with one that is about 23 feet and see if you get results more like your original SWR readings.  The reading you would get at the input to the antenna will repeat about every 23 feet at around 14.100.  

How much coax is between K3 and PWMaster?

Stan, K5GO

Sent from my iPad

On Dec 30, 2011, at 6:06 PM, "Jorge Diez - CX6VM" <cx6vm.jorge at gmail.com> wrote:

> Hello,
> 
> I have a 20M5 and 15M6 antennas from M2
> After 3 years using this antennas, I noticed a change in the SWR of the 20M5
> when I added a High power BPF, for what I need to add some coaxial jumpers.
> 
> Today I did some tests. I removed the filters to have my original setup: K3,
> Amplifier, SWR meter (Powermaster), antenna switch (Six Pack) and antenna.
> 
> The measurements in the Powermaster and in the K3 meters are a little
> different, so I take notes of both
> 
> I add a 8.35 ft long jumper to the antenna, and this is the results:
> 
> FREQ        ORIGINAL SWR    SWR WITH ADITIONAL 8.35 FT (2.55 MTS)
>            PWMASTER  K3        PWMASTER  K3
> 14025        1.82      2.0       1.39      1.6
> 14300       1.37      1.3       1.48      2.3      
> 
> So what do you think is the problem?  
> 
> With the additional 8.35ft jumper, the SWR is very good in the PowerMaster,
> but not good in the K3 meter
> 
> Really I don´t like to see that measurements diference, seems something bad,
> and want to solve this problem.
> 
> Thanks in advance!
> 
> Happy New Year 2012!!!
> 
> 73,
> Jorge
> CX6VM/CW5W 
> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk