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[TowerTalk] HIGH SWR because of loops between amp and wattimeter

To: "'Tower and HF antenna construction topics.'" <towertalk@contesting.com>
Subject: [TowerTalk] HIGH SWR because of loops between amp and wattimeter
From: "Jorge Diez - CX6VM" <cx6vm.jorge@adinet.com.uy>
Reply-to: "Tower and HF antenna construction topics." <towertalk@contesting.com>
Date: Sat, 24 Apr 2010 20:44:09 -0300
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Hello,

 

Today I was reading high SWR in my 20 mts yagi.

 

2.5:1 in 14020

1.9:1 in 14200

1.7:1 in 14300

 

I have the radio connected to the amp, to the wattmeter and to WX0B
six-pack. In all this runs I have small pieces of 50 ohms coaxial.

 

I connected the 20 mts yagi antenna direct to the K3 and the readings in the
radio were:

 

1.4:1 in 14020

1.0:1 in 14200

1.0:1 in 14300

 

I know will be some variation when you go through all the runs from radio to
amp, wattmeter and antennas switch, but not too high that happens in 20 mts.

 

I tested all the other bands and SWR is lower when the antenna is connected
directly, but not too much difference, for example:

 

SWR in the

Main setup

(amp, wattmeter,           SWR with antenna

Frequency          Antenna switch)              direct to the K3

 

28030                    1.5:1                                     1.2:1

28500                    1.1:1                                     1.0:1

21020                    1.5:1                                     1.3:1

21200                    1.2:1                                     1.0:1

21300                    1.1:1                                     1.0:1

 

14020              2.5:1                           1.4:1

14200              1.9:1                           1.0:1

14300              1.7:1                           1.0:1

 

7010                      1.3:1                                     1.0:1

7050                      1.7:1                                     1.3:1

7100                      2.0:1                                     1.5:1

3505                      1.5:1                                     1.5:1

3550                      1.2:1                                     1.2:1

3600                      2.5:1                                     2.5:1

1810                      1.2:1                                     1.1:1

1830                      1.7:1                                     1.6:1

1850                      2.3:1                                     2.3:1

 

So SWR is reasonable higher when connected through the amp, wattmeter and
antenna switch in all bands, except in 20 mts that there´s a big
diference!...

 

Is not a problem of the sixpack. I connected the 20 mts antenna with the
same runs of coaxial with a 2 position Daiwa switch and have the same SWR
that it have when connected to the sixpack.

 

Any idea how can I lower the SWR in the 20 mts antenna when connected to the
antenna switch?

 

Thanks,

Jorge

CX6VM

 

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