[Elecraft] SWR bars higher than display numbers

[Jorge Diez - CX6VM]

Hello Ron,

thanks for your help.

I continue trying, also with the antenna directly to the K3, and I
discovered that the problem is when I have ON my ALS1300 amplifier.

If the ALS1300 is OFF or in STANDBY, the SWR in the K3 is 1.0 and I see only
1 bar in the meter.

If the ALS1300 is ON, then the SWR in the K3 is 1.7 and I have the 5-6 bars.

So something wrong with this new Amplifier?

73,
Jorge
CX6VM/CW5W
K3 #4077

-----Mensaje original-----
De: Ron D'Eau Claire [mailto:ron at cobi.biz] 
Enviado el: Jueves, 17 de Febrero de 2011 03:23 p.m.
Para: 'Jorge Diez - CX6VM'; elecraft at mailman.qth.net
Asunto: RE: [Elecraft] SWR bars higher than display numbers

Hello Jorge:

Assuming you have a KAT3 built in tuner in the K3, the TUNE (autotune)
attempts to set the SWR between the output filters in the K3 and the KAT3
input to 1:1 for maximum efficiency. The "tuner" can do nothing to change
the SWR on the transmission line leaving the tuner (or K3 if using the
KAT3). 

If you do not have the KAT3 or have it bypassed, the readings still will not
be identical. 

How long is the cable between the coupler on your Powermaster and the K3? 

Whenever the SWR is not 1:1, the SWR value will vary along the length of the
transmission line. The "length" is, of course, length is wavelengths or
fractions of a wavelength, so the higher the frequency the more impact a
given line will have on the reading. 

Try mounting the Powermaster coupler directly on the antenna jack of the K3
using a male-male adapter for a close to a zero length connection as you can
get. The readings should be much closer. They are unlikely to ever agree
exactly on all frequencies since SWR meters are not precision instruments -
they don't need to be. Small variations are not important to the performance
of the system. 

Ron AC7AC

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Jorge Diez - CX6VM
Sent: Thursday, February 17, 2011 8:39 AM
To: elecraft at mailman.qth.net
Subject: [Elecraft] SWR bars higher than display numbers

Hello,

 

I noticed that I have 6 SWR bars that is over 2:1

 

I did TUNE and I read 1.6

 

In my Powermaster SWR I read 1.23

 

Why the difference, at least between the 1.6 I read in my K3 display and the
bars in the meter of the K3 that show +2 of SWR?

 

Thanks

Jorge

CX6VM/CW5W

K3 #4077

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