[Elecraft] SWR bars higher than display numbers

[Guy Olinger K2AV]

If you get normal power output from the ALS1300 I would not worry about it.
The actual drive impedance of most amplifiers varies considerably with load,
frequency and power level. SWR does not tell you if power is being
transferred, just that as the power is being transferred the sink impedance
is not 50 ohms resistive.

73, Guy.

On Thu, Feb 17, 2011 at 12:47 PM, Jorge Diez - CX6VM <
cx6vm.jorge at adinet.com.uy> wrote:

> 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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