[Elecraft] K3 SWR Accuracy - reprise

[Stewart]

Of course Robert, the ATU was OFF. My typing error.
Any measurements made with it ON would be meaningless.

73
Stewart G3RXQ 
On Wed, 4 Nov 2009 07:14:43 -0600, Robert Naumann wrote:
> After reading your table and comments again, I'm also curious 
why you are
> using the antenna tuner in these measurements?
>
> Shouldn't the internal ATU be OFF in order to evaluate the SWR 
meter?
>
> With the tuner on, the K3's SWR meter is showing the results of 
the tuner
> doing it's job - no? I would hope that the K3 SWR meter would 
read different
> in this case.
>
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Stewart
> Sent: Wednesday, November 04, 2009 2:45 AM
> To: Elecraft Reflector
> Subject: [Elecraft] K3 SWR Accuracy - reprise
>
> Hi,
> Now traffic on the new K3 Macro functions has somewhat died 
down,
> I would like to raise again the issue of the K3's SWR 
measurement
> accuracy.
>
> I did some tests using dummy loads and a LP-100 meter as 
follows.
>
> The dummy load is a precision 100W one which I measured with a 
VNA
> and has a VSWR of <1.03 from 1 to 30 Mhz. To simulate a 2:1 VSWR
> I used another dummy load (not quite as good) in parallel.
>
> The K3 output was from ANT1 using the internal ATU. The ATU was
> automatically tuned to 1:1 on all bands.
> The results I got for 2:1 VSWR are as follows:-
>
>               LP-100           K3
> 160         1.99                1.8
> 80           1.99                1.8
> 60           1.99                1.8
> 40           1.95                1.8
> 30           1.97                1.6
> 20           1.97                1.4
> 17           1.97                1.3
> 15           1.96                1.2
> 12           1.96                1.5
> 10           1.96                1.4
>
> As can be seen my K3 SWR indication consistently under reads.
> However, it really gets bad on 20,17 & 15.
>
> From previous replies I understand that this under reading would
> be compensated for in the firmware, sometime in the future .
>
> Is this still on the list of problems to be addressed ?
>
> 73
> Stewart G3RXQ
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