[Elecraft] K3 VSWR Meter Calibration

Fri May 6 17:14:49 EDT 2016

Eric;

Here’s what I submitted to Howard from Elecraft a few minutes ago:

Howard:

I performed the tests using an MFJ Model 260C Dummy Load with less that a foot of RG-58 coax to the Antenna 1 output of the K3. Here are the results you requested:

Freq. 3930 KHz
Tuner bypassed: VSWR=1:1
Auto Tuner engaged: VSWR = 1.1

Freq. 7200 KHz
Tuner bypassed: 1.1
Tuner engaged: 1.0

Freq. 10100 KHz
Tuner bypassed: 1.1
Tuner engaged: 1.0

Freq. 14200 KHz
Tuner bypassed: 1.1
Tuner engaged: 1.0

Freq. 18120
Tuner bypassed: 1.2
Tuner engaged: 1.0

Freq. 21200 KHz
Tuner bypassed: 1.3
Tuner engaged: 1.1

Freq. 24950 KHz
Tuner bypassed: 1.4
Tuner engaged: 1.0

Freq. 28300 KHz
Tuner bypassed: 1.7
Tuner engaged: 1.1

Freq. 50100 KHz
Tuner bypassed: 1.1
Tuner engaged: 1.1

I repeated the tests above with the same stub of coax, same dummy load but in series with the wattmeter in a Palstar AT2KD. The indication on the Palstar was always 1.0 VSWR with the K3 tuner in bypass mode in all tests. Power level for measurements was 15 watts in all cases. The MCU in my K3 is 05.38, FPF is 1.25, DSP1 is 2.86. Please update my records from KP4GE to my new callsign: NQ9V. My K3 and P3 have been performing flawlessly until I noticed the variation in the VSWR display. I also ran the transmitter gain calibration this morning using the same dummy load.

Here is the transmitter calibration summary:

K3 Tx Gain Calibration data written on 2016-05-06 at 16:22:43
K3 Serial Number 04416
K3 MCU revision 05.38. RS-232 speed 38400 bit/s.
Elecraft K3 Utility Revision 1.15.12.7
1900 kHz TxGain LP  15
3750 kHz TxGain LP  11
5336 kHz TxGain LP  18
7150 kHz TxGain LP  14
10125 kHz TxGain LP  18
14200 kHz TxGain LP  08
18110 kHz TxGain LP  08
21200 kHz TxGain LP  05
24930 kHz TxGain LP  07
29000 kHz TxGain LP  07
52000 kHz TxGain LP  10
1900 kHz TxGain HP  25
3750 kHz TxGain HP  30
5336 kHz TxGain HP  48
7150 kHz TxGain HP  36
10125 kHz TxGain HP  36
14200 kHz TxGain HP  16
18110 kHz TxGain HP  11
21200 kHz TxGain HP  05
24930 kHz TxGain HP  03
29000 kHz TxGain HP  08
52000 kHz TxGain HP  04

Ramón E. Tristani Sr.
ramon.tristani at icloud.com <mailto:ramon.tristani at icloud.com>
https://www.flickr.com/photos/nq9v/ <https://www.flickr.com/photos/nq9v/>
www.tristaniministries.org <http://www.tristaniministries.org/>
www.tristaniphotography.com <http://www.tristaniphotography.com/>
> On May 6, 2016, at 5:10 PM, Ramon Tristani <r.tristani at gmail.com> wrote:
> 
> Yes, I performed tests with and without the ATU in the circuit. Howard, from Elecraft Support contacted me off the list and requested information that I just sent to him. 
> 
> Thank you,
> Ramon, NQ9V
> 
> 
> Ramón E. Tristani Sr.
> ramon.tristani at icloud.com <mailto:ramon.tristani at icloud.com>
> https://www.flickr.com/photos/nq9v/ <https://www.flickr.com/photos/nq9v/>
> www.tristaniministries.org <http://www.tristaniministries.org/>
> www.tristaniphotography.com <http://www.tristaniphotography.com/>
>> On May 6, 2016, at 3:06 PM, Eric Swartz - WA6HHQ, Elecraft <eric at elecraft.com <mailto:eric at elecraft.com>> wrote:
>> 
>> Is the K3 ATU in bypass?
>> 
>> Eric
>> elecraft.com <http://elecraft.com/>
>> 
>> On 5/6/2016 11:26 AM, Don Wilhelm wrote:
>>> Ramon, 
>>> 
>>> There is a calibration procedure in the manual to calibrate the wattmeter for forward power, but not for SWR. 
>>> I suggest you contact K3support for further assistance. 
>>> 
>>> 73, 
>>> Don W3FPR 
>>> 
>>> On 5/6/2016 11:50 AM, Ramon Tristani wrote: 
>>>> The VSWR indication in my K3 seems to be off considerably when connected to a 50 ohm dummy load. An external VSWR meter indicates 1:1 while the K3 most of the time indicates readings varying up to 2:1 at times. I am using the same short coax stub to connect the instruments one at a time to eliminate other possibilities. Is there a way to “calibrate” the VSWR indicator in the K3? My K3 is serial number 4416. The Auto Tuner in it works fine and reduces the indication to 1:1 as it is supposed to but when bypassing it the VSWR indication will always be off. Any suggestions? 
>>>> 
>>> 
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>> 
> 