[Elecraft] KX3 atu anomalies - or it is me.

Wed Sep 19 00:47:31 EDT 2012

Thank you Matt,

> By "SWR graph", you mean the bar graph on the display of the KX3, right? If so, are you sure it is set to measure VSWR rather than compression? 
No, I read it on the SWR of course.
> 
> If you have initiated a tuning cycle with the KXAT3, and subsequently hold the XMIT/TUNE button, and the radio reports a VSWR of 1.4, then this means that the KXAT3 has not matched the impedance of the antenna system. This would be the case, for example, is the KXAT3 was set in bypass mode.
It is not on bypass mode.
> 
> As Don notes below, if you put an SWR meter between the KX3 and the antenna, then the KXAT3 will have no effect whatsoever on the reading of this meter (after all, the KXAT3 is matching the impedance between the antenna system and the PA stage inside the KX3, and has no effect all on the VSWR on the section of transmission line between the KXAT3 and the antenna).
I don't own an external swr meter so no, I didn't read between the radio and the antenna.
> 
> If the SWR graph in your KX3 is set to read VSWR, and the KXAT3 has matched the antenna ad reported a VSWR of 1.0, and you see the SWR graph jumping around during transmit, then this could indicate flashover in the KXAT3. Normally this should only happen if the antenna system is very far away from 50 ohms. This is not likely to be the case here, if you indeed measured the VSWR of the antenna system independently with the MFJ antenna analyser, and found it only to be 1.4:1.  

This seems to be the case. So is it normal or not? Any idea how to fix it?

Thanks again and I apologize for my English that apparently isn't good enough to explain what happened to me.

Cheers.

Luca
> 
> 73, Matt VK2ACL
> 
> 
> 
> On 19/09/2012, at 12:36 PM, luca de marinis <surfshot at gmail.com> wrote:
> 
>> Hi Don, I read the 1.4 SWR on my MFJ 259b then tuned with the KX3 atu to 1.0
>> 
>> On transmitting the swr graph showed peaks near to 2 and if I press the XMIT (tune) the reading is about 1.4 same as without ATU.
>> 
>> Luca
>> 
>> 
>> 
>> 
>> On Sep 18, 2012, at 7:12 PM, Don Wilhelm <w3fpr at embarqmail.com> wrote:
>> 
>>> Lucia,
>>> 
>>> You say that you had an SWR of 1.4, then used the ATU which lowered the 
>>> SWR to 1.0
>>> OK, That was on the KX3 display.
>>> 
>>> Please tell us where you were reading the continued 1.4 SWR.  The KX3 
>>> display does not show the SWR during transmit - only during a TUNE.
>>> The SWR shown externally to the KX2 ATU will not change, so if you are 
>>> using an external device, you will not see any  change in the SWR reading.
>>> 
>>> The KX3 ATU will reduce the SWR between the KX3 output PA and the input 
>>> to the KXATU3 to the value shown during on the KX3 display during a 
>>> TUNE, but the SWR between the KXATU3 and the antenna (as measured by an 
>>> external device) will not change.
>>> 
>>> 73,
>>> Don W3FPR
>>> 
>>> On 9/18/2012 8:14 PM, luca de marinis wrote:
>>>> Hi,
>>>> 
>>>> I completed my KX3 #1715 few days ago and today I went to the park and using a Buddipole I tried to make some contacts. Buddipole swr was 1.4 on 20m so I used the ATU. It worked fine lowered the swr to 1.0 but then I transmitted I still could read a 1.4 swr. I moved up and down the band and tuned again and every time the ATU started from 9.9 and did the all cycle. Sometime couldn't go lower than 1.4. Sometimes after tuning the power was reduced to 2W
>>>> 
>>>> Am I missing something. I did a search on the reflector but didn't show anything.
>>>> 
>>>> Thank you in advance for your help
>>>> 
>>>> 
>>> 
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