K3 internal SWR meter
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Hello all,
this weekend I tested my new K3 transceiver received last week. TRX is a factory build version with 100 watt, KAT3 tuner, KXV3A and KDVR3. I use a Elecraft MH-2 microphone. While testing I recognized strange internal SWR meter behavior during SSB operation. The internal SWR bar meter shows wrong SWR if KAT3 is set to bypass. It shows spikes up to SWR 1:3 but my real SWR is about 1:1.5. only. If I press tune button correct SWR is shown on SWR bar meter and in digits on display. Also in CW mode correct values are shown. I am afraid K3 will drop SSB power if SWR bar meter shows SWR of 3. Is this a known issue ? Regards Joerg (DL3QQ) ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Jorg,
You said the SWR meter "spikes" up to and SWR of 3. I suspect that is simply an 'artifact' of the sampling of forward and reverse power combined with the varying characteristics of the SSB RF envelope. This is just a guess on my part, you will have to wait for a response from someone who knows the firmware sampling of the power and whether or not any averaging of SWR is done prior to displaying the value. The forward power and reverse power cannot be both recorded at the same instant in time - the times are close together, but due to digital sampling of the values, they cannot occur at the same time. If the RF voltage when the forward power was sampled was at as low point, and then, due to speech irregularities, when the reverse power was sampled, the RF output was higher, then the calculation of SWR would be higher than the actual SWR. Similarly, the indicated SWR could at other instances be less than actual. I also believe the K3 takes several samples before deciding that the SWR is high enough to reduce the power. 73, Don W3FPR On 9/22/2013 3:17 PM, Jörg Rüschenschmidt wrote: > this weekend I tested my new K3 transceiver received last week. TRX is a > factory build version with 100 watt, KAT3 tuner, KXV3A and KDVR3. I use a > Elecraft MH-2 microphone. While testing I recognized strange internal SWR > meter behavior during SSB operation. The internal SWR bar meter shows wrong > SWR if KAT3 is set to bypass. It shows spikes up to SWR 1:3 but my real SWR > is about 1:1.5. only. If I press tune button correct SWR is shown on SWR bar > meter and in digits on display. Also in CW mode correct values are shown. I > am afraid K3 will drop SSB power if SWR bar meter shows SWR of 3. > > > > Is this a known issue ? > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 internal SWR meter
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Don,
As always you hit the nail the first time right :-) In 2012 I built my own SWR meter with a microcontroller readout for Pwr and SWR. This was one thing i had to fix in the software. 73 Arie PA3A Op 22-9-2013 21:36, Don Wilhelm schreef: > Jorg, > > You said the SWR meter "spikes" up to and SWR of 3. I suspect that is > simply an 'artifact' of the sampling of forward and reverse power > combined with the varying characteristics of the SSB RF envelope. > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Jörg Rüschenschmidt
Joerg,
FWIW, I do not have the KAT3 yet, and I have no SWR troubles with the meter. Also FWIW, I wonder how your meter will behave into a known good dummy load? Dick,n0ce ----- Original Message ----- From: "Jörg Rüschenschmidt" <[hidden email]> To: [hidden email] Sent: Sunday, September 22, 2013 2:17:12 PM Subject: [Elecraft] K3 internal SWR meter Hello all, this weekend I tested my new K3 transceiver received last week. TRX is a factory build version with 100 watt, KAT3 tuner, KXV3A and KDVR3. I use a Elecraft MH-2 microphone. While testing I recognized strange internal SWR meter behavior during SSB operation. The internal SWR bar meter shows wrong SWR if KAT3 is set to bypass. It shows spikes up to SWR 1:3 but my real SWR is about 1:1.5. only. If I press tune button correct SWR is shown on SWR bar meter and in digits on display. Also in CW mode correct values are shown. I am afraid K3 will drop SSB power if SWR bar meter shows SWR of 3. Is this a known issue ? Regards … Joerg (DL3QQ) ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 internal SWR meter
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Richard,
If I use a dummy load or perfect tuned antenna (SWR 1:1.1) the problem is not recognized. I think SWR measurement will done in KAT3 if this unit is installed, even in bypass mode. Maybe this issue is related to users with KAT3 only. Don, W3FPR assumes it could be a software problem. Let's wait for someone who knows how SWR measurement is done in K3 firmware. 73 de Joerg (DL3QQ) -----Ursprüngliche Nachricht----- Von: Richard Fjeld [mailto:[hidden email]] Gesendet: Montag, 23. September 2013 18:54 An: Jörg Rüschenschmidt Cc: [hidden email] Betreff: Re: [Elecraft] K3 internal SWR meter Joerg, FWIW, I do not have the KAT3 yet, and I have no SWR troubles with the meter. Also FWIW, I wonder how your meter will behave into a known good dummy load? Dick,n0ce ----- Original Message ----- From: "Jörg Rüschenschmidt" <[hidden email]> To: [hidden email] Sent: Sunday, September 22, 2013 2:17:12 PM Subject: [Elecraft] K3 internal SWR meter Hello all, this weekend I tested my new K3 transceiver received last week. TRX is a factory build version with 100 watt, KAT3 tuner, KXV3A and KDVR3. I use a Elecraft MH-2 microphone. While testing I recognized strange internal SWR meter behavior during SSB operation. The internal SWR bar meter shows wrong SWR if KAT3 is set to bypass. It shows spikes up to SWR 1:3 but my real SWR is about 1:1.5. only. If I press tune button correct SWR is shown on SWR bar meter and in digits on display. Also in CW mode correct values are shown. I am afraid K3 will drop SSB power if SWR bar meter shows SWR of 3. Is this a known issue ? Regards … Joerg (DL3QQ) ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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"Let's wait for someone who knows how SWR measurement is done in K3 firmware."
I'll add that I asked because I chased a similar problem before I got my K3. Two pieces of good test equipment found no trouble. But the lash-up I was using caused trouble when power was applied. 73, Dick, n0ce ----- Original Message ----- From: "Jörg Rüschenschmidt" <[hidden email]> To: "Richard Fjeld " <[hidden email]> Cc: [hidden email] Sent: Monday, September 23, 2013 2:30:33 PM Subject: AW: [Elecraft] K3 internal SWR meter Richard, If I use a dummy load or perfect tuned antenna (SWR 1:1.1) the problem is not recognized. I think SWR measurement will done in KAT3 if this unit is installed, even in bypass mode. Maybe this issue is related to users with KAT3 only. Don, W3FPR assumes it could be a software problem. Let's wait for someone who knows how SWR measurement is done in K3 firmware. 73 de Joerg (DL3QQ) ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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