KPA500 - SWR into K3
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In 10m contest [CW], I'm seeing 2:1 SWR on the K3 display feeding the
KPA500. SWR from the antenna to KPA500 is 1.1:1. Is this normal? 73, Fred K6DGW - Northern California Contest Club - CU in the 2013 Cal QSO Party 5-6 Oct 2013 - www.cqp.org ______________________________________________________________ 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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Fred,
Yes I have. To correct this reading, I activated the K3 ATU and tuned, I then went to Bypass on the KAT3 and all returned to 1.1:1 See if this works in your setup. Gary On 9 December 2012 09:18, Fred Jensen <[hidden email]> wrote: > In 10m contest [CW], I'm seeing 2:1 SWR on the K3 display feeding the > KPA500. SWR from the antenna to KPA500 is 1.1:1. Is this normal? > > 73, > > Fred K6DGW > - Northern California Contest Club > - CU in the 2013 Cal QSO Party 5-6 Oct 2013 > - www.cqp.org > > ______________________________**______________________________**__ > Elecraft mailing list > Home: http://mailman.qth.net/**mailman/listinfo/elecraft<http://mailman.qth.net/mailman/listinfo/elecraft> > Help: http://mailman.qth.net/mmfaq.**htm<http://mailman.qth.net/mmfaq.htm> > Post: mailto:[hidden email].**net <[hidden email]> > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > -- *Gary - VK1ZZ Motorhome Portable The Shack* *Elecraft K3 P3 Panadapter KPA500FT KAT500FT** KX3-K * ______________________________________________________________ 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 k6dgw
I have observed some different SWR readings on 10 and 6 meters with
relatively small differences in cable lengths between rig, amp, and ATU. My K3 works better on 30 meters when I engage the K3's ATU. The K3 is measuring the SWR it sees (the input to the amp or the ATU, depending on the amp key line), and the KPA500 is measuring what it sees (the input to the ATU) and the KAT500 is measuring what it sees (the antenna system and the ATU's L and C), and they're all at slightly different points in the path with cables of varying lengths between. 73 de Dick, K6KR -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Ron D'Eau Claire Sent: Saturday, December 08, 2012 4:01 PM To: [hidden email]; 'Elecraft Reflector' Subject: Re: [Elecraft] KPA500 - SWR into K3 Fred, my K3 reports 1.7:1 into the KPA500 on 10 meters. 6 meters and 12 meters are both 1.4:1. All other bands are 1.1:1 or better. That's with the K3's internal tuner in bypass of course. 73 Ron AC7AC -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Fred Jensen Sent: Saturday, December 08, 2012 2:18 PM To: Elecraft Reflector Subject: [Elecraft] KPA500 - SWR into K3 In 10m contest [CW], I'm seeing 2:1 SWR on the K3 display feeding the KPA500. SWR from the antenna to KPA500 is 1.1:1. Is this normal? 73, Fred K6DGW - Northern California Contest Club - CU in the 2013 Cal QSO Party 5-6 Oct 2013 - www.cqp.org ______________________________________________________________ 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 ______________________________________________________________ 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 k6dgw
Ron, maybe you saw the reply from Gary, VK1ZZ? His fix worked, I don't
know why however. I have the KAT3 in bypass on all bands right now since getting the KAT500. I thought that meant the K3 was connected straight thru to the KPA500 input circuit so it should see a fairly low SWR. It usually runs around 1.1 or so. So Gary's advice was, 1) Put the KAT3 into AUTO; 2) Tap ATU TUNE on the K3; 3) Hold ATU TUNE until the KAT3 goes into BYPASS. When I did this, I think something also happened in the KAT500, although I'm not totally sure where the noise came from nor do I understand why it should have done anything. The SWR on the K3 was now 1:1, but the SWR on the KPA500 was now high. Retuning the KAT500 made it 1:1. As I said, I can't explain this with the model I have in my head, time for a new model I guess. And, thanks again to Alan for the monochrome waterfall option on the P3. I can see signals I can't really hear initially, but when I get on them, I can then use the APF much more effectively and I've picked up several mults today. 10m is way above El Stinko today, but still fairly puny. 73, Fred K6DGW - Northern California Contest Club - CU in the 2013 Cal QSO Party 5-6 Oct 2013 - www.cqp.org On 12/8/2012 4:01 PM, Ron D'Eau Claire wrote: > Fred, my K3 reports 1.7:1 into the KPA500 on 10 meters. 6 meters and 12 > meters are both 1.4:1. All other bands are 1.1:1 or better. > > That's with the K3's internal tuner in bypass of course. ______________________________________________________________ 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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On 12/8/2012 7:57 PM, Ron D'Eau Claire wrote:
> Well, putting the KAT3 in operation will "correct' whatever is causing the > high VSWR in the KPA500 by providing a conjugate match, but when the KPA500 > is in Standby it passes the K3 output through to the KAT500. Now the input > to the KAT500 is no longer the same value it was with the KAT3 bypassed so > it needs to retune too. Too many K's, P's, T's and A's. :-) Let's start over. 1. Original config on *all* bands was: KAT3=BYPASS, KPA500=OPER, KAT500=tuned [all segments, all bands, all applicable antennae for each band]. 2. In original config, SWR seen by K3=1.1:1 max, often 1:1. SWR seen by KPA500=whatever the KAT500 could produce, always below 1.5:1. All this is as expected. 3. Still in original config, I started ARRL 10 CW and after awhile noticed K3 SWR=1.5:1 and wondered if something had gone south in the KPA500 input circuit. Note: KAT3 is still in bypass, SWR seen by KPA500 is still 1.1:1 where it was when I started on 10M. 4. Posted a question to the list, Gary offered: "Put KAT3 in AUTO, do ATU TUNE on the K3, put KAT3 back in BYPASS. When I did this, three things happened: a) I heard the KAT3 tune, and I heard a quick relay noise from the KAT500 [not the amp], as if it *too* was adjusting. b) The SWR seen by the K3 went to 1:1 c) The SWR seen by the KPA500 was now off scale, and it faulted. 5. I then did a TUNE cycle on the KAT500, and SWR seen by KPA500 went back to 1.1:1 where it had been. SWR seen by the K3 [i.e. looking into the KPA500] remained 1:1. <digression>When I did all of the above, I was somewhere between 28000 and 28050. It was late afternoon Sat, contest activity was waning, and I ended the day without going above 28050. This AM, there was contest activity up to about 28075 or so. The first time I tried transmitting in that segment, I had to do a TUNE cycle on the KAT500, which is even more puzzling since I had already done it in that segment and the KAT500 had memorized it.</digression> I understand your reply, that's not what puzzles me: -- With KAT3 in BYPASS, is the K3 not looking directly into the input impedance of the KPA500? SWR seen by K3 should be 1:1 [or very close]. It wasn't, that's what started this puzzle in the first place. -- Obviously, I can use the KAT3 to minimize the SWR seen by the K3 ... shouldn't have to but I can. And yes, that has side effects should I go to low power with KPA500 in STBY. Remember though, after doing the ATU TUNE on the K3, *the KAT3 went back to BYPASS*. -- If "BYPASS" on the KAT3 really means what it says, the sequence: "KAT3 AUTO, ATU TUNE [on K3], KAT3 BYPASS" should do nothing to the original issue ... 1.5:1 seen by the K3 ... but it did, just like Gary said it would. -- Regardless however, messing with the load seen by the K3 should not affect the load provided to the KPA500 by the KAT500, but it seems it did. -- Why would doing ATU TUNE [on K3 feeding the amp] cause the KAT500 to do anything? I've checked all the K's, P's, T's, and A's in the above and I'm convinced I got them all right. You have to read carefully. :-)) I haven't figured out how to repeat the issue since I don't know how to get the KAT3 back to whatever it was doing in BYPASS when this all started. 73, Fred K6DGW - Northern California Contest Club - CU in the 2013 Cal QSO Party 5-6 Oct 2013 - www.cqp.org ______________________________________________________________ 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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Fred,
You logic is correct *except* for 2 things. First, the KAT3 BYPASS switches in elements to make the output 50 ohms. That compensates for residual reactance in the tuner itself (relay paths etc.) - so it is not a direct path from in to out. Secondly, the K3 SWR indication is at the input to the KAT3 - so if the KAT3 gets "mixed up" and somehow loses its memory for the inductors and capacitors to use for the BYPASS condition. the SWR indication will go up even though there is a good 50 ohm load on the output. 73, Don W3FPR On 12/9/2012 4:48 PM, Fred Jensen wrote: > On 12/8/2012 7:57 PM, Ron D'Eau Claire wrote: >> Well, putting the KAT3 in operation will "correct' whatever is >> causing the >> high VSWR in the KPA500 by providing a conjugate match, but when the >> KPA500 >> is in Standby it passes the K3 output through to the KAT500. Now the >> input >> to the KAT500 is no longer the same value it was with the KAT3 >> bypassed so >> it needs to retune too. > > Too many K's, P's, T's and A's. :-) Let's start over. > > 1. Original config on *all* bands was: KAT3=BYPASS, KPA500=OPER, > KAT500=tuned [all segments, all bands, all applicable antennae for > each band]. > > 2. In original config, SWR seen by K3=1.1:1 max, often 1:1. SWR seen > by KPA500=whatever the KAT500 could produce, always below 1.5:1. All > this is as expected. > > 3. Still in original config, I started ARRL 10 CW and after awhile > noticed K3 SWR=1.5:1 and wondered if something had gone south in the > KPA500 input circuit. Note: KAT3 is still in bypass, SWR seen by > KPA500 is still 1.1:1 where it was when I started on 10M. > > 4. Posted a question to the list, Gary offered: "Put KAT3 in AUTO, do > ATU TUNE on the K3, put KAT3 back in BYPASS. When I did this, three > things happened: > > a) I heard the KAT3 tune, and I heard a quick relay noise from the > KAT500 [not the amp], as if it *too* was adjusting. > > b) The SWR seen by the K3 went to 1:1 > > c) The SWR seen by the KPA500 was now off scale, and it faulted. > > 5. I then did a TUNE cycle on the KAT500, and SWR seen by KPA500 went > back to 1.1:1 where it had been. SWR seen by the K3 [i.e. looking > into the KPA500] remained 1:1. > > <digression>When I did all of the above, I was somewhere between 28000 > and 28050. It was late afternoon Sat, contest activity was waning, > and I ended the day without going above 28050. This AM, there was > contest activity up to about 28075 or so. The first time I tried > transmitting in that segment, I had to do a TUNE cycle on the KAT500, > which is even more puzzling since I had already done it in that > segment and the KAT500 had memorized it.</digression> > > I understand your reply, that's not what puzzles me: > > -- With KAT3 in BYPASS, is the K3 not looking directly into the input > impedance of the KPA500? SWR seen by K3 should be 1:1 [or very > close]. It wasn't, that's what started this puzzle in the first place. > > -- Obviously, I can use the KAT3 to minimize the SWR seen by the K3 > ... shouldn't have to but I can. And yes, that has side effects > should I go to low power with KPA500 in STBY. Remember though, after > doing the ATU TUNE on the K3, *the KAT3 went back to BYPASS*. > > -- If "BYPASS" on the KAT3 really means what it says, the sequence: > "KAT3 AUTO, ATU TUNE [on K3], KAT3 BYPASS" should do nothing to the > original issue ... 1.5:1 seen by the K3 ... but it did, just like Gary > said it would. > > -- Regardless however, messing with the load seen by the K3 should not > affect the load provided to the KPA500 by the KAT500, but it seems it > did. > > -- Why would doing ATU TUNE [on K3 feeding the amp] cause the KAT500 > to do anything? > > I've checked all the K's, P's, T's, and A's in the above and I'm > convinced I got them all right. You have to read carefully. :-)) > > I haven't figured out how to repeat the issue since I don't know how > to get the KAT3 back to whatever it was doing in BYPASS when this all > started. > > 73, > > Fred K6DGW > - Northern California Contest Club > - CU in the 2013 Cal QSO Party 5-6 Oct 2013 > - www.cqp.org > > > ______________________________________________________________ > 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 > ______________________________________________________________ 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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