K3: Strange SWR reading
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Dear Dick,
I posted this problem on the reflector some time back, but noone picked up on it, so I'll try again. This is a before and after story and has me puzzled. BEFORE: I connected DL1 dummy load to Ant 1 using only a BNC-MtoM and a PL259-FtoF (no coax at all, just small straight-through adapters). I set the KAT3 to BYPASS. I pressed TUNE and saw 1.0, on all bands. Fine, this is what I expect. Also, using my link-coupled external tuner with the antenna connected (I seldom use the KAT3), I was able to adjust to 1.0 on all bands (except 6 meters). AFTER: After the first time I ran the "Calibrate Transmitter Gain" routine from the Elecraft K3 Utility, I pressed TUNE with the DL1 still connected and saw a SWR reading of 1.1 on all bands, not 1.0 as before. Also, when I use my external tuner, the lowest SWR I can obtain now is 1.1, not 1.0 as before. WHY? I just upgraded the K3 (#1741) with all current mods and the new DSP board. So, I re-calibrated everything. Same result re the 1.1 SWR reading. Here is what happens: I attach the DL1 and set KAT3 to BYPASS as per the instructions. I run through the steps and click on Calibrate in the 5 Watt page. The calibration routine runs to completion successfully. At every frequency I see on the K3 front panel readout the following two-step sequence: - The frequency to be used - The numbers 1.1 which quickly change to 1.0 It seems as if the software is adjusting something to get to 1.0 for the SWR. What? I don't hear any clicks so doubt it is adjusting any toroids or capacitors the ATU. Maybe it is adjusting the final transistor bias? After this calibration, pressing TUNE with the DL1 still connected and the KAT3 still in BYPASS, I see 1.1 SWR. I then did the routine again, but this time doing the 5 watt and then the 50 Watt Calibration (the DL1 doesn't get very hot due to the short duty cycle). At 5 Watts, the result is the same as above. At 50 Watts, I see the following for each frequency step: - The frequency to be used - The number 1.0 This time it doesn't seem to be adjusting anything. Maybe that was already done at 5 Watts? It just starts out at 1.0 and stays there. After this calibration, pressing TUNE with the DL1 still connected and the KAT3 still in BYPASS, I see 1.1 SWR. So, what is going on? It seems to me that if I adjust the transmitter using DL1 as the reference for 1.0 SWR, then pressing TUNE with the DL1 attached and KAT3 still in BYPASS should also give 1.0. So, two question: (1) What is the software adjusting that affects the SWR shown on the K3 front panel display? (2) Why is the end result a lowest SWR of 1.1 instead of 1.0? Thanks for any information. Oliver Johns W6ODJ PS: Configuration information: K3 #1741, KPA3, KAT3, KBPF3, KTCXO3-1, KXV3, K3DSPUPGD upgrade, REMIOUPGD upgrade, all Elecraft-recommended user mods up to 1 Jan 2010 done, and no other mods done. No KRX3. No KXV3A upgrade. ______________________________________________________________ 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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Gents,
Problem solved, or at least worked around. I had the TUNE PWR set to 4 Watts. But my K3 SWR reading is inaccurate below 5 Watts. I set TUNE PWR to 7 Watts and now the problem is solved. With the DL1 connected to Ant 1, and KAT3 on BYPASS, pressing TUNE now gives 1.0 on all bands. Here are the readings at various powers with my K3 in the 40 meter band: 1 Watt ---> no reading 2 Watt ---> 1.2 3 Watt ---> 1.1 4 Watt ---> 1.1 5 Watt ---> 1.0 6 Watt and above ---> 1.0 73, Oliver Johns W6ODJ P.S. The reason the Elecraft K3 Utility seemed to be adjusting the SWR reading was that it was ramping up the power to 5 Watts. As it passed 3 and 4 Watts, it showed 1.1; when it reached 5 Watts it showed 1.0. On 5 Jan 2010, at 5:23 PM, O. Johns wrote: > Dear Dick, > > I posted this problem on the reflector some time back, but noone picked up on it, so I'll try again. This is a before and after story and has me puzzled. > > BEFORE: I connected DL1 dummy load to Ant 1 using only a BNC-MtoM and a PL259-FtoF (no coax at all, just small straight-through adapters). I set the KAT3 to BYPASS. I pressed TUNE and saw 1.0, on all bands. Fine, this is what I expect. Also, using my link-coupled external tuner with the antenna connected (I seldom use the KAT3), I was able to adjust to 1.0 on all bands (except 6 meters). > > AFTER: After the first time I ran the "Calibrate Transmitter Gain" routine from the Elecraft K3 Utility, I pressed TUNE with the DL1 still connected and saw a SWR reading of 1.1 on all bands, not 1.0 as before. Also, when I use my external tuner, the lowest SWR I can obtain now is 1.1, not 1.0 as before. > > WHY? > > I just upgraded the K3 (#1741) with all current mods and the new DSP board. So, I re-calibrated everything. Same result re the 1.1 SWR reading. > > Here is what happens: > > I attach the DL1 and set KAT3 to BYPASS as per the instructions. I run through the steps and click on Calibrate in the 5 Watt page. The calibration routine runs to completion successfully. At every frequency I see on the K3 front panel readout the following two-step sequence: > - The frequency to be used > - The numbers 1.1 which quickly change to 1.0 > It seems as if the software is adjusting something to get to 1.0 for the SWR. What? I don't hear any clicks so doubt it is adjusting any toroids or capacitors the ATU. Maybe it is adjusting the final transistor bias? > > After this calibration, pressing TUNE with the DL1 still connected and the KAT3 still in BYPASS, I see 1.1 SWR. > > I then did the routine again, but this time doing the 5 watt and then the 50 Watt Calibration (the DL1 doesn't get very hot due to the short duty cycle). At 5 Watts, the result is the same as above. At 50 Watts, I see the following for each frequency step: > - The frequency to be used > - The number 1.0 > This time it doesn't seem to be adjusting anything. Maybe that was already done at 5 Watts? It just starts out at 1.0 and stays there. > > After this calibration, pressing TUNE with the DL1 still connected and the KAT3 still in BYPASS, I see 1.1 SWR. > > So, what is going on? It seems to me that if I adjust the transmitter using DL1 as the reference for 1.0 SWR, then pressing TUNE with the DL1 attached and KAT3 still in BYPASS should also give 1.0. > > So, two question: > (1) What is the software adjusting that affects the SWR shown on the K3 front panel display? > (2) Why is the end result a lowest SWR of 1.1 instead of 1.0? > > Thanks for any information. > > Oliver Johns > W6ODJ > > PS: Configuration information: > K3 #1741, KPA3, KAT3, KBPF3, KTCXO3-1, KXV3, K3DSPUPGD upgrade, REMIOUPGD upgrade, all Elecraft-recommended user mods up to 1 Jan 2010 done, and no other mods done. No KRX3. No KXV3A upgrade. > > > > > ______________________________________________________________ > 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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Tnx Dick,
Then I guess it is the K3 MCU firmware code that is "ramping up the power" because I see it doing it on the K3 front panel display as the Calibrate routine is running. It approaches 5 Watts from below, takes a fraction of a second to get there. Until it gets there, the SWR reading on the K3 screen is 1.1. When it does get there (e.g., to 5 Watts), the SWR reading changes to 1.0. Then the K3 stays in transmit for about a second or two before moving on to the next frequency. At 50 Watts, the ramp-up time (if any) is so quick that it doesn't have time to show up on the K3 front panel display. I guess I was thinking that the K3 Utility was doing more than it was doing. Thanks for the description. It must be a gas to write this stuff and have it work so well. Wish the code were public so we could admire it. 73, Oliver Johns W6ODJ On 6 Jan 2010, at 1:16 PM, Dick Dievendorff wrote: > The K3 Utility doesn't "ramp up the power" during the Tx Gain calibration. > It sets the power to exactly 5 watts, and the K3 MCU firmware code performs > calibration at that power level (and also at exactly 50 watts). > > Tx Calibration also sets TUN PWR to "Normal" and restores your setting > afterward. > > Glad it's working for you now! > > 73 d Dick, K6KR > > > -----Original Message----- > From: O. Johns [mailto:[hidden email]] > Sent: Wednesday, January 06, 2010 12:04 PM > To: Dick Dievendorff > Cc: Elecraft; Gary Surrency > Subject: Re: [Elecraft] K3: Strange SWR reading > > Gents, > > Problem solved, or at least worked around. > > I had the TUNE PWR set to 4 Watts. But my K3 SWR reading is inaccurate > below 5 Watts. I set TUNE PWR to 7 Watts and now the problem is solved. > With the DL1 connected to Ant 1, and KAT3 on BYPASS, pressing TUNE now gives > 1.0 on all bands. > > Here are the readings at various powers with my K3 in the 40 meter band: > 1 Watt ---> no reading > 2 Watt ---> 1.2 > 3 Watt ---> 1.1 > 4 Watt ---> 1.1 > 5 Watt ---> 1.0 > 6 Watt and above ---> 1.0 > > 73, > > Oliver Johns > W6ODJ > > P.S. The reason the Elecraft K3 Utility seemed to be adjusting the SWR > reading was that it was ramping up the power to 5 Watts. As it passed 3 and > 4 Watts, it showed 1.1; when it reached 5 Watts it showed 1.0. > > > On 5 Jan 2010, at 5:23 PM, O. Johns wrote: > >> Dear Dick, >> >> I posted this problem on the reflector some time back, but noone picked up > on it, so I'll try again. This is a before and after story and has me > puzzled. >> >> BEFORE: I connected DL1 dummy load to Ant 1 using only a BNC-MtoM and a > PL259-FtoF (no coax at all, just small straight-through adapters). I set > the KAT3 to BYPASS. I pressed TUNE and saw 1.0, on all bands. Fine, this > is what I expect. Also, using my link-coupled external tuner with the > antenna connected (I seldom use the KAT3), I was able to adjust to 1.0 on > all bands (except 6 meters). >> >> AFTER: After the first time I ran the "Calibrate Transmitter Gain" > routine from the Elecraft K3 Utility, I pressed TUNE with the DL1 still > connected and saw a SWR reading of 1.1 on all bands, not 1.0 as before. > Also, when I use my external tuner, the lowest SWR I can obtain now is 1.1, > not 1.0 as before. >> >> WHY? >> >> I just upgraded the K3 (#1741) with all current mods and the new DSP > board. So, I re-calibrated everything. Same result re the 1.1 SWR reading. > >> >> Here is what happens: >> >> I attach the DL1 and set KAT3 to BYPASS as per the instructions. I run > through the steps and click on Calibrate in the 5 Watt page. The > calibration routine runs to completion successfully. At every frequency I > see on the K3 front panel readout the following two-step sequence: >> - The frequency to be used >> - The numbers 1.1 which quickly change to 1.0 >> It seems as if the software is adjusting something to get to 1.0 for the > SWR. What? I don't hear any clicks so doubt it is adjusting any toroids or > capacitors the ATU. Maybe it is adjusting the final transistor bias? >> >> After this calibration, pressing TUNE with the DL1 still connected and the > KAT3 still in BYPASS, I see 1.1 SWR. >> >> I then did the routine again, but this time doing the 5 watt and then the > 50 Watt Calibration (the DL1 doesn't get very hot due to the short duty > cycle). At 5 Watts, the result is the same as above. At 50 Watts, I see > the following for each frequency step: >> - The frequency to be used >> - The number 1.0 >> This time it doesn't seem to be adjusting anything. Maybe that was > already done at 5 Watts? It just starts out at 1.0 and stays there. >> >> After this calibration, pressing TUNE with the DL1 still connected and the > KAT3 still in BYPASS, I see 1.1 SWR. >> >> So, what is going on? It seems to me that if I adjust the transmitter > using DL1 as the reference for 1.0 SWR, then pressing TUNE with the DL1 > attached and KAT3 still in BYPASS should also give 1.0. >> >> So, two question: >> (1) What is the software adjusting that affects the SWR shown on the K3 > front panel display? >> (2) Why is the end result a lowest SWR of 1.1 instead of 1.0? >> >> Thanks for any information. >> >> Oliver Johns >> W6ODJ >> >> PS: Configuration information: >> K3 #1741, KPA3, KAT3, KBPF3, KTCXO3-1, KXV3, K3DSPUPGD upgrade, REMIOUPGD > upgrade, all Elecraft-recommended user mods up to 1 Jan 2010 done, and no > other mods done. No KRX3. No KXV3A upgrade. >> >> >> >> >> ______________________________________________________________ >> 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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