K3 power output problems
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On a new to me K3, I am having problems with power output below 15M. For
example the power output on 80 maxed out at 30 watts. (good swr etc., no alarms, voltage input is good etc.). So figured it was a TX gain issue so set up recalibrate it. The 5 W calibration goes fine on 160, but fails on 80 with the following dialog Starting 5 watt calibration Calibrating at 1.900 MHz Calibrating at 3.750 MHz SWR 3.7-1 is too high for calibration Verify that a dummy load is attached to "AN2;" (and yes the dummy load was connected to AN2, I had previously tried it on AN1 with the same results.) If I then transmit manually, the SWR indicated is 1:1 and I can adjust power up to the same 30W indicated previously. So, the TX calibrate complains of high SWR, but manually cannot replicate it. Any ideas (really, really) welcome. Unit does have the AntTuner which is set to bypass (and it looks like the calibrate routine also does this.) Mark n2qt ______________________________________________________________ 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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one more bit of info.
If I use the tuner into 50 ohms it finds a match but when I manually transmit the swr through the tuner is high, for example 4.4:1 on 40. Bypassing the tuner gives the 1:1 expected with the dummy load, although at 30 some watts. I really think there is a floating cable ground somewhere in there. Mark n2qt -----Original Message----- From: Mark n2qt Sent: Saturday, September 22, 2012 1:44 PM To: [hidden email] Subject: [Elecraft] K3 power output problems On a new to me K3, I am having problems with power output below 15M. For example the power output on 80 maxed out at 30 watts. (good swr etc., no alarms, voltage input is good etc.). So figured it was a TX gain issue so set up recalibrate it. The 5 W calibration goes fine on 160, but fails on 80 with the following dialog Starting 5 watt calibration Calibrating at 1.900 MHz Calibrating at 3.750 MHz SWR 3.7-1 is too high for calibration Verify that a dummy load is attached to "AN2;" (and yes the dummy load was connected to AN2, I had previously tried it on AN1 with the same results.) If I then transmit manually, the SWR indicated is 1:1 and I can adjust power up to the same 30W indicated previously. So, the TX calibrate complains of high SWR, but manually cannot replicate it. Any ideas (really, really) welcome. Unit does have the AntTuner which is set to bypass (and it looks like the calibrate routine also does this.) Mark n2qt ______________________________________________________________ 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 Mark n2qt
thanks for the suggestion John. I tried it but it didn't allow calibration
to occur. However I noticed that after the ATU tuned the 50 ohm load the rig showed high SWR (4.1:1 or so) when I manually keyed it. Also on the bands the power output it good, the Current drawn is shown as 2.3 Amps, which would be pretty spectacular. I did confirm the ~100W output power on a W2 wattmeter. So something is definitely up Mark n2qt -----Original Message----- From: Dr John Farmer Sent: Saturday, September 22, 2012 2:01 PM To: Mark n2qt Subject: Re: [Elecraft] K3 power output problems Hi Mark, Just read your posting. I had some quirky things happen with my K3 with the tuner in Bypass mode. I needed to "set" the bypass LC settings in the tuner to remedy them. Try the following: Switch back to ANT 1. Attach 50 ohm dummy load to ANT 1. Engage the ATU Tune the ATU in to the dummy load on every band sequentially from 160 to 6m Put ATU back into bypass mode and then retry the tx gain calibration routine. Hope that helps. 73 John VK7JB Sent from my iPhone On 23/09/2012, at 3:44, "Mark n2qt" <[hidden email]> wrote: > On a new to me K3, I am having problems with power output below 15M. For > example > the power output on 80 maxed out at 30 watts. (good swr etc., no alarms, > voltage input > is good etc.). > > So figured it was a TX gain issue so set up recalibrate it. The 5 W > calibration goes fine > on 160, but fails on 80 with the following dialog > > Starting 5 watt calibration > Calibrating at 1.900 MHz > Calibrating at 3.750 MHz > SWR 3.7-1 is too high for calibration > Verify that a dummy load is attached to "AN2;" > > (and yes the dummy load was connected to AN2, I had previously tried it > on > AN1 with the > same results.) > > If I then transmit manually, the SWR indicated is 1:1 and I can adjust > power > up to the same > 30W indicated previously. > > So, the TX calibrate complains of high SWR, but manually cannot replicate > it. > > Any ideas (really, really) welcome. > > Unit does have the AntTuner which is set to bypass (and it looks like the > calibrate routine also > does this.) > > Mark n2qt > > > ______________________________________________________________ > 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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Mark,
There is one possibility of a loose connection in the ground path for the antenna connectors. At the upper right-rear corner of the K3 there is a 2D connector, a long screw and a standoff is fastened to the threads of that long screw. The tightness of that standoff is important to the ground path to the antenna connectors. See page 22 of the K3 Assembly manual. To tighten the standoff, you will have to first loosen the screw that goes into the inside end of that standoff, then tighten the standoff with pliers (or better yet, a 3/16 inch wrench). Once you have tightened the standoff against the 2D connector, you can tighten the screw again. I believe recent K3s are built with an enlarged hole in the 2D connector so the threads of the screw are not held captive by both the standoff and 2D connector. On 9/22/2012 5:14 PM, Mark n2qt wrote: > thanks for the suggestion John. I tried it but it didn't allow calibration > to occur. > However I noticed that after the ATU tuned the 50 ohm load the rig showed > high SWR (4.1:1 or so) when I manually keyed it. Also on the bands the > power output it good, the Current drawn is shown as 2.3 Amps, which would > be pretty spectacular. I did confirm the ~100W output power on a W2 > wattmeter. > > ______________________________________________________________ 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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Don Wilhelm wrote:
> >There is one possibility of a loose connection in the ground path for >the antenna connectors. > >At the upper right-rear corner of the K3 there is a 2D connector, a >long screw and a standoff is fastened to the threads of that long >screw. The tightness of that standoff is important to the ground path >to the antenna connectors. See page 22 of the K3 Assembly manual. > >To tighten the standoff, you will have to first loosen the screw that >goes into the inside end of that standoff, then tighten the standoff >with pliers (or better yet, a 3/16 inch wrench). Once you have >tightened the standoff against the 2D connector, you can tighten the >screw again. That slender pillar is the main return path for an ampere or more of RF current flowing between the KAT3 board and the rear panel sockets. As someone whose design instincts were developed at VHF, where all RF ground paths must be short, broad and direct, I didn't feel comfortable about that corner of the K3. Yes, we know that "it works" and "it's good enough for HF". But in these days of compulsory EMC testing and microscopically detailed product reviews, even HF designers are coming to realise that bending the rules for good RF grounding will eat into the margins of performance, spurious signal rejection and stability. RF grounding of the KAT3 board is also far too dependent on the tightness of the screws at each end of the pillar and the cleanness of all the contact surfaces. That ground return path can be much improved by connecting the mounting screw of J1 directly to the corner of the KAT3 board, using two solder tags that are overlapped and soldered directly together. My K3 doesn't necessarily work any better, but it does satisfy the instincts of an old VHF hound :-) -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek ______________________________________________________________ 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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As an update, (for all those following this thread with bated breath)
It looks like the problem of being unable to get full power out on the bands below 17M, and the inability to do a TXGain calibration, was due to some issue with the configuration of the ATU. I set ATU to not installed and then back to installed and power output came back up. In addition when the ATU is enabled and used to tune the 50 ohm load, the SWR after tuning is 1:1. (those who are following this will remember that originally tuning made the SWR worse). My idea of a loose connection appears to be wrong. Now, the remaining problem is that the Current Display does not indicate the current actually drawn. The display 'saturates' somewhere around 3 amps or so. (It appears to read sensibly up to that level, and then flattens out as power is turned up). I'll ask Elecraft Tech support for guidance on this one.... I'm hoping to use the rig in the upcoming CQWW, so if there anything amiss, it's sure to show up then. Mark n2qt -----Original Message----- From: Ian White GM3SEK Sent: Sunday, September 23, 2012 4:54 AM To: [hidden email] Subject: Re: [Elecraft] K3 power output problems Don Wilhelm wrote: > >There is one possibility of a loose connection in the ground path for >the antenna connectors. > >At the upper right-rear corner of the K3 there is a 2D connector, a >long screw and a standoff is fastened to the threads of that long >screw. The tightness of that standoff is important to the ground path >to the antenna connectors. See page 22 of the K3 Assembly manual. > >To tighten the standoff, you will have to first loosen the screw that >goes into the inside end of that standoff, then tighten the standoff >with pliers (or better yet, a 3/16 inch wrench). Once you have >tightened the standoff against the 2D connector, you can tighten the >screw again. That slender pillar is the main return path for an ampere or more of RF current flowing between the KAT3 board and the rear panel sockets. As someone whose design instincts were developed at VHF, where all RF ground paths must be short, broad and direct, I didn't feel comfortable about that corner of the K3. Yes, we know that "it works" and "it's good enough for HF". But in these days of compulsory EMC testing and microscopically detailed product reviews, even HF designers are coming to realise that bending the rules for good RF grounding will eat into the margins of performance, spurious signal rejection and stability. RF grounding of the KAT3 board is also far too dependent on the tightness of the screws at each end of the pillar and the cleanness of all the contact surfaces. That ground return path can be much improved by connecting the mounting screw of J1 directly to the corner of the KAT3 board, using two solder tags that are overlapped and soldered directly together. My K3 doesn't necessarily work any better, but it does satisfy the instincts of an old VHF hound :-) -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek ______________________________________________________________ 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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