KX1 Power Output
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Hi,
I just finished building KX1 Serial Number 2879 which is the standard 20M/40M version. It's a great little rig but, I have a few issues, one major and two minor: A) On final testing I only had about 2.5W on 20M and 2.0W on 40M with power supply at 13.8V. I tried to compress the winding on L2, as suggested, but this only degraded the output slightly (2.2W on 20M and 1.8W on 40M). Checked the components on the board against the schematic and everything checked out OK. Any ideas on what else I should try? Any idea what RF voltage levels I should see at each stage? (I have several decent oscilloscopes for testing if need be.) B) The receiver is sensitive (I can hear 0.1 microvolt RF signal on 20 & 40) but the audio level (particularly for weak signals) is pretty low unless I advance the AF Gain control to full clockwise. Is this normal? Do I just need to experiment with different sets of ear-buds? C) The firmware on my KX1 is version 1.02. The Menu on my unit is different than the Manual. It does not include SLO, SHI or CAL. Instead there are SIG, DDS and BFO. Are support documents for revised version available? For background, I had no difficulty during assembly. The KX1 passed all tests except the transmit power output. I did make one mistake during assembly however. I mistakenly inserted a .1 microfarad capacitor at C30 instead of a .01 microfarad capacitor. Since everything seemed to be working, so I have not corrected this issue. Think this could be significant? Thanks for any assistance you can provide. Lee KG5VU |
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> I did make one mistake during assembly however. I mistakenly inserted a .1
> microfarad capacitor at C30 instead of a .01 microfarad capacitor. Since > everything seemed to be working, so I have not corrected this issue. Wouldn’t that mean you made two mistakes. Unless of course you had an extra 0.1 mF capacitor. But, if you have exactly the right amount of parts, which is the usual thing, then all misplaced part mistakes come in pairs. 73, phil, K7PEH > On Jun 17, 2015, at 7:58 AM, KG5VU <[hidden email]> wrote: > > Hi, > > I just finished building KX1 Serial Number 2879 which is the standard > 20M/40M version. It's a great little rig but, I have a few issues, one > major and two minor: > > A) On final testing I only had about 2.5W on 20M and 2.0W on 40M with power > supply at 13.8V. I tried to compress the winding on L2, as suggested, but > this only degraded the output slightly (2.2W on 20M and 1.8W on 40M). > Checked the components on the board against the schematic and everything > checked out OK. Any ideas on what else I should try? Any idea what RF > voltage levels I should see at each stage? (I have several decent > oscilloscopes for testing if need be.) > > B) The receiver is sensitive (I can hear 0.1 microvolt RF signal on 20 & 40) > but the audio level (particularly for weak signals) is pretty low unless I > advance the AF Gain control to full clockwise. Is this normal? Do I just > need to experiment with different sets of ear-buds? > > C) The firmware on my KX1 is version 1.02. The Menu on my unit is different > than the Manual. It does not include SLO, SHI or CAL. Instead there are > SIG, DDS and BFO. Are support documents for revised version available? > > For background, I had no difficulty during assembly. The KX1 passed all > tests except the transmit power output. > > I did make one mistake during assembly however. I mistakenly inserted a .1 > microfarad capacitor at C30 instead of a .01 microfarad capacitor. Since > everything seemed to be working, so I have not corrected this issue. Think > this could be significant? > > Thanks for any assistance you can provide. > > Lee > KG5VU > > > > > > > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/KX1-Power-Output-tp7604063.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > 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 > Message delivered to [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
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Phil,
Fortunately, I had a spare .1 microfarad capacitor on hand. Not exactly the same size but very close. Thanks, Lee |
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In reply to this post by KG5VU
Lee,
Yes, I would change that capacitor - there is a chance that it will increase the output of the DDS and solve your power output problem. There is a difference in some KX1s due to care during construction, component tolerances, and a host of other factors. Make certain you counted the toroid turns correctly - a straight wire through the core is one turn, a full wrap around the core is 2 turns. Count the turns that go through the core center. If all else fails, you can install the KX1 power mod. If you have a good stock of 1/4 watt resistors you may not need to order the kit. Change R11 to 4.7 ohms and R30 to 33 ohms. If those steps do not solve the power output situation, send me an off-list email and we can make comparison measurements with my KX1. The KX1 audio is not 'earbusting', but is normally adequate. Yes, you may want to try headphones or earbuds with a higher SPL rating. The "Quick Reference" is the only place in the KX1 manual where SLO, SHI, and CAL are mentioned - I guess someone overlooked updating that portion of the manual since the VERY early days of the KX1. Look at the listing of menu items on page 65 and you will see DDS, BFO, and SIG to make those settings. This has been true since firmware rev 1.01. 1.02 is the latest version. 73, Don W3FPR On 6/17/2015 10:58 AM, KG5VU wrote: > Hi, > > I just finished building KX1 Serial Number 2879 which is the standard > 20M/40M version. It's a great little rig but, I have a few issues, one > major and two minor: > > A) On final testing I only had about 2.5W on 20M and 2.0W on 40M with power > supply at 13.8V. I tried to compress the winding on L2, as suggested, but > this only degraded the output slightly (2.2W on 20M and 1.8W on 40M). > Checked the components on the board against the schematic and everything > checked out OK. Any ideas on what else I should try? Any idea what RF > voltage levels I should see at each stage? (I have several decent > oscilloscopes for testing if need be.) > > B) The receiver is sensitive (I can hear 0.1 microvolt RF signal on 20 & 40) > but the audio level (particularly for weak signals) is pretty low unless I > advance the AF Gain control to full clockwise. Is this normal? Do I just > need to experiment with different sets of ear-buds? > > C) The firmware on my KX1 is version 1.02. The Menu on my unit is different > than the Manual. It does not include SLO, SHI or CAL. Instead there are > SIG, DDS and BFO. Are support documents for revised version available? > > For background, I had no difficulty during assembly. The KX1 passed all > tests except the transmit power output. > > I did make one mistake during assembly however. I mistakenly inserted a .1 > microfarad capacitor at C30 instead of a .01 microfarad capacitor. Since > everything seemed to be working, so I have not corrected this issue. Think > this could be significant? > > ______________________________________________________________ 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 Message delivered to [hidden email] |
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Don,
I installed the .1 microfarad capacitor at C30, but this didn’t change the output. After testing the C30 fix, I subsequently changed R30 to 33 ohms and R11 to 4.7 ohms. This did change things, but did not entirely resolve the problem. At 13.8V input, my power meter shows 3.0 watts on both 20M and 40M. When I lower the input voltage to 9.0 volts, the meter shows 1.4 watts on 40M and 1.7 watts on 20M. I guess this is within or nearly within specs, but it’s odd that there is more output on 20M than on 40M. Anything else I should try, or should I just use it like this for a while? Thanks again, Lee KG5VU > On Jun 17, 2015, at 1:02 PM, Don Wilhelm <[hidden email]> wrote: > > Lee, > > Yes, I would change that capacitor - there is a chance that it will increase the output of the DDS and solve your power output problem. > There is a difference in some KX1s due to care during construction, component tolerances, and a host of other factors. > Make certain you counted the toroid turns correctly - a straight wire through the core is one turn, a full wrap around the core is 2 turns. > Count the turns that go through the core center. > > If all else fails, you can install the KX1 power mod. If you have a good stock of 1/4 watt resistors you may not need to order the kit. Change R11 to 4.7 ohms and R30 to 33 ohms. > > If those steps do not solve the power output situation, send me an off-list email and we can make comparison measurements with my KX1. > > The KX1 audio is not 'earbusting', but is normally adequate. Yes, you may want to try headphones or earbuds with a higher SPL rating. > > The "Quick Reference" is the only place in the KX1 manual where SLO, SHI, and CAL are mentioned - I guess someone overlooked updating that portion of the manual since the VERY early days of the KX1. Look at the listing of menu items on page 65 and you will see DDS, BFO, and SIG to make those settings. > This has been true since firmware rev 1.01. 1.02 is the latest version. > > 73, > Don W3FPR > > On 6/17/2015 10:58 AM, KG5VU wrote: >> Hi, >> >> I just finished building KX1 Serial Number 2879 which is the standard >> 20M/40M version. It's a great little rig but, I have a few issues, one >> major and two minor: >> >> A) On final testing I only had about 2.5W on 20M and 2.0W on 40M with power >> supply at 13.8V. I tried to compress the winding on L2, as suggested, but >> this only degraded the output slightly (2.2W on 20M and 1.8W on 40M). >> Checked the components on the board against the schematic and everything >> checked out OK. Any ideas on what else I should try? Any idea what RF >> voltage levels I should see at each stage? (I have several decent >> oscilloscopes for testing if need be.) >> >> B) The receiver is sensitive (I can hear 0.1 microvolt RF signal on 20 & 40) >> but the audio level (particularly for weak signals) is pretty low unless I >> advance the AF Gain control to full clockwise. Is this normal? Do I just >> need to experiment with different sets of ear-buds? >> >> C) The firmware on my KX1 is version 1.02. The Menu on my unit is different >> than the Manual. It does not include SLO, SHI or CAL. Instead there are >> SIG, DDS and BFO. Are support documents for revised version available? >> >> For background, I had no difficulty during assembly. The KX1 passed all >> tests except the transmit power output. >> >> I did make one mistake during assembly however. I mistakenly inserted a .1 >> microfarad capacitor at C30 instead of a .01 microfarad capacitor. Since >> everything seemed to be working, so I have not corrected this issue. Think >> this could be significant? >> >> > ______________________________________________________________ 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 Message delivered to [hidden email] |
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You mean a .01 uF?
Sent from my iPhone Chuck (Jack)
Chuck, KE9UW
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Correct, Thanks
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In reply to this post by KG5VU
Lee,
That is better, but I normally expect 3.5 watts with a true 13.8 volt input. Measure the voltage at the KX1 end (remove the insulating handle from the power cord to gain access). Then try a TUNE and measure the voltage again. If it drops substantially, check the connections at the power source to be sure they are tight. I normally recommend using #18 wire or larger to reduce the voltage drop. You did not mention the wattmeter that you were using. Many analog wattmeters are only accurate to 20% of the full scale reading - that means if using a 20 watt scale, the reading could be incorrect by as much as 4 watts at any point on the scale, making them not reliable for low power work. It is more accurate to connect a god 50 ohm dummy load and measure the RF voltage across that load and 'do the math' to figure the power output. There are a few accurate wattmeters available, and most of them are digital - the Elecraft WM1, W2, or the Telepost LP-100 and LP-200 are ones I know I can trust. You may be able to move the 40/20 power output relationship by changing the spacing on the turns of L1 and L2. Try spreading the turns as well as squeezing them. The most important factor when spreading or squeezing the turns is the spacing between the wires at the ends of the winding - spreading or squeezing the middle of the winding will not do much. 73, Don W3FPR On 6/17/2015 4:08 PM, M L Hooper wrote: > Don, > > I installed the .1 microfarad capacitor at C30, but this didn’t change the output. > > After testing the C30 fix, I subsequently changed R30 to 33 ohms and R11 to 4.7 ohms. This did change things, but did not entirely resolve the problem. > > At 13.8V input, my power meter shows 3.0 watts on both 20M and 40M. > When I lower the input voltage to 9.0 volts, the meter shows 1.4 watts on 40M and 1.7 watts on 20M. > I guess this is within or nearly within specs, but it’s odd that there is more output on 20M than on 40M. > > Anything else I should try, or should I just use it like this for a while? > > Thanks again, > > Lee > KG5VU > > >> On Jun 17, 2015, at 1:02 PM, Don Wilhelm <[hidden email]> wrote: >> >> Lee, >> >> Yes, I would change that capacitor - there is a chance that it will increase the output of the DDS and solve your power output problem. >> There is a difference in some KX1s due to care during construction, component tolerances, and a host of other factors. >> Make certain you counted the toroid turns correctly - a straight wire through the core is one turn, a full wrap around the core is 2 turns. >> Count the turns that go through the core center. >> >> If all else fails, you can install the KX1 power mod. If you have a good stock of 1/4 watt resistors you may not need to order the kit. Change R11 to 4.7 ohms and R30 to 33 ohms. >> >> If those steps do not solve the power output situation, send me an off-list email and we can make comparison measurements with my KX1. >> >> The KX1 audio is not 'earbusting', but is normally adequate. Yes, you may want to try headphones or earbuds with a higher SPL rating. >> >> The "Quick Reference" is the only place in the KX1 manual where SLO, SHI, and CAL are mentioned - I guess someone overlooked updating that portion of the manual since the VERY early days of the KX1. Look at the listing of menu items on page 65 and you will see DDS, BFO, and SIG to make those settings. >> This has been true since firmware rev 1.01. 1.02 is the latest version. >> >> 73, >> Don W3FPR >> >> On 6/17/2015 10:58 AM, KG5VU wrote: >>> Hi, >>> >>> I just finished building KX1 Serial Number 2879 which is the standard >>> 20M/40M version. It's a great little rig but, I have a few issues, one >>> major and two minor: >>> >>> A) On final testing I only had about 2.5W on 20M and 2.0W on 40M with power >>> supply at 13.8V. I tried to compress the winding on L2, as suggested, but >>> this only degraded the output slightly (2.2W on 20M and 1.8W on 40M). >>> Checked the components on the board against the schematic and everything >>> checked out OK. Any ideas on what else I should try? Any idea what RF >>> voltage levels I should see at each stage? (I have several decent >>> oscilloscopes for testing if need be.) >>> >>> B) The receiver is sensitive (I can hear 0.1 microvolt RF signal on 20 & 40) >>> but the audio level (particularly for weak signals) is pretty low unless I >>> advance the AF Gain control to full clockwise. Is this normal? Do I just >>> need to experiment with different sets of ear-buds? >>> >>> C) The firmware on my KX1 is version 1.02. The Menu on my unit is different >>> than the Manual. It does not include SLO, SHI or CAL. Instead there are >>> SIG, DDS and BFO. Are support documents for revised version available? >>> >>> For background, I had no difficulty during assembly. The KX1 passed all >>> tests except the transmit power output. >>> >>> I did make one mistake during assembly however. I mistakenly inserted a .1 >>> microfarad capacitor at C30 instead of a .01 microfarad capacitor. Since >>> everything seemed to be working, so I have not corrected this issue. Think >>> this could be significant? >>> >>> > ______________________________________________________________ > 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 > Message delivered to [hidden email] > ______________________________________________________________ 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 Message delivered to [hidden email] |
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