KAT100 Problem
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I have encountered difficulty with the KAT100. I am pretty sure the problem resulted from RF feedback in the shack from a Zero-Five flagpole antenna with an unun at its base, an ugly balun with Polyphaser ground after 80 feet of coax prior to entry into the shack, and a Balun Designs isolation balun following the 20 feet or so of coax that enters the shack. The isolation balun is inside the shack for stealth reasons because of a very intrusive HOA. Thae KAT100 would not tune the antenna or a dry dummy load on 20 meters. It will indicate a high SWR and the K2 registers a hot power amplifier. If I run it for a while, the RF gets into the radio and the other bands may be affected. As a consequence, I will eventually move the isolation balun between the KAT100 and the K2/100 and place another one on the line that leads into the shack. I tested the components as stipulated in the manual. When I switch from C5 to C6, the SWR jumps from 2.5 to off scale (9.9) on 20 meters and
1.4 to 7.0 on 40 meters. Based on the knowledge and past experience of others, does it seem reasonable to assume that C6 is defective and the cause of the problem? Many thanks beforehand for any advice you folks have to offer. Vy 73, Dick, K8RBW. ______________________________________________________________ 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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Dick,
Are you doing the component tests (C5 to C6 for example) into a dummy load or into your antenna. Trying that test into an antenna just adds a lot of other unknowns into the formula - use a dummy load. Not only that, check the dummy load and the coax going to it - if you have an antenna analyzer, put it on the end of the coax that you are connecting to the KAT100 and see what the impedance is - it should be 50 ohms resistive and zero ohms reactive (or very close). Bad coax is a frequently overlooked problem spot as are PL-259 connectors that are not fully tightened. In other words, reduce the system to its bare essentials when doing any tests. With the known good dummy load and coax, now try the manual instructions again. If you get the same results on 20 meters, drop down to 40 meters and try the same test. Often the switch between one capacitor and another will cause the SWR to 'go offscale' on a higher frequency, but be just fine at a lower frequency. The jump in capacity between C5 and C6 is quite large - C5 is 150 pF while C6 is 300 pF, and that is a LOT on 20 meters. Your results when dropping down to 40 meters seem to be in line with reality. There is an alternative test (not in the manual) that you can do if you have a capacity meter. Connect the capacity meter between the center conductor and the shell of the input jack. With C0 selected, zero the meter (or record the stray capacitance shown), then cycle through the C1 thru C8. The capacitance should approximately double with each step upward in Cx. If you are not using a capacity meter that has a zero capability, subtract the capacitance measured at C0 from the reading at the other capacitors to arrive at the real capacitance value that the KAT100 is connecting. Yes, your RF-in-the-shack can be confusing things a lot. 73, Don W3FPR On 7/7/2013 7:06 PM, [hidden email] wrote: > I have encountered difficulty with the KAT100. I am pretty sure the problem resulted from RF feedback in the shack from a Zero-Five flagpole antenna with an unun at its base, an ugly balun with Polyphaser ground after 80 feet of coax prior to entry into the shack, and a Balun Designs isolation balun following the 20 feet or so of coax that enters the shack. The isolation balun is inside the shack for stealth reasons because of a very intrusive HOA. Thae KAT100 would not tune the antenna or a dry dummy load on 20 meters. It will indicate a high SWR and the K2 registers a hot power amplifier. If I run it for a while, the RF gets into the radio and the other bands may be affected. As a consequence, I will eventually move the isolation balun between the KAT100 and the K2/100 and place another one on the line that leads into the shack. I tested the components as stipulated in the manual. When I switch from C5 to C6, the SWR jumps from 2.5 to off scale (9.9) on 20 meters an d > 1.4 to 7.0 on 40 meters. Based on the knowledge and past experience of others, does it seem reasonable to assume that C6 is defective and the cause of the problem? Many thanks beforehand for any advice you folks have to offer. Vy 73, Dick, K8RBW. > ______________________________________________________________ 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, Thanks for your prompt response. Yes, I reduced everything to its bare minimum and tested it on a dry dummy load. I am sorry; I should have stated that. I also used about different jumper cables to connect to the dummy load, all yielding the same results on both 20 and 40. I also tested 10 and 80. It went off scale with much sooner on 10 meters as I progressed through the capacitors, but there didn't seem to be any dramatic change on 80. The results with the dummy load almost precisely mirror those experienced with the antenna on 20 meters. I was just using it with the antenna on 30 and 17 with excellent results. It loads the antenna beautifully on all bands 10 through 160, with the exception of 20. I will check the capacitors again on 30 meters later this evening. Unfortunately, I do not have a capacity meter. I am in Florida with the bare minimum of test equipment and scheduled to follow the snow birds north this week. i'lllet you know what results I find on 30 me ters. 73, Dick -----Original Message----- From: Don Wilhelm <[hidden email]> To: richardjwiltgen <[hidden email]> Cc: elecraft <[hidden email]> Sent: Sun, Jul 7, 2013 7:45 pm Subject: Re: [Elecraft] KAT100 Problem Dick, Are you doing the component tests (C5 to C6 for example) into a dummy load or into your antenna. Trying that test into an antenna just adds a lot of other unknowns into the formula - use a dummy load. Not only that, check the dummy load and the coax going to it - if you have an antenna analyzer, put it on the end of the coax that you are connecting to the KAT100 and see what the impedance is - it should be 50 ohms resistive and zero ohms reactive (or very close). Bad coax is a frequently overlooked problem spot as are PL-259 connectors that are not fully tightened. In other words, reduce the system to its bare essentials when doing any tests. With the known good dummy load and coax, now try the manual instructions again. If you get the same results on 20 meters, drop down to 40 meters and try the same test. Often the switch between one capacitor and another will cause the SWR to 'go offscale' on a higher frequency, but be just fine at a lower frequency. The jump in capacity between C5 and C6 is quite large - C5 is 150 pF while C6 is 300 pF, and that is a LOT on 20 meters. Your results when dropping down to 40 meters seem to be in line with reality. There is an alternative test (not in the manual) that you can do if you have a capacity meter. Connect the capacity meter between the center conductor and the shell of the input jack. With C0 selected, zero the meter (or record the stray capacitance shown), then cycle through the C1 thru C8. The capacitance should approximately double with each step upward in Cx. If you are not using a capacity meter that has a zero capability, subtract the capacitance measured at C0 from the reading at the other capacitors to arrive at the real capacitance value that the KAT100 is connecting. Yes, your RF-in-the-shack can be confusing things a lot. 73, Don W3FPR On 7/7/2013 7:06 PM, [hidden email] wrote: > I have encountered difficulty with the KAT100. I am pretty sure the problem resulted from RF feedback in the shack from a Zero-Five flagpole antenna with an unun at its base, an ugly balun with Polyphaser ground after 80 feet of coax prior to entry into the shack, and a Balun Designs isolation balun following the 20 feet or so of coax that enters the shack. The isolation balun is inside the shack for stealth reasons because of a very intrusive HOA. Thae KAT100 would not tune the antenna or a dry dummy load on 20 meters. It will indicate a high SWR and the K2 registers a hot power amplifier. If I run it for a while, the RF gets into the radio and the other bands may be affected. As a consequence, I will eventually move the isolation balun between the KAT100 and the K2/100 and place another one on the line that leads into the shack. I tested the components as stipulated in the manual. When I switch from C5 to C6, the SWR jumps from 2.5 to off scale (9.9) on 20 meters and > 1.4 to 7.0 on 40 meters. Based on the knowledge and past experience of others, does it seem reasonable to assume that C6 is defective and the cause of the problem? Many thanks beforehand for any advice you folks have to offer. Vy 73, Dick, K8RBW. > ______________________________________________________________ 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 Dick Wiltgen
I'm wondering, kinda thinking in the blind, if there might be a coil not making contact, either a lead at the solder point, or a relay contact not good any more..???
Have a great day, Dale - WC7S -----Original Message----- From: [hidden email] Date: Mon, 8 Jul 2013 00:09:05 To: <[hidden email]> Cc: <[hidden email]> Subject: Re: [Elecraft] KAT100 Problem Don, Thanks for your prompt response. Yes, I reduced everything to its bare minimum and tested it on a dry dummy load. I am sorry; I should have stated that. I also used about different jumper cables to connect to the dummy load, all yielding the same results on both 20 and 40. I also tested 10 and 80. It went off scale with much sooner on 10 meters as I progressed through the capacitors, but there didn't seem to be any dramatic change on 80. The results with the dummy load almost precisely mirror those experienced with the antenna on 20 meters. I was just using it with the antenna on 30 and 17 with excellent results. It loads the antenna beautifully on all bands 10 through 160, with the exception of 20. I will check the capacitors again on 30 meters later this evening. Unfortunately, I do not have a capacity meter. I am in Florida with the bare minimum of test equipment and scheduled to follow the snow birds north this week. i'lllet you know what results I find on 30 me ters. 73, Dick -----Original Message----- From: Don Wilhelm <[hidden email]> To: richardjwiltgen <[hidden email]> Cc: elecraft <[hidden email]> Sent: Sun, Jul 7, 2013 7:45 pm Subject: Re: [Elecraft] KAT100 Problem Dick, Are you doing the component tests (C5 to C6 for example) into a dummy load or into your antenna. Trying that test into an antenna just adds a lot of other unknowns into the formula - use a dummy load. Not only that, check the dummy load and the coax going to it - if you have an antenna analyzer, put it on the end of the coax that you are connecting to the KAT100 and see what the impedance is - it should be 50 ohms resistive and zero ohms reactive (or very close). Bad coax is a frequently overlooked problem spot as are PL-259 connectors that are not fully tightened. In other words, reduce the system to its bare essentials when doing any tests. With the known good dummy load and coax, now try the manual instructions again. If you get the same results on 20 meters, drop down to 40 meters and try the same test. Often the switch between one capacitor and another will cause the SWR to 'go offscale' on a higher frequency, but be just fine at a lower frequency. The jump in capacity between C5 and C6 is quite large - C5 is 150 pF while C6 is 300 pF, and that is a LOT on 20 meters. Your results when dropping down to 40 meters seem to be in line with reality. There is an alternative test (not in the manual) that you can do if you have a capacity meter. Connect the capacity meter between the center conductor and the shell of the input jack. With C0 selected, zero the meter (or record the stray capacitance shown), then cycle through the C1 thru C8. The capacitance should approximately double with each step upward in Cx. If you are not using a capacity meter that has a zero capability, subtract the capacitance measured at C0 from the reading at the other capacitors to arrive at the real capacitance value that the KAT100 is connecting. Yes, your RF-in-the-shack can be confusing things a lot. 73, Don W3FPR On 7/7/2013 7:06 PM, [hidden email] wrote: > I have encountered difficulty with the KAT100. I am pretty sure the problem resulted from RF feedback in the shack from a Zero-Five flagpole antenna with an unun at its base, an ugly balun with Polyphaser ground after 80 feet of coax prior to entry into the shack, and a Balun Designs isolation balun following the 20 feet or so of coax that enters the shack. The isolation balun is inside the shack for stealth reasons because of a very intrusive HOA. Thae KAT100 would not tune the antenna or a dry dummy load on 20 meters. It will indicate a high SWR and the K2 registers a hot power amplifier. If I run it for a while, the RF gets into the radio and the other bands may be affected. As a consequence, I will eventually move the isolation balun between the KAT100 and the K2/100 and place another one on the line that leads into the shack. I tested the components as stipulated in the manual. When I switch from C5 to C6, the SWR jumps from 2.5 to off scale (9.9) on 20 meters and > 1.4 to 7.0 on 40 meters. Based on the knowledge and past experience of others, does it seem reasonable to assume that C6 is defective and the cause of the problem? Many thanks beforehand for any advice you folks have to offer. Vy 73, Dick, K8RBW. > ______________________________________________________________ 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 Dick Wiltgen
Dick,
I figure you are using a multiband antenna. It may be presenting a very low or very high impedance to the KAT100 on 20 meters. The solution is to add or subtract about 1/8 wavelength of feedline to the antenna system. On 20 meters, that would be about 8 feet of feedline. Of course, that may transfer the problem to another band, but keep trying, you will eventually be able to get it to tune properly on all bands. 73, Don W3FPR On 7/7/2013 8:09 PM, [hidden email] wrote: > Don, > > Thanks for your prompt response. Yes, I reduced everything to its bare minimum and tested it on a dry dummy load. I am sorry; I should have stated that. I also used about different jumper cables to connect to the dummy load, all yielding the same results on both 20 and 40. I also tested 10 and 80. It went off scale with much sooner on 10 meters as I progressed through the capacitors, but there didn't seem to be any dramatic change on 80. The results with the dummy load almost precisely mirror those experienced with the antenna on 20 meters. I was just using it with the antenna on 30 and 17 with excellent results. It loads the antenna beautifully on all bands 10 through 160, with the exception of 20. I will check the capacitors again on 30 meters later this evening. Unfortunately, I do not have a capacity meter. I am in Florida with the bare minimum of test equipment and scheduled to follow the snow birds north this week. i'lllet you know what results I find on 30 me > ters. > ______________________________________________________________ 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, I had been trying that to no avail. I drew up a a table with the data for all the capacitors. After that, I decided to pull out an LDG-100pro to see what would happened. Much to my surprise, I found out that I had been barking up the wrong tree. The LDG responds the same way. Both the KAT100 and the LDG fold back to 10 watts when tuning on 20 meters, regardless of whether I am using the antenna or the dummy load. The problem is obviously in the radio, not the tuner. It threw me for a loop because all the other bands tune up just fine. I never would have guessed the problem was in the K2/100. If I can't figure it out in the next couple of days, I'll just have to leave it for next fall when I return to Florida with decent test equipment. I have been sitting around waiting for some physicians to approve my departure. If I had known this a couple of weeks ago, I would have had plenty of time to work on it. I really like the K2. In many respects, I like it better tha n my K3 and KX3, as it fits better with my "CW back to basics" personality. Any new suggestions? 73, Dick -----Original Message----- From: Don Wilhelm <[hidden email]> To: richardjwiltgen <[hidden email]> Cc: elecraft <[hidden email]> Sent: Sun, Jul 7, 2013 10:38 pm Subject: Re: [Elecraft] KAT100 Problem Dick, I figure you are using a multiband antenna. It may be presenting a very ow or very high impedance to the KAT100 on 20 meters. The solution is o add or subtract about 1/8 wavelength of feedline to the antenna ystem. On 20 meters, that would be about 8 feet of feedline. Of course, that may transfer the problem to another band, but keep rying, you will eventually be able to get it to tune properly on all bands. 73, on W3FPR On 7/7/2013 8:09 PM, [hidden email] wrote: Don, Thanks for your prompt response. Yes, I reduced everything to its bare inimum and tested it on a dry dummy load. I am sorry; I should have stated hat. I also used about different jumper cables to connect to the dummy load, ll yielding the same results on both 20 and 40. I also tested 10 and 80. It ent off scale with much sooner on 10 meters as I progressed through the apacitors, but there didn't seem to be any dramatic change on 80. The results ith the dummy load almost precisely mirror those experienced with the antenna n 20 meters. I was just using it with the antenna on 30 and 17 with excellent esults. It loads the antenna beautifully on all bands 10 through 160, with the xception of 20. I will check the capacitors again on 30 meters later this vening. Unfortunately, I do not have a capacity meter. I am in Florida with he bare minimum of test equipment and scheduled to follow the snow birds north his week. i'lllet you know what results I find on 30 me ters. ______________________________________________________________ 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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Dick,
It is very strange that the K2 would have a problem like that on only one band. Does your KPA100 have a shield over the speaker magnet? About the only thing that I can think of is that the speaker shield is missing and its magnetic field is interfering with the operation of the VFO Range Select relays on the K2 board below it. Other than that, my only other guess is that something has happened to a capacitor in the 17/20 meter LPF in the KPA100 or in the 20/30 LPF in the base K2. If you operate the K2/100 directly into the dummy load, do you get full output? 73, Don W3FPR On 7/8/2013 1:07 AM, [hidden email] wrote: > Don, > > I had been trying that to no avail. I drew up a a table with the data for all the capacitors. After that, I decided to pull out an LDG-100pro to see what would happened. Much to my surprise, I found out that I had been barking up the wrong tree. The LDG responds the same way. Both the KAT100 and the LDG fold back to 10 watts when tuning on 20 meters, regardless of whether I am using the antenna or the dummy load. The problem is obviously in the radio, not the tuner. It threw me for a loop because all the other bands tune up just fine. I never would have guessed the problem was in the K2/100. If I can't figure it out in the next couple of days, I'll just have to leave it for next fall when I return to Florida with decent test equipment. I have been sitting around waiting for some physicians to approve my departure. If I had known this a couple of weeks ago, I would have had plenty of time to work on it. I really like the K2. In many respects, I like it better t ha > n my K3 and KX3, as it fits better with my "CW back to basics" personality. > > ______________________________________________________________ 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 Dick Wiltgen
Dick, you wrote: "I will eventually move the isolation balun between the KAT100 and the K2/100".
It doesn't seem to be a good idea. You may get potential difference between the two. Here is much about it: http://www.w8ji.com/rfi_rf_grounding.htm regards Peter, SP2BPD |
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