KAT500 Performance Clarification
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KAT500 Performance Clarification
 
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Gang, I was surprised last night when I got a descent low SWR tuning my 80-meter (ladder-line fed into 4:1 balun) dipole on 160 meters. I have had the KAT500 for a couple of months and I never bothered trying it on 160 meters because on all previous attempts with other manual tuners I have failed to get a good match.
But, last night, just as a lark, I switched up to 160 meters and gave the KAT500 a try. Sure enough it found a match of 1.05:1 at 1900 KHz with the Bypass VSWR reading about 17:1. Given I have most of the transmission line in lower-loss ladder line helps with the losses to the antenna with that high bypass SWR. This was at 100 watts out from the K3. Now, I decided to give a try with the KPA500 in-line at about 475 watts and the best I could get is about 4:1 tuned SWR. Now, I am not quite sure I understand the dynamics of the KAT500 with higher power. This is what I did. I tuned at 20 watts to the 1.05:1 SWR (bypass was ~17:1). At 100 watts, my LP-100A was still reading about 1.1:1 SWR. But, when I turned on the KPA500 (switched out of standby) the reading was roughly 4:1 with a fault on the KPA500. Question, how does the higher power affect the match of the KAT500. I understand how higher power might stress the KAT500 with maybe arcing or something but I don't understand why the match actually changed unless that higher power caused some change in the KAT500 capacitor or inductor components. 73, phil, K7PEH ______________________________________________________________ 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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Many tuners tried to match anything. At the borderline most of the power stays in toroids and the tuner smokes.
Perhaps KAT500 like MFJ-998 reduces the matching range at higher power. You may try 1:1 balun. I use MFJ-998 at KW level with 80m ladderline and 1:1 balun. No problem matching 160-80m. On higher bands almost all bands matched with homemade 1:1 balun but fewer with heavy-duty 1:1 commercial balun. Ignacy |
Re: KAT500 Performance Clarification
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Ignacy,
I have a 1:1 balun as well and I have experimented with both. They sit right next to each other under the eve on the side of my house so switching back and forth between the 1:1 and 4:1 is a 5 minute task where the first 4 minutes is just getting the latter to reach up to where they are located. The 4:1 balun seems to work the best in this case. phil On Jan 23, 2013, at 9:12 AM, Ignacy <[hidden email]> wrote: > Many tuners tried to match anything. At the borderline most of the power > stays in toroids and the tuner smokes. > > Perhaps KAT500 like MFJ-998 reduces the matching range at higher power. > > You may try 1:1 balun. I use MFJ-998 at KW level with 80m ladderline and 1:1 > balun. No problem matching 160-80m. On higher bands almost all bands matched > with homemade 1:1 balun but fewer with heavy-duty 1:1 commercial balun. > > Ignacy > > > > > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/KAT500-Performance-Clarification-tp7569058p7569061.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 ______________________________________________________________ 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 |
Re: KAT500 Performance Clarification
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In reply to this post by Ignacy
Lets use the proper terms here please. Balun is incorrect because it is inaccurate; it is either a voltage or current choke. It may also be a transformer (4:1, 6:1, 9:1).
A 1:1 current choke is recommended for ladder line to keep common mode RF out of the shack if one does not use a balanced tuner. Then use the shortest possible run of coax to the choke because everything downstream of the tuner is potentially high loss, more so in coax. Yes, the greater the bypassed mismatch, the lower the power requirements for the KAT500. Mine has issues (is borderline) on a 75 M double extended Zepp on 75 and won't load on 160 M. It loads everything else great so I can use the KPA500. Rick wa6nhc Tiny iPhone 5 keypad, typos are inevitable On Jan 23, 2013, at 9:12 AM, Ignacy <[hidden email]> wrote: > Perhaps KAT500 like MFJ-998 reduces the matching range at higher power. > > You may try 1:1 balun. I use MFJ-998 at KW level with 80m ladderline and 1:1 > balun. No problem matching 160-80m. On higher bands almost all bands matched > with homemade 1:1 balun but fewer with heavy-duty 1:1 commercial balun. > > Ignacy ______________________________________________________________ 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 |
Re: KAT500 Performance Clarification
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In reply to this post by Phil Hystad-3
Hi, Phil.
Although the KAT500, like most tuners, will attempt to find a match whenever it can, it protects itself from the very high voltages and currents that can appear on internal components when the match is poor. We rate the tuner for 500 watts at 10:1 SWR. When you use an antenna that shows 17:1 SWR (the "untuned" or "bypass" VSWR), the ATU measures the forward power and computes the power it can safely handle with the high mismatch. It's less than 500 watts. You should be able to operate safely at 250 watts or so with that high a bypass VSWR. If you exceed the ATU's safety values, it should illuminate the red FAULT led, make a fault log entry, and put the ATU into BYPASS at the next opportunity. It should also interrupt the amplifier key line. Dick, K6KR -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Phil Hystad Sent: Wednesday, January 23, 2013 8:48 AM To: [hidden email] List Subject: [Elecraft] KAT500 Performance Clarification Gang, I was surprised last night when I got a descent low SWR tuning my 80-meter (ladder-line fed into 4:1 balun) dipole on 160 meters. I have had the KAT500 for a couple of months and I never bothered trying it on 160 meters because on all previous attempts with other manual tuners I have failed to get a good match. But, last night, just as a lark, I switched up to 160 meters and gave the KAT500 a try. Sure enough it found a match of 1.05:1 at 1900 KHz with the Bypass VSWR reading about 17:1. Given I have most of the transmission line in lower-loss ladder line helps with the losses to the antenna with that high bypass SWR. This was at 100 watts out from the K3. Now, I decided to give a try with the KPA500 in-line at about 475 watts and the best I could get is about 4:1 tuned SWR. Now, I am not quite sure I understand the dynamics of the KAT500 with higher power. This is what I did. I tuned at 20 watts to the 1.05:1 SWR (bypass was ~17:1). At 100 watts, my LP-100A was still reading about 1.1:1 SWR. But, when I turned on the KPA500 (switched out of standby) the reading was roughly 4:1 with a fault on the KPA500. Question, how does the higher power affect the match of the KAT500. I understand how higher power might stress the KAT500 with maybe arcing or something but I don't understand why the match actually changed unless that higher power caused some change in the KAT500 capacitor or inductor components. 73, phil, K7PEH ______________________________________________________________ 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 |
Re: KAT500 Performance Clarification
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Dick,
Thanks, this is exactly the kind of clarification I was looking for. Now, if you or someone says this was described in the manual I will be ashamed and embarrassed. I already knew about the higher power at lower bypass SWR. But, I did not realize the lower power at higher bypass SWR. phil PEH's iPad On Jan 23, 2013, at 9:58 AM, Dick Dievendorff <[hidden email]> wrote: > Hi, Phil. > > Although the KAT500, like most tuners, will attempt to find a match whenever > it can, it protects itself from the very high voltages and currents that can > appear on internal components when the match is poor. We rate the tuner for > 500 watts at 10:1 SWR. When you use an antenna that shows 17:1 SWR (the > "untuned" or "bypass" VSWR), the ATU measures the forward power and computes > the power it can safely handle with the high mismatch. It's less than 500 > watts. You should be able to operate safely at 250 watts or so with that > high a bypass VSWR. If you exceed the ATU's safety values, it should > illuminate the red FAULT led, make a fault log entry, and put the ATU into > BYPASS at the next opportunity. It should also interrupt the amplifier key > line. > > Dick, K6KR > > > > > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Phil Hystad > Sent: Wednesday, January 23, 2013 8:48 AM > To: [hidden email] List > Subject: [Elecraft] KAT500 Performance Clarification > > Gang, I was surprised last night when I got a descent low SWR tuning my > 80-meter (ladder-line fed into 4:1 balun) dipole on 160 meters. I have had > the KAT500 for a couple of months and I never bothered trying it on 160 > meters because on all previous attempts with other manual tuners I have > failed to get a good match. > > But, last night, just as a lark, I switched up to 160 meters and gave the > KAT500 a try. Sure enough it found a match of 1.05:1 at 1900 KHz with the > Bypass VSWR reading about 17:1. Given I have most of the transmission line > in lower-loss ladder line helps with the losses to the antenna with that > high bypass SWR. > > This was at 100 watts out from the K3. Now, I decided to give a try with > the KPA500 in-line at about 475 watts and the best I could get is about 4:1 > tuned SWR. Now, I am not quite sure I understand the dynamics of the KAT500 > with higher power. This is what I did. I tuned at 20 watts to the 1.05:1 > SWR (bypass was ~17:1). At 100 watts, my LP-100A was still reading about > 1.1:1 SWR. But, when I turned on the KPA500 (switched out of standby) the > reading was roughly 4:1 with a fault on the KPA500. Question, how does the > higher power affect the match of the KAT500. I understand how higher power > might stress the KAT500 with maybe arcing or something but I don't > understand why the match actually changed unless that higher power caused > some change in the KAT500 capacitor or inductor components. > > > 73, phil, K7PEH > > ______________________________________________________________ > 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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I think the MFJ 998 which I used prior to getting the KAT500 limited the selection of values for the L network based on the band and the assumption that 1500 watts was the possible power. I am able to tune much more of the 160M and 40M bands with the KAT500 than with the MFJ. Since I was using 100 to 400 watts and not the 1500 the MFJ was supposedly rated for, I found it's limits very restrictive to no good purpose.
Good for the KAT500 in the smart programming it has. Sent from my iPad Chuck, KE9UW (Jack for BMW motorcycles) On Jan 23, 2013, at 12:06 PM, "Phil Hystad" <[hidden email]> wrote: > Dick, > > Thanks, this is exactly the kind of clarification I was looking for. Now, if you > or someone says this was described in the manual I will be ashamed and > embarrassed. I already knew about the higher power at lower bypass > SWR. But, I did not realize the lower power at higher bypass SWR. > > phil > > PEH's iPad > > > On Jan 23, 2013, at 9:58 AM, Dick Dievendorff <[hidden email]> wrote: > >> Hi, Phil. >> >> Although the KAT500, like most tuners, will attempt to find a match whenever >> it can, it protects itself from the very high voltages and currents that can >> appear on internal components when the match is poor. We rate the tuner for >> 500 watts at 10:1 SWR. When you use an antenna that shows 17:1 SWR (the >> "untuned" or "bypass" VSWR), the ATU measures the forward power and computes >> the power it can safely handle with the high mismatch. It's less than 500 >> watts. You should be able to operate safely at 250 watts or so with that >> high a bypass VSWR. If you exceed the ATU's safety values, it should >> illuminate the red FAULT led, make a fault log entry, and put the ATU into >> BYPASS at the next opportunity. It should also interrupt the amplifier key >> line. >> >> Dick, K6KR >> >> >> >> >> -----Original Message----- >> From: [hidden email] >> [mailto:[hidden email]] On Behalf Of Phil Hystad >> Sent: Wednesday, January 23, 2013 8:48 AM >> To: [hidden email] List >> Subject: [Elecraft] KAT500 Performance Clarification >> >> Gang, I was surprised last night when I got a descent low SWR tuning my >> 80-meter (ladder-line fed into 4:1 balun) dipole on 160 meters. I have had >> the KAT500 for a couple of months and I never bothered trying it on 160 >> meters because on all previous attempts with other manual tuners I have >> failed to get a good match. >> >> But, last night, just as a lark, I switched up to 160 meters and gave the >> KAT500 a try. Sure enough it found a match of 1.05:1 at 1900 KHz with the >> Bypass VSWR reading about 17:1. Given I have most of the transmission line >> in lower-loss ladder line helps with the losses to the antenna with that >> high bypass SWR. >> >> This was at 100 watts out from the K3. Now, I decided to give a try with >> the KPA500 in-line at about 475 watts and the best I could get is about 4:1 >> tuned SWR. Now, I am not quite sure I understand the dynamics of the KAT500 >> with higher power. This is what I did. I tuned at 20 watts to the 1.05:1 >> SWR (bypass was ~17:1). At 100 watts, my LP-100A was still reading about >> 1.1:1 SWR. But, when I turned on the KPA500 (switched out of standby) the >> reading was roughly 4:1 with a fault on the KPA500. Question, how does the >> higher power affect the match of the KAT500. I understand how higher power >> might stress the KAT500 with maybe arcing or something but I don't >> understand why the match actually changed unless that higher power caused >> some change in the KAT500 capacitor or inductor components. >> >> >> 73, phil, K7PEH >> >> ______________________________________________________________ >> 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 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
Chuck, KE9UW
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