[Elecraft] KPA500 Voltage range?
My kpa500 has the taps set to provide 71-72 VDC no load and drops to 60 at 500 watts. Is this fine or should I change the tap from red to yellow. The yellow gives me 79-80 no load. Thanks, Gordon - N1MGO __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] KPA500 Voltage range?
"My kpa500 has the taps set to provide 71-72 VDC no load and drops to 60 at 500 watts." Do you know how your house line input voltage varies? Mine can be as high as 122 and as low as 118 and the local transformer is less than 50 ft from my house. I see unloaded KPA500 voltage over 80 with tap selected to keep loaded KPA500 voltage at or above 60. If your loaded voltage does not drop below 60 for all bands, all antenna loads, and all used output powers, I see no reason to change the tap. Band, loading, and power output all have a very significant influence on efficiency, PA current, and voltage drop in the PA HV supply. Spot check values: Line voltage 122.0 Unloaded HV 81.4 TX 500 W, 6 m band, SWR 1.15, HV 60.3 Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KPA500 Voltage range?
Andy, Thanks, I'm looking for the VDC allowed voltage, unloaded and loaded. I don't remember the AC, can check it later, but think its 231-232. Gordon - N1MGO On 7/6/2022 8:53 AM, Andy Durbin wrote: "My kpa500 has the taps set to provide 71-72 VDC no load and drops to 60 at 500 watts." Do you know how your house line input voltage varies? Mine can be as high as 122 and as low as 118 and the local transformer is less than 50 ft from my house. I see unloaded KPA500 voltage over 80 with tap selected to keep loaded KPA500 voltage at or above 60. If your loaded voltage does not drop below 60 for all bands, all antenna loads, and all used output powers, I see no reason to change the tap. Band, loading, and power output all have a very significant influence on efficiency, PA current, and voltage drop in the PA HV supply. Spot check values: Line voltage 122.0 Unloaded HV 81.4 TX 500 W, 6 m band, SWR 1.15, HV 60.3 Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to gordon.lapo...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KPA500 Voltage range?
"I don't remember the AC, can check it later, but think its 231-232." Your use of nominal 240 would explain why your HV sag is a lot less than mine. I have always run my KPA500 on 120. Maybe someone who uses nominal 240 would provide their typical loaded and unloaded HV values. Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KPA500 Voltage range?
Andy - I'm also running 120. My HV idle runs about 68v, and under full load drops to 50v @ 12a. Seems a little low, but it's happy. 73 Lyn, W0LEN -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Andy Durbin Sent: Wednesday, July 06, 2022 12:00 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] KPA500 Voltage range? "I don't remember the AC, can check it later, but think its 231-232." Your use of nominal 240 would explain why your HV sag is a lot less than mine. I have always run my KPA500 on 120. Maybe someone who uses nominal 240 would provide their typical loaded and unloaded HV values. Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to l...@lnainc.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KPA500 Voltage range?
"Seems a little low, but it's happy." I though Elecraft wanted HV to be kept at or above 60 to avoid unacceptable IMD. No sure where I found that but don't think I imagined it. Anyone have a reference? Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KPA500 Voltage range?
"I though Elecraft wanted HV to be kept at or above 60 to avoid unacceptable IMD. No sure where I found that but don't think I imagined it. " The problem with making measurements is that one may not like the results. It's a nice warm afternoon here in Glendale AZ and I expect every air conditioner in the street is running. Line voltage is down to 116.4 and loaded HV is well below 60 now. 1:13:59.663 KPA Mon frozen TX freq = 50314500 Hz Drv pwr = 027 W Pwr meter = 12 dots KAT SWR = 1.18 KPA SWR = 01.2 PA voltage = 56.8 V PA current = 13.7 A PA input = 778 W RF out = 495 W PA diss = 283 W PA effic = 63% Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KPA500 Voltage range?
Yup. That's exactly what's happening here - except the numbers are a notch or two lower. 73 Lyn, W0LEN From: Andy Durbin [mailto:a.dur...@msn.com] Sent: Wednesday, July 06, 2022 2:58 PM To: elecraft@mailman.qth.net; l...@lnainc.com Subject: Re: [Elecraft] KPA500 Voltage range? "I though Elecraft wanted HV to be kept at or above 60 to avoid unacceptable IMD. No sure where I found that but don't think I imagined it. " The problem with making measurements is that one may not like the results. It's a nice warm afternoon here in Glendale AZ and I expect every air conditioner in the street is running. Line voltage is down to 116.4 and loaded HV is well below 60 now. 1:13:59.663 KPA Mon frozen TX freq = 50314500 Hz Drv pwr = 027 W Pwr meter = 12 dots KAT SWR = 1.18 KPA SWR = 01.2 PA voltage = 56.8 V PA current = 13.7 A PA input = 778 W RF out = 495 W PA diss = 283 W PA effic = 63% Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
