Re: [Elecraft] KPA-500 270V ERR
Well, at the risk of offending Fred ... A PIN diode has an intrinsic (I) region between the P and N junctions. The I region is almost completely undoped and therefore the carrier lifetimes are long relative to the frequency of the signal being switched. A PIN diode is turned on with CURRENT bias, and as long as the signal current is less than the bias current the carriers live long enough in the I region that the signal just swishes the carriers back and forth without the diode ever becoming reverse biased ... and that holds pretty much no matter what the signal peak to peak voltage is. You turn off a PIN by removing the bias current ... or better yet, reversing it to pull out the carriers. The hard part of making a normal PIN diode is that you have to start with an intrinsic wafer and then diffuse first from one side and then the other side ... and while you're diffusing the second side the dopant from the first side wants to contaminate the I region. (There are other techniques but they get even weirder). A PN diode, on the other hand, is forward biased (i.e., "on") as long as the control VOLTAGE exceeds the signal voltage. As soon as the voltage across the diode reverses, mobile carriers are soon swept out of the junction area and the diode becomes reverse biased and shuts off. As you say, that reverse bias could from either the control voltage OR a higher than expected signal voltage if the reverse peaks of the signal voltage exceed the control voltage. How fast all of that that happens depends upon the carrier lifetimes in the junction region and the frequency of the signal being switched. Fast switching diodes are built with high doping levels to give a narrow junction and short carrier lifetimes, but some high voltage diodes have low doping levels, wide junctions, and therefore moderately slow carrier recombination times. If it just happens that the carrier lifetimes are long enough compared to the signal frequency, it can work. However, I think it's generally bad practice to use a standard diode as a PIN because unexpectedly high signal voltages can reverse bias the diode and create signal distortion ... plus the fact that diode manufacturers are NOT designing standard diodes for use as a PIN diode, and they are NOT specifically trying to control carrier lifetimes during fabrication. A pair of high voltage switching diodes can both fully meet the data sheet specs, while one works quite a bit better than the other when used as a PIN. That which works with today's batch might not work with tomorrow's. 73, Dave AB7E On 8/26/2021 3:58 PM, jerry wrote: On 2021-08-26 15:19, David Gilbert wrote: Pedantic? If those were truly PIN diodes like you called them the 270v bias wouldn't have been used there. Actually, I'm finding this interesting. So with real PIN diodes, you don't have to strongly bias them off? The HV is obtained in various ways. W6JL does diode switching with a tube amp, so he has ample HV available. My K2 has a crystal oscillator feeding a toroid transformer and a voltage multiplier. Hans Summers uses a voltage doubler running off the RF output of his amplifier. I have heard discussions of people using fluorescent ballast transformers. A complication is that the voltage at a transmitter output - even though it's nominal 50 ohms - can rise quite high with high SWR, especially in the "looks like an open circuit" direction. So even though modern LDMOS PA transistors are rated to tolerate extremely high SWRs, your equipment is limited to the SWR that produces a voltage lower than the diode bias. Hans Summers' design is elegant - since he's rectifying and multiplying the RF itself, the DC is guaranteed to be higher than the RF itself. Only thing is - there is surely a delay in creating that bias. I will say that the QRP-labs approach somehow results in the cleanest, most transparent-sounding QSK I've ever heard. Better than my K2. But it's only one band, the selectivity is just ok, and it has no AGC... - Jerry KF6VB Dave AB7E On 8/26/2021 2:56 PM, Fred Jensen wrote: This morphed into a pedantic discussion of solid state diodes. Chuck's original question was about the 270 V error. I'm fairly sure the only purpose for the 270 V in a KPA500 is bias for the T-R switch. He asked for suggestions. The T-R switch and the source for the 270 V might be a good place to start troubleshooting. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 2:23 PM, David Gilbert wrote: High voltage rectifier diodes would have very low doped N-regions, which means fairly long carrier lifetimes so no doubt they work somewhat like a PIN diode if properly biased. But they aren't really the same thing, and I still say that a PIN diode has performance advantages in many situations. They are more difficult and costly to build, though. I used to manage a large
Re: [Elecraft] KPA-500 270V ERR
On 2021-08-26 15:19, David Gilbert wrote: Pedantic? If those were truly PIN diodes like you called them the 270v bias wouldn't have been used there. Actually, I'm finding this interesting. So with real PIN diodes, you don't have to strongly bias them off? The HV is obtained in various ways. W6JL does diode switching with a tube amp, so he has ample HV available. My K2 has a crystal oscillator feeding a toroid transformer and a voltage multiplier. Hans Summers uses a voltage doubler running off the RF output of his amplifier. I have heard discussions of people using fluorescent ballast transformers. A complication is that the voltage at a transmitter output - even though it's nominal 50 ohms - can rise quite high with high SWR, especially in the "looks like an open circuit" direction. So even though modern LDMOS PA transistors are rated to tolerate extremely high SWRs, your equipment is limited to the SWR that produces a voltage lower than the diode bias. Hans Summers' design is elegant - since he's rectifying and multiplying the RF itself, the DC is guaranteed to be higher than the RF itself. Only thing is - there is surely a delay in creating that bias. I will say that the QRP-labs approach somehow results in the cleanest, most transparent-sounding QSK I've ever heard. Better than my K2. But it's only one band, the selectivity is just ok, and it has no AGC... - Jerry KF6VB Dave AB7E On 8/26/2021 2:56 PM, Fred Jensen wrote: This morphed into a pedantic discussion of solid state diodes. Chuck's original question was about the 270 V error. I'm fairly sure the only purpose for the 270 V in a KPA500 is bias for the T-R switch. He asked for suggestions. The T-R switch and the source for the 270 V might be a good place to start troubleshooting. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 2:23 PM, David Gilbert wrote: High voltage rectifier diodes would have very low doped N-regions, which means fairly long carrier lifetimes so no doubt they work somewhat like a PIN diode if properly biased. But they aren't really the same thing, and I still say that a PIN diode has performance advantages in many situations. They are more difficult and costly to build, though. I used to manage a large semiconductor entity that manufactured these things. 73, Dave AB7E On 8/26/2021 2:05 PM, jerry wrote: Using 1N4007's and 1N5208's ( I could have the last # wrong ) as "Poor Man PIN diodes" is pretty established practice in the amateur community. Look up W6JL on QRZ.com. He has an extensive article about it on his page there. Also Hans Summers of qrp-labs uses them in his 50W QSK amplifier. Apparently, these kilovolt rectifiers behave very much like PIN diodes, at speed. - Jerry KF6VB On 2021-08-26 11:46, David Gilbert wrote: That sounds odd to me. True PIN diodes are current actuated devices. The carrier lifetimes are long enough that the devices are "on" even if the signal peaks exceed the voltage of the control current ... as long, of course, as the control current exceeds the signal current. On the other hand, I've heard that Elecraft has sometimes used regular switching diodes instead of PINs, and for those you need a voltage that exceeds the peak voltage of whatever you're switching. Both types of diodes have their place ... using one where the other works better is not good practice. 73, Dave AB7E On 8/26/2021 11:33 AM, Fred Jensen wrote: I think the 270 V circuit is DC bias for the PIN diodes in the TR-switch. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 10:32 AM, Chuck Chandler wrote: My KPA-500 has been running great for several years. Recently I noticed it was making the occasional extra "click" or "thunk" upon powering up or down. Usually it would "click" when powered up and again when powered down, but recently a few seconds after the first click there would be another one, maybe more of a thunk sound. This afternoon I turned it on and when I pushed the Operate/Standby button I got a fault light and the 270V ERR message on the display. The menu HV option shows 68.4V, varying a bit, on my 240V line. I put it on the bench and opened up the top cover. There is a smell of overheated components, maybe burnt but more like too hot. I've submitted the contact form on the Elecraft support page. Any suggestions? For now, I'm running barefoot... 73 de Chuck, WS1L __ 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 ab7e...@gmail.com __ Elecraft mailing list Home:
Re: [Elecraft] KPA-500 270V ERR
Pedantic? If those were truly PIN diodes like you called them the 270v bias wouldn't have been used there. Dave AB7E On 8/26/2021 2:56 PM, Fred Jensen wrote: This morphed into a pedantic discussion of solid state diodes. Chuck's original question was about the 270 V error. I'm fairly sure the only purpose for the 270 V in a KPA500 is bias for the T-R switch. He asked for suggestions. The T-R switch and the source for the 270 V might be a good place to start troubleshooting. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 2:23 PM, David Gilbert wrote: High voltage rectifier diodes would have very low doped N-regions, which means fairly long carrier lifetimes so no doubt they work somewhat like a PIN diode if properly biased. But they aren't really the same thing, and I still say that a PIN diode has performance advantages in many situations. They are more difficult and costly to build, though. I used to manage a large semiconductor entity that manufactured these things. 73, Dave AB7E On 8/26/2021 2:05 PM, jerry wrote: Using 1N4007's and 1N5208's ( I could have the last # wrong ) as "Poor Man PIN diodes" is pretty established practice in the amateur community. Look up W6JL on QRZ.com. He has an extensive article about it on his page there. Also Hans Summers of qrp-labs uses them in his 50W QSK amplifier. Apparently, these kilovolt rectifiers behave very much like PIN diodes, at speed. - Jerry KF6VB On 2021-08-26 11:46, David Gilbert wrote: That sounds odd to me. True PIN diodes are current actuated devices. The carrier lifetimes are long enough that the devices are "on" even if the signal peaks exceed the voltage of the control current ... as long, of course, as the control current exceeds the signal current. On the other hand, I've heard that Elecraft has sometimes used regular switching diodes instead of PINs, and for those you need a voltage that exceeds the peak voltage of whatever you're switching. Both types of diodes have their place ... using one where the other works better is not good practice. 73, Dave AB7E On 8/26/2021 11:33 AM, Fred Jensen wrote: I think the 270 V circuit is DC bias for the PIN diodes in the TR-switch. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 10:32 AM, Chuck Chandler wrote: My KPA-500 has been running great for several years. Recently I noticed it was making the occasional extra "click" or "thunk" upon powering up or down. Usually it would "click" when powered up and again when powered down, but recently a few seconds after the first click there would be another one, maybe more of a thunk sound. This afternoon I turned it on and when I pushed the Operate/Standby button I got a fault light and the 270V ERR message on the display. The menu HV option shows 68.4V, varying a bit, on my 240V line. I put it on the bench and opened up the top cover. There is a smell of overheated components, maybe burnt but more like too hot. I've submitted the contact form on the Elecraft support page. Any suggestions? For now, I'm running barefoot... 73 de Chuck, WS1L __ 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 ab7e...@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] KPA-500 270V ERR
This morphed into a pedantic discussion of solid state diodes. Chuck's original question was about the 270 V error. I'm fairly sure the only purpose for the 270 V in a KPA500 is bias for the T-R switch. He asked for suggestions. The T-R switch and the source for the 270 V might be a good place to start troubleshooting. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 2:23 PM, David Gilbert wrote: High voltage rectifier diodes would have very low doped N-regions, which means fairly long carrier lifetimes so no doubt they work somewhat like a PIN diode if properly biased. But they aren't really the same thing, and I still say that a PIN diode has performance advantages in many situations. They are more difficult and costly to build, though. I used to manage a large semiconductor entity that manufactured these things. 73, Dave AB7E On 8/26/2021 2:05 PM, jerry wrote: Using 1N4007's and 1N5208's ( I could have the last # wrong ) as "Poor Man PIN diodes" is pretty established practice in the amateur community. Look up W6JL on QRZ.com. He has an extensive article about it on his page there. Also Hans Summers of qrp-labs uses them in his 50W QSK amplifier. Apparently, these kilovolt rectifiers behave very much like PIN diodes, at speed. - Jerry KF6VB On 2021-08-26 11:46, David Gilbert wrote: That sounds odd to me. True PIN diodes are current actuated devices. The carrier lifetimes are long enough that the devices are "on" even if the signal peaks exceed the voltage of the control current ... as long, of course, as the control current exceeds the signal current. On the other hand, I've heard that Elecraft has sometimes used regular switching diodes instead of PINs, and for those you need a voltage that exceeds the peak voltage of whatever you're switching. Both types of diodes have their place ... using one where the other works better is not good practice. 73, Dave AB7E On 8/26/2021 11:33 AM, Fred Jensen wrote: I think the 270 V circuit is DC bias for the PIN diodes in the TR-switch. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 10:32 AM, Chuck Chandler wrote: My KPA-500 has been running great for several years. Recently I noticed it was making the occasional extra "click" or "thunk" upon powering up or down. Usually it would "click" when powered up and again when powered down, but recently a few seconds after the first click there would be another one, maybe more of a thunk sound. This afternoon I turned it on and when I pushed the Operate/Standby button I got a fault light and the 270V ERR message on the display. The menu HV option shows 68.4V, varying a bit, on my 240V line. I put it on the bench and opened up the top cover. There is a smell of overheated components, maybe burnt but more like too hot. I've submitted the contact form on the Elecraft support page. Any suggestions? For now, I'm running barefoot... 73 de Chuck, WS1L __ 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] KPA-500 270V ERR
High voltage rectifier diodes would have very low doped N-regions, which means fairly long carrier lifetimes so no doubt they work somewhat like a PIN diode if properly biased. But they aren't really the same thing, and I still say that a PIN diode has performance advantages in many situations. They are more difficult and costly to build, though. I used to manage a large semiconductor entity that manufactured these things. 73, Dave AB7E On 8/26/2021 2:05 PM, jerry wrote: Using 1N4007's and 1N5208's ( I could have the last # wrong ) as "Poor Man PIN diodes" is pretty established practice in the amateur community. Look up W6JL on QRZ.com. He has an extensive article about it on his page there. Also Hans Summers of qrp-labs uses them in his 50W QSK amplifier. Apparently, these kilovolt rectifiers behave very much like PIN diodes, at speed. - Jerry KF6VB On 2021-08-26 11:46, David Gilbert wrote: That sounds odd to me. True PIN diodes are current actuated devices. The carrier lifetimes are long enough that the devices are "on" even if the signal peaks exceed the voltage of the control current ... as long, of course, as the control current exceeds the signal current. On the other hand, I've heard that Elecraft has sometimes used regular switching diodes instead of PINs, and for those you need a voltage that exceeds the peak voltage of whatever you're switching. Both types of diodes have their place ... using one where the other works better is not good practice. 73, Dave AB7E On 8/26/2021 11:33 AM, Fred Jensen wrote: I think the 270 V circuit is DC bias for the PIN diodes in the TR-switch. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 10:32 AM, Chuck Chandler wrote: My KPA-500 has been running great for several years. Recently I noticed it was making the occasional extra "click" or "thunk" upon powering up or down. Usually it would "click" when powered up and again when powered down, but recently a few seconds after the first click there would be another one, maybe more of a thunk sound. This afternoon I turned it on and when I pushed the Operate/Standby button I got a fault light and the 270V ERR message on the display. The menu HV option shows 68.4V, varying a bit, on my 240V line. I put it on the bench and opened up the top cover. There is a smell of overheated components, maybe burnt but more like too hot. I've submitted the contact form on the Elecraft support page. Any suggestions? For now, I'm running barefoot... 73 de Chuck, WS1L __ 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 ab7e...@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 je...@tr2.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] KPA-500 270V ERR
Using 1N4007's and 1N5208's ( I could have the last # wrong ) as "Poor Man PIN diodes" is pretty established practice in the amateur community. Look up W6JL on QRZ.com. He has an extensive article about it on his page there. Also Hans Summers of qrp-labs uses them in his 50W QSK amplifier. Apparently, these kilovolt rectifiers behave very much like PIN diodes, at speed. - Jerry KF6VB On 2021-08-26 11:46, David Gilbert wrote: That sounds odd to me. True PIN diodes are current actuated devices. The carrier lifetimes are long enough that the devices are "on" even if the signal peaks exceed the voltage of the control current ... as long, of course, as the control current exceeds the signal current. On the other hand, I've heard that Elecraft has sometimes used regular switching diodes instead of PINs, and for those you need a voltage that exceeds the peak voltage of whatever you're switching. Both types of diodes have their place ... using one where the other works better is not good practice. 73, Dave AB7E On 8/26/2021 11:33 AM, Fred Jensen wrote: I think the 270 V circuit is DC bias for the PIN diodes in the TR-switch. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 10:32 AM, Chuck Chandler wrote: My KPA-500 has been running great for several years. Recently I noticed it was making the occasional extra "click" or "thunk" upon powering up or down. Usually it would "click" when powered up and again when powered down, but recently a few seconds after the first click there would be another one, maybe more of a thunk sound. This afternoon I turned it on and when I pushed the Operate/Standby button I got a fault light and the 270V ERR message on the display. The menu HV option shows 68.4V, varying a bit, on my 240V line. I put it on the bench and opened up the top cover. There is a smell of overheated components, maybe burnt but more like too hot. I've submitted the contact form on the Elecraft support page. Any suggestions? For now, I'm running barefoot... 73 de Chuck, WS1L __ 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 ab7e...@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 je...@tr2.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] KPA-500 270V ERR
My schematic shows TR Switch diode type is S1M. Datasheet easily found on-line. I doubt this has any influence of 270 V failure. 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] KPA-500 270V ERR
That sounds odd to me. True PIN diodes are current actuated devices. The carrier lifetimes are long enough that the devices are "on" even if the signal peaks exceed the voltage of the control current ... as long, of course, as the control current exceeds the signal current. On the other hand, I've heard that Elecraft has sometimes used regular switching diodes instead of PINs, and for those you need a voltage that exceeds the peak voltage of whatever you're switching. Both types of diodes have their place ... using one where the other works better is not good practice. 73, Dave AB7E On 8/26/2021 11:33 AM, Fred Jensen wrote: I think the 270 V circuit is DC bias for the PIN diodes in the TR-switch. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 10:32 AM, Chuck Chandler wrote: My KPA-500 has been running great for several years. Recently I noticed it was making the occasional extra "click" or "thunk" upon powering up or down. Usually it would "click" when powered up and again when powered down, but recently a few seconds after the first click there would be another one, maybe more of a thunk sound. This afternoon I turned it on and when I pushed the Operate/Standby button I got a fault light and the 270V ERR message on the display. The menu HV option shows 68.4V, varying a bit, on my 240V line. I put it on the bench and opened up the top cover. There is a smell of overheated components, maybe burnt but more like too hot. I've submitted the contact form on the Elecraft support page. Any suggestions? For now, I'm running barefoot... 73 de Chuck, WS1L __ 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 ab7e...@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] KPA-500 270V ERR
I think the 270 V circuit is DC bias for the PIN diodes in the TR-switch. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/26/2021 10:32 AM, Chuck Chandler wrote: My KPA-500 has been running great for several years. Recently I noticed it was making the occasional extra "click" or "thunk" upon powering up or down. Usually it would "click" when powered up and again when powered down, but recently a few seconds after the first click there would be another one, maybe more of a thunk sound. This afternoon I turned it on and when I pushed the Operate/Standby button I got a fault light and the 270V ERR message on the display. The menu HV option shows 68.4V, varying a bit, on my 240V line. I put it on the bench and opened up the top cover. There is a smell of overheated components, maybe burnt but more like too hot. I've submitted the contact form on the Elecraft support page. Any suggestions? For now, I'm running barefoot... 73 de Chuck, WS1L __ 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] KPA-500 270V ERR
Well if it were mine I'd check the voltage on the nominal 270 V connector on the PA module then work back from there. I keep notes from discussion of other peoples problems and their resolution. You can find all this in the archive but this is what I have in my notes for KPA 270 V problems: KPA500 270V failure: (two post by Dr. William J. Schmidt ) There are two voltage Test Points "TP" on the board under with the diodes and you need to check the voltages on those test points. Here it is. From Elecraft technical support: Nominally: TP2= RX 13.1 TX 0.8 TP4= RX 3.9 TX 13 >From Rene Morris at Elecraft (great guy!). and Thanks for the reply but in my case the problem is the voltage multiplier circuit on the power supply PCB. I just disconnected the HV (~70V) and 270V lines so they did not go anywhere and the 270V line still only measures 85V. Thanks Bruce, WB6IZG Thanks to the 2 people who replied. Thanks to Keith VE7KW who had R16 (100 Ohm) SMD resistor fail on his PS board in his KPA500. I had the same problem here. R16 tested open. It does not appear to be cracked or burnt, just a failure. R16 appears to be a resistor that feeds the voltage multiplier circuit for the 270V line. Bottom line is my KPA500 is back in service. Bruce, WB6IZG Good luck and let us know what you find. 73, 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
[Elecraft] KPA-500 270V ERR
My KPA-500 has been running great for several years. Recently I noticed it was making the occasional extra "click" or "thunk" upon powering up or down. Usually it would "click" when powered up and again when powered down, but recently a few seconds after the first click there would be another one, maybe more of a thunk sound. This afternoon I turned it on and when I pushed the Operate/Standby button I got a fault light and the 270V ERR message on the display. The menu HV option shows 68.4V, varying a bit, on my 240V line. I put it on the bench and opened up the top cover. There is a smell of overheated components, maybe burnt but more like too hot. I've submitted the contact form on the Elecraft support page. Any suggestions? For now, I'm running barefoot... 73 de Chuck, WS1L chandler...@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
