Re: [Elecraft] KPA100 problem with SWR bridge - High SWR
Thanks for all the help. Got it working FB and made my first contact tonight. 73 Stan AE7UT -- View this message in context: http://elecraft.365791.n2.nabble.com/KPA100-problem-with-SWR-bridge-High-SWR-tp7580050p7580069.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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] KPA100 problem with SWR bridge - High SWR
I'm building a KPA100 and am having trouble with the SWR bridge adjustment. I'm getting high swr on the lower bands and can't get 1:1 on even the upper bands. 160 9.9:1 809.9:1 409.9:1 309.5:1 206.7:1 175.0:1 154.5:1 124.0:2 103.7:1 (I know 9.9 is the highest it will show and it's probably higher on some) I've checked T4 and it seems to be working properly. The toroid was build by the toroid guy. The diodes all seem to be in the proper orientation and working. Can anyone point me in the next step in figuring this one out? Thanks Stan AE7UT -- View this message in context: http://elecraft.365791.n2.nabble.com/KPA100-problem-with-SWR-bridge-High-SWR-tp7580050.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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] KPA100 Problem
Well, I wanted to change the bridge diodes in the KPA 100 cause I was getting some wierd readings and hi swr readings so I decided to upgrade it while I had it apart. I did the whole upgrade and now as soon as I put it in high power, even at only 15 watts, I get PA HOT readings. I have checked all the parts values twice and did the calibration again including the C6 adjust, the r26 and 27 adjusts and even pulled the finals to make sure they weren't shorted or anything. Q3 and Q4 seem fine and are not cracked. The voltages seem to be fine and I readjusted R6 bias as per book. Whats wierd is as soon as I hit the key, even at 15 watts the fan comes on with the keying. A dot gives a short fan wiggle and an dash gives a loneger fan activation. Eventually it comes on and then I get the PA HOT. The fan even responds to my voice on SSB. I mean it comes on almost instantly. I have checked the archives and am starting to suspect the finals. I put on new pads on the transisto rs and checked it all twice. Resoldered all connections. All works fine at 10 watts. Im sure Im missing something but I dont seem to be able to find it. Any ideas where I can check before I order new finals and go through that work again. Thanks MarkN5MF __ 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
Re: [Elecraft] KPA100 Problem
Mark, Have you checked the setting of the K2 CAL TPA menu? It should read the same as the actual temperature of the PA transistor cases. Let everything acclimate to the ambient room temperature (power off for 30 minutes should do it), then turn power on and set CAL TPA to the room temperature in degC. 73, Don W3FPR On 11/26/2011 11:44 AM, Mark Flavin wrote: Well, I wanted to change the bridge diodes in the KPA 100 cause I was getting some wierd readings and hi swr readings so I decided to upgrade it while I had it apart. I did the whole upgrade and now as soon as I put it in high power, even at only 15 watts, I get PA HOT readings. I have checked all the parts values twice and did the calibration again including the C6 adjust, the r26 and 27 adjusts and even pulled the finals to make sure they weren't shorted or anything. Q3 and Q4 seem fine and are not cracked. The voltages seem to be fine and I readjusted R6 bias as per book. Whats wierd is as soon as I hit the key, even at 15 watts the fan comes on with the keying. A dot gives a short fan wiggle and an dash gives a loneger fan activation. Eventually it comes on and then I get the PA HOT. The fan even responds to my voice on SSB. I mean it comes on almost instantly. I have checked the archives and am starting to suspect the finals. I put on new pads on the transis to rs and checked it all twice. Resoldered all connections. All works fine at 10 watts. Im sure Im missing something but I dont seem to be able to find it. Any ideas where I can check before I order new finals and go through that work again. Thanks MarkN5MF __ 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
Re: [Elecraft] KPA100 Problem
Yeah. I did that too. Im dreading changing the finals lol T-Mobile. America's First Nationwide 4G Network. -Original message- From: Don Wilhelm w3...@embarqmail.com To: Mark Flavin markf1...@hotmail.com Cc: elecraft@mailman.qth.net Sent: Sat, Nov 26, 2011 17:45:04 GMT+00:00 Subject: Re: [Elecraft] KPA100 Problem Mark, Have you checked the setting of the K2 CAL TPA menu? It should read the same as the actual temperature of the PA transistor cases. Let everything acclimate to the ambient room temperature (power off for 30 minutes should do it), then turn power on and set CAL TPA to the room temperature in degC. 73, Don W3FPR On 11/26/2011 11:44 AM, Mark Flavin wrote: Well, I wanted to change the bridge diodes in the KPA 100 cause I was getting some wierd readings and hi swr readings so I decided to upgrade it while I had it apart. I did the whole upgrade and now as soon as I put it in high power, even at only 15 watts, I get PA HOT readings. I have checked all the parts values twice and did the calibration again including the C6 adjust, the r26 and 27 adjusts and even pulled the finals to make sure they weren't shorted or anything. Q3 and Q4 seem fine and are not cracked. The voltages seem to be fine and I readjusted R6 bias as per book. Whats wierd is as soon as I hit the key, even at 15 watts the fan comes on with the keying. A dot gives a short fan wiggle and an dash gives a loneger fan activation. Eventually it comes on and then I get the PA HOT. The fan even responds to my voice on SSB. I mean it comes on almost instantly. I have checked the archives and am starting to suspect the finals. I put on new pads on the transisto rs and checked it all twice. Resoldered all connections. All works fine at 10 watts. Im sure Im missing something but I dont seem to be able to find it. Any ideas where I can check before I order new finals and go through that work again. Thanks MarkN5MF __ 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
Re: [Elecraft] KPA100 Problem
Mark, I don't think the finals are the problem. I would check Q3 for good soldering and the value and soldering of R5 - make certain you used the 1k trimmer at R6 rather than the 100k trimmers for R26 and R27. The soldering at U1 pin 5 should also be checked, and be certain U1 pin 5 is not bent under the socket or sticking out the side. Make certain there is 5 volts on one end of R5 - if not, find out why. The temperature of the heatsink is sensed by the conduction through Q3 from the base to the emitter (and collector), that resulting voltage is sent to U1 pin 5 for calculation by the firmware - it has nothing to do with the actual PA transistors, just the temperature of the heatsink at the Q3 location. 73, Don W3FPR On 11/26/2011 1:04 PM, Mark Flavin wrote: Yeah. I did that too. Im dreading changing the finals lol T-Mobile. America's First Nationwide 4G Network. -Original message- From: Don Wilhelmw3...@embarqmail.com To: Mark Flavinmarkf1...@hotmail.com Cc: elecraft@mailman.qth.net Sent: Sat, Nov 26, 2011 17:45:04 GMT+00:00 Subject: Re: [Elecraft] KPA100 Problem Mark, Have you checked the setting of the K2 CAL TPA menu? It should read the same as the actual temperature of the PA transistor cases. Let everything acclimate to the ambient room temperature (power off for 30 minutes should do it), then turn power on and set CAL TPA to the room temperature in degC. 73, Don W3FPR On 11/26/2011 11:44 AM, Mark Flavin wrote: Well, I wanted to change the bridge diodes in the KPA 100 cause I was getting some wierd readings and hi swr readings so I decided to upgrade it while I had it apart. I did the whole upgrade and now as soon as I put it in high power, even at only 15 watts, I get PA HOT readings. I have checked all the parts values twice and did the calibration again including the C6 adjust, the r26 and 27 adjusts and even pulled the finals to make sure they weren't shorted or anything. Q3 and Q4 seem fine and are not cracked. The voltages seem to be fine and I readjusted R6 bias as per book. Whats wierd is as soon as I hit the key, even at 15 watts the fan comes on with the keying. A dot gives a short fan wiggle and an dash gives a loneger fan activation. Eventually it comes on and then I get the PA HOT. The fan even responds to my voice on SSB. I mean it comes on almost instantly. I have checked the archives and am starting to suspect the finals. I put on new pads on the transisto rs and checked it all twice. Resoldered all connections. All works fine at 10 watts. Im sure Im missing something but I dont seem to be able to find it. Any ideas where I can check before I order new finals and go through that work again. Thanks MarkN5MF __ 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 __ 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
Re: [Elecraft] KPA100 Problem
Thanks Don. This thing worked before I did the upg kit. I will check that again but I didn't really touch those. Perhaps I will remove the Q3 and check that area. Best I can tell the upgrade didn't really address any of that but I don't know. The finals don't get hot at all. I even took the heatsink off to make sure there were no shorts or anything and its the same. The weird thing is how the fan starts and stops as I key even at low (11 to 15 watts) power. I just hope its not the finals. I don't think so either but I want to try everything else first. Could Q3 just be too sensitive due to something. I could try changing it I suppose. T-Mobile. America's First Nationwide 4G Network. -Original message- From: Don Wilhelm w3...@embarqmail.com To: Mark Flavin markf1...@hotmail.com Cc: elecraft@mailman.qth.net Sent: Sat, Nov 26, 2011 19:00:07 GMT+00:00 Subject: Re: [Elecraft] KPA100 Problem Mark, I don't think the finals are the problem. I would check Q3 for good soldering and the value and soldering of R5 - make certain you used the 1k trimmer at R6 rather than the 100k trimmers for R26 and R27. The soldering at U1 pin 5 should also be checked, and be certain U1 pin 5 is not bent under the socket or sticking out the side. Make certain there is 5 volts on one end of R5 - if not, find out why. The temperature of the heatsink is sensed by the conduction through Q3 from the base to the emitter (and collector), that resulting voltage is sent to U1 pin 5 for calculation by the firmware - it has nothing to do with the actual PA transistors, just the temperature of the heatsink at the Q3 location. 73, Don W3FPR On 11/26/2011 1:04 PM, Mark Flavin wrote: Yeah. I did that too. Im dreading changing the finals lol T-Mobile. America's First Nationwide 4G Network. -Original message- From: Don Wilhelmw3...@embarqmail.com To: Mark Flavinmarkf1...@hotmail.com Cc: elecraft@mailman.qth.net Sent: Sat, Nov 26, 2011 17:45:04 GMT+00:00 Subject: Re: [Elecraft] KPA100 Problem Mark, Have you checked the setting of the K2 CAL TPA menu? It should read the same as the actual temperature of the PA transistor cases. Let everything acclimate to the ambient room temperature (power off for 30 minutes should do it), then turn power on and set CAL TPA to the room temperature in degC. 73, Don W3FPR On 11/26/2011 11:44 AM, Mark Flavin wrote: Well, I wanted to change the bridge diodes in the KPA 100 cause I was getting some wierd readings and hi swr readings so I decided to upgrade it while I had it apart. I did the whole upgrade and now as soon as I put it in high power, even at only 15 watts, I get PA HOT readings. I have checked all the parts values twice and did the calibration again including the C6 adjust, the r26 and 27 adjusts and even pulled the finals to make sure they weren't shorted or anything. Q3 and Q4 seem fine and are not cracked. The voltages seem to be fine and I readjusted R6 bias as per book. Whats wierd is as soon as I hit the key, even at 15 watts the fan comes on with the keying. A dot gives a short fan wiggle and an dash gives a loneger fan activation. Eventually it comes on and then I get the PA HOT. The fan even responds to my voice on SSB. I mean it comes on almost instantly. I have checked the archives and am starting to suspect the finals. I put on new pads on the transisto rs and checked it all twice. Resoldered all connections. All works fine at 10 watts. Im sure Im missing something but I dont seem to be able to find it. Any ideas where I can check before I order new finals and go through that work again. Thanks MarkN5MF __ 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 __ 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
Re: [Elecraft] KPA100 Problem
Mark, If there was a marginal solder connection, it may have worked but with the movement involved with the upgrade, it may have finally failed. Yes, investigate those components that I mentioned. If the temperature is not being sensed, the fan will be turned on and off by the firmware because the firmware is not getting correct information about the actual temperature. Are the thermal pads under Q3 and Q4 in good shape? It may be worth replacing them if there is any question. 73, Don W3FPR On 11/26/2011 2:24 PM, Mark Flavin wrote: Thanks Don. This thing worked before I did the upg kit. I will check that again but I didn't really touch those. Perhaps I will remove the Q3 and check that area. Best I can tell the upgrade didn't really address any of that but I don't know. The finals don't get hot at all. I even took the heatsink off to make sure there were no shorts or anything and its the same. The weird thing is how the fan starts and stops as I key even at low (11 to 15 watts) power. I just hope its not the finals. I don't think so either but I want to try everything else first. Could Q3 just be too sensitive due to something. I could try changing it I suppose. __ 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
Re: [Elecraft] KPA100 Problem
Ok. I will do that. Anything is worth a try T-Mobile. America's First Nationwide 4G Network. -Original message- From: Don Wilhelm w3...@embarqmail.com To: Mark Flavin markf1...@hotmail.com Cc: elecraft@mailman.qth.net Sent: Sat, Nov 26, 2011 20:05:50 GMT+00:00 Subject: Re: [Elecraft] KPA100 Problem Mark, If there was a marginal solder connection, it may have worked but with the movement involved with the upgrade, it may have finally failed. Yes, investigate those components that I mentioned. If the temperature is not being sensed, the fan will be turned on and off by the firmware because the firmware is not getting correct information about the actual temperature. Are the thermal pads under Q3 and Q4 in good shape? It may be worth replacing them if there is any question. 73, Don W3FPR On 11/26/2011 2:24 PM, Mark Flavin wrote: Thanks Don. This thing worked before I did the upg kit. I will check that again but I didn't really touch those. Perhaps I will remove the Q3 and check that area. Best I can tell the upgrade didn't really address any of that but I don't know. The finals don't get hot at all. I even took the heatsink off to make sure there were no shorts or anything and its the same. The weird thing is how the fan starts and stops as I key even at low (11 to 15 watts) power. I just hope its not the finals. I don't think so either but I want to try everything else first. Could Q3 just be too sensitive due to something. I could try changing it I suppose. __ 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
[Elecraft] KPA100 problem
Hello from north Italy. I have a K2 sn 6822. With my 1nd KPA100 it's ok (Rev F Oct 2009) With my 2nd KPA100 (Rev B June 2003) , I have a little problem. If 11 WATT work fine. If 11 WATT, I have HI CUR on display, for a bit moment, 5 watt on display is reality abt 15 watt Need I upgrade my KPA100 ? Let me konw Tnx vy 73 in3acv, Luva __ 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
Re: [Elecraft] KPA100 problem
Luca, I believe you also have a problem at 11 watts. If you check the actual power I believe you will find it is always high (100 watts) at any setting of the power control above 11 watts. The problem is that the power output from the KPA100 is not being reported to the base K2 microprocessor. Yes, this also happens at low power. The result is that the microprocessor detects no power output and ramps up the drive to full in an attempt to obtain more power. The most likely problem source is that the diodes D16 and D17 have been damaged - probable cause is a lightning (or rain or wind or snow) static. The normal recommendation is to remove the antenna when not in use. Other possible failure points are U5 and U6 in the KPA100. If you do find the diodes damaged, it may be a wise step to put a 100 uHy inductor in your antenna system, located near the K2. Inside an antenna switch or relay box is one possibility, but lacking that, put the inductor inside the barrel of a PL-259 connector (one inductor lead to the center conductor, the other to the shell), then connect that assembly to the feedline using a coax TEE adapter. I will not guarantee that the added inductor will prevent all future diode failures, but it will reduce the probability of failure. 73, Don W3FPR 73, Don W3FPR Luca Valer wrote: Hello from north Italy. I have a K2 sn 6822. With my 1nd KPA100 it's ok (Rev F Oct 2009) With my 2nd KPA100 (Rev B June 2003) , I have a little problem. If 11 WATT work fine. If 11 WATT, I have HI CUR on display, for a bit moment, 5 watt on display is reality abt 15 watt Need I upgrade my KPA100 ? Let me konw Tnx vy 73 in3acv, Luva __ 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 __ 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
Re: [Elecraft] KPA100 problem / Update
OK,my new MAX1406's came in today. I really made a point to check out every possible cause for the previous chip issues. Installed the new MAX1406 and now have 122.1 V's at the junction of C77 and R11. Also have a -22.4 V's at pin 8 of U4. So, the new chip fixed this issue Now to move on to the next challenge. Thanks to everybody for your suggestions and support. 73JerryN0JRN - Original Message - From: Don Wilhelm d...@w3fpr.com To: n0jrn n0...@mchsi.com Sent: Monday, December 14, 2009 6:22 AM Subject: Re: [Elecraft] KPA100 problem Jerry, I will take back what I said about U4 - it is faulty. That negative voltage is there only to allow the RS-232 drivers to produce a negative level, the current draw should be minimal. The only thing U4 does is convert RS-232 levels to TTL levels and vice-versa. __ 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
Re: [Elecraft] KPA100 problem
Good Morning Don / Andrew: I very much appreciate both your suggestions. DON:I do have the KPA100UPKT installed and R4 is 100K. So, I will lift D8 and see what results I get. BUT first, I'll check the caps in the rectifier section as Andrew suggests to make sure all is well there. Now to call Mouser and get another MAX1406 on the way Thanks guys and I'll keep you up on how things work out. 72JerryN0JRN On 12/14/2009 6:22:37 AM, Don Wilhelm (d...@w3fpr.com) wrote: Jerry, I will take back what I said about U4 - it is faulty. That negative voltage is there only to allow the RS-232 drivers to produce a negative level, the current draw should be minimal. The only thing U4 does is convert RS-232 levels to TTL levels and vice-versa. Actually -28 volts is a bit much and does exceed the maximum speced voltage for the chip. -12 volts is more than sufficient and even -5 volts is OK, so lowering the voltage a bit will help with the life of the chip. Do you have the KPA100UPKT installed (look for blue toroid cores at L16 and RFC1)? If installed, change R4 to 100k if it is not already. If R4 is already 100k or you have red toroid cores at L15 and L16, remove D8 to drop the negative voltage to about half its present value. The KPA100 amplifier will function fine without U4 installed, but you will not be able to use the RS-232 portion of the AUX I//O connector. 73, Don W3FPR __ 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
Re: [Elecraft] KPA100 problem
Don: Just to clarify ! The -28V's I'm seeing at pin 8 of U4 is measured without the IC installed. Lets say for the sake of conversation that I install a good MAX1406 and it draws on the rectifier circuit a minimal amount. Would / could that bring the -28V's back into specs for this chip???. ( I have to figure Wayne designed the circuit taking this draw into consideration ) OR is my -28V's so abnormal that I need to be looking at other issues in my rectifier pack to bring this negative voltage back into spec ??? Could the negative voltage I'm getting be responsible for damaging this chip ??? I have 2 new chips coming from Mouser. I'm not installing them until I'm satisfied that I've checked and double checked EVERYTHING involved. Thanks again and happy holidays to the group: 72 Jerry N0JRN - Original Message - From: Don Wilhelm d...@w3fpr.com To: n0jrn n0...@mchsi.com Sent: Monday, December 14, 2009 6:22 AM Subject: Re: [Elecraft] KPA100 problem Jerry, I will take back what I said about U4 - it is faulty. That negative voltage is there only to allow the RS-232 drivers to produce a negative level, the current draw should be minimal. The only thing U4 does is convert RS-232 levels to TTL levels and vice-versa. Actually -28 volts is a bit much and does exceed the maximum speced voltage for the chip. -12 volts is more than sufficient and even -5 __ 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
Re: [Elecraft] KPA100 problem
Jerry, That answer depends on which set of specifications you want to believe. I am saying that the Absolute Maximum Specification for the Maxim MAX1406 for Vss (pin 8) is -14 volts - you can check the data sheet for yourself. Yes, many KPA100s exceed that value - note that the KPA100 DC voltage chart lists the nominal voltage at U4 pin 8 at -22 volts. Whether that is a cause for failure of the chip is reason for speculation, there is not enough data to say yeah or nay. . What I have offered is a way to reduce the Vss voltage to the MAX1406 without also reducing the bias voltage to the KPA100 T/R switch. That involves removing D8, and D8 alone. The data sheet Electrical Characteristics current for pin 8 (Iss) is typical 185 uA with a maximum of 500 uA. for a Vss of -13.2 volts Minimum to -10.8 Maximum - that is not a lot of current draw on that pin. I am stating that a Vss (U4 pin 8) voltage less than -14 volts exceeds the Absolute Maximum Voltage rating per the MAX1406 datasheet - nothing more and nothing less. 73, Don W3FPR n0jrn wrote: Don: Just to clarify ! The -28V's I'm seeing at pin 8 of U4 is measured without the IC installed. Lets say for the sake of conversation that I install a good MAX1406 and it draws on the rectifier circuit a minimal amount. Would / could that bring the -28V's back into specs for this chip???. ( I have to figure Wayne designed the circuit taking this draw into consideration ) OR is my -28V's so abnormal that I need to be looking at other issues in my rectifier pack to bring this negative voltage back into spec ??? Could the negative voltage I'm getting be responsible for damaging this chip ??? I have 2 new chips coming from Mouser. I'm not installing them until I'm satisfied that I've checked and double checked EVERYTHING involved. Thanks again and happy holidays to the group: 72 Jerry N0JRN - Original Message - From: Don Wilhelm d...@w3fpr.com To: n0jrn n0...@mchsi.com Sent: Monday, December 14, 2009 6:22 AM Subject: Re: [Elecraft] KPA100 problem Jerry, I will take back what I said about U4 - it is faulty. That negative voltage is there only to allow the RS-232 drivers to produce a negative level, the current draw should be minimal. The only thing U4 does is convert RS-232 levels to TTL levels and vice-versa. Actually -28 volts is a bit much and does exceed the maximum speced voltage for the chip. -12 volts is more than sufficient and even -5 __ 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 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.716 / Virus Database: 270.14.107/2564 - Release Date: 12/14/09 02:37:00 __ 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
[Elecraft] KPA100 problem
Gang: I need some advise please. I'm trying to finish my KPA100 but I can't seem to get beyond voltage tests on page 46 of the manual. I should be getting 90 to 150 V's at the junction of C77 R11 but only getting 47 volts. I should be getting -5 to -25 V's at pin 8 of U4 BUT I'm only seeing -4.1. I did some research in the archives and came up with a few ideas.Checked D1 - D8 and T3 pads. All diodes pass continuity test and T3 seems fine and shows zero resistance between pads. Checking the schematics prompted me to lift the anode of D7 to remove U4. In doing this, the voltage at the junction of R11 came up into spec and shows 150 V's. This means that U4 is drawing the circuit down. SO, I sent Elecraft an e-mail and Gary sent me a new MAX1406. Figured I would install it and all would be good.NOT ! After installing the new U4,I rechecked voltage at R11 and found it is still just 47 V's. I've double checked orientation of U4, and it's fine. I was very careful to observe anti static procedures when installing the new chip. SO, I'm confused and not sure where to go from here. Any advise would be greatly appreciated. Thanks 72: Jerry N0JRN __ 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
Re: [Elecraft] KPA100 problem
Jerry, That means U4 is not the problem, the problem is somewhere in the rectifier stack and goes away when you lift the anode of D7. Check both D7 and D8 for proper orientation (use the parts placement diagram since the board silkscreen is covered). Check for a solder bridge across the leads of C38. Be certain C35 is soldered properly. If you lift the anode of D7 and place a 0.1 uF capacitor from the flying lead of D7 to ground, what is the voltage at the D7 anode? I know that did not fully identify the failure point, but hopefully it gives you some clues. 73, Don W3FPR n0jrn wrote: Gang: I need some advise please. I'm trying to finish my KPA100 but I can't seem to get beyond voltage tests on page 46 of the manual. I should be getting 90 to 150 V's at the junction of C77 R11 but only getting 47 volts. I should be getting -5 to -25 V's at pin 8 of U4 BUT I'm only seeing -4.1. I did some research in the archives and came up with a few ideas.Checked D1 - D8 and T3 pads. All diodes pass continuity test and T3 seems fine and shows zero resistance between pads. Checking the schematics prompted me to lift the anode of D7 to remove U4. In doing this, the voltage at the junction of R11 came up into spec and shows 150 V's. This means that U4 is drawing the circuit down. SO, I sent Elecraft an e-mail and Gary sent me a new MAX1406. Figured I would install it and all would be good.NOT ! After installing the new U4,I rechecked voltage at R11 and found it is still just 47 V's. I've double checked orientation of U4, and it's fine. I was very careful to observe anti static procedures when installing the new chip. SO, I'm confused and not sure where to go from here. Any advise would be greatly appreciated. Thanks 72: Jerry N0JRN __ 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 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.716 / Virus Database: 270.14.105/2562 - Release Date: 12/13/09 02:39:00 __ 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
[Elecraft] KPA100 Problem
Dealing with the last unresolved problem with my K2/100: When using the K2/KPA100 on CW, regardless of power setting (above 11 watts, that is), the power output fluctuates above the set power level by about 10%. With the power setting at 90 watts, the output will alternate between about 98 and 88 watts, at about one cycle per 2 seconds. At 30 watts, its +/- about 4 watts, etc. Using a dummy load. It will do this indefinitely. All other aspects of the KPA100 operation are normal. With PA turned OFF in the menu, the barefoot K2 does not exhibit this power fluctuation. Any suggestions on what to look at? 73 Jim Stoneback K4AXF Drake SW8 K2.ssb.100.at sn 6194 K2.at sn 6263 (under construction) ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] KPA100 Problem; scratched thermal pads OK
Minor scratches are OK. This material melts and fills the gaps between the PA transistors and the heatsink as the devices heat up the first couple of times. (That is one of the reasons we require tightening of the transistor mounting screws after a initial short period of use.) 73, Eric WA6HHQ Elecraft --- Harvey Howell wrote: While working on the amp I noticed that the black coatings on the thermal pads seem to scratch easily. Mine have a couple of minor scratches that go thru the black. Does this reduce their ability to conduct heat away? Should I replace them? Thanks. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] KPA100 Problem
Hello everyone. I almost made it to the finish line with my K2. I'm encountering a problem with the KPA100 SWR Bridge Null Adjustment (C1). I have everything hooked up correctly as far as I can determine. I set the power knob for 5.0 W. Enter tune mode and adjust C1 to get 1.0-1 SWR on the K2 display. The best I can achieve is 3.6w and 3.4-1 SWR. When the display reads this value my SX-200 power meter indicates about 18 watts out!! Also some of the voltages read a little high: D13 cathode should be 90 to 150v : reads 158v. U4 (MAX 1406) pin 8 should be -5 to -25v : reads -28v Test Equipment Used: DL-1 and MFJ dummy loads. SX-200 power meter. I have given the board a close visual inspection and nothing looks bad. The red and green leads on T4 go to the correct pads. Any ideas? Thanks very much. Harvey KN6VPNo virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.394 / Virus Database: 268.8.3/361 - Release Date: 6/11/2006 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] KPA100 Problem
Harvey, At first glance it would seem like there is something awry with your wattmeter section of the KPA100. Check the T4 windings again and check carefully to be certain everything is well soldered with no solder bridges. Check the diodes for proper orientation, then try again to balance the wattmeter bridge. If you do not get the trimmer capacitor correct, the power and SWR indications will be 'funny', so be certain that you have a good null (use the DVM on the test point). The capacitor setting is quite 'touchy' so adjust it very slowly waiting for your DVM to settle down with each small change. The increased voltages at D13 and U4 pin 8 are to be expected since the change of R4 to 39k - the voltages in the KPA100 unfortunately have not been updated to reflect this change. They are NOT related to your wattmeter problem. 73, Don W3FPR -Original Message- Hello everyone. I almost made it to the finish line with my K2. I'm encountering a problem with the KPA100 SWR Bridge Null Adjustment (C1). I have everything hooked up correctly as far as I can determine. I set the power knob for 5.0 W. Enter tune mode and adjust C1 to get 1.0-1 SWR on the K2 display. The best I can achieve is 3.6w and 3.4-1 SWR. When the display reads this value my SX-200 power meter indicates about 18 watts out!! Also some of the voltages read a little high: D13 cathode should be 90 to 150v : reads 158v. U4 (MAX 1406) pin 8 should be -5 to -25v : reads -28v Test Equipment Used: DL-1 and MFJ dummy loads. SX-200 power meter. I have given the board a close visual inspection and nothing looks bad. The red and green leads on T4 go to the correct pads. Any ideas? Thanks very much. Harvey KN6VP ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] KPA100 Problem again
Some of you may remember my problem with the KPA100 not being recognized by the K2 after a little mishap I had. On the sound advice of a few on this list, I purchased a new 78L05 (U3), EL5146 (U6) and a MAX1406 (U4). I just swapped all of these out, and am getting 5V in places I should now. Probably U6 was bad. The K2 is still giving me a NO PA PS message with a PS plugged into the KPA100. In fact, it's the ONLY PS plugged in. The menu gives me an E12 and an F1.10 whatever that is. I did some measurements, and U1 is ok *except* for these: Pin 7: .8v (Book says 4V with note 2, depends on PS voltage) Pin 10: 2.25v (book says 2.4v, seems a *little* fishy?) Pins 12, 13, 14: all 0.0v, book says 0.5V Pin 26: 5v. Book says 0v?? I checked it 3 times to see if I counted wrong, but nope, that's the pin. So my question... is U1 bad, or is something that's feeding U1 bad?? Could it be something on the K2 control board? Any ideas appreciated! -Chris KL9A ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] KPA100 problem
Hi all, In my previous email I had described that I had my kpa100 working in the K2 enclosure but that it had died when I tried to install it in the EC2 case. I was getting info 080 and Lyle Johnson had suggested a problem with the aux bus line. I have refined search down to the 5 V line that supplies the max 1406. When I remove U1 on the kpa100 board I get a dead short at pin 1 of U1. This could mean that the 5 V regulator is bad but there are other components connected to this line and any one of these components could be defective (U3, U4, C23, C89, U6, etc). I am now faced with developing a procedure to isolate the bad part. I have already inspected the board for shorts and do not see any. The fact that the kpa100 worked before leads me to believe that a component may have shorted itself out. I could destructively remove each component until the short disappeared but then I would need to replace possibly a lot of parts. The other option would be to isolate each part one at a time by cutting traces. Once the part was deemed OK, I would have to patch the trace and go on to the next part. I would end up with a lot of patched traces. Any suggestions? Thanks, Steve, W2MY -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.323 / Virus Database: 267.9.1/51 - Release Date: 7/18/2005 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] KPA100 problem
Steve, First remove the regulator which you suspect anyway. If that does not remove the short, then start removing one component at a time until you find it. A good de-soldering tool makes the task a lot easier, and if the price of the potential parts replacement is high, perhaps it is time to invest in a de-soldering tool - you won't be sorry, and you can remove parts non-destructively in most cases. If you do not have a de-soldering tool, the easiest is to cut traces - start by cutting a trace so it divides the suspect components into 2 equal groups, find out which half the short remains in and divide that section into 2 groups again - you don't have to make as many cuts, and you will find it more quickly. I don't know of an easier method unless you happen to spot a solder bridge along the way. 73, Don W3FPR -Original Message- . When I remove U1 on the kpa100 board I get a dead short at pin 1 of U1. This could mean that the 5 V regulator is bad but there are other components connected to this line and any one of these components could be defective (U3, U4, C23, C89, U6, etc). I am now faced with developing a procedure to isolate the bad part. I have already inspected the board for shorts and do not see any. The fact that the kpa100 worked before leads me to believe that a component may have shorted itself out. I could destructively remove each component until the short disappeared but then I would need to replace possibly a lot of parts. The other option would be to isolate each part one at a time by cutting traces. Once the part was deemed OK, I would have to patch the trace and go on to the next part. I would end up with a lot of patched traces. Any suggestions? Thanks, Steve, W2MY -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.323 / Virus Database: 267.9.1/51 - Release Date: 7/18/2005 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.323 / Virus Database: 267.9.1/51 - Release Date: 7/18/2005 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.323 / Virus Database: 267.9.1/51 - Release Date: 7/18/2005 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] KPA100 Problem?
I am not an experienced builder, but having purchased a ready built K2, I decided that the experience of building a KPA100 would be good for me. And everything has gone pretty well until I got to page 41 of the manual and conducted the tests. Most (J3 lead, Q1 and Q2, and J2) are fine and the readings are as expected. However, Q9 and D13 readings should be over 10K and I am getting 15Megs on my DMM, which is an older digital type. Granted, 15M is greater than 10K. Q9 (MOSFET) and D13 (Diode) appear OK and I have worked through the schematic, taking resistance checks along the way, and everything appears OK. I am thinking that it could be my DMM and any thoughts from the group would be appreciated. Larry (G0IKE) ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
FW: [Elecraft] KPA100 Problem?
You are absolutely right. 15M is 10K. Reverse the meter leads, and maybe you'll see the 8M 10K too! Carry on! Dan / WG4S / K2 #2456 snip Granted, 15M is greater than 10K. /snip ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] KPA100 problem
I've been testing the KPA100 that I've just finished building and have found a problem. The symptoms are a little weird, so bear with me. On 40m and 80m SSB, once the K2 PWR control is set to 11W or over, the RF output corresponds to peak full power. This seems to be frequency dependent and the audio frequency at which peak power is delivered changes between USB and LSB. When I whistle into the mike, I see full output on a scope and the power indication on the K2 also shows full scale, and the K2/KPA is drawing around 20A. If I turn the power to 10W, I see the expected power level on these two bands. If I turn the PA menu option to OFF, then power delivery throughout the power range 0.1 to 15W is as expected. On these two bands, CW power control is fine with the PA turned on, and varies as expected from 0-10, and then with tha PA on from 11W to 100W+. On 160m, 30m, 20m, SSB (USB and LSB) power delivery is correct. I didn't try any bands higher than 20m for this. So the problem seems to be PA ON only, affecting SSB only (USB and LSB) and only on two bands. The base K2 seems fine on these two bands within its normal 15W range. It appears as if there is a PA ALC/power control problem on these two bands in SSB mode. All the resistance checks and voltage checks during construction were fine. The only ones that were slightly off were the PA transistor base resistance check. I measured 11.6 ohms instead of the 12-18 ohms indicated on my DMM. All the others were within spec.I figured that 11.6 was within 5% of 12 and that might be DMM inaccuracy. Any ideas where to start looking for the problem? Thanks, David, M0DHO. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] KPA100 Problem still exists, but some new measurements
Hi there, I'm still on page 43 in the process and I have now narrowed the problem area. You remember, I measured a negative voltage of 0.15V on J3+. Now: I removed Z1 and found the voltage measured at the collectors of Qs 1 and 2 to be -0.4V (J3+ is ok now). I don't know where it could come from. Shorting the collectors to ground via 1k resistor it takes 3 seconds to eliminate the voltage. I measure 0V. Removing the resistor it takes abt. 20 seconds for the voltage to go to -0.4V again. T2-4,5 are ok. The base of the transistors are ok, 0V. The emitters also, 0V. The body of T2 also has -0.4V. Any idea and testing procedures appreciated! Kind regards Gerhard Schwanz DH3FAW mailto:[EMAIL PROTECTED] http://www.gs-personal.de ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] KPA100 Problem still exists, but some new measurements
Gerhard, That small negative voltage may be coming from the AC ripple on the '90-150 V' supply to the TR switch that is being coupled through the RF chokes and capacitors into the Q1 and Q2 collector circuit and then being rectified by the transistors themselves. If that is the case, it may not be a problem at all once you connect a +12 volt supply. Put an RF probe on the cathode of D13 and see how much RF voltage is present there (it would be at the approximate frequency of X1). 73, Don W3FPR -Original Message- Hi there, I'm still on page 43 in the process and I have now narrowed the problem area. You remember, I measured a negative voltage of 0.15V on J3+. Now: I removed Z1 and found the voltage measured at the collectors of Qs 1 and 2 to be -0.4V (J3+ is ok now). I don't know where it could come from. Shorting the collectors to ground via 1k resistor it takes 3 seconds to eliminate the voltage. I measure 0V. Removing the resistor it takes abt. 20 seconds for the voltage to go to -0.4V again. T2-4,5 are ok. The base of the transistors are ok, 0V. The emitters also, 0V. The body of T2 also has -0.4V. Any idea and testing procedures appreciated! ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] KPA100 Problem still exists, but some new measurements
G'day, Did you have a light shining on the PA transistors? J3+ on my KPA100 had -0.18V. Apparently something to do with illumination of the PA's. Well noted by others. Regards, Mike VP8NO - Original Message - From: Gerhard Schwanz [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Friday, February 04, 2005 10:42 AM Subject: [Elecraft] KPA100 Problem still exists, but some new measurements Hi there, I'm still on page 43 in the process and I have now narrowed the problem area. You remember, I measured a negative voltage of 0.15V on J3+. Now: I removed Z1 and found the voltage measured at the collectors of Qs 1 and 2 to be -0.4V (J3+ is ok now). I don't know where it could come from. Shorting the collectors to ground via 1k resistor it takes 3 seconds to eliminate the voltage. I measure 0V. Removing the resistor it takes abt. 20 seconds for the voltage to go to -0.4V again. T2-4,5 are ok. The base of the transistors are ok, 0V. The emitters also, 0V. The body of T2 also has -0.4V. Any idea and testing procedures appreciated! Kind regards Gerhard Schwanz DH3FAW mailto:[EMAIL PROTECTED] http://www.gs-personal.de ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] KPA100 Problem still exists, but some new measurements
Well, um, yes. And I noticed another thing which led me think everything is fine. The voltage was there, even without power connected to the K2 at all. All is well now, I neglected the voltage. I will go on air tomorrow for on air tests. RS232 test is next now, then shield and final assembly. And thanks to all who helped!!! Gerhard Schwanz DH3FAW mailto:[EMAIL PROTECTED] http://www.gs-personal.de - Original Message - From: Mike Harris [EMAIL PROTECTED] To: Gerhard Schwanz [EMAIL PROTECTED]; Sent: Friday, February 04, 2005 5:14 PM Subject: Re: [Elecraft] KPA100 Problem still exists, but some new measurements G'day, Did you have a light shining on the PA transistors? J3+ on my KPA100 had -0.18V. Apparently something to do with illumination of the PA's. Well noted by others. Regards, Mike VP8NO - Original Message - From: Gerhard Schwanz [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Friday, February 04, 2005 10:42 AM Subject: [Elecraft] KPA100 Problem still exists, but some new measurements Hi there, I'm still on page 43 in the process and I have now narrowed the problem area. You remember, I measured a negative voltage of 0.15V on J3+. Now: I removed Z1 and found the voltage measured at the collectors of Qs 1 and 2 to be -0.4V (J3+ is ok now). I don't know where it could come from. Shorting the collectors to ground via 1k resistor it takes 3 seconds to eliminate the voltage. I measure 0V. Removing the resistor it takes abt. 20 seconds for the voltage to go to -0.4V again. T2-4,5 are ok. The base of the transistors are ok, 0V. The emitters also, 0V. The body of T2 also has -0.4V. Any idea and testing procedures appreciated! Kind regards Gerhard Schwanz DH3FAW mailto:[EMAIL PROTECTED] http://www.gs-personal.de ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] KPA100 Problem still exists, but some new measurements
Now: I removed Z1 and found the voltage measured at the collectors of Qs 1 and 2 to be -0.4V (J3+ is ok now). I don't know where it could come from. Hi Gerhard: Dunno if this is related, but I got a small voltage J3 by shining a bright light on the final transistors. There is some sort of photoelectric effect. Your numbers are close to what I measured then: http://www.ac6rm.net/mailarchive/html/elecraft-list/2003-11/msg00574.html -- Ward ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] KPA100 Problem
Whats a KAP100? Sorry about the typo. I just put up an 1/2 wave antenna for 160 meters that is 260 feet long and center fed with 450 ladder line. When RXing on all bands and moving the PWR contorl to 11 watts or more so the relay in the PA switches over to high, I get erratic noise in the receiver. If I back the PWR down to QRP, then RX is OK again. I am almost sure that this noise is rectified AM signals within the TR switch. Not sure if this can be expected with this switching method or if I have a component that's bad. Most of my antennas are Loops or match and fed with coax, and don't display this condition. Several years ago I had a Ten Tec transceiver the experinced the sam problem, I resolved by building a high pass fillter and installing it in the receive line and the problem went away. Not sure there is room for this in the K2. Any ideas? Kurt K0ARO ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
