K3 low Power
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Elecrafters,
a little while ago i had an issue with loss of rf-power. I thought i had found the problem. I hadn't. Symptom now: Power out only about 3 Watts. I removed the 100W-PA, changed the Menue to 'not inst'. With TUN PWR set to 12W i can achieve about 2.5W . Only 1 of the 3 Transistors on the low-Power PA gets warm during (short) transmissions with the bottom cover removed. There are 2 RD15HVF1 and 1 RD06HHF1. How can i check if a transistor is defective? Any help welcome. I think the 100W PA is ok. Well , i hope . -- Ohne CW ist es nur CB.. 73, Martin DM4iM ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Martin,
I have to ask since you did not mention it -- did you install the PA jumper block after removing the KPA3? If not, you need to do that. As for operating the transistors in the Low Power PA getting warm - one should *never* operate the K3 in transmit with that bottom cover removed. The cover serves as a heat sink. Hopefully you have not already destroyed those transistors. 73, Don W3FPR On 5/12/2014 5:53 PM, Martin wrote: > Elecrafters, > a little while ago i had an issue with loss of rf-power. > I thought i had found the problem. I hadn't. > > Symptom now: > Power out only about 3 Watts. > > I removed the 100W-PA, changed the Menue to 'not inst'. > > With TUN PWR set to 12W i can achieve about 2.5W . > > Only 1 of the 3 Transistors on the low-Power PA gets warm during > (short) transmissions with the bottom cover removed. > > There are 2 RD15HVF1 and 1 RD06HHF1. How can i check if a transistor > is defective? > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Don,
no i didn't install the jumper block. I'm not even sure if i still have it. I transmitted only for very short periods touching all 3 transistors. I felt only one of them getting warm. So i need to find the jumper block first before i proceed the testing. Thank you for the reply. Am 13.05.2014 01:28, schrieb Don Wilhelm: > Martin, > > I have to ask since you did not mention it -- did you install the PA > jumper block after removing the KPA3? If not, you need to do that. > > As for operating the transistors in the Low Power PA getting warm - one > should *never* operate the K3 in transmit with that bottom cover > removed. The cover serves as a heat sink. Hopefully you have not > already destroyed those transistors. > > 73, > Don W3FPR > > On 5/12/2014 5:53 PM, Martin wrote: >> Elecrafters, >> a little while ago i had an issue with loss of rf-power. >> I thought i had found the problem. I hadn't. >> >> Symptom now: >> Power out only about 3 Watts. >> >> I removed the 100W-PA, changed the Menue to 'not inst'. >> >> With TUN PWR set to 12W i can achieve about 2.5W . >> >> Only 1 of the 3 Transistors on the low-Power PA gets warm during >> (short) transmissions with the bottom cover removed. >> >> There are 2 RD15HVF1 and 1 RD06HHF1. How can i check if a transistor >> is defective? >> > > -- Ohne CW ist es nur CB.. 73, Martin DM4iM ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Martin
Martin,
I had the same problem on this end, and I can guarantee your problem is on the LPF board (bad MOS FET). If you key up with no power out, and any of the three on the LPR board are cool, they are bad. One is the driver, and the two are the finals to drive the 100W amp. Hopefully, the two "cool" ones are the RD15SHVF1. It is best you replace the two finals at the same time. They are easy to replace, and it can be done without removing the LPF board (but I found it easier to do it with the board out). Dick K8ZTT -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Martin Sent: Monday, May 12, 2014 3:53 PM To: elecraft Subject: [Elecraft] K3 low Power Elecrafters, a little while ago i had an issue with loss of rf-power. I thought i had found the problem. I hadn't. Symptom now: Power out only about 3 Watts. I removed the 100W-PA, changed the Menue to 'not inst'. With TUN PWR set to 12W i can achieve about 2.5W . Only 1 of the 3 Transistors on the low-Power PA gets warm during (short) transmissions with the bottom cover removed. There are 2 RD15HVF1 and 1 RD06HHF1. How can i check if a transistor is defective? Any help welcome. I think the 100W PA is ok. Well , i hope . -- Ohne CW ist es nur CB.. 73, Martin DM4iM ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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