Re: [Elecraft] K2 PA Failure

2011-02-17 Thread John Ragle
Am I missing something here? Seems to me that the rational thing to do is turn on the power supply and let it stabilize (should only take a second or two), then turn on the K2/K3? Turning a K2 or K3 on and off using the power supply switch never gives the firmware/software a chance to

Re: [Elecraft] K2 PA Failure

2011-02-17 Thread Dave Sergeant
The K2 has a real on/off switch. So always using that to turn it on and off is certainly a good idea. I am certainly puzzled at these claims of pa blowups. My original pair of transistors is going fine after 9 years and some 30k QSOs. I have removed the heatsink several times while fitting

[Elecraft] K2 PA Failure

2011-02-17 Thread Georges Ringotte F6DFZ
Yes you are missing something. The power supply was first switch on, then the K2. At switch on the capacitors into the K2 charges themself, and the power supply answered to this by emiting spikes. I never write that all power supply have the same behavior, but for mine, it explained the K2 PA

Re: [Elecraft] K2 PA Failure

2011-02-17 Thread Mike Harris
: [Elecraft] K2 PA Failure Am I missing something here? Seems to me that the rational thing to do is turn on the power supply and let it stabilize (should only take a second or two), then turn on the K2/K3? Turning a K2 or K3 on and off using the power supply switch never gives the firmware

Re: [Elecraft] K2 PA Failure

2011-02-16 Thread john petters
--- Hi Folks, I have had another PA transistor failure in my 2003 vintage K2. The transistors have been replaced several times over the years and the board is now a mess. I'm planning to rebuild the PA on an external board with a proper heat sink mounted on the back panel of the K2. This

Re: [Elecraft] K2 PA Failure

2011-02-16 Thread Wayne Burdick
John, K2 PAs are generally extremely reliable, and the heat sinking is entirely adequate as determined by extensive temperature tests of the PA device itself and the heat sink. There are some 7000 K2s in the field and few failures. This suggests that you may have a defective part elsewhere

[Elecraft] K2 PA Failure

2011-02-16 Thread Johnny Siu
...@traditional-jazz.com 收件人﹕ Elecraft elecraft@mailman.qth.net 傳送日期﹕ 2011/2/17 (四) 4:15:25 AM 主題: Re: [Elecraft] K2 PA Failure --- Hi Folks, I have had another PA transistor failure in my 2003 vintage K2. The transistors have been replaced several times over the years and the board is now a mess

Re: [Elecraft] K2 PA Failure

2011-02-16 Thread Don Wilhelm
: [Elecraft] K2 PA Failure --- Hi Folks, I have had another PA transistor failure in my 2003 vintage K2. The transistors have been replaced several times over the years and the board is now a mess. I'm planning to rebuild the PA on an external board with a proper heat sink mounted on the back

[Elecraft] K2 PA Failure

2011-02-16 Thread Georges Ringotte F6DFZ
Hi to the group, When I had my K2/10, I had multiple failures of the PA transistors. Close investigation showed that the problem came from my switching power supply (a professional 5A one from Friwo). When switching on the K2, the power supply emited large spikes that destroyed the PA