Brian, The KDSP2 is not likely the cause of the problem.
Your 3.53 volts on D9 is within the range of sanity for 12 to9 15 watts output. The fact that the K2 display indicates P 1.0 says that voltage is not making it back to the MCU - or that the MCU has a damaged input at pin 2. The voltage at the cathode of D9 should be carried through R66 (check both ends), and from there go to the connector J7 pin 10. From that point, it will go to Control Board P2 pin 12, and then to CB P4 pin 10 - then on to CB R12 and finally to CB U6 pin 2. Check all those places for good soldering, and then check to see if the DC voltage during a TUNE at the RF Board D9 cathode equals the DC voltage at Control Board U6 pin 2. If it does, then CB U6 has a damaged input pin. If the voltages between D9 cathode and CB U6 pin 2 are substantially different, then there is a bad connection somewhere in the path between those two points. It is not unusual for a bad solder connection to take some time to cause problems - it will conduct just fine due to the mechanical connection until oxidation creates additional resistance in the path and thus a failure. If solder connection oxidation is not the problem, then the MCU IC could have been damaged by static during assembly. Such damage may not be immediate, but will drastically reduce the life of integrated circuits. 73, Don W3FPR On 2/20/2012 9:40 PM, [email protected] wrote: > > Gary and Don: > > No KAT2 installed: (I am building it but have not finished it yet) > > There is about 3.53 volts on D9 when TUNE is pressed, 0 volts > otherwise. I set the power level to 15 watts but, as I said before, > roughly 20 watts comes out no matter what I set the power to, and the > HI CUR warning is always there with "P 1.0" power indicated. > > Do I check the MCU next? Is that on the Control Board? Could the > KDSP2 board be causing a problem? > > Thanks again guys! > > Brian KB1VBF > > ------------------------------------------------------------------------ > > *From: *"Gary Surrency" <[email protected]> > *To: *"b denley" <[email protected]> > *Sent: *Monday, February 20, 2012 3:05:13 PM > *Subject: *KB1VBF Re: [Elecraft] [K2] Hi Current...still > > Don't connect a KAT2, KAT100, or KPA100 until the power control > problem is fixed, since any of those can have damage that affects the > power control. > > Damage to D9 on the RF board or to the VRFDET input pin 2 of the > 18C452 MCU can cause a loss of power control too. If OK, there should > be up to about 4VDC at the cathode of D9 when transmitting at full > power (14-15 watts). > > > -- > 73, Gary AB7MY > > ========= > [email protected] > Elecraft Technical Support > > > On 2/20/2012 11:58 AM, [email protected] wrote: > > Thanks Gary. The rig does put out power as it turns out (plenty > in fact) but is not controlling that power. High power comes out > at any power setting with the associated Hi Cur warning. See Don > Wilhelm's latest advice below. > > Brian KB1VBF > > ------------------------------------------------------------------------ > > *From: *"Gary Surrency" <[email protected]> > *To: *[email protected] > *Cc: *"Don Wilhelm" <[email protected]>, "b denley" > <[email protected]>, "Wayne Burdick" <[email protected]>, > "[email protected] Wilhelm" <[email protected]> > *Sent: *Monday, February 20, 2012 1:20:22 PM > *Subject: *KB1VBF Re: [Elecraft] [K2] Hi Current...still > > Try all bands. > > Make sure no relays have a soldering iron burn. > > Check the t-r switch has no reversed diodes or Q2 is reversed. The > pictorial in the back of the manual shows which way these parts go. > > An open RFC6 will cause self oscillation. This part is under Q6 on > the bottom of the RF board. > > Check all parts are correct in the Q5-Q8 area. > > Check D9's cathode has about 4VDC at 14-15w if the rig will > produce that power level. > > Check the BNC connector does not have a broken ground pin. I have > seen that before. > > -- > 73, Gary AB7MY > > ========= > [email protected] > Elecraft Technical Support > > > > On 2/18/2012 10:33 PM, Don Wilhelm wrote: > > Brian, > > Is this condition on one band, or does it exist on all bands? > > The winding of T4 will affect all bands, > A Low Pass Filter problem will affect one or two bands. > > Transmit into a 50 ohm dummy load - then: > Quickly measure the voltage at the base of Q7 or Q8 during a > TUNE. It should be between 0.60 and 0.64 volts. > > Count the turns on T4 carefully, the green winding should have > 2 turns and the white winding should have 3 turns. The "link" > wires should go from the front of the transformer directly to > the back (they do not wrap through both holes).. > > 73, > Don W3FPR > > On 2/18/2012 10:15 PM, Wayne Burdick wrote: > > Did you check the winding on the PA transformer? If the > impedance were much too low, the current could be too > high. Could also be excessive bias current. What's the > current drain in transmit mode, key up (i.e. tapping XMIT > but not the key)? > > Wayne > N6KR > > On Feb 18, 2012, at 7:09 PM, [email protected] wrote: > > > > After getting the HiCur message, I replaced the two PA > transistors, the associated hardware, Q11 and Q13, and > R50. Unfortunately I stll get the same message: > HiCur when I press TUNE with power any higher than > about 1.5 watts inot a 50 ohm dummy load. Any have > any ideas about what else might cause this problem? > > > > Brian KB1VBF > > ______________________________________________________________ > > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
