So this morning I started rechecking everything. I've found that the 5V on U4 pin 5 is intermittent. Not in a way that would indicate a loose or poor connection, but either that it is there, or it isn't (mostly isn't) when powering up the unit. U7 always has the 5V on pin2. I checked the resistance between U7 pin2 and U4 pin 5 and found about 300k. Looking at the schematics however, it looks like U4 pin5 is actually connected to U7 pin5 (SDO). There is less than 1 ohm of resistance between U4 pin5 and U7 pin5, so it would appear that U7 may have an issue.
The other odd thing is that even when there is 5V coming into U4 pin5, the symptoms at R30 (0.020V) and the low band frequencies are still there. It looks like U7 may provide U4 a clock signal as well. I was seeing the 8V at R30 after reflowing all of the joints near the PLL Reference. Could the increase in temperature in the are have triggered the thermistor? The only thing changed between having the 8V at R30 last night and then losing it was the rewinding of T5 to bring it back up to 16 turns of red. The continuity checks are good through it, and L30 still changes the frequency when adjusted. -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-VCO-Alignment-only-0-02V-R30-tp7569523p7569573.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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
