I have reached the "Alignment and Test, Part II" for the RF board. This is where the PLL & BFO alignment takes place.
The PLL reference Oscillator alignment went very well with 12,1098.18 kHz measured and a 12.81 kHz range. The VCO test at TP1 however resulted in no frequency reading with either internal or external frequency counter. The DC voltage measured at the left edge of R30 never changes when I adjust L30 or the VFO freq (8.015 VDC). I measured the voltage at all the VCO varactors and only D16 & D17 show change, the other varactors (D21-D26) are all locked in at 8.015 VDC. D16 & D17 voltages actually just jump at certain VFO points... The 12-bit DAC does the same thing at it's output (as expected) I wouldn't say that they actually track the VFO display. adjustment of L30 does not have any affect on anything. Detailed voltage readings in the PLL circuit: U4 voltage readings MC145170 (U4) =================== pin 1 = 2.1788 VDC pin 2 = 2.2925 VDC pin 3 = 0.0041 VDC pin 4 = 2.4677 VDC pin 5 = 4.9861 VDC pin 6 = 4.9861 VDC pin 7 = 4.9861 VDC ?? pin 8 = 0.1087 VDC pin 9 = 0.0007 VDC pin 10 = 0.0007 VDC pin 11 = 0.0002 VDC pin 12 = 0.0000 VDC pin 13 = 0.0012 VDC ?? pin 14 = 4.8343 VDC pin 14 = 4.8343 VDC pin 16 = 4.8343 VDC U5 voltage readings LTC1451 (U5) =================== pin 1 = 4.9887 VDC ?? pin 2 = 0.0011 VDC ?? pin 3 = 4.9887 VDC pin 4 = 4.8512 VDC pin 5 = 0.0000 VDC pin 6 = 2.0470 VDC pin 7 = 4.0874 VDC pin 8 = 4.8512 VDC U6 voltage readings LMC662 (U6) =================== pin 1 = 7.685 VDC pin 2 = 4.0875 VDC pin 3 = 4.0873 VDC pin 4 = 0.0000 VDC pin 5 = 4.0554 VDC pin 6 = 0.0011 VDC ?? pin 7 = 8.015 VDC pin 8 = 8.025 VDC The BFO test is also a wee bit out of range. The upper freq is 4917.81 (OK) The lower freq is 4915.04 (HI) I am thinking that there is probably some central theme that is afoot causing all this difficulty. I will find it soon enough.. But maybe someone has some insight to speed things along.. Any ideas? Ken Lotts aa7jc _______________________________________________ Elecraft mailing list Post to: [email protected] 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
