Al, Just to add a little to the "sensibility" of the VCO (R30) voltage readings: The range of voltages possible is from 0 to about 8 volts. Your high voltage readings indicate that the PLL is trying to increase the voltage to the varactors in order to reduce the capacity - and the op amp has simply "run out of steam" and can go no higher. Voltages between 1.5 and 7 volts are workable, but outside that range, the varactors are not linear.
A higher than normal voltage means there is excess capacity in the VFO range select controls, and a low voltage means that there is not enough capacity in the circuit. Relays K13, K14, and K15 control which fixed capacitors are placed in the circuit, and are in parallel with varactors D23 through D26. On 9/6/2011 9:03 AM, Alan Davenport wrote: > I just performed the VCO voltage checks you asked for and here are the > results. It looks like it was worse than I thought. 40,30,20 and 12 meteres > are all within spec. The other bands are as follows: > > 3.5 MHz = no output > 4.0 MHz = no output > 18.0 = 7.94v > 18.2 = 7.94v > 21.0, 21.45, 28.0 and 28.8 are all also fixed at 7.94V. > > I never noticed the other bands had gone dead as I operate mostly on 40m CW > some operation on 20m and 30m. "When are the higher bands ever going to open > up?" hihi > > ______________________________________________________________ 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
