My perpetually drifting 10811 pretty quickly made it to the negative voltage rail on the control voltage.
I was looking at the oscillator output with an O-scope and it looked pretty nasty. My equipment is not so hot, so I first chalked that up to bad probes. But I did some google work on that and found an old time-nuts message thread about the 10811 looking bad if the output impedance is bad. The VE2ZAZ board has provision for a 50 ohm resistor on the oscillator output. I have one on the board but it is a little-bitty thing, maybe 1/8th of a watt? Something I probably got from the guts of a VCR or whatnot. Hmm. So I put in a 1/4 watt 50 ohm resistor (like the parts list called for). My working hypothesis is that the small resistor was changing impedance due to heat. I have reset the control voltage to center value and got the coarse trimmer all beautifully centered. It's been running for about a day and I am hopeful that I've made a difference. So far so good. While I was interrupting the flow of 10 Mhz, I also mapped out the control voltage and corresponding digital control value and an approximate frequency. You EE guys are probably snickering and will want to tear the epaulettes off my time-nuts coat and break my sword. What can I say. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
