Hi There are two things you may be talking about:
1) The pressure springs on things like FT-243 holders, they are generic springs. 2) The connection leads on plated blanks, they are indeed strange *and* soldering to the blank is a big problem. I’m guessing you are in bucket number 2. Bob > On Jun 4, 2016, at 1:41 PM, Mike Cook <michael.c...@sfr.fr> wrote: > > Thanks all for your advice, hints, tips and links. Lots to read , do and some > hardware to check. I don’t have a frequency generator so I’ll have to go > another route. > > Oh. One last Q. Has anyone tried repairing the « spring » wire electric > connections on large quartz plates. In one large unit I have they had > corroded and dropped the plate, luckily no damage. I have done one, but I > have no Idea what the original wire composition was so have certainly induced > some stray capacitance/resistance. It is possible that it was a filter rather > than a frequency source as it was not in a vacuum. > > Have a good one. > >> Le 4 juin 2016 à 18:49, Bernd Neubig <bneu...@t-online.de> a écrit : >> >> >> Tim Shoppa wrote: >>> The Pierce logic-gate-biased-active oscillator is pretty reliable to start >>> and will oscillate somewhere with most crystals from kHz to MHz. >>> As you found out, it will often come up on one of many overtones. >>> To reduce chance of coming at an overtone, a series resistor from logic >>> gate output to the crystal is often enough. If not, a RC low-pass will cut >>> down even further (although of course adding phase shift.) >> >> This is certainly the easiest and fastest way for a go/no-go test and to >> find the approximate resonance frequency. >> In the attached circuit diagram make CX1 and CX2 about 10 pF and RGK several >> MegOhms. >> The inverter gate should be preferably an unbuffered HCMOS or other fast >> inverter. >> For crystals in the MHz range you can replace RV by a short, for kHz >> crystals make it a few kOhms. If testing small watch crystals @ 32768 kHz or >> around, RV should be 100 kOhm at least. RV reduces the crystal drive level >> (RF current) to an acceptable level to avoid overloading or even damaging of >> the crystal. For low frequency crystals the RV-CX2 lowpass also avoids >> start-up at the overtone. >> It is recommended to add a second inverter gate at the output to isolate >> your oscilloscope or counter input from the oscillator stage. Add some >330 >> ohm in series to the output of the 2nd inverter, if you connect a coaxial >> cable. Then terminate the coax at the oscilloscope or frequency counter end >> with 50 Ohms, so the square wave form will be roughly maintained. >> >> In this circuit the crystal will not operate at its series resonance, but at >> a load resonance with load capacitance of something between 8 pF and 10 pF >> (depending on the inverter input and output capacitance plus the stray >> capacitances of your test fixture). >> If you want to operate the oscillator at a (low) overtone, such as 3rd (or >> maybe 5th), you must add a series combination of 10 nF plus an inductor in >> parallel to CX2. The 10 nF is to avoid DC short-circuiting of the output. >> The inductor together with CX2 must have a resonance frequency mid between >> fundamental mode and 3rd overtone (not at one of them). So the tuned circuit >> acts like a capacitor at the 3rd OT and is inductive at fundamental mode >> (thus the phase condition for oscillation is not fulfilled at the >> fundamental mode) >> Have fun >> >> Bernd >> DK1AG >> <Pierce_Logic_Gate.gif>_______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > "The power of accurate observation is commonly called cynicism by those who > have not got it. » > George Bernard Shaw > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.