13436	2017-01-02 19:21:32	zf2scka9p	W7ZOI Crystal Oscillator question
Message	Date	From	Subject
So my W7ZOI receiver is working great, and the DDS converter works great, had a ball on SKN on 80, 40 and 20 but I've started on the single band converters because, well I guess because I want to compare the results, and move the DDS onto something else. So I was overjoyed to find in an old junked HA350, the set of crystals that could work well for 40, 20, 15 and all of 10. The 11 mhz crystal fired right up in the ZOI oscillator circuit, and 40 meters plays great. But none of the others - 18, 24.5, 25 etc. would oscillate, despite the fact that they fired right off in my crystal tester with plenty of activity. After scratching my head for a bit, I tuned around to see if perhaps they oscillated on 1/3 of the marked frequency, and of course they did - does this mean they are third overtone crystals? And then, assuming a third overtone crystal isn't optimal for the ZOI oscillator board, is there a tweak to that circuit that might entice these guys to oscillate in it? Thanks for any thoughts. 73 Scott
13437	2017-01-02 19:42:42	John Marshall	Re: W7ZOI Crystal Oscillator question
Scott, I've had good luck getting that circuit to work with overtone crystals. In fact, I've even used it to get third OT crystals oscillate on their fifth or seventh OT. Could it be that your tank circuit just isn't tuning the overtone frequency? If your oscillator is giving output at the fundamental, it's a pretty good indication that the tank is tuned there rather than the overtone frequency. It's been a while but I think if you short the crystal, that oscillator will oscillate at the tank frequency. That would be a good way to verify that the tank frequency is where you want it. John, KU4AF Pittsboro, NC
13438	2017-01-03 10:16:17	zf2scka9p	Re: W7ZOI Crystal Oscillator question
John, THANK YOU!! Your recollection is impeccable. I shorted the crystal, tuned for oscillati
13439	2017-01-03 18:43:42	kb1gmx	Re: W7ZOI Crystal Oscillator question
That detail is in EMRFD and THe ARRL Handbook and SSD to name a few. Allison
13440	2017-01-03 19:33:35	John Marshall	Re: W7ZOI Crystal Oscillator question
Glad that worked for you, Scott. I've seen the tip in the literature but couldn't recall where. Good luck with your receiver. I built one based on the Progressive Receiver back in the 80's for 6 and 10 meters using a pre-mixed LO and it worked very well. John, KU4AF Pittsboro, NC
13441	2017-01-04 10:52:23	zf2scka9p	Re: W7ZOI Crystal Oscillator question
Thanks Allison, you raise an interesting point. Having followed the recent thread on the demise of homebrewing on the amps reflector, FWIW I'll tee up a few comments in response. I'm sitting here with a sweetly performing double conversion superhet receiver that I've been using recently on a daily basis, that I never could have built without the quality help I've gotten off this reflector and the qrp-tech reflector, and the web sites and stored messages about the radio. I did look in EMRFD - a borrowed copy it took my library 4 weeks to get from a library 1200 miles away BTW - before posting And I found a snippet about replacing the crystal in a Butler crystal oscillator with a resistor of equivalent ESR and tuning the circuit to resonance. But when you haven't spent your life herding electrons, and you see something like that for the first time, it really doesn't jump off the page at ya for a lot of reasons like "is that only a Butler oscillator you can do that with?" and "do I have a Butler oscillator?" and "I wonder what I've done wrong on this board?" to name a few. So as a relatively rookie to this particular situation, you ask a question here, and someone gives you really patient, timely, helpful. practical advice, presented in a way that's not in a handbook, that helps you understand and solve your problem. In this case, in literally about 10 minutes. And because of that you learn the missing piece that wasn't clear from the book. And you're ready to take on the next learning opportunity. So when I say it would be great if this info was in a place where a rookie could find it, I'm sorry if I suggested it wasn't in a book, but rather was trying to say: 1) thanks to everyone who's been willing to take the time to say "duh, Scott, try this :)); and 2) it would be great if those types of things were captured somewhere where they are easily found by people like me, who are coming to their first rodeo, and don't know what they are looking at. A great example is the stuff on the W7ZOI site, and AA3SJ's site to name a few. I think that's the kind of stuff that gets people building for the first time, and keeping up the enthusiasm to take on progressively more complex projects, and learn a bit about a hobby. In hindsight it may be in a book, and now I know where to find it, and what it means, but 24 hours ago, it wasn't all that clear. Cheers, Scott In a message dated 1/3/2017 8:43:44 P.M. Central Standard Time, emrfd@yahoogroups.com writes: That detail is in EMRFD and THe ARRL Handbook and SSD to name a few. Allison
13442	2017-01-04 11:12:12	kb1gmx	Re: W7ZOI Crystal Oscillator question
Actually rather than what oscillator am I using the question is... Is the crystal in the feedback path? Why is that important? Every oscillator is an amplifier with positive feedback which supports oscillation. So the specific type or implementation is less important than how does the feedback happen (its path) and what device provides it. But hey, we all had to ask those questions. What makes a difference is not so much a, do this, answer but why doing that is meaningful. I was maybe lucky in the quality of the explanations I got or found for myself made it easier to understand what the next question is or maybe should be. Above all else, ask questions. Allison
13443	2017-01-04 12:13:50	blumu	Re: W7ZOI Crystal Oscillator question
Thanks for posting this, Scott. It mirrors my experience closely. I bought emrfd and continue to learn a lot, although much is beyond my understanding and my resources. Pointers and additional guidance from others are priceless and much appreciated. MichaelUK ______________________________________ On 04.01.17 04:12, ka9p@aol.com [emrfd] wrote: ... > So as a relatively rookie to this particular situation, you ask a > question here, and someone gives you really patient, timely, helpful. > practical advice, presented in a way that's _not_ in a handbook, that > helps you understand and solve your problem. ... And you're ready to take on the next learning opportunity. ... > > 1) thanks to everyone who's been willing to take the time to say "duh, > Scott, try this :)); and > > 2) it would be great if those types of things were captured somewhere > where they are easily found by people like me, who are coming to their > first rodeo, and don't know what they are looking at. A great example > is the stuff on the W7ZOI site, and AA3SJ's site to name a few. > > I think that's the kind of stuff that gets people building for the first > time, and keeping up the enthusiasm to take on progressively more > complex projects, and learn a bit about a hobby. ... > Cheers, Scott
13444	2017-01-04 15:19:40	zf2scka9p	Re: W7ZOI Crystal Oscillator question
Thanks Allison, that certainly helps my understanding. I'm operating about at the level of EMFRD for Dummies, but hell bent on having a credible 400 watt homebrew station running by year's end, which creates a lot of cognitive dissonance between taking the time to really understand things and just getting them working. Thanks for keeping me honest. I expect there's gonna be a lot more questions, tho :) Thanks again and 73 Scott In a message dated 1/4/2017 1:12:18 P.M. Central Standard Time, emrfd@yahoogroups.com writes: Actually rather than what oscillator am I using the question is... Is the crystal in the feedback path? Why is that important? Every oscillator is an amplifier with positive feedback which supports oscillation. So the specific type or implementation is less important than how does the feedback happen (its path) and what device provides it. But hey, we all had to ask those questions. What makes a difference is not so much a, do this, answer but why doing that is meaningful. I was maybe lucky in the quality of the explanations I got or found for myself made it easier to understand what the next question is or maybe should be. Above all else, ask questions. Allison
13445	2017-01-06 09:30:47	kb1gmx	Re: W7ZOI Crystal Oscillator question
The biggest thing I can say is: if your not asking questions you have missed something. Keep asking. Also keep in mind there is a files area and many years of history on the board so its likely to have come up before. Allison