Re: [time-nuts] Valpey-Fisher VFT22H OCXO Output
Logan It looks alright to me - it's a sine wave output with some 2nd and higher order harmonics, nothing unusual there. If you want a cleaner output then an external low pass filter will soon clean it up. regards Grant From: Logan Cummings To: time-nuts@febo.com Subject: [time-nuts] Valpey-Fisher VFT22H OCXO Output Message-ID: Content-Type: text/plain; charset="utf-8" Hi All, Curious what could give this waveform (attached) - I presume this is not correct output for this oscillator (surplus/salvage from Harris Constellation receiver). Frequency looks OK with +2V EFC but output looks like neither sine nor any CMOS I've seen into 10Mohm (first capture, scope probe alone) or 50ohm (50ohm term at SMA connector, probed by same scope probe) . What gives? If I open up the can, what am I looking to possibly replace/eliminate? How to open it? It's soldered shut (2x2in case). I need a good low-noise 100MHz sine wave for my application so I'm tempted to open this guy up and replace the output circuitry with something more suitable. Thanks in advance for any pointers/info on these units! -Logan ___ 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.
Re: [time-nuts] Valpey-Fisher VFT22H OCXO Output
Waveform is similar to that produced by an inductive input low pass filter with all but the first section inoperative when driven by a square wave input. Bruce On Saturday, January 30, 2016 09:33:45 AM Bob Camp wrote: > Hi > > Unless it’s a really weird termination impedance, it’s broke. The SMA is a > pretty good indication that it *should* work into a 50 ohm load. > > The only other possibility is that your probe is taking the load far enough > off of 50 ohms to mis-tune the output filter. I’d set the scope to 50 ohm > input and cabe the output directly to it. If that’s not practical, put a 6 > db 50 ohm pad on the output of the oscillator and see what it looks like > after that. > > Bob > > > On Jan 29, 2016, at 10:19 PM, Logan Cummings > > wrote: > > > > Hi All, > > > > Curious what could give this waveform (attached) - I presume this is > > > > not correct output for this oscillator (surplus/salvage from Harris > > Constellation receiver). > > > > Frequency looks OK with +2V EFC but output looks like neither sine nor > > > > any CMOS I've seen into 10Mohm (first capture, scope probe alone) or 50ohm > > (50ohm term at SMA connector, probed by same scope probe) . > > > > What gives? If I open up the can, what am I looking to possibly > > > > replace/eliminate? How to open it? It's soldered shut (2x2in case). > > > > I need a good low-noise 100MHz sine wave for my application so I'm > > > > tempted to open this guy up and replace the output circuitry with > > something > > more suitable. > > > >Thanks in advance for any pointers/info on these units! > > > > -Logan > > __ > > _ > > 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. ___ 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.
Re: [time-nuts] Valpey-Fisher VFT22H OCXO Output
Looks like the output of a simple single ended emitter follower that isn't being loaded properly. Try again, but this time with a 50 ohms load. -Chuck Harris Logan Cummings wrote: Hi All, Curious what could give this waveform (attached) - I presume this is not correct output for this oscillator (surplus/salvage from Harris Constellation receiver). Frequency looks OK with +2V EFC but output looks like neither sine nor any CMOS I've seen into 10Mohm (first capture, scope probe alone) or 50ohm (50ohm term at SMA connector, probed by same scope probe) . What gives? If I open up the can, what am I looking to possibly replace/eliminate? How to open it? It's soldered shut (2x2in case). I need a good low-noise 100MHz sine wave for my application so I'm tempted to open this guy up and replace the output circuitry with something more suitable. Thanks in advance for any pointers/info on these units! -Logan ___ 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.
Re: [time-nuts] Valpey-Fisher VFT22H OCXO Output
Hi Unless it’s a really weird termination impedance, it’s broke. The SMA is a pretty good indication that it *should* work into a 50 ohm load. The only other possibility is that your probe is taking the load far enough off of 50 ohms to mis-tune the output filter. I’d set the scope to 50 ohm input and cabe the output directly to it. If that’s not practical, put a 6 db 50 ohm pad on the output of the oscillator and see what it looks like after that. Bob > On Jan 29, 2016, at 10:19 PM, Logan Cummings wrote: > > Hi All, > > Curious what could give this waveform (attached) - I presume this is > not correct output for this oscillator (surplus/salvage from Harris > Constellation receiver). > > Frequency looks OK with +2V EFC but output looks like neither sine nor > any CMOS I've seen into 10Mohm (first capture, scope probe alone) or 50ohm > (50ohm term at SMA connector, probed by same scope probe) . > > What gives? If I open up the can, what am I looking to possibly > replace/eliminate? How to open it? It's soldered shut (2x2in case). > > I need a good low-noise 100MHz sine wave for my application so I'm > tempted to open this guy up and replace the output circuitry with something > more suitable. > >Thanks in advance for any pointers/info on these units! > -Logan > ___ > 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.
Re: [time-nuts] Valpey-Fisher VFT22H OCXO Output
Hi Logan, My guess is there is some second or third harmonic energy present. I have observed the very same thing on another oscillator. Look at it with a spectrum analyzer and see what kind of harmonic energy is there. BillWB6BNQ Logan Cummings wrote: Hi All, Curious what could give this waveform (attached) - I presume this is not correct output for this oscillator (surplus/salvage from Harris Constellation receiver). Frequency looks OK with +2V EFC but output looks like neither sine nor any CMOS I've seen into 10Mohm (first capture, scope probe alone) or 50ohm (50ohm term at SMA connector, probed by same scope probe) . What gives? If I open up the can, what am I looking to possibly replace/eliminate? How to open it? It's soldered shut (2x2in case). I need a good low-noise 100MHz sine wave for my application so I'm tempted to open this guy up and replace the output circuitry with something more suitable. Thanks in advance for any pointers/info on these units! -Logan ___ 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.
[time-nuts] Valpey-Fisher VFT22H OCXO Output
Hi All, Curious what could give this waveform (attached) - I presume this is not correct output for this oscillator (surplus/salvage from Harris Constellation receiver). Frequency looks OK with +2V EFC but output looks like neither sine nor any CMOS I've seen into 10Mohm (first capture, scope probe alone) or 50ohm (50ohm term at SMA connector, probed by same scope probe) . What gives? If I open up the can, what am I looking to possibly replace/eliminate? How to open it? It's soldered shut (2x2in case). I need a good low-noise 100MHz sine wave for my application so I'm tempted to open this guy up and replace the output circuitry with something more suitable. Thanks in advance for any pointers/info on these units! -Logan ___ 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.
