Hi, So what is the « best » design for DIY a high stability OCVXO ? I am looking after one, needed for an exotic frequency : 5184kHZ Thx, Gilles.
> Le 14 mars 2017 à 18:02, Richard (Rick) Karlquist <[email protected]> a > écrit : > > > > On 3/14/2017 4:03 AM, Bruce Griffiths wrote: > >> >> Looking at oscillator circuits like the HP10811A will give some idea of some >> of the additional complexity required for a overtone operation. Dissecting a >> few ocxos may also be helpful. Some start with a 10MHz crystal and a >> Colpitts sustaining stage and use a 74HC74 or similar to divide the 10Mhz >> by 2 and drive the output pin. Even when a sinewave output is required often >> a CMOS inverter drives the output pin via an LC filter. >> >> Bruce >> > > I don't agree here. The 10811 is not a good tutorial for general oscillator > design. Because it is SC cut, it has a complicated > mode suppression network across the base emitter junction to > suppress mode B as well as the fundamental. > > The E1983A oscillator uses the same crystal (in a low profile > package). You can read my paper about it and see that I > used a very simple bridged tee oscillator circuit. That is > all you need to select the right overtone and mode. > > This is the same circuit that I used at Zeta Labs 40 years > ago to design hundreds of custom VCXO's, up to the 9th > overtone. It simply worked every time, unlike various other > designs that were in use at Zeta. > > Around 1985, I got a consulting gig at Equatorial Communications > to redesign their 5th overtone VCXO. Only about half of the > crystals would work in their circuit. They had thousands > of "reject" crystals. I just used my old Zeta circuit and > all the crystals started working again. > > Equatorial owned the 10 meter dish that you used to see on > your right going south on 237 just before passing over > Central Expressway in Mountain View. > > Rick N6RK > > > _______________________________________________ > 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. _______________________________________________ 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.
