Bruce, The 10544 I have doesn't correspond to the 10544 schematic I found on leapsecond.com. Here's a photo of the AGC board inside mine:
http://www.nerdnetworks.org/~bistromath/photos/misc/10544.JPG It's an RCA CA3045 array instead of the 3094's used in the schematic I saw. Looks like the best thing to do is pull it out and test it, and replace if necessary. I imagine that despite the transistor change the schematic is mostly the same. Do you happen to know for sure? Thanks, Nick > Date: Sat, 16 Jan 2010 09:35:03 +1300 > From: [email protected] > To: [email protected] > Subject: Re: [time-nuts] HP 10544A with dodgy output? > > The output of the diode detector is compared with the dc base voltage of > the oscillator transistor adjusting the oscillator transitor current > whenever the detector output deviates from > Oscillator transistor base voltage - 2*Vbe. > > Bruce > > Nick Foster wrote: > > Thanks for the quick reply, John. > > > > > >> From: [email protected] > >> Okay, 12V on the oscillator (pin 3) and 20V on the oven (pin 14). How much > >> on the oven controller, pin 8? > >> > > +12V. The oscillator uses the same supply as the filter, with the addition > > of a 10mH inductor + decoupling caps. > > > > > >> Are pins 2, 4, 5, 9, and 15 grounded? Pin 6 (EFC) should be grounded for > >> initial testing. > >> > > Yes and yes. > > > > Upon looking further, something jumped out at me: the output is 2.2V RMS > > into 1000 ohms instead of the 1V RMS spec'ed in the datasheet. So I suppose > > the problem might be in the AGC circuitry, instead of the output emitter > > follower. It doesn't look as though the AGC in this oscillator contains a > > trimpot, like the 10811 does. > > > > I'm using the schematic at > > http://www.leapsecond.com/museum/10544/10544-3.gif, but I don't have a good > > idea of how that AGC works. > > > > --n > > > > > >> From: [email protected] > >> To: [email protected] > >> Date: Fri, 15 Jan 2010 15:06:42 -0500 > >> Subject: Re: [time-nuts] HP 10544A with dodgy output? > >> > >> Okay, 12V on the oscillator (pin 3) and 20V on the oven (pin 14). How much > >> on the oven controller, pin 8? > >> Are pins 2, 4, 5, 9, and 15 grounded? Pin 6 (EFC) should be grounded for > >> initial testing. > >> > >> John WA4WDL > >> > >> -------------------------------------------------- > >> From: "Nick Foster"<[email protected]> > >> Sent: Friday, January 15, 2010 2:53 PM > >> To:<[email protected]> > >> Subject: [time-nuts] HP 10544A with dodgy output? > >> > >> > >>> Hi all, > >>> > >>> I've just built a GPS-disciplined oscillator built around a 10544A, > >>> somewhat in the style of the Brooks Shera unit, just to use around the > >>> shack. Problem is, now that it's wired up, I notice the output is heavily > >>> distorted. It's clipped on the negative side of the waveform, like an > >>> emitter follower without enough headroom. The more I load the oscillator > >>> output, the heavier the clipping. When I load the oscillator output with > >>> 1000 ohms, spec for this unit, almost 30% of the waveform is clipped on > >>> the negative side. If I don't load it at all and just put a probe on the > >>> output, it looks OK, but still some flattening of the bottom half of the > >>> waveform. > >>> > >>> I've got it wired up according to the datasheet, with +12V on the > >>> oscillator and +20V on the heater. The grounds for the > >>> oscillator/amplifier, oven controller, heater, and output are all tied > >>> together. > >>> > >>> I know these are old units, and I'm wondering if this is a problem (for > >>> instance in the output emitter follower amp) that others know about, > >>> before I tear into it looking for a solution. > >>> > >>> Thanks for your time, > >>> Nick > >>> > >>> _________________________________________________________________ > >>> Your E-mail and More On-the-Go. Get Windows Live Hotmail Free. > >>> http://clk.atdmt.com/GBL/go/196390709/direct/01/ > >>> _______________________________________________ > >>> 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. > >> > > > > _________________________________________________________________ > > Hotmail: Free, trusted and rich email service. > > http://clk.atdmt.com/GBL/go/196390708/direct/01/ > > _______________________________________________ > > 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. _________________________________________________________________ Hotmail: Free, trusted and rich email service. http://clk.atdmt.com/GBL/go/196390708/direct/01/ _______________________________________________ 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.
