Magnus I am systematically checking every thing. Power is every where, get a very strong 60 MHz with the 5.3125 clearly visible on the spectrum analyzer also counted both with a counter, checked the 85 Hz modulation on the tuning diode, is a small signal but the same on my working M 100. Some is off the M 100 some off the FRS. Working on the Servo assembly. Because of dense packaging it is very difficult to find the output signal, but I am now sitting down with the ohm meter and retracing all the interconnects on the servo board. It is multi layer. Once I have the 85/170 pass I will inject a variable frequency, maybe 85 Hz is wrong. I will keep you posted. The biggest problem is the packing density, very hard to get to the pins of the IC's. Bert In a message dated 4/1/2012 6:56:55 P.M. Eastern Daylight Time, magnus@rubidium.dyndns.org writes: Bert, On 04/01/2012 07:50 PM, EWKehren@aol.com wrote: > In the past I have asked if some one has any info of the Efratom M3100. I > have carefully dissected the unit and checked functionality. It sweeps but > does not lock. Lamp signal is strong 60 MHz and 5.xx all work properly and > can be seen on a spectrum analyzer The problem is in the loop and there is > not enough signal into the phase detector. Trying to follow the detector > output is challenging because lack of information and packaging density. > Typical loop frequency in a M100 is 127/254 in this case I see 85/160. I would > expect in a military application they would go up not down for vibration > purposes. Tracing the circuits is also made more difficult because of the use > of mil parts and mil nomenclature. I have most cross correlated and I am > down to one PMI part 38510/11201BCA. Does any one have any info, such a > nice unit, would like to make it work. OK, does all the parts have operational power? Does the modulation work? Maybe it needs phase-trimming for best detection gain? Can you hook up a scope so you have modulation sweep on X and detector response at Y? You should be able to probe around. I had some part success with a similar rubidium, until I had reversed it to such a degree that I knew that it was a power-supply in the thick-film module that had failed. Cheers, Magnus _______________________________________________ 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.

On 04/02/2012 02:33 AM, EWKehren@aol.com wrote: > Magnus > I am systematically checking every thing. Power is every where, get a very > strong 60 MHz with the 5.3125 clearly visible on the spectrum analyzer also > counted both with a counter, checked the 85 Hz modulation on the tuning > diode, is a small signal but the same on my working M 100. Some is off the M > 100 some off the FRS. Working on the Servo assembly. Because of dense > packaging it is very difficult to find the output signal, but I am now sitting > down with the ohm meter and retracing all the interconnects on the servo > board. It is multi layer. Once I have the 85/170 pass I will inject a variable > frequency, maybe 85 Hz is wrong. > I will keep you posted. The biggest problem is the packing density, very > hard to get to the pins of the IC's. Lot's of test-points. The 4060 (U3) is hooked up as RC oscillator based. 4053 (U2) demodulates. Isn't the large 1 uF cap the integrator cap? TP10, TP11, TP13 and TP15 looks like suspects. TP17, TP5, TP14 and TP9 looks like coming out of modulation counter, but the last seems to come from the analog frontend at the bottom part. Cheers, Magnus