I have had a lot of fun repairing these units and I have learned a lot from the experience and from folks on the list, particularly Bert Kehren, Corby Dawson and John Miles.
If you can think of a way I can help, let me know. I was able to avoid the need for a pico/femto amp meter. I probably would have burned it up anyway. Joe -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Wednesday, July 07, 2010 8:21 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 5061A Problem Child - It Lives! Completely agree congrats and thanks for the update. I may be getting back involved with my 5061a soon now that I have a HP pico/femto amp meter. By golly I will go hunting for the elusive I beam current ghost directly off the tube or at least learn that I can't. On Wed, Jul 7, 2010 at 6:29 AM, Didier Juges <did...@cox.net> wrote: > Congratulations Joe!!! > > Didier > > > -----Original Message----- > > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] > > On Behalf Of J. L. Trantham > > Sent: Tuesday, July 06, 2010 11:44 PM > > To: 'Discussion of precise time and frequency measurement' > > Subject: [time-nuts] 5061A Problem Child - It Lives! > > > > Just a wrap up on the 5061A that had a Beam I but no 2nd Harmonic > > indication. > > > > I was originally stymied by swaps of modules with another > > 'functioning unit' with no help. I then swapped CS tubes with A4 > > Harmonic Generators attached and A11 Cesium controllers at which > > point neither unit worked. I added an > > A15 Power regulator swap and still neither unit worked. I > > undid the swaps, got the 'functioning unit' working again > > (found a leaky A11C2, a 2.2 uF film capacitor with a > > resistance of about 1800 ohms, that prevented the 2.8 KHz > > Control Oscillator from oscillating), then went through some > > tests of both units, assembly by assembly and found A7 > > faulty. Problem was a 'weak' Q1 (1854-0023, the input > > transistor in a 3 transistor amplifier)) with a Beta of about > > 20. An identical transistor at Q2 had a Beta of about 200. > > I installed a 2N2222A that had a Beta of about 150 and all > > was well. The 2nd Harmonic came up normally but the Alarm > > light would not go out. However, when put in Operate, the > > Continuous Operation light would come on and the unit seemed > > to 'lock' normally. > > > > I found an open Q20 and a shorted Q22 (both 1854-0003's) on the A14 > > Logic Assembly causing the Alarm light to stay on. Replaced these > > with 2N2222A's and now all seems well. > > > > I can't explain why swapping A7 modules early on did not resolve the > > 2nd Harmonic indication problem unless both A7's were 'weak' > > allowing them to work with a stronger signal but not a weak signal > > or all the swapping of tubes, back and forth, in and out, etc., > > fixed a dirty connection. On reflection, probably the latter. > > > > In any event, it works and seems to be one of my stronger tubes. > > > > I could not find any cross reference for either of these NPN > > transistors but the 2N2222A seemed to do just fine. > > > > Thanks for everyone's help. > > > > Joe > > > > > > _______________________________________________ > > 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. _______________________________________________ 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.