cool congrats !! -pete
On Tue, Jul 6, 2010 at 9:43 PM, J. L. Trantham <jlt...@att.net> wrote: > 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.