Will agree I would hack something in. The same for the synthesiser. I could swear someone on time-nuts already has. The phase detection circuit is audio and it would take some experimentation. I think Corby supplied an alternative approach on the A7 opamp so a lot of good work. But the charcoal problem mentions really would be the worst problem to deal with. I guess it would be ebay parts. $$$ Whats a dead 5065 go for chuckle? Regards Paul WB8TSL
On Tue, Oct 6, 2020 at 6:27 PM Bob kb8tq <[email protected]> wrote: > Hi > > Replacing the synthesizer with something more modern is certainly > possible. I have > a project (slowly moving along) to do just that. There is nothing crazy on > the logic board, > it could easily be replaced with something more modern for not a lot of > money. > > The phase detector / photo amp / modulator chain is a bit more > problematic. My guess is that > a replacement of both the photo amp (preamp) and the phase detector at the > same time > would make sense. Both are “audio” circuits. There is nothing in them that > makes them > totally nutty to replace. > > The physics package *is* the long term question. When the lamps die, I > doubt we can find > ( or fab) replacements. If the temperature controller fails in a fashion > that the entire “tube” > turns into a chunk of charcoal, that would be a long tough fixer upper. > > Fun !!! > > Bob > > > On Oct 6, 2020, at 3:39 PM, Ulf Kylenfall via time-nuts < > [email protected]> wrote: > > > > > > Having been shut of for several months I fired up the > > refurbished 5065A a few weeks ago. > > > > It has since been equipped with a new AC-amplifier > > (A7) and a new Rubidium cell with the repaired lamp > > (thanks to Corby Dawson) and a receiver with a > > TED that was connected according to HP instructions. > > > > Also the 5 MHz original crystal oscillator has been replaced > > with an 10811 upgrade kit. > > > > Almost immedeately, the FET's in the 60 MHz Multiplier A3 > > not replaced during the first repair all failed. > > They were replaced with metal can 2N4416 and all was well. > > > > The next thing that happened was that the amber > > pilot light "Continuous Operation" > > went out. From just a single event, the lamp started > > going out just every time I turned my back on the > > instrument. Since there were no sign of out-off lock > > conditions and I had no clue other that removing the > > logic assy A14 and checking the lamp driver Q18 > > (1854-0003, selected from 2N1711) I found the transistor > > to be leaky. After replacing it with a 2N1893, I have > > only had one single such event in a week. Looking at > > the 1854-0003 from the bottom, the TO-5 package is most > > likely sealed with brown epoxy. And the A14 board > > is littered with them. > > > > I could of course replace all these > > small signal transistors, be it NPN or PNP with modern > > types but contemplating on this, I wonder how long a 5065 > > can be operational if the heater windings in the Rb cavity > > remains OK and the synthesizer with its unobtanium > > logics are OK. From the records on the inside > > of the meter and switch parts on the front panel, I can > > see that the photo current of the original unit > > slowly decreased over the years. I have one more > > Rb TX unit but the Rb bulb in that one is really "brownish" > > and not in any way clear as the one presently used. > > > > Standard "non-critical" semiconductors can of course > > be replaced, even the integrator IC. But what about > > transistors in the phase detector assy A8? There > > are some oddly looking packages and trying to find > > data sheets only returns bad photocopies from > > years ago, not really detailing what criteria > > I should be looking for. > > > > Many web-pages from time nuts displays modern > > versions of the 5065 (digital clock). The one > > in my lab dates back from 1968 so it is over > > 50 years old. > > > > Any research made on possible replacement > > types for those exotic semiconductors used > > in the critical parts as eg. the phase detector? > > Best Regards > > Ulf KylenfallSM6GXV > > > > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
