Hi Bob like the DDS pcboards? On Wed, Oct 7, 2020 at 10:40 AM Bob kb8tq <kb...@n1k.org> wrote:
> Hi > > People have successfully mounted eBay synthesizers in 5065’s. They work > and it is one way to take care of that. > > Bob > > > On Oct 6, 2020, at 10:49 PM, paul swed <paulsw...@gmail.com> wrote: > > > > 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 <kb...@n1k.org> 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 < > >> time-nuts@lists.febo.com> 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 -- time-nuts@lists.febo.com > >>> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >>> and follow the instructions there. > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@lists.febo.com > >> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> and follow the instructions there. > >> > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.