[time-nuts] Aging 5065A ?

Wed Oct 7 15:10:34 UTC 2020

Hi

Yup, Bert has lashed up at least one that way ( I have it here in the basement).
I am working on a board with a higher resolution DDS than the typical eBay parts.

Bob

> On Oct 7, 2020, at 10:42 AM, paul swed <paulswedb at gmail.com> wrote:
> 
> Hi Bob like the DDS pcboards?
> 
> On Wed, Oct 7, 2020 at 10:40 AM Bob kb8tq <kb8tq at 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 <paulswedb at 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 <kb8tq at 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 at 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
>>>>> 
>>>>> 
>>>>> 
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>>>> 
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