[time-nuts] New Guy, has HP 5061A with DATUM 7105A tube seeks advice

[Wayne Holder]

Thanks for all the great suggestions.  I was able to unplug and remove the
battery and, as suggested, also removed the center PCB (battery charger?/
cutover switch?)

The back of the unit indicates it has three options installed.  Option 3,
option 4 and option J15.  Option 3 seems to be the combination of the
battery option and the time standard option (PPS, etc.), but I'm not sure
what option 4 and option J15 are.  Can anyone tell me?  Also, the first two
option stickers (3 & 4) look like they were put on at the factory, as they
match the serial number label in style (see attached photo.)  However, the
option J15 sticker is a completely different color (blue) and put only
slight askew, although it does say "Hewlett Packard" on the bottom of the
label.

AS for the suggestions about leaving the unit powered up for a few weeks,
or more, so it can pump down; I'll give that a try.  However, before I
power it up, do I need to check anything in particular (cables, switches,
etc.) to make sure it's ready to be turned on?  I'd hate to break it just
because I didn't know some needed startup voodoo.

Wayne

[image: Inline image 1]

On Thu, Nov 6, 2014 at 10:01 AM, paul swed <paulswedb at gmail.com> wrote:

> Pete thats quite a hint on the official fumes measurement scale.
> Frankenstein takes a solid 24 or so hours to your one. So it seems on the
> CS scale of life you are fumes and I am wisps. The meter shows just about 0
> photo. Very tough to work with have to play games with meter amplifiers and
> such.
> But I do get the green and the darn thing does lock on its own with
> reasonable 2nd harmonic.
> So there you go Wayne. Always hope.
> Regards
> Paul
> WB8TSL
>
> On Thu, Nov 6, 2014 at 12:54 PM, Pete Lancashire <pete at petelancashire.com>
> wrote:
>
> > If after say a week and the current does not go down, there is one more
> > thing you can do before you have a tube that qualifies as a door stop.
> You
> > replace the internal HV supply with 3,500V @ 5 mA I had to do this on
> mine.
> > Keep doing it a few minutes at a time, took something like 3 hours.
> > No drop in current until the very end and all of a sudden the current
> > starting going down. I put the tube back in the 5061A and after the
> current
> > dropped there was enough Cs left to get the thing to work. Just like Paul
> > I'm sure there is very little left.
> >
> > I turn it on every 3-4 months and let it run for about an hour. The last
> > few times it took a while to lock and go 'green'
> >
> > -pete
> >
> >
> >
> > On Wed, Nov 5, 2014 at 11:21 PM, Wayne Holder <wayne.holder at gmail.com>
> > wrote:
> >
> > > I recently picked up a 5061A surplus, but have no idea whether it works
> > or
> > > not.  The first hurdle is getting a power cord, but I'm still waiting
> for
> > > the proper connector to show up (the first one I ordered had the wrong
> > > orientation on the 3 pins.)  In the meantime, I've been reading though
> > what
> > > materials I can find online in order to figure out how to  try and
> safely
> > > turn it on and see if the tube is OK, or dead.
> > >
> > > However after removing the top cover, I can see that my unit doesn't
> seem
> > > to contain the typical kind of cesium tube assembly I see in the HP
> docs
> > > I've found online.  Instead, it has a tube made by DATUM with the
> > following
> > > markings on the label:
> > >
> > > Model: 7105A
> > > Serial: 9951991226
> > > Part No: 03667-501
> > > Oven Temp: 92 degrees C
> > > Oven Monitor Therm: 101 Ohms
> > > EMV: 2000 DC
> > > NSN ______ 5960 01214 7475
> > >
> > > Can anyone tell me about this model and why it might have a DATUM tube
> > > rather than the kind I see in the HP oc?  Also, any advice on how to
> > safely
> > > check it out?
> > >
> > > I bought this thing out of curiosity but, upon looking inside at all
> the
> > > various dials and switches and multi-turn potentiometers, I find I'm
> > rather
> > > intimated by it, even though I have a fairly decent background in
> > > electronics.
> > >
> > > Wayne
> > > _______________________________________________
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