[time-nuts] hp 5061b replacement tube

paul swed paulswedb at gmail.com
Sat Jun 13 12:41:07 EDT 2015

Dead tube is a huge issue.At least for most of us finding a replacement
tube is zero especially at a cost that is reasonable. I speculate that
given the age of all 5061s pretty much all the tubes should be in very bad
shape. They only had a life of 7 years and we are many years beyond that.

I have done some craziness to get an alternate tube working. Like a new
oven controller to actually raise the temp very carefully... But the tubes
absolutely run out of Cs and thats that.

I picked up a 5061 and it had a dead tube (Hey for $125 you get what you
pay for) and another time-nut was kind enough to give me his dead tube.
That started my 6 month journey to see if I could get a few Cs. And I did.
Just a few but enough to ultimately lock and even today the unit will
re-lock on its own after 24 or so hours. What a pain in the $%^&. But heck
I learned an awful lot from the effort.
Jeeze are the 5061s heavy.

So there you go hope you did not invest to much money. Further comment
there is a good oven osc that would work well for a GPDSO. But there are
also quite nice gpsdos on ebay for little money. Do not want to get into x
is better then y discussion. But they do work draw little power and are
just simply there and working.
Happy to discuss off line.

On Fri, Jun 12, 2015 at 10:03 PM, lincoln <lincoln at ampmonkeys.com> wrote:

> Hello,
>         I'm guessing I all ready know the answer to this but:
> A friend gave me a hp 5061b but in need a tube. Symmetricom was listing
> the price of a replacement at 35k before the go bought out by Microsemi.
> Given Microsemi has a tendency to rebrand equipment and then charge 4x the
> price, an official tube is likely a way non starter. Friend seemed to think
> there were "other" sources for tubes, but I am rather pessimistic.
>         What do you think? Is this thing junk? I would hate to scrap it.
> Maybe use it to house a GPSDO.
> Link
> On Jun 12, 2015, at 6:55 AM, Cube Central <cubecentral at gmail.com> wrote:
> > Hi Max!  Thanks for the information, I was wondering if you had
> documented what you did to your Raspberry Pi so that it might be
> reproducible to someone like me (a newcomer time-nut and intermediate Linux
> user) ... you had said:
> >
> >>> "Here is what I have been able to do with a Motorola Oncore UT+ that I
> got from Bob Stewart awhile back.  This is with a Raspberry PI 2 with a
> number of tweaks and a custom compiled kernel.  Nothing too drastic... plus
> the current Dev version of NTP compile on the Raspberry PI."
> >
> > What tweaks?  What options have you compiled?  What are the gritty
> details of your setup?
> >
> >>> "I'm getting better results letting ntpd discipline the clock over
> doing kernel discipline...
> > not surprising because the algorithms in the ntpd code are much more
> sophisticated than the Linux kernel pps code... ntpd discipline provides
> much lower jitter in my experience."
> >
> > what setting is this and how might I go about experimenting with it?  Is
> that the "flag3" option in the "Generic NMEA GPS Receiver" documented
> here?  https://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html
> >
> > <snip>
> >
> >>> "Not too shabby for a killer deal on an Oncore UT+ for $5 from Bob!
> I'm running the PPS out of the UT+ through a level converter to get the
> ~3.3v PPS output... the serial output on the UT+ is also going through a
> level converter direct into the Pi 2.  Using the oncore ntpd
> driver and again, i'm not using hardpps kernel discipline."
> >
> > I see word HARDPPS in the driver you mentioned (
> https://www.eecis.udel.edu/~mills/ntp/html/drivers/driver30.html ) but
> that documentation is a bit scarce... Could you fill me in on how you have
> it set up?  Is the PPSAPI also used for the "Generic NMEA GPS Receiver"
> (driver 20) or the PPS driver (driver 22)?
> >
> > Thanks so much for your assistance!  Sorry if these questions have been
> posted before, but I am very curious about your setup as it nearly matches
> mine!
> >
> >    -Randal "r3" of CubeCentral
> >
> >
> >
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