[time-nuts] Used Hydrogen Maser

[Bob kb8tq]

Hi

One of the gotcha’s if you are in the US is that the most often seen “alternate 
brand” of Maser comes out of Russia. Depending on the phase of the moon and
just what the rule book says this week, you may well not be able to bring one 
into the country. 

Back when things were a bit more cordial and trade was more rational, the quoted
price was in the $150 $200K range. 

Bob

> On Jul 10, 2019, at 8:57 AM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> 
> Perry,
> 
> The only H-maser with which I've had direct experience (the MHM-2010) costs
> around $250,000 new.  But there are some other brands, mostly foreign.
> 
> The immediate operating cost is that of AC power.  IIRC, the '2010 uses
> about
> 100W or maybe 125W, *all the time*.  The H-maser is *not* the kind of thing
> one
> turns on when needed and back off in between uses.
> 
> The hydrogen supply is usually large enough to last about 15 years or more.
> 
> A sort of hidden cost is that the unit must be operated in a
> temperature-controllled
> environment for best stability- hence there is also the purchase and
> operating costs
> of a suitable A/C system.
> 
> Also note that H-masers *do* drift in frequency over time.  The one we had
> at Arecibo
> typically needed frequency correction of about 3.5E-14 about every 4 months
> on average,
> to keep the observatory's master clock on time within 25-50 nsec as needed
> for certain
> types of radio astronomy situations.  We used the H-maser because it has
> the best
> stability (over the range of seconds to hours) of anything commercially
> available.
> 
> The maser operated without difficulty for about the first 8 years before it
> lost one of
> its two vacion pumps.  We had to pay $12k for an engineer from Symmetricom
> to
> bring down a pair of new pumps and oversee the installation.  He replaced
> the failed
> one on one day while I took notes; then the next day I replaced the 2nd one
> under
> his close supervision and scrutiny.  Because the maser was well designed
> with vacuum
> isolation valves, both pump replacements were accomplished without shutting
> down
> the maser and with no disturbance to observations.
> 
> A few years later the maser's internal log data showed that the hydrogen
> pressure
> was oscillating, along with synchronized fluctuations in drive to the Pd Pd
> "valve",
> with a period of about 11 days.   At this point there was no noticeable
> effect on timing
> accuracy.  A series of calls to Symmetricom customer service indicated that
> they had
> no idea what was going on, and they counseled "watchful waiting".  We did
> that for
> several more years up until I retired in Dec 2016, with the only change
> being a very
> gradual drift in oscillation period and amplitude.  The in late Dec 2018,
> the maser
> basically died outright, and Symmetricom (then part of Micro-Semi) was
> unable to
> provide a definite diagnosis- just a couple of theories.  But they advised
> against
> trying to fully diagnose and repair the unit, considering its advanced age
> (approx
> 15 years at the time).
> 
> Hope this helps ...
> 
> Dana
> 
> 
> 
> 
> On Wed, Jul 10, 2019 at 7:00 AM Perry Sandeen via time-nuts <
> time-nuts at lists.febo.com> wrote:
> 
>> Yo Bubba Dudes!,
>> OK, I'll finally ask the question that probably a lot of list members
>> wanted to know but were reticent to ask.
>> First, what is the price of one of a new Hydrogen Maser? (This is
>> important if I win the lottery.)
>> Second, what would be prices for used Hydrogen Maser in *reasonable*
>> working condition and what might be the long term costs to keep it running?
>> Thirdly, what are the chances of finding a used one?
>> Then again, might it be better, money wise just to limp along with used HP
>> Cs?
>> Regards,
>> Perrier
>> 
>> 
>> 
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