[time-nuts] Maser 0.7 nsec jumps solved

Tim Shoppa tshoppa at gmail.com
Sun May 22 10:44:19 EDT 2016


Interesting math: Hydrogen maser frequency standards use the 1420 MHz line.

Period of 1420MHz is 0.7 ns.

It's not so clear to me that the maser itself is being disrupted, it seems
more likely the external noise is inducing an extra count or causing a
count to be slipped.

A different Australian observatory 1400 MHz RFI problem:
http://arxiv.org/abs/1504.02165 "Subsequent tests revealed that a peryton
can be generated at 1.4 GHz when a microwave oven door is opened
prematurely and the telescope is at an appropriate relative angle. Radio
emission escaping from microwave ovens during the magnetron shut-down phase
neatly explain all of the observed properties of the peryton signals."

Tim N3QE

On Sun, May 22, 2016 at 7:43 AM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:

> Jim,
>
> On 05/22/2016 03:58 AM, Jim Palfreyman wrote:
>
>> Hi all,
>>
>> Awhile back I posted about some mysterious 0.7 ns jumps in three different
>> masers (of the same brand) at three different locations around Australia.
>>
>> Well we think we've found the problem. All three locations also have
>> in-room air conditioners of the same brand. These are used for cooling
>> only. When these units turn on, we think they induce a magnetic field from
>> the inrush current that briefly disrupts the maser. We don't think it's
>> electrical because moving to another phase did not change things.
>>
>> These air conditioners are all quite close to the masers. Typically a
>> metre
>> or 2 away.
>>
>> Much was done to discover this, but the clincher was that when the weather
>> cooled enough at the southern most location (Hobart), we turned off the
>> air
>> con (only heating was needed) and the problem vanished.
>>
>> So there's a lesson here for all maser owners. The jump of 0.7 nsec is not
>> much, but it's huge for VLBI and for time-nuts.
>>
>
> Good that you have found the offender, but have you been able to remedy it
> by other means than turning the AC off?
> I think others H-maser owners would love to know, and potentially the
> vendor you have.
>
> Cheers,
> Magnus
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