[time-nuts] Cheap Rubidium (heatpipe cooling for)

[Bruce Griffiths]

Try the "cooler" search term other models occur on the first 2-3 pages 
but none in the $20 range.

The 2.5A 12V models were relatively widespread and not very effective 
I've had one for several years.

A 70W Peltier heat pump from Melcor should be cheaper than $150 I have a 
couple of them.

However a very low thermal resistance heatsink is required not just a 
piece of finned (~ 1" fins abort 4" square) extrusion with a small fan 
as typically used in the cheap coolers.

The 70W module when clamped to a large but inadequate natural convection 
heatsink will cool down sufficiently to freeze ice from atmospheric 
water vapour for about 5 minutes or so until the heatsink warms up. It 
really needs a water cooled heatsink or similar.

Bruce

Richard W. Solomon wrote:
> That's a tad more than the $20 John mentioned. I'd risk $20
> but not $150 !!
>
> 73, Dick, W1KSZ
>
>
> -----Original Message-----
>    
>> From: Bruce Griffiths<bruce.griffiths at xtra.co.nz>
>> Sent: Dec 25, 2009 10:32 PM
>> To: "Richard W. Solomon"<w1ksz at earthlink.net>, Discussion of precise time and frequency measurement<time-nuts at febo.com>
>> Subject: Re: [time-nuts] Cheap Rubidium (heatpipe cooling for)
>>
>> See:
>> http://www.walgreens.com/store/catalog/Accessories/Kool-Kaddy-12V-Cooler/ID=prod1833617&navCount=0&navAction=push-product
>> <http://www.walgreens.com/store/catalog/Accessories/Kool-Kaddy-12V-Cooler/ID=prod1833617&navCount=0&navAction=push-product>
>>
>> located using search term:
>> cooler
>>
>> using the search term
>> thermoelectric
>> is even better
>>
>> Bruce
>>
>> Richard W. Solomon wrote:
>>      
>>> Can you be a little more specific about the cooler ? Walgreens
>>> search function is rather laborious and clumsy.
>>>
>>> Tnx, Dick, W1KSZ
>>>
>>>
>>> -----Original Message-----
>>>
>>>        
>>>> From: "J. Forster"<jfor at quik.com>
>>>> Sent: Dec 24, 2009 6:58 PM
>>>> To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
>>>> Subject: Re: [time-nuts] Cheap Rubidium (heatpipe cooling for)
>>>>
>>>> That's why I've been suggesting active control with TE devices.
>>>>
>>>> You can buy a small TE cooler at Walgreens for about $20. It's big enough
>>>> for a 6-pack of Coke cans and already comes in an insulated box. Add a
>>>> simple temperature control in series w/ the DC supply and you should be
>>>> well on the way.
>>>>
>>>> -John
>>>>
>>>> =================
>>>>
>>>>
>>>>
>>>>          
>>>>> Hi
>>>>>
>>>>> The original intent was to simply take an existing "cheap" rubidium and do
>>>>> simple things to it. Tearing it into pieces and redesigning parts of it
>>>>> was not anything I originally contemplated. The tight integration of the
>>>>> physics package to the electronics would make this a fairly involved
>>>>> process.
>>>>>
>>>>> Bob
>>>>>
>>>>>
>>>>> On Dec 24, 2009, at 5:42 PM, Magnus Danielson wrote:
>>>>>
>>>>>
>>>>>            
>>>>>> Hal Murray wrote:
>>>>>>
>>>>>>              
>>>>>>>> A heat pipe might work if the fluid had a sufficiently low boiling
>>>>>>>> point. The rubidium isn't terribly tolerant of high temperatures, and
>>>>>>>> I'm going to pick up some heat rise as I put it inside some baffles /
>>>>>>>> shields. You need to find something that fits a fairly narrow window.
>>>>>>>>
>>>>>>>>                  
>>>>>>> This is all backwards.
>>>>>>> The main reason the typical Rubidium box needs a serious heat sink is
>>>>>>> that there is an active heater inside it heating up the lamp to get it
>>>>>>> up to operating temperature.  That part of the system better be
>>>>>>> "tolerant" of high (enough) temperature.
>>>>>>>
>>>>>>>                
>>>>>> ... or a less heat-producing alternative could be used. The
>>>>>> Rubidium-lamp produces two wavelengths of which one is filtered by a
>>>>>> Rubidium-filter which leaves the final pumping wavelength. This is what
>>>>>> a laser diode could supply instead.
>>>>>>
>>>>>>
>>>>>>              
>>>>>>> Maybe things would be a lot better/simpler if the heating/cooling we
>>>>>>> have been discussing were split into two sections.  One for the lamp
>>>>>>> assembly, and a second for the electronics.
>>>>>>>
>>>>>>>                
>>>>>> Most of the discussion has been on thermal isolation of the entier
>>>>>> units. Not what needs generates temperature and what requires
>>>>>> temperature stability etc.
>>>>>>
>>>>>>
>>>>>>              
>>>>>>> Anybody know what the thermal coefficient of the lamp is relative to
>>>>>>> the electronics?
>>>>>>>
>>>>>>>                
>>>>>> I am not sure I know what you mean by this...
>>>>>>
>>>>>> Cheers,
>>>>>> Magnus
>>>>>>
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>>>>>>
>>>>>>              
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>>>>>
>>>>>            
>>>>
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>>>        
>>
>>      
>
>