[time-nuts] Wenzel Oscillator Repair

[Bruce Griffiths]

The relatively low thermal conductivity of the steel can will help
considerably in avoiding thermal damage if the heat is applied to the joint.
If the can were copper it would be much more difficult to avoid thermal
damage.

Bruce

John Miles wrote:
> You probably have a lot more room to play with, given the larger housing on
> your OCXO.  The ULN series is rather densely packaged, and that was one
> reason why I wasn't crazy about going after it with a propane torch.  In
> your case I'd be tempted to try the torch method before actually damaging
> the housing with a Dremel tool.
>
> While fixing a couple of Ovenaire OCXOs that use a similar form factor, I've
> noticed that their PC board edges don't come anywhere near the endcap.  The
> Ovenaire parts were sealed with epoxy, so a heat gun was all that was needed
> to open them, but I'm sure I could've opened them with a torch without
> hurting anything, if they'd been soldered shut.
>
> -- john, KE5FX
>
>   
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
>> Behalf Of Ed Palmer
>> Sent: Tuesday, January 20, 2009 5:59 AM
>> To: time-nuts at febo.com
>> Subject: Re: [time-nuts] Wenzel Oscillator Repair
>>
>>
>> Now I understand!  I was planning to reuse the case.  It didn't occur to
>> me to sacrifice the case and put the oscillator in another box.
>>
>> Thanks for the idea, John.
>>
>> Ed
>>
>>     
>>> Message: 3
>>> Date: Mon, 19 Jan 2009 21:20:54 -0800
>>> From: "John Miles" <jmiles at pop.net>
>>> Subject: Re: [time-nuts] Wenzel Oscillator Repair
>>> To: "Discussion of precise time and frequency measurement"
>>> 	<time-nuts at febo.com>
>>> Message-ID: <PKEGJHPHLLBACEOICCBJMECCBCAC.jmiles at pop.net>
>>> Content-Type: text/plain; charset="us-ascii"
>>>
>>> I used a fiberglass-reinforced cutoff wheel.  This can open practically
>>> anything, but it puts a lot of vibration and dust into the innards of
>>> whatever you're taking apart.  My guess was that this was safer
>>>       
>> than using a
>>     
>>> torch.
>>>
>>> Since I wasn't going to be able to maintain the original hermeticity, I
>>> remounted the oscillator in a Hammond box, like so:
>>>
>>> http://www.thegleam.com/ke5fx/w1.jpg
>>>
>>> I brought the trimmer (which was also damaged in this
>>>       
>> particular oscillator)
>>     
>>> and oven-status LED out to the box lid, along with the four original
>>> terminals.  Makes a nice package that can be easily opened for
>>>       
>> maintenance:
>>     
>>> http://www.thegleam.com/ke5fx/w2.jpg
>>>
>>> The repackaged OCXO seems to work fine.  I haven't made any hardcore
>>> measurements with it but I can tell just by watching the
>>>       
>> counter that its
>>     
>>> short-term stability is similar to my other unmolested 5 MHz ULN.
>>>
>>> -- john, KE5FX
>>>
>>>       
>>>> -----Original Message-----
>>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
>>>> Behalf Of Ed Palmer
>>>> Sent: Monday, January 19, 2009 4:07 PM
>>>> To: time-nuts at febo.com
>>>> Subject: Re: [time-nuts] Wenzel Oscillator Repair
>>>>
>>>>
>>>> I hadn't thought of using a Dremel.  Did you use an abrasive wheel or a
>>>> steel cutter?  The case on mine looks to be about 20 ga. tin-plated
>>>> steel (~0.04" thick).  The gap is so small it might have been
>>>>         
>> a friction
>>     
>>>> fit to start with.
>>>>
>>>> Ed
>>>>
>>>>         
>>>>> From: "John Miles" <jmiles at pop.net>
>>>>> Subject: Re: [time-nuts] Wenzel Oscillator Repair
>>>>> To: "Discussion of precise time and frequency measurement"
>>>>> 	<time-nuts at febo.com>
>>>>> Message-ID: <PKEGJHPHLLBACEOICCBJMEPMBBAC.jmiles at pop.net>
>>>>> Content-Type: text/plain; charset="us-ascii"
>>>>>
>>>>> I had a similar problem with a 5 MHz OCXO from their ULN
>>>>>
>>>>>           
>>>> series.  There was
>>>>
>>>>         
>>>>> a bad solder joint on the output connection, easy enough to fix
>>>>>
>>>>>           
>>>> once I got
>>>>
>>>>         
>>>>> the unit open.
>>>>>
>>>>> In my case I used a Dremel tool to cut the seam.  Suggest
>>>>>           
>> wearing a dust
>>     
>>>>> mask, obviously, and keep your cuts close to the perimeter of
>>>>>
>>>>>           
>>>> the can, in
>>>>
>>>>         
>>>>> case the PC board comes right up to the edge like mine did.
>>>>>
>>>>> -- john, KE5FX
>>>>>
>>>>>           
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