[time-nuts] Wenzel Oscillator Repair

Magnus Danielson magnus at rubidium.dyndns.org
Tue Jan 20 21:47:26 UTC 2009


Joseph M Gwinn skrev:
> time-nuts-bounces at febo.com wrote on 01/20/2009 04:32:15 PM:
> 
>> Bruce Griffiths skrev:
>>> 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.
>> When I needed to have a McCoy oscillator can opened my trusty good old 
>> friend Sten did the usual trick of pre-heating the can and then when 
>> applying heat to the solder the thermal difference is lower and hence 
> the 
>> heat-flow away from the joint. Didn't take much time and I think the 
>> oscillator is 100% intact.
>>
>> Pre-heating and hot air are his main tools for tricky soldering jobs. He 
> 
>> has low fatality rate on problems like that. This is why we let him do 
>> that kind of stuff at work.
> 
> I imagine that Sten works *very* fast.  I've found that when soldering 
> thermally sensitive things like small coil bobbins made of nylon that a 
> high temperature and relatively large iron is best - the terminals come up 
> to temperature almost instantly, and it's all over before the heat can 
> spread and melt the bobbin.
> 
> Hot air has the advantage over a flame that overtemperature is less likely 
> with hot air.

Actually, the pre-heating takes a bit of time... but then it doesn't 
take much effort to push the solder over to melting and it took 
relatively little time. The pre-heating doesn't go all the way up there, 
so melting of plastics isn't really a problem.

The pre-heating trick actually makes the big soldering iron rest most of 
the time...

We have boards with so much ground/power grids that it is really a 
headache to do without pre-heating, which is similar to the iron case 
soldering problem.

So, doing it this way makes it go fast.

Cheers,
Magnus




More information about the Time-nuts_lists.febo.com mailing list