[time-nuts] DIY FE-5680A lobotomy (disable temp compensation)

Bob Camp kb8tq at n1k.org
Fri Jul 4 08:23:21 EDT 2014


Hi

There is a bunch of stuff on the Wentzel site about their double wall mini-test chambers. It’s probably the best approach to the gradient issue. You still have a gradient around the inner chamber / box, but it’s consistent. You eliminate the coupling of the gradient to the ambient temperature. 

The downside is the higher thermal resistance of the structure. That may force you right back to thermo electric cooling. I’d try a conventional heat pipe designed for high power desktop CPU cooling first. The things are cheap, come with way more fan than you need and the plate that mates to the CPU is about the right size for this application. 

Bob


On Jul 3, 2014, at 9:35 PM, Angus <not.again at btinternet.com> wrote:

> 
> Hi Bert,
> 
> I am thinking about testing a heat pipe on a fan cooled setup I use.
> The first temp controlled chassis I did used a peltier and works very
> well, but was a lot more work to do and is much more power hungry. 
> 
> The main problem I find is not the temp controller itself, but rather
> the change in the temperature across the chassis as the ambient
> changes. However good the temp controller is, it only controls a
> single point, but other points further away from the sensing
> thermistor can vary a lot. 
> I noticed you posted a picture of a heat pipe cooler a couple of weeks
> ago - did you happen to compare the temperature across the unit with
> direct fan cooling and the heat pipe cooler, or with different heat
> pipes?
> 
> Angus.
> 
> 
> 
> On Sat, 28 Jun 2014 12:37:37 -0400 (EDT), you wrote:
> 
>> Will someone beside us use heat pipe. Would love to have an impendent  
>> input. What does it take to get a test going. Scott has done a lot of work, how  
>> about some one else step up to the plate. There are a lot of time nuts out 
>> there  with the 5680A,many for the first time will have a very good 
>> reference and some  of our experts with proper equipment can make a big difference.
>> Bert Kehren
>> 
>> 
>> In a message dated 6/28/2014 12:20:12 P.M. Eastern Daylight Time,  
>> newell+timenuts at n5tnl.com writes:
>> 
>> At 04:32  AM 6/28/2014, wb6bnq wrote:
>> 
>>> monitoring process ?  In other  words have you traced out the 
>>> connections to see what is driving the  pin you think is the temperature 
>> input ?
>> 
>> No. I've only traced back from  the ADC input to the voltage divider.
>> 
>> 
>>> The next big question is  have you monitored the frequency and its 
>>> stability, externally, to  observe what effects are taking place when 
>>> you disable this input to  the A/D ?
>> 
>> I have not.
>> 
>> 
>>> That sounds complicated and messy  but may be easier than it 
>>> appears.  An appropriate container  would be:
>> 
>> It does sound messy. I don't think I'm willing to dunk one of  my units.
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