[time-nuts] DIY FE-5680A lobotomy (disable temp compensation)
EWKehren at aol.com
EWKehren at aol.com
Tue Aug 19 12:07:54 UTC 2014
There is no question that direct fan control in combination with a heat
sink is the best solution and we use it on FRK and M 100 with proper thermal
insulation we get 0.01 C on the back plate and better than 0.1 C on the
front. For us the FE 5680 A is not in that class so we looked for a solution
that gives us 0.1 C.
The shape of the FE 5680 does not lend itself easily for fan cooling if you
want to mount it in a chassis horizontally, I did using two L shaped
plates with a back plate heat sink and fan. How ever few have access to metal
work and it gets quickly expensive. A picture is attached. I did extensive
test with heat pipes first with a power resistor on a Alu plate followed by
tests with a FRS, FE 5650 and FE 5680. You have to take in to consideration
the function of the heat pipe in other words set the temperature of the
base plate above the boiling point of the liquid. In my case 46 C was a good
tradeoff between fan speed and operating range of the fan. To much heat pipe
can also be a problem. No question a uprocessor controlled temperature
control would be better, but till now typical time nuts, all talk while we
have working analog circuits and boards.
If worried about temperature change across the unit it can not be totally
be eliminated but if important enclose the unit totally in foam. Easy when
you use a heat pipe. I use a an 1/8 Alu base plate between the Rb and the
heat pipe so I can also tap threads in to it to hold the heat pipe and I did
away with the bottom plate of the FE 5680. Many options.
Bert Kehren
In a message dated 8/19/2014 3:02:49 A.M. Eastern Daylight Time,
ed_palmer at sasktel.net writes:
Is a heatpipe really appropriate for this application? The heatpipe
expects that the heat source wants to burn up and so there's lots of
heat available to vaporize the liquid in the pipe. It's not clear to me
whether that situation exists with these Rb standards. My tests with an
FE-5680A showed a maximum temperature of about 62C without a heatsink.
That's far lower than a CPU or GPU. Some of them run at that
temperature *with* the heatpipe.
I think that a heatsink/fan (maybe from a video card) equipped with a
PWM controller might be a better fit. Many of those combinations have a
ducted fan to provide better control of the airflow. That would reduce
the effects of drafts and convection. One nuisance with using a video
card heatsink is that the back side typically has a raised area that
contacts the GPU. For this application you'd have to have a flat back
over the entire heatsink.
Ed
On 8/18/2014 6:58 PM, Angus wrote:
> On Fri, 04 Jul 2014 02:35:41 +0100, you 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.
>>
> I finally got around to playing with a couple of laptop heat pipes,
> fixed to a 25x50x75mm block of aluminium which is fixed to the 12mm
> thick baseplate.
> On a quick test of it, a sensor near the end of the baseplate showed
> 1.5-2x greater variation with temperature compared with just having a
> fan blow directly onto the baseplate.
> The oscillator also had to be allowed to run a few degrees C hotter
> for the heatpipe coolers to work to the same max ambient temp.
>
> One cooler had two heatpipes with about 12cm between the aluminium
> block and the heatsink fins (cast in this case) The other had a
> single, wider heat pipe with about 5cm between the block and the
> heatsink (this time with a lot more fine fins)
>
> The second cooler was rather more efficient, allowing a extra degreee
> of cooling at the top end, but more problematic was that it entered
> 'bang-bang' mode with the analogue temperature controller even sooner,
> and the temperature fluctuations there were greater. Both were rather
> worse than with the fan just blowing onto the baseplate.
>
> Using a PWM fan controller would help a good bit, but getting more
> creative with a microcontroller would be better. That way you can give
> the fan a minimum of a small kick every so often, and vary the
> repetition rate as well as the duty cycle as more cooling is needed.
> With feedback from the fan and even air temperature monitoring, you
> could get a good idea of exactly how much cooling was being applied.
>
> Another problem is that the overall temp control range is lower with
> the coolers - barely 8-9 DegC compared with 12+ DegC with the fan
> blowing directly on the baseplate. That's mainly the result of the
> poorer cooling at the top end of the range.
>
> The Rb osc fitted during this test was a SA.22c which takes a good bit
> less power than a 5680A, and the fan blowing onto the baseplate was
> normally a 60mm one fitted about 50mm away from it. The baseplate was
> horizontal with the fan blowing onto it from below.
>
> Maybe fitting a heatsink directly onto the base would help further
> with the maximum temp, but it would increase the convection cooling at
> the minimum temp, reducing the overall benefit. It could also be more
> susceptible to drafts, and would make the fan control much more
> delicate.
>
> Anyway, that's the results I got with my setup. Other setups and more
> fine tuning could change things a good bit, but I just wanted to get
> an idea of how the two cooling methods compared on the same setup.
>
> 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.
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
>
_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: DSCN1606 web.jpg
Type: image/jpeg
Size: 80709 bytes
Desc: not available
URL: <http://febo.com/pipermail/time-nuts_lists.febo.com/attachments/20140819/8e28ecff/attachment.jpg>
More information about the Time-nuts_lists.febo.com
mailing list