I would like to put my Thunderbolt into a chassis with power supply and would like to have the most favorable thermal environment since the unit is somewhat temperature dependent.

I was thinking of mounting the unit in insulating material, but am worried it will get too hot to the point the temp control loop won't work properly. Has anyone experimented with this and found the best solution?  I would like to remove the strong dependence on room temperature that I have currently.

Peter

On Jul 11, 2012, at 11:18 AM, Gary Fiber gfiber@comcast.net wrote:

On Wed, Jul 11, 2012 at 8:28 AM, Peter Gottlieb nerd@verizon.net wrote:

A simple cardboard box with some vents is enough to keep the temp daily
stable.  The next step I did is to make a fan controller.  Use a
temperature sensor to turn a fan off and on.  The active fan controller
really does work.

Chris Albertson
Redondo Beach, California

10MHz output you mean, not 19MHz, surely it was a typo. Yes, best to use
LadyHeather: learn how to use and you will have the best monitoring utility
for the TBolt.

On Wed, Jul 11, 2012 at 5:18 PM, Gary Fiber gfiber@comcast.net wrote:

Yes it was a typo meant 10 MHz. I've got the readme for Lady Heather and will go through it. I was hopeful someone had any needed basic settings for the Thunderbolt otherwise I will leave it as it came out of the box from the seller.

Gary Fiber K8IZ

Sent from my iPad

On Jul 11, 2012, at 10:36 AM, Azelio Boriani azelio.boriani@screen.it wrote:

I have mine in a nice case along with the switcher supply. Am debating on the need of including a small fan. I made a shelf from 2 sided PCB material and mounted the Thunderbolt onto that shelf.
The switching power supply sits below the Thunderbolt mounted to the case bottom.

Gary Fiber K8IZ

Sent from my iPad

On Jul 11, 2012, at 10:28 AM, Peter Gottlieb nerd@verizon.net wrote:

Does anyone know if there's a means to log max and min temps for these
things? I was going to make a crude box for mine out of 2 inch cavity wall
insulation hard foam, with an air space between the box internal walls
and the TB, but like the other poster, I am unsure if it would cause too
high a temp without an additional fan and ventilation slots? Do most
users do what i do and leave them on 24 hours a day, seven days a
week?

--
Best Regards,
Chris Wilson.

I tried putting my thunderbolt in a styrofoam box.  It got hotter than I liked and didn't seem to perform any better than when I left it in a cardboard box.

I worry about the long term implications for component life as the temperature goes up.

Sent from my iPod

On 2012-07-11, at 5:15 PM, Chris Wilson chris@chriswilson.tv wrote:

On 7/11/2012 8:15 PM, Chris Wilson wrote:

The TB reports it's own temperature. Lady Heather will track it.

I'm surprised no one has mounted one to a Peltier cooler, and stabilized
the temp with PID control, based on the self-reported temp. Why not run
it cooler than ambient? I'd assume a simple microcontroller could handle
the task, but don't have any deep PID control knowledge myself.

Mike:

Lady Heather implements a PID temp control feature using the  "TT" command.

from lady heather's heather.cpp file:

//                      - Added ability to actively stabilize the device
//                        temperature. (/TT=degrees or TT command line option).
//                        Uses the serial port RTS and DTR lines.  RTS is the
//                        temperature controller enable (+12=off, -12=on)
//                        DTR is the heat (-12V) / cool (+12V) line.  Simple
//                        implementation:  Isolate tbolt in a box,  set control
//                        temperature below typical unit operating temp and
//                        above normal room temp,  when unit signals COOL turn
//                        on fan to move room air into the box.  You want the
//                        fan to move enough air to cool the unit,  but not so
//                        much air that the temperature drops by more than 0.01C
//                        per second.  The indicator of too much airflow is a
//                        temperature curve that spikes down around 0.1C several
//                        times per minute.  Too little airflow shows up as a
//                        curve that oscillates around 0.25C about set
point over
//                        a couple of minutes.  Good airflow should show a
//                        temperature curve stable to with 0.01C with
a period of
//                        between 1 and 3 minutes.  Generally you do not want
//                        the fan to blow directly on the unit (mine
is surrounded
//                        by foam).  You want to gently move air through the
//                        box.  It can help to include a large thermal mass in
//                        the box (I use a 2kg scale weight).

-Eric

On Wed, Jul 11, 2012 at 7:00 PM, Mike S mikes@flatsurface.com wrote:

--
--Eric

Eric Garner

On Wed, Jul 11, 2012 at 6:55 PM, Mark Spencer mspencer12345@yahoo.cawrote:

The advantage of the insulation comes in when you build the fan controller.
Mine uses a temperature sensor and an IC comparator that drives a
transistor that drives a 12V fan.  The fan does on when the set point is
reached then goes off.  If you set the operating point a little higher then
the inside of yur house then the fan cycles and keeps the inside of the box
and roughly, more or less constant.  The parts to build a fan controller
are about $5

If you don't have a temperature controlled fan then the next best thing is
a well vented cardboard box whose only purpose is to keep air currents off
the unit. Insulation without an active temperature controller is only going
to make it hotter, not more stable

Chris Albertson
Redondo Beach, California

When I had my Tbolt running full time, I just had it sitting in the bottom corner of a bookcase that was hard to get to (Tek 7104 on a cart packed with other gear too was in the way, along with piles of other things). No drafts, so the temp stayed pretty constant. It was taken out of full service when I got a Z3801.

I want to build a home for it and my two Rb units in a temp controlled box, but haven't gotten there yet.

-Dave

----- Original Message -----
From: "Gary Fiber" gfiber@comcast.net
To: "Discussion of precise time and frequency measurement" time-nuts@febo.com
Sent: Wednesday, July 11, 2012 4:12:04 PM
Subject: Re: [time-nuts] Thunderbolt mounting

I have mine in a nice case along with the switcher supply. Am debating on the need of including a small fan. I made a shelf from 2 sided PCB material and mounted the Thunderbolt onto that shelf.
The switching power supply sits below the Thunderbolt mounted to the case bottom.

Gary Fiber K8IZ

Sent from my iPad

On Jul 11, 2012, at 10:28 AM, Peter Gottlieb nerd@verizon.net wrote:

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Just thinking outside of the Styrofoam box, wouldn't an analog
controller on the fan be better? That is use a DC fan and adjust the
current to change the speed.

On 7/11/2012 8:54 PM, Chris Albertson wrote:

On 07/12/2012 05:54 AM, Chris Albertson wrote:

You really don't want an on/off regulation scheme. The OCXO gets
dynamic thermal stress from it which causes it to go off in frequency as
the heat wave (or cooling wave) comes in and has a rate faster than the
oven can steer. The oven gain will be much less than for slow
semi-static temperature changes. Old ovens used on/off schemes, but it
was dropped as electronics allowed for continuous feedback loops.

You will see a bump in your ADEV at about the cycling period of your
fan. If you have quick cycling period, it will affect your close in
phase noise and ADEV, but you might suppress your room/house AC/heating
loop. If you run continuous, there will be a much quieter response.

Another side-effect of cycling power for an OCXO is that it will for
each cycle shifts its phase. The OCXO control will return it to
temperature as fast as it can, which should return it to frequency. What
happens is that the curve around the balancing point isn't completely
symmetric, but the heat-up/cool-off temperature profile certainly isn't.
The end result becomes that the frequency error under the curve isn't 0
over such a cycle, and that integrated over time will become phase. So,
this unstable phase creep will keep the control loop active to fight it
back, until you reach holdover, when the error will be exposed completely.

I've learned this the hard way, from observing frequency and phase
fluctuations and fighting them.

Using a cardboard box or other "wall" around the oscillator will as a
passive oven work well, if the unit is still allowed to dissipate it's
excess heat to the surrounding. The effect is really great and helps the
control loop as temperature shifts occurs more gradually such that the
control loop can track it within it's bandwidth. Long term temperature
shifts like the bang-bang regulator of the building AC/heating will
still eat into the box.

Cheers,
Magnus

I think that the only action is to wipe out any old setup present (use the
TBolt monitor program), especially a previous position hold setting. You
know, timing receivers have the position hold capability and it is
mandatory to restart the survey for your location.
I have 2 TBolts but (what a shame for me) never tried to start them up so I
cannot be more practical like go there, click that, check this and so on. I
use an HP Z3815A as a reference and have yet to prepare a good linear power
supply for the TBolts.

On Thu, Jul 12, 2012 at 1:09 AM, Gary Fiber gfiber@comcast.net wrote:

On 7/11/12 7:00 PM, Mike S wrote:

PID controller code for Arduinos and the like is readily available..

However, as to why not run it cooler?

The internal oven tries to keep the crystal at the temperature where the
frequency vs temp curve has the lowest slope.  If you cool the outside,
then you just burn more power in the internal oven.

On 07/12/2012 03:22 PM, Jim Lux wrote:

You can run it at higher temperature if you maintain that actively.
There is a balance between elevated temperature and shorting of life
that way and elevated oven current and shorting of life that way.

Whatever cooling mechanism used (and a PID controller is a good start) a
linear control is recommended.

Cheers,
Magnus

Sorry about the bad URL. I corrected it below.
On 07/12/2012 12:22 AM, Chuck Forsberg WA7KGX N2469R wrote:

The Tbolt in its cabinet currently sits atop my office computer,
next to a south facing window.  Putting it in a dark corner would
doubtlessly improve its temperature stability but the cat would be
disappointed.

--
Chuck Forsberg WA7KGX N2469R    caf@omen.com  www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc      "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231  503-614-0430

Sorry guys, but using a fan on a thunderbolt is nuts. Not time nuts.

First you get ADEV humps as discussed here. Then the fan vibrations will show up as massive spurs in the phase noise plots. Then the fan's commutator emi will go everywhere. Then the fan may modulate the supply voltage going into the thunderbolt if the same supply is used -not good.

Get a better docxo and replace the thunderbolt oven, done. If you need the best thermal stability. Shield it from airflow as best as possible. That should do it.

Bye,
Said

Sent from my iPad

On Jul 12, 2012, at 12:05, Chuck Forsberg WA7KGX N2469R caf@omen.com wrote:

On Thu, Jul 12, 2012 at 6:56 PM, Said Jackson saidjack@aol.com wrote:

Have you actually tried using a fan and measured EMI and the supply voltage
modulation.  I'm curious how much the fan pulled down the power supply.

Those things could happen but at what level?  Is the effect even
measurable?  I think it might be like standing of a single sheet of paper
so you are taller and can see farther.  Yes in theory it works but the
effect is small.

Chris Albertson
Redondo Beach, California

Not small when you are trying to achieve a -160dBc noise floor. Then even a small fan can show up as a massive -120dbc or higher spur easily and ruin your day due to the microphonics of the crystal. Some time ago there was a discussion here about how entering a room measurably changed an ocxo frequency due to the steps causing vibration..

So we stabilize the temp but ruin our phase noise. Doesn't make sense to me.

We deal with big fans all the time, viz. Turboprop engines running at up to 2000rpm. Generates nasty massive spurs below 100hz.

Putting an ocxo in front of a fan is one of the worst things one can do, even if it is hiding in an enclosure such as a thunderbolt. It probably raises your ADEV very easily measurable at the fan turn on/off frequency as well.

Btw, the math of what -160dBc means in terms of power below carrier is very impressive. getting close to the thermal noise of a 50 ohm resistor.

Bye,
Said

Sent from my iPad

On Jul 12, 2012, at 21:38, Chris Albertson albertson.chris@gmail.com wrote:

Peltier cooler on top of the OCXO or on top of the TBolt?

On Fri, Jul 13, 2012 at 9:54 AM, Chuck Forsberg WA7KGX N2469R
caf@omen.comwrote:

Hi

If you want to isolate things, the answer is fairly simple. Get a water cooler system (like on a high end PC) and adapt the cooling block to a metal box that goes around the TBolt. Put the pump and fan a good ways away and run them on an isolated supply (as in independently regulated. I assume you are already running a 15 or 18 volt supply into linear regulators to power the +12 on the TBolt.

You could also do acceleration compensation on the OCXO....

Bob

On Jul 13, 2012, at 7:55 AM, Azelio Boriani wrote:

Apply the Peltier to the cabinet.
Or put the Tbolt in a fridge.
Mount the Tbolt on a granite slab inside the cabinet so lorries won't
affect it.

On 07/13/2012 04:55 AM, Azelio Boriani wrote:

--
Chuck Forsberg WA7KGX N2469R    caf@omen.com  www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc      "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231  503-614-0430

Oh, I have no vibrations from lorries, I'm all the way across the ocean. ;)

My thought was to mount it in a constant temperature enclosure via thermal insulating standoffs. The enclosure could be a PID controlled Peltier CPU cooler run box, something COTS pretty much.

Peter

On Jul 13, 2012, at 10:04 AM, Chuck Forsberg WA7KGX N2469R caf@omen.com wrote:

Hi

There's no real need to keep the TBolt at / below room temperature. A constant temperature in the 40 to 50C range works just fine. There's nothing inside that's going to take a major reliability hit from that sort of temperature.

Bob

On Jul 13, 2012, at 10:17 AM, Peter Gottlieb wrote:

I've got a foundation trench open right now.  I've been thinking it is a
great opportunity to keep some electronics at a very stable temperature.
What's better then tossing it in a big hole in the ground then dumping a
truckload of concrete on top?  Likely the only thing I'll burry is a $2
temperature sensor.  In So. California you don't need to go very deep to
reach stable temp.

On Fri, Jul 13, 2012 at 5:25 PM, Neville Michie namichie@gmail.com wrote:

--

Chris Albertson
Redondo Beach, California