开云体育

Is it better to ventilate a TCXO or keep it away from room temp variations

Dennis Tillman W7pF Member Profile All Messages By This Member #76119 开云体育 Specifically, if you have a Temperature Controlled Crystal Oscillator (TCXO) like you find in a few Tek TM5000 instruments with the high stability time base option: ·???????? Is it better to enclose the plugin with a solid aluminum top extrusion, bottom extrusion, and side covers? OR ·???????? Is it better to allow it to breathe with a vented top, bottom and side panels (the ones with all the holes)? ? By BETTER mean which choice will result in a more stable TCXO frequency output? And by STABLE I mean the least drift over time, And by TIME I mean anything from a day to a week. ? ASSUMPTIONS: Assume for arguments sake we are talking about a temperature controlled environment like a home or office where the room temperature doesn’t vary by more than 10 deg F. Assume there are no power line fluctuations. Assume the local temperature rise due to the oven is not great enough to be detrimental to the lifetime of the rest of the components around it. Ignore crystal aging which is another matter. ? It seems to me, if you enclose the plugin that the TCXO resides in, the temperature will reach a stable equilibrium and fluctuate less than if you ventilate the plug-in. But I think there are also good reasons to keep things cool with a fan blowing heat away. ? Is there a definitive answer or does it depend on something I might have missed? ? Dennis
gridleakrick All Messages By This Member #76128 Some manufacturers enclose the crystal or oscillator in styrofoam to maintain temperature stability and to prevent drafts. Rick ================================================================== toggle quoted message Show quoted text --- In TekScopes@..., "Dennis Tillman" <dennis@...> wrote: Specifically, if you have a Temperature Controlled Crystal Oscillator (TCXO) like you find in a few Tek TM5000 instruments with the high stability time base option: . Is it better to enclose the plugin with a solid aluminum top extrusion, bottom extrusion, and side covers? OR . Is it better to allow it to breathe with a vented top, bottom and side panels (the ones with all the holes)? By BETTER mean which choice will result in a more stable TCXO frequency output? And by STABLE I mean the least drift over time, And by TIME I mean anything from a day to a week. ASSUMPTIONS: Assume for arguments sake we are talking about a temperature controlled environment like a home or office where the room temperature doesn't vary by more than 10 deg F. Assume there are no power line fluctuations. Assume the local temperature rise due to the oven is not great enough to be detrimental to the lifetime of the rest of the components around it. Ignore crystal aging which is another matter. It seems to me, if you enclose the plugin that the TCXO resides in, the temperature will reach a stable equilibrium and fluctuate less than if you ventilate the plug-in. But I think there are also good reasons to keep things cool with a fan blowing heat away. Is there a definitive answer or does it depend on something I might have missed? Dennis
G?ran Krusell #76132 开云体育 Hi Dennis, ? There are five parameters which affect frequency accuracy of high quality oscillators like OCXO and TCXO (in falling importance): aging, initial offset, temperature variation, capactive load variation, supply voltage variation. You will have the best stability over time if you let the oscillator operate under constant conditions within its operating temperature range. What a fan does is to add a cooling effect and this may affect the frequency or phase drift. This can easily be seen if you have an oscillator locked in a loop with a low bandwidth, like 1 mHz, and then you breath or blow on it. The phase will take a walk... ? G?ran ?
Didier Juges All Messages By This Member #76153 The time constant is likely to be less than an hour in either case, probably much less if the case is vented, so it will only make a difference against temperature changes that are faster than that. If the equipment is in a relatively stable room (basement or downstairs in a 2 story house), the difference is likely to be small. You would need a much bigger mass to make a significant difference Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... From: "Dennis Tillman" <dennis@...> Sender: TekScopes@... Date: Mon, 21 May 2012 19:06:48 -0700 To: <TekScopes@...> ReplyTo: TekScopes@... Subject: [TekScopes] Is it better to ventilate a TCXO or keep it away from room temp variations ? Specifically, if you have a Temperature Controlled Crystal Oscillator (TCXO) like you find in a few Tek TM5000 instruments with the high stability time base option: ·???????? Is it better to enclose the plugin with a solid aluminum top extrusion, bottom extrusion, and side covers? OR ·???????? Is it better to allow it to breathe with a vented top, bottom and side panels (the ones with all the holes)? ? By BETTER mean which choice will result in a more stable TCXO frequency output? And by STABLE I mean the least drift over time, And by TIME I mean anything from a day to a week. ? ASSUMPTIONS: Assume for arguments sake we are talking about a temperature controlled environment like a home or office where the room temperature doesn’t vary by more than 10 deg F. Assume there are no power line fluctuations. Assume the local temperature rise due to the oven is not great enough to be detrimental to the lifetime of the rest of the components around it. Ignore crystal aging which is another matter. ? It seems to me, if you enclose the plugin that the TCXO resides in, the temperature will reach a stable equilibrium and fluctuate less than if you ventilate the plug-in. But I think there are also good reasons to keep things cool with a fan blowing heat away. ? Is there a definitive answer or does it depend on something I might have missed? ? Dennis

Previous Topic Next Topic