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I'm getting ready to build an HF / CW kit and just finished setting up a workbench in my garage. While I was wrapping up, I started wondering if the cold temperatures this winter might be harmful to any of the radio equipment. I live in Portland, OR, so I don't expect the temperatures to get too extreme, but it does seem possible for my garage to hit freezing temperatures. Are low / freezing temperatures known to be harmful to ham radio equipment?

To give a sense of what equipment I have on hand.. my shack is currently pretty simple - I have a pair of inexpensive VHF/UHF handheld HTs (BTECH UV-5X3), and will have the DIY HF radio on hand soon. In the coming year, I may add other equipment (e.g. power supply, tuner, an actual base station, etc).

It seems like electronics in general would be okay with the cold (it hasn't really occurred to me in the past to be worried about other electronics in the cold). At this point, though, I want to be really careful before leaving expensive equipment or hard-to-build projects in conditions that may eventually prove harmful.

Really appreciate any thoughts / advice!

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  • $\begingroup$ Really appreciate everyone's thoughtful answers - thank you!! $\endgroup$ – Jim Nov 16 '18 at 21:35
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Amateur radio equipment is not greatly different from electronics in general. Some items might be unusually chunky and robust (e.g. a manual HF antenna tuner is a box full of metal shapes and insulators). Some might be unusually fragile — but more likely in an electronic way (if you misuse this you destroy an input circuit; this tuned circuit changes tuning with temperature; that sort of thing) than environmentally.

Notable items for cold temperatures:

  • Batteries in general perform worse in cold conditions, and may be damaged.

    • Lithium-ion batteries are at risk; I have found varying statements of the exact conditions, but you should definitely not charge them below freezing (0°C? some lower freezing temperature of the battery electrolyte?) and possibly should not let them reach that temperature even when not in use.

    • Lead-acid batteries can be more readily damaged by freezing when they have low charge, because the state of charge affects the electrolyte's ratio of water to sulfuric acid and thus the freezing point. However, as we can see from the fact that almost every car has a lead-acid battery in it — as long as you keep them mostly charged, you should be fine for all reasonable garage temperatures.

  • LCD displays will be faint and slow to update in lower temperatures. You can partially compensate for the faintness with a "contrast" setting if one is available (I see that your planned kit does have one).

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  • $\begingroup$ Appreciate you calling out specific risks, thank you! $\endgroup$ – Jim Nov 16 '18 at 21:29
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The other answers do a good job of covering the theoretical risks and the manufacturers' recommendations. I wouldn't think that you would bump into those limits in a garage in Portland, Oregon. As a practical matter, if I were "in your shoes", then the only thing that I would worry about would be condensation. Moisture can be a problem for some electronics. So if dew is forming on your rig, warm it up until the dew goes away before powering the equipment.

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    $\begingroup$ Having spent a fair amount of time in the Portland area on business, I can attest to the fact that it does get cold enough to produce snow, sleet and freezing rain. Since weather like this can create the situations that might require you to turn on the radio, you might want to err on the side of caution. $\endgroup$ – Brian K1LI Oct 11 '18 at 19:34
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    $\begingroup$ Makes sense that condensation could become an issue - have a cheap temperature / humidity monitor up on my workbench now to keep an eye on it. Appreciated your answer, thanks! $\endgroup$ – Jim Nov 16 '18 at 21:30
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I have had a Yaesu FT890 stored in an unheated shed in Saskatchewan for 15 years. Just recently dusted it off, and it fired up just fine.

It gets to -40C here for weeks at a time in winter.

YMMV of course, but its one datapoint :-)

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    $\begingroup$ I was going to comment that my VHF/UHF car rig (and my prior VHF-only rig) have spent the winter in my car parked on my driveway for the last several years and still work fine. It's gotten to the low -30s C in my car many times, and possibly colder (air temperature, not ambient). 73 from Regina :) $\endgroup$ – Jim MacKenzie VE5EV Oct 14 '18 at 16:16
  • $\begingroup$ Very helpful data point! -40C.. that's impressive! $\endgroup$ – Jim Nov 16 '18 at 21:30
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I think Kevin and Brian covered the important aspects, and these are the failure modes I'd expect to.

Aside from the battery damage, nothing too dramatic.

It's unlikely your electrolytic caps freeze, but that would be another fatal blow to your equipment.

Note that there's a lot of parameters of your electronic components that change with temperature – not only do semiconductors become less conductive, and resistors become more conductive, in isolation, you have to account for the combination of all such effects.

For example, if you have a control loop that controls the output voltage in a voltage regulator, that's often done by an internal transistor used to mirror/amplify the voltage over an external resistor. Now, if both the resistance of the resistor and the amplification speed due to reduced electron mobility in low temperatures in the transistor, then your power supply suddenly has a slightly (maybe not even measurable) drop in voltage, but a very measurable drop in the ability to react to sudden load changes.

That slight misbehaviour can lead to permanent damage, if for example you turn on your PA, which draws a lot of power, but that leads to a load jump, which in turn leads to a sharp voltage drop (due to the above effects), which then might lead to damage, e.g. because something becomes improperly biased.

So, long story short: Devices are designed for a specific range of temperatures. That range is typically specified for every device you can buy. Operating things outside of that is a "good luck!" situation when the device you operate becomes a little more complex than a handful of transistors.

Realistically, and from experience: Heat is way more problematic; things heat up all by themselves, but they can't cool down. Make sure your things don't get wet (be sure to ventilate and not have your device be colder than moist air).

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  • $\begingroup$ Your post really helped me imagine (and appreciate) the dynamics of an electrical circuit (how the different components could respond to each other in unexpected ways, in the cold in this case). Thank you for outlining what could happen at the circuit level! It's interesting to think about - makes me really appreciate the hard work that goes into spec-ing / rating equipment. $\endgroup$ – Jim Nov 16 '18 at 21:33
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The semiconductors which comprise the bulk of components in all modern ham gear are rated to operate over at least the "commercial" temperature range whose low end is 0C / 32F.

Since most active and passive components have a positive temperature coefficient of resistance, one would expect inrush current to be the dominant failure mode. The negative coefficient characteristic of thermistors can protect against low-temperature inrush current.

Check with the factory or your favorite outlet to see if your power supply and/or rigs already have these parts installed. Otherwise, distributors like Digikey and Mouser sell inexpensive parts under the heading of "inrush current limiters."

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  • $\begingroup$ It's helpful to hear that there's gear I could get to help protect the circuits - will have to check out the inrush current limiters! Thanks! $\endgroup$ – Jim Nov 16 '18 at 21:34

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