Cool Temperature Ranges Affecting USB Wireless Adapters Reception

I have been having trouble with USB adapters in colder temperature ranges. The manufacturers list a functional temperature range with low around

35 degrees fahrenheit. You would not think with solid state electronics that temperature would have a great effect. At around that temperature ( 35 of so) the adapters power up fine. the computer knows it is there but there is no reception of any type. I have tried shorter usb cords and added a powered hub. Any connections are taped in plastic so as to avoid humidity shorting out the circuit . Anyone have any ideas or experience in this matter.

thank you

Reply to
frankdowling1
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Sure. The problem is not cold but water. At temperatures just above freezing or actually near the dew point, water will condense on your USB adapter circuit board. It will detune antennas, short out adjacent traces, act as an attenuator to RF radiation, and general wreak havoc with the circuitry. If you're in a marine atmosphere, the salt in the condensed water will do an even better job of shorting out the board. Whatever "taped in plastic" is suppose to do does nothing for condensation unless your box is hermetically sealed and desiccated.

Your best bet is a polyurethane or acrylic conformal coating, such as the various products made by Humiseal.

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comes in spray cans. You will need some tape or masking goo:
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protect connectors, adjustments, and antenna surfaces. You'll also need a UV lamp to inspect the results to be sure you've covered everything. When I used to design marine radios, this was the stuff we used to protect the boards.

You will have a big problem with circuit board antennas. The dielectric constant of the conformal coating will probably detune the antenna. Therefore, I suggest you consider using an external antenna. This can simply be a half wave long dipole made from two pieces of stiff wire. Just get the antenna off the board.

Good luck and don't do this in the kitchen.

Reply to
Jeff Liebermann

Jeff,

thanks as usual you came through. A couple questions-

the adapter used is a USB pen type adapter which allows the length of USB wire from the computer. Signal strength loss can be a problem with a length of wire that is why I am trying to retain use of the simple, efective USB adapter setup. Could the adapter be placed in a sealed container such as a sealed glass container to keep out humidity. The cold in the middle of winter is actually a very dry cold- they say it is drier than the Sahara Desert. In the middle of the coldest weather would the adapter work if it is really dry ? Interestingly enough the problems started as you explained in the temperature around freezing where moisture is a problem.

thank you

Jeff Liebermann wrote:

Reply to
frankdowling1

I like to answer the easy questions and leave the tough ones for others to answer.

16ft maximum USB cable. If you want to go longer, you need an amplified cable or a few USB powered hubs. The hubs are cheaper.

Length of the USB cable has no effect on signal strength. However, it does limit the location of the USB wirless adapter, which will have a serious effect on signal strength.

Sorta. I've done quite a bit with pressurized coax and boxes. Basically, you take a bicycle valve stem (available at auto parts stores for some other purpose) and seal a NEMA plastic waterproof box. These usually have a rubber seal around the cover and can easily be made air tight. Dump some desicant (silica gel) into the box. If it's old, bake it in a toaster oven for a while to drive off the moisture. Seal the box and test pressurize with a bicycle pump. Attach a tire pressure guage and measure the pressure. If ambitious, spray the box with kids bubble mix to check for leaks. Mine always seem to leak around the cable entry, which I like to bury in silicon bathroom caulk. When you're sure it's air tight, install the radio, close the cover, pressurize, and hope it lasts the winter. I usally have a small pressure bottle and regulator attached to the bicycle valve to make sure the pressure holds. This also works with heliax and other air dielectric coax cables.

Well, I don't have any experience with low humidity cold. However, it's easy enough to test. Take a mirror or piece of glass and leave it outside in the cold for a while. Wipe it clean. Take it inside where it's warm. If it's instantly covered with condensed water, you have a problem. If not, ignore my ranting and try something else like installing a small heater (resistor) to the keep the board warm.

Check your local weather station for the dew point (temperature).

Geobytes says 24.70.95.203 is in Edmonton, Alberta, Canada with an 88% certainty. (How close did I guess)? |

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local weather is: |
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a: temperature: 35F dew point: 25F humidity: 65% Humidity goes to 75% at night and 53% during the day. That's anything but dry. What are you talking about?

Reply to
Jeff Liebermann

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