Do I Need to let the radios warm up? (Newb Question)

[pilotmattk]

Is it standard practice to let your radios warm up in the winter? I'm still in my first year of flying and last Saturday was the first time I jumped in a plane, first thing, after it had sat outside in a sub 40 degree night. I did my standard checks, ran up, and everything was good, but after I got in the air the radios were real finicky for about 15-20min. I had to keep switching between them to make/recive calls out of class C. After about 20 min or less of use, they acted fine and I made it 3 more legs to pick up/ drop off family to and from the Blue Angels show at Muskogee without issue.

I asked a flight instructor and he acted like it was somewhat normal, I but wanted to double check here. Maybe someone has a tip or 2. I don't want to burn 15 min on the ground while still renting!

Thanks,
Matt K.

 

[Steve]

condensation in the radio and/or radio tray and/or antenna connections is my swag

if it were my plane i'd clean, or have cleaned, the contacts and connectors

 

[KennyFlys]

All electronics have a "temperature operating range" for normal use specified in the manual. While a preheated engine may be running and its parameters operating normally with regard to temperature, I don't think I'd depart with avionics still in the ice-cold end of the spectrum.

Many have ranges down to -50c and as high as +70c. While the equipment may handle that range, you most likely will not. The G1000 suggest a few minutes warm up. Typically, by the time you're done with run-up, the equipment will be close enough to center of range.

However, if your radio is still using nixie tubes...

 

[Anymouse]

Although it's probably not an option on a rental, pre-heating the cockpit, in addition to the engine, is not a bad idea.

 

[Graueradler]

Pre-heating the cabin would be more important for the gyros. Unless your radios are still using vacuum tubes, I have trouble seeing how the temperatures you mentioned would affect the electronics. As Steve suggested, you may have a problem with condensation/moisture. However, the proof is in the pudding. If they consistently have problems until warmed up, then warm them up.

 

[mikea]

I have a vague idea that older altitude encoders have a heater in them.

The way I understand it, that's why the checklist has putting the transponder in standby from engine start. The heater coil gets power in the standby mode.

 

[jesse]

Given how you are located in Arkansas and the fact that it's October. No--it is not normal. There is an issue with the radios.

What model radio are they? I've flown some really old radios in below zero temperatures without issue. How cold was it outside? I really doubt it was all that cold given the location and time of year.

 

[Bill]

I have a vague idea that older altitude encoders have a heater in them.

The way I understand it, that's why the checklist has putting the transponder in standby from engine start. The heater coil gets power in the standby mode.

As I understand it, the older transponders used tubes in the power transmitter section, and putting the xponder in standby heated the tubes.

 

[Eamon]

With a rental it is hard to prewarm but in my personal plane I have a small propane lantern. I let it run for 10--20 mins in the plane whenever the temp is below freezing. As somone else said, the gyros will benifit most from the prewarm.

My first plane had a Narco Mark 12A. I used to use that radio to preheat the plane. It warmed up the C-150 in 10 min.

 

[Sticky1]

It was back in the 30's

 

[Sleek-Jet]

As I understand it, the older transponders used tubes in the power transmitter section, and putting the xponder in standby heated the tubes.

Yes, until the manufacturers came out with fully solid state transponders a few years ago (thanks Garmin), all transponders had cavity tubes that were used for frequency generation for the transmitters.

The warm up time is set inside the transponder, so even if you cycle the transponder from "on" to "off" and then back "on", the unit will go through the warm up cycle, i.e. even if it's on and warmed up, it will "warm up" again.

 

[pilotmattk]

Given how you are located in Arkansas and the fact that it's October. No--it is not normal. There is an issue with the radios.

What model radio are they? I've flown some really old radios in below zero temperatures without issue. How cold was it outside? I really doubt it was all that cold given the location and time of year.

One was a KX-165 and the other was a MX-300. It got below 40 over night. Upper 30's was the low. The plane usually has two KX-165's. One's off getting refurbed. I'll wait until that other one comes back and give it a whirl again. I'll leave a maintence squawk next if it happens again now that I know it's not normal. I will have to keep the transponder warm up in mind for the future though. Thanks for the input!

-Matt

 

[jesse]

One was a KX-165 and the other was a MX-300. It got below 40 over night. Upper 30's was the low. The plane usually has two KX-165's. One's off getting refurbed. I'll wait until that other one comes back and give it a whirl again. I'll leave a maintence squawk next if it happens again now that I know it's not normal. I will have to keep the transponder warm up in mind for the future though. Thanks for the input!

-Matt

KX-165 temperature range is -20 to 55C.

 

[KennyFlys]

One was a KX-165 and the other was a MX-300. It got below 40 over night. Upper 30's was the low. The plane usually has two KX-165's. One's off getting refurbed. I'll wait until that other one comes back and give it a whirl again. I'll leave a maintence squawk next if it happens again now that I know it's not normal. I will have to keep the transponder warm up in mind for the future though. Thanks for the input!

-Matt

Upper 30s? My, my... y'all really suffer there in razorback country.

My years in Colorado usually brought a couple-week period during January when the highs were still below 0°F.

 

[jkaduk]

Yes, until the manufacturers came out with fully solid state transponders a few years ago (thanks Garmin), all transponders had cavity tubes that were used for frequency generation for the transmitters.

The warm up time is set inside the transponder, so even if you cycle the transponder from "on" to "off" and then back "on", the unit will go through the warm up cycle, i.e. even if it's on and warmed up, it will "warm up" again.

And there are still lots of them around. If your Txponder has rotary switches on it, it's got a tube.

 

[Steve]

True for most, but not all.

My Garmin GTX 320 is solid state.

And there are still lots of them around. If your Txponder has rotary switches on it, it's got a tube.

 

[gismo]

First like others have said, 30F shouldn't be of any concern WRT any electronics installed in your plane. Pretty much any TSO will require proper operation to at least -20 C or so. Second, while condensation could create a short term problem I think it's extremely unlikely that you are suffering from any condensation issues unless you just moved the plane from the cold (with the radios off) to a heated and humidified hangar.

There are some avionics that do require a warm up period, specifically anything with a vacuum tube such as some transponders, most radars, as well as some obsolete nav and comm radios. Also there are a couple of situations where the equipment actually has a heater to provide a stable temperature or because it's cheaper/simpler to provide heat than to use components that don't need it. Examples of this are some old altitude encoders (like a Narco AR-500) and many units with LCD screens (LCDs get very "sluggish" at low temps).