Using XPDR swithed power

[RVG8tor]

I am installing an equipment cooling fan, the Garmin 327 has a switched power pin I guess normally used to run an encoder (I think). It has a max AMP of 1.5 and that is above the requirements of the cooling fan. I am thinking of powering the fan from this source that way when the transponder comes on the cooling fan is on.

Anyone do anything like this, did you add a switch to disable the fan? In thinking of bad things that might happen, my though is a problem with a fan burning up from some reason, I would have to turn off the transponder to remove the electrical to the fan. I am not even sure that would or could be a failure mode in the fan, and it would not be a big deal to lose the transponder in most cases.

So good or bad idea to use the switched power off the transponder. More weight, but not much, to add a dedicated wire, fuse and switch for the fan.

Cheers

 

[Walt]

Bad idea in my opinion, you risk damaging an expensive piece of equipment to gain very little utility. I run an avionics cooling fan in the summer, the "switch" is the fuse, I put it in when the weather starts getting warm and remove the fuse during the winter months. The fan simply comes on with bus power when the fuse is installed.