Transponder antenna sensitivity question

[Timbeck2]

I have this hole about three inches in front of the existing transponder antenna. I assume it was an old location for the transponder or some deer hunter took a pot shot at the airplane at some point. Anyway, I want to use the hole (I'll have to modify it somehow to make it smaller) to install the outside air temperature probe which will only be about a half inch protrusion in front of the transponder antenna. Will this cause a problem?

 

[Timbeck2]

And also, I have a set of holes where an antenna used to be (small round hole, larger round hole, small round hole in a line) which is directly behind the battery vent (Cherokee 140) and were never plugged. Wondering what the best fix for that is.

 

[Caramon13]

I have this hole about three inches in front of the existing transponder antenna. I assume it was an old location for the transponder or some deer hunter took a pot shot at the airplane at some point. Anyway, I want to use the hole (I'll have to modify it somehow to make it smaller) to install the outside air temperature probe which will only be about a half inch protrusion in front of the transponder antenna. Will this cause a problem?

Found a thread here from a while ago, where another guy mounted it near his transponder antenna. Don't see why it would be a problem:

http://www.vansairforce.com/community/archive/index.php?t-19620.html

 

[Timbeck2]

Thanks, I didn't think that it would be an issue but I thought I'd ask first.

 

[unsafervguy]

most transponder antennas are on the bottom, how close is it to the exhaust stream? might not be a good place for a temp probe.

bob

 

[flyingron]

Did you ever have a DME in the plane? Pretty much the same antenna.

 

[Timbeck2]

I think at one point there was along with ADF, GPS and an ILS but all are gone now except for the antennas or holes where the antennas used to be.

 

[weirdjim]

And also, I have a set of holes where an antenna used to be (small round hole, larger round hole, small round hole in a line) which is directly behind the battery vent (Cherokee 140) and were never plugged. Wondering what the best fix for that is.

There are a few names for what you want for a plug. Butch plug, botch button are two of the most common. The true name is hole plug. They are made by Keystone Electronics and most of the major distributors (Mouser, DigiKey, Jameco, etc.) carry them. They come in black nylon or nickel-plated steel and in sizes from quarter inch diameter to inch and a half. I recommend the nylon when working with aluminum. If you just want to make the hole a little smaller, a rubber grommet of the appropriate size would work well, but you will need to figure out how to make a metal to metal contact if you need the ground return for electrical reasons.

You can also get nylon or fibre shoulder washers from the same company. Browse www.keyelco.com for an idea of what might work for you.

 

[Timbeck2]

Appreciate your efforts Jim...I went a slightly "easier" way. It involved masking tape, epoxy, sandpaper and paint. The holes are gone and un-noticeable now. One of them contains my new OAT sensor.