Mounting Your Eggfinder TX in a Rocket
The Eggfinder TX board is about 3” long and .9” wide; with its “stick” antenna it’s about 6”
long and .9” wide. It will fit into just about any rocket with a BT-50 or larger payload bay,
although some of the batteries may not fit in a space that small. (9V batteries and 7.4V 2S
LiPo packs are about the same size, and require a BT-55 or larger body tube.).
The cardinal rule of tracking transmitter mounting is
KEEP METAL AWAY FROM THE ANTENNA
.
This means that if you have an A/V bay with two allthreads running the length of the bay, this
is going to be a really bad place to mount your Eggfinder. Large metallic or conductive items,
including batteries, hardware, and other electronics will significantly reduce the range of your
Eggfinder TX. Note that this also applies to metallic paints, and metallic film trim as they can
also block out radio signals. So can carbon fiber nose cones and body tubes. If you have any
of these, your best bet would be to mount the antenna outside of the body tube/nose cone.
If you HAVE to mount it somewhere near metal, you should keep the metal at least 2” away
from the antenna, farther is better. You may be able to get away with this in a very large-
diameter rocket, but if you’re putting it in a minimum-diameter mach-buster, you will be very
disappointed in the range that you get out of it.
The best place to mount a telemetry tracker is in the nose cone. There are many ways that you
can mount it, we have had good success with simply mounting it on a small piece of
basswood/plywood located in the nose cone, with either a bulkhead or a piece of BT-55-sized
tubing to hold it in. This works very well for plastic and fiberglass nose cones. (It will work
for wood nose cones too, if you can still find one…)
We’ve seen some people wrap them in bubble wrap and stuff them into the nose cone. If you
do this, be aware that bubble wrap can generate static electricity, so be warned. Better would
be the natural foam rubber that is used in RC airplanes to cushion receivers, it does not
generate static electricity. You will also need to make sure that it can’t slide out at ejection,
and that it’s sealed off from corrosive ejection charge gases. Masking tape works fine for that
purpose.
We’ve also seen them mounted inside coupler tubes attached to the nose cone or shock cord.
This works fine, as long as you seal up the coupler so no ejection gases can get in. Also we
strongly recommend that if you tape it to the shock cord, you do not use plastic electrical tape;
the heat of the ejection charge gases can melt it, and you may end up finding your Eggfinder
sans the rocket. A few layers of duct tape works fine.
Important points to note are:
• If you use the mounting holes, use a nylon or polycarbonate screw or a plastic rivet in the
hole next to the antenna. Do not use a metal screw. It’s OK to use a metal screw at the back
(near the RDY LED).
