"Morgans" wrote in message
news

"Ron Natalie" wrote

I've never seen a hand held transponder since Terra went out of business.
They used to make a balloon pack (essentially the TRT250
and a battery) as you suggest.

I was never sure of the legality of this especially once you get
to the point of needing mode C (which the Terra didn't address,
mind you back in the day, unless you were very high or near one
of the busier TCA's you didn't need mode C).

I doubt that it would be legal as mode C, unless it was a hard
installation, and properly set up, blessed, pontified, and so forth. You
could still go to the effort to get it approved; but nobody has to know
that you are not going run it all of the time.
--
Yes, Terra did set up a transponder w/Mode C for a hot air balloon. It was
done while I worked there in '95 or '96. It was done for the Abruzzo family
who were attempting an altitude record. They needed a transponder (in
addition to the recording altimeter) since they were going into Class A
airspace. IIRC, they made it somewhere around 31K ft.

The "system" was a ruggedized instrument case with the TRT250, a gel cell
and the altitude encoder mounted inside. The case "mounted" on the edge of
the basket just like the balloon's instruments. The only tricky part was
the antenna. It was mounted on an aluminum ground plane that had stabilizing
lines run about 3 feet back along the coax. Once the balloon was airborne,
it was slung over the side of the basket and hung about 5 feet below the
basket. The lines kept the ground plane approximately level. (There's no
real problem with wind in a free balloon.)

Gerry