Transponder: Mode-C or Mode-S?

On Sep 12, 7:07*am, Stefan wrote:
Am 12.09.11 14:57, schrieb jcarlyle:

Using the same logic, don't buy anything other than V rated tires for
your car, as the common S rating is only good for 112 mph (180 kph).

If I wanted to drive with 112 mph (180 kph), then you'd be perfectly
correct. Glider pilots on the other hand tend to want to climb as high
as they can. In fact, the possibility to get a clearance to climb has
been the main reason for me to buy a transponder. So it would have been
pretty pointless to buy a class 2 transponder.

As always YMMV, but at least one should be aware of this limitation
before spending money on a class 2 transponder.

Except for the fact that the folks on the ground that grant the
clearance don't know or care whether you've a Class 1 or Class 2
transmitter as long as they are receiving your signal. They also
don't care about you when you are more than 40 miles out, and if 135
watts won't get you 40 miles, something's wrong with your
installation. A properly installed* Class 2 with a dipole antenna in
a fiberglass (not carbon) fuselage glider will get more radiated power
out than most GA with metal fuselages and the 1/4 wave monopole
antenna they are forced to use. If you've got a carbon fuselage,
you're stuck with the 1/4 wave.
* a major contributor to lost outpout power is the cable from the
transceiver to the antenna. Don't use RG-58. It's unsuitable for L-
band.