You can also ask for flight following without a transponder, but
primary echo's are not reliable. I have tried this in the past around
the ISP Class-C. Even 10nm out, with a 20m Carbon wing, they couldn't
see me on some headings.

If you do call ATC without a transponder, the proper phraseology is to
add "slant X-ray" after your call sign. The slant codes indicate
equipment like transponder and DME, and "/X" means none. I've had
controllers give me a squawk code anyway, because they may not be
familiar with this one, but at least it makes you sound professional.

If you have a Mode-C transponder only, the code is "slant Uniform. I am
/U now, and I carry 2 x 13 Ah batteries that can run the transponder
and everything else for over 12 hours.

Ray Lovinggood wrote:
Doug,

You don't have to have a transponder to get the controllers
to know you are there. True, I'm not talking 'Flight
Following' but more like 'Flight Awareness.'

On occassions, I have called the local controllers
for the Class C airport (RDU) and let them know I was
there and was monitoring their frequency. They would
first reply to 'Squak' such and such and I would tell
them I didn't have a transponder. They would then
find me on radar. Ok, maybe they aren't as busy as
some other locations, but at least I make them aware
that I'm out there. Occassionaly, they might call
up and ask how I'm doing, and just being friendly.

Ray Lovinggood
Carrboro, North Carolina, USA