50kHz pitch shifter

[Toby Paddock]

Hello,
A friend is doing a physics experiment for school and 
one of the resulting signals is a 50kHz sine wave with 
noise on it. The noise and ringing is one indication 
of what is going on. We thought it might be worth 
bonus points to be able to listen to it. 
So we need a pitch shifter or divider.

Maybe a 1/100 divider. Sample one cycle and play it 
back slow and do it again. Sync could be direct from 
the clean sine source. The wave is periodic and fairly 
repetitive, cycle to cycle. But the sample rate would 
be pretty high.  

Maybe a ring mod (my favorite). Assuming the carrier 
is a clean sine wave would the output have the same 
waveform as the input. It would not need to be perfect 
as long as you could hear the change. Any tips on 
what ring mods like 50kHz inputs? 
I have a sample AD633, but have never built a ring mod.

Ideas?

Thanks,
 - -- -  Toby Paddock