3280 and AD533 availability, EN frequency shifter

[Paul R. Higgins]

Does anyone know what the current status is on the availibility of the 3280 OTA?
My Digi-Key catalog claims that they still carry it, but people on the list have
said otherwise.

I was also looking at the frequency shifter in the EN Builder's Guide and I had 
a couple of questions that I knew the DIYers would have answers to. 

1)  The dumb question first: what the heck does a frequency shifter do, and what
is it useful for?  I know it's not the same as a pitch transposer, but that's 
all I know. 

2)  Can you still get the AD533 analog multiplier used in the EN frequency 
shifter?  If not, is there a substitution available?

Thanks,
-PRH

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Paul Higgins
email: higg0008 at tc.umn.edu
University College, University of Minnesota
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