multiplier: was Re: 3280 and AD533 availability, EN frequency shifter

[Haible Juergen]

	> AD633  (crap, if you ask me)

(;->) 

Glad I didn't try it. I was sceptical after reading the specs, and decided
not to spend money on them. Only heard good things about them on the
list so far - good to hear the other side now !

	> I've bought 4200, but expect problems due to the unsymmetry of the
	> circuit. It is basically one quadrant.  We'll see.

Works fine. Be careful with the offset trimmer networks, though.
The ones in the data sheet are *right* (why do I have to stress that ?),
but some of the published ring modulator circuits use less components,
thus sacrificing stability. It's all bipolar, so you *need* to match
impedance
oft the offset trimmer dividers to the rest of the circuit.

JH.