[Lowfer] TAG in PSKAM10 Mode

[Ed Phillips]

John Andrews wrote:
> 
> Ed,
> 
> >A block diagram would be a good start as I have build a number of 90�
> differential phase shifters and understand the design. What did you use
> for balanced modulators and what kind of RF phase shifter did you use to
> get the two reference signals?<
> 
> I used SBL-3's as balanced modulators. A fine choice, but you're stuck with
> 50 ohm ports.
> 
> The RF phase shift was done with a +45 degree RC combination into one opamp,
> and a -45 degree RC into another. Trimmer caps allow precise adjustment. The
> opamps are LM6182's which are available, but unfortunately discontinued.
> That's a current-feedback opamp that is happy with low impedance loads. I
> drove the SBL-3 inputs through 50 ohm series resistors.
> 
> I may have some time to sketch this out over the weekend.
> 
> John A.

	Good enough.  I'm not thrilled at the thought of using those
low-impedance devices.  I have a number of old HP balanced modulators
with BNC inputs which might be used, but have to look up their specs.  I
was hoping to use high-impedance modulators such as some of the
Gilbert-cell devices but didn't want to go to the trouble of thinking it
out!

Ed