[Lowfer] TAG in PSKAM10 Mode

[Ed Phillips]

"Hi Ed,

I built a phasing RX for DGPS beacon reception a few years ago
and I got some 40 dB rejection of the unwanted sideband using
only two "all-pass" filters in the AF phasing section.
The bandwidth was only a few hundred Hz, limited by a 3-section
active BPF centered at 500 Hz. Achieving accurate 90 degree
phase shift over the entire voice spectrum is a completely different
story... 

73
Johan SM6LKM"

	The all-pass filters for generating 90� differential phase aren't a
problem, but figuring out the simplest hardware takes some thinking. 
I'd like to use high-impedance balanced modulators rather than some of
the RF ones which can be had so cheaply.  I built part of a filter-type
exciter about twenty years ago.  It consisted of one balanced modulator
driving a crystal filter.  I have the hardware but the wire-wrap is so
messy that I haven't yet traced out the schematic. Used a CD4066 switch
with transformer inputs.  I need to look at it again.

Ed