Message-ID: <000a01c4f9ea$1bf9dd80$0702a8c0@parissn2>
From: "Stewart Nelson" <sn@scgroup.com>
To: rsgb_lf_group@blacksheep.org
References: <41E58B5D.6070700@freenet.de> <41E5A312.5040500@usa.net> <41E6AD88.6000903@freenet.de> <001301c4f9a2$21863c00$3801a8c0@JKA>
Date: Fri, 14 Jan 2005 04:35:34 +0100
MIME-Version: 1.0
Subject: Re: LF: Simple image-cancelling exciter for digimodes
Content-Type: text/plain; charset=iso-8859-1; format=flowed
Content-Transfer-Encoding: 8bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org

Hi,

You may wish to consider a dual 4-input analog mux such as
the '4052.  For instance, see
http://www.semiconductors.philips.com/pip/74HC4052.html

You can connect the quadrature LO outputs directly
to the S1 and S0 inputs.  Then, because there are two
muxes, you can create a differential output without
needing to phase-split the incoming audio.

For example, assuming address sequence is 0-1-3-2-0-1-3-2 
(S1 lags S0) connect:

1Y0=Left ch.
1Y1=Right ch.
1Y2=GND
1Y3=GND

2Y0=GND
2Y1=GND
2Y2=Right ch.
2Y3=Left ch.

Then, the voltage between 1Z and 2Z is the SSB output.

Perhaps, you can use a transformer-coupled output.
Put a cap across the primary to resonate at the
approximate output frequency, and connect it from 1Z to 2Z
through a suitable resistor.  No op-amps or precise
resistors needed, and it provides the first stage of
filtering.

Disclaimer: I have not tried this, and there may be
a stupid reason why it won't work.  Please don't
laugh too hard.

73,

Stewart KK7KA