The link did not work for me.
73, Gary - G4WGT.
----- Original Message -----
From: "Stefan Schäfer" <[email protected]>
To: <[email protected]>
Sent: Tuesday, March 20, 2012 10:04 PM
Subject: LF: 137 kHz transmit IQ converter schematic
I took the time to draw the circuit of my transmit IQ converter in the new
program i have.
This is the circuit i use to generate my transmit signal to drive the
exciter of my PA. The 137 kHz signal is directly generated in this
circuit. It is mixed with 125 kHz internally.
The basic idea is taken from Andy/G4JNT, tnx agn. The circuit is however
modified for an input frequency of 10.7...12.8 kHz which can be generated
by the soundcard. The 125 kHz generator can be locked to a reference
signal, into a PLL which isn't shown here (separate circuit). Anyway the
circuit is a stand alone device. The input signal level may be 0 (=100%)
down to -30 dB full scale of the soundcard without a change of the output
signal (including a safety factor of > 10 dB).