Hello,
in the moment I am building the DR2A from YU1LM.
I have an xtal with 36Mc/s for receiving 9Mc/s.
For my first experiences I will use an PSK-20 as HF front end. The
PSK-20 has a 9MC IF and I take the signal after the SA612-mixer.
Tasa mentioned that the IP3 is abt 30dBm with 4066-mixers.
I found no measurements from the IP3 of SA612. I think it is not so
good and I loose the good IP3 from SDR. Right ?

How can I get an RX for the most amateur radio bands ?
Here some considerations:
With a 96Kc soundcard I can receive abt 100kc. Right ?

First:
40m has a bandwidth of 100kc  -> one crystal  abt. 28.2 MC
30m bandwidth less 100kc      -> one crystal  abt. 40.5 MC
12m bandwidth less 100kc      -> one crystal  abt. 99.6 MC

For all other bands I need several crystals with custom frequencies.
Not very cheap!!
I will discard this solution.

Second:
Build the HF front end with an high IP3 mixer and convert to 9Mc IF.
LO with DDS, maximum frequency is less than 20Mc. I know the problem
with spurs and I think I need additionaly an input bandpass filter.
Can I avoid the problem with spurs if I convert the sine-wave of the
DDS into a ractangle (Schmitt-Trigger) and use an 4066 as mixer?

Third:
??????

How do you think about this ideas ?
Are there solutions for all band amateur radio receiver and (in
future) transmitter ?

Many thanks

73
Uli
DF5SF










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