> My best bet for a simple QSD is the Quad Bilateral Switch. But we > will try the NAND gate out first.
I wouldn't waste any time on NAND gates... If you find those fast bus switches too esoteric, or too small, you can build a QSD with plain vanilla standard HCMOS analog switches. I have used 74HC4052 in a QSD with good results on low frequencies (up to a few MHz). I got the impression that it worked better at a higher impedance level, probably because the "ON resistance" is quite high in these parts, so I settled for 200 ohms. Just double the number of turns of the secondary windings of the input transformer. I made no serious performance measurements though... 73 Johan SM6LKM
