I see that the RF and LO inputs are not balanced to ground whereas the IF output is. And I would say that you are most likely correct in assuming that the source and load impedances are 50 ohms (This, of course can be determined by measurement).
What immediately springs to mind is a 1:1 toroid on the LO and RF inputs with each of the primaries being driven from a cathode follower (Zout = 50 ohms) - or a higher figure and change the turns ratio of the toroid accordingly - but I wouldn't exceed an impedance transformation of about 3:1. As for the IF output, a roofing filter might be advisable or perhaps straight into the primary of the 1st. IF transformer. Obviously, a 50 ohm match will be required here and the drive level of the LO is important - but you are doubtless aware of that.
Aside: In the past, when I've worked / experimented with DBMs, I've always found a spectrum analyzer to be an essential tool.
When I find the time to think about this a bit more, I'll come back.
Edit: this pdf from Mini-Circuits: [attachment=4204].
Look at the last entry: it makes it clear that Mini-Circuits DBMs are designed for 50-ohm systems.
Al. / March 3, 2012 //
What immediately springs to mind is a 1:1 toroid on the LO and RF inputs with each of the primaries being driven from a cathode follower (Zout = 50 ohms) - or a higher figure and change the turns ratio of the toroid accordingly - but I wouldn't exceed an impedance transformation of about 3:1. As for the IF output, a roofing filter might be advisable or perhaps straight into the primary of the 1st. IF transformer. Obviously, a 50 ohm match will be required here and the drive level of the LO is important - but you are doubtless aware of that.
Aside: In the past, when I've worked / experimented with DBMs, I've always found a spectrum analyzer to be an essential tool.
When I find the time to think about this a bit more, I'll come back.
Edit: this pdf from Mini-Circuits: [attachment=4204].
Look at the last entry: it makes it clear that Mini-Circuits DBMs are designed for 50-ohm systems.
Al. / March 3, 2012 //
