I'm building an experimental direct sequence spread spectrum modulator along the lines of that described in this article:
The PRBS sequence XOR'ed with the data is fed to the IF port from a logic gate.
I think the mixer IF port is incorrectly terminated and the IF drive level seems excessive - even for a high-level mixer. Assuming the impedance looking into the IF port is 50 ohms, surely the drive is +/- 35mA not 25mA as claimed? Mini-Circuits don't recommend a drive level for the TFM1H IF port; they only specify the absolute maximum as 40mA.
I want to use an unsymmetrical resistive pad to both set the drive level and present the IF port with a true 50-ohm termination; and I only have an SBL-1 (Level 7) mixer to hand at the moment. What IF port drive level should I use for this?
PS Another interesting SS link: