I am currently designing a receiver for the 40 meter band and will be using an NE602 for my mixer. I have most of the individual circuits built (pre-amp, bandpass filter, crystal filter etc) and they are all 50 ohm impedance.
As the NE602 has around 1.5k ohm input impedance I have have wound a 4:22 toroid for the RF input to convert from 50 ohm to 1.5k ohm.
Using my NanoVNA I want to measure the impedance (and return loss / VSWR) of my RF input circuit so I can adjust the windings to get a good match but the NanoVNA outputs around -13 to -9 dBm, this is too high for the NE602 RF input which has a maximum input of about -25dBm.
How would I go about attaching the NanoVNA to the RF input of the NE602 without causing an overload?
Thanks in advance for any suggestions or advise,
Kerr
