[R-390] R-390A sensitivity measurements

[DJED1 at aol.com]

What we old microwave guys are used to is having an impedance match between 
components, so maximum power is transferred.   For newer equipment, we almost 
always work in a 50 ohm system, and measure in dBm.   For older radios, where 
the impedance is not 50 ohms, measurments were not so clearly defined.   This 
is true for the op-amp also, because its output impedance probably does not 
match that of the receiver.   That's why I'm troubled by using resistors to fudge 
the sensitivity measurement-it terminates the generator properly, by part of 
the signal power is lost in the resistor.   I think we need a good low-loss 
transformer to properly feed the R-390. Anyone have such a thing?
Ed