Wednesday, September 20, 2017

Settling on the LO for the DBM.

The datasheet shows the LO level at 7dbm for the DBM and it shows the effect if the Lo is weak.
As you can see higher LO signal is better.
So what does this ADE-2 or ADE-5 consist of?
They are ICs which have two transformer and a diode ring inside. So we need a pair of transformers. What are the requirements for the transformers? The coil must have an inductive reactance of 4 times the circuit impedance at the lowest operating frequency. We need to know the circuit impedance and the operating frequency to size the coil. Assume our Rf circuits are all 50 ohm and we will not be using the DBM below 500Khz and we will need Xl => 4 * 50 at 500Khz.

The calculator say 14 turns on a FT50-43 will be good . for 1-50Mhz. I will look at so more cores and see if I find one for 500Khz. So begins the search for a core. More on that later.

 I'm using a 10 mv feed and getting a fair drive. Andy's oscillator will produce 250 mv feed so it should be plenty.

The above spice program is linked here

If you click the link and save as .ASC file type you can play with the sim.
I'm going to look up some core data more later.

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