I managed to get the prototype board up and running. Naturally nothing I do is perfect to start off. Missed drawing a trace between pins 6 and 7 for the AD8307 chip. Explains I suppose why the 1st round of testing was behaving erratically. Pin 7 is the ENB pin which should be high. So since it was floating, I guess that's the erratic readings I was getting. I was ready to blame the signal generator for the problem. Gawd forbid it was my fault. hihi
Here's the results. As predicted, I was able to get down to -70 -75dbm. Apply a correction factor and -80 comes into play. Not bad I'd say. Reading the datasheet hints at getting a little further but I'm not sure its worth the effort. However it can't hurt to have another read and try to understand some of the finer details of the 8307.
73, Peter
Peter
ReplyDeleteI would not worry about trying to get much below -75dBm or so. With good shielding that is about the best noise floor I can get. I had a computer die and lost a lot of my older e-mail messages. So send me a email and I will send you the board layout I use for 8307 power meters. It was what I had in the probe at FDIM. duwayne@kv4qb.us
DuWayne KV4QB