End block for a spectrum analyzer add on.

Is it preferable to have an spectrum analyzer for ocasional rf work or a nice scope and then make a spectrum analyzer add on module?

Well for me, and for now I'm going the path of the spectrum analyzer module add on, since a stand alone spectrum analyzer is far more expensive than any of my radios....you get the point. Some past experiments on a similar module were already made some blog posts ago

 by using the RSI from a AM detector chip, now I'm using another approach with the AD8307 logarithmic amplifier.

On to the schematic:

It's basicaly a "Bitx" 10 Mhz filter terminated in 50 Ohm (I hope, not measured yet)
connected to an AD8307 with about 45 Ohm input (from Analog datasheet)

On the right of the schematic there's an option for a common 10.7 Mhz filter from Murata (did not test this option).

Here's some signal "injection" for a preliminary test:


With the output from the "signal generator" (dip meter) 1 Mhz from the filter center frequency:

Without signal:
 
 And at filter ressonance:


The AD8307 is the SOIC version and after all was not that hard to solder, I removed some cooper from the board and lay'd there the IC, then soldered some wires to the necessary pins:


Will continue this experiments as soon as possible....that may take some time...

Until then, solder what you can... and have a nice week!