At the moment I'm using this EB100 from Rohde & Schwarz. Its an old model from the 80s but it is a very high end product and the IF filters are top quality. In these modern times with Software Defined Radios the EB100 is connected to an SDR-14 from RF Space. Now this is a setup!!!
The EB100 covers 20 - 1000 MHz with 7.5, 15, and 150 kHz bandwidth. This is really a nice receiver. The only problem is the scanning feature. It can store about 20-30 frequencies and scan them but its slow. I need a receiver from the 21st century that has all the features we nerds need. But where do I find such a receiver?!
I got the EB-100 from Helmut Singer Elektronik in Germany.
Below is the manual (in german).
The DIN power connector on the EB100 also has some outputs. One of these is the signal strength output. The level is 0 to 3.5V and the 101-led display that I had in my "junk box" was a 0 to 5V meter. So I needed a small DC amplifier which is the LT1498 circuit in the schematic.
The schematics for the signal strength indicator can be found here.
I'm also considering building a lead acid battery charger for the 6V battery. The charger that came with the EB100 was not good. So my battery looses charge pretty fast. But I have been told that Unitrode (TI) has made a complete lead acid battery charger IC. The UC3906 wired as a 6V charger is described in detail in their U-104 application note. That's the next project...!