|Calibration oscillator is connected to the SA|
I chose a 2nd IF of 25Mhz there are disadvantages in using this frequency.1. The chosen log amplifier AD8037 has better linearity at 10Mhz
2. Narrow band 10.7Mhz IF filter are readily available.
Other things that are highly recommended when building an SA.
1. Signal Generator with frequency range that can cover the BPF filters
2. Highly sensitive RF Power meter.
3. Lots of BNC connectors
4. A copy of EMRFD
People that helped me a lot.
1. Wes Hayward- http://w7zoi.net
2. Todd Gale -http://http://www.qrp.pops.net
Here are a few more pictures.
I am using a 100Mhz clock IC for my 2nd LO. To remove the harmonics a low pass is used. The latest version is using a 9th order filter.
|5th Order low pass filter.|
|The 2nd LO is being tested for proper output levels.|
1. Rigol Oscilloscope used for the build and testing - Rigol DS1052E 50MHz Digital Oscope with 2 Channels, USB Storage Access, 1 GSa/sec sampling
2. Hammond Aluminum Boxes - Hammond 1590B Aluminum Diecast Case
3. Coaxial Cables - CableWholesale 6-Feet RG58 AU Stranded BNC Cable, Braided (10X1-01106)