![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhd2BzeD3BhtkghK4XVz8hKmhD2rvTdZxH3enduSiQFxvVJGVA6SGtwZNIfnhzlfFWHlLzeRiKNItElRHnGAdv2Vl_r9PN_7QQYay7cGBDgyTeTjW-GBsTMZTL6qlyxZpDRr9Kvo1SNbfeh/s320/Norcal+S9.jpg)
http://norcalqrp.org/files/NorCal_S9_Assy_V1.pdf
This is very close to the circuit for the Elecraft XG2 Receiver Test Oscillator
http://www.elecraft.com/manual/E740084%20XG2%20Manual%20Rev%20F.pdf
This looked like something that might be useful for testing the Spectrum Analyzer after I get it finished. I decided to build a similar unit, using parts from both design. Looking at the NorCal circuit, I saw that they used 20 and 14 db pads instead of the single 34 db pad used in the Elecraft model. I went with the NorCal circuit and added switching around both pads to have options of 50, 10, 5, and 1 uv. outputs.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCU8mMgruS0c9BflEC_xT-FEyRVFSQvxnb_AuP_vnqJDxYtnAVIm2TXWG5-zRTZkOQqAKhhR0WaZuaCFFLhtM027gwQ539ygiQgfRTfJB5z70hHrU6rc3usgZXpqykGiX19Pwzaj4DGU4m/s400/s9+signal+source+board+layout+1.png)
Now to etch the board after I get back from a hamfest tomorrow.
11/8/15
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9shEcofMu-iwLiHdhF15FMaPx5nsZloK97MqyaXfPhMKXHls_Esk2nsGbPOPqd0LOhIjoJCx-9Ga9czsjtVQAXLieBzzZ_yY8c7h3H2xgJ2HA7KNpeOgC_iSkOBqBXCd-UmVc5oTG2Vx-/s320/s9+signal+source+board.jpg)
I built the oscillator portion of the board to test how much output I was getting. From the Elecraft document it looks like the oscillator should put out about -50 dBm before the attenuators. Hooked mine to my home-brew AD8307 power meter and got a reading of -48dBm. Checked the voltage to the oscillator and had about 1.6 volts, I might try adding another diode in series to drop the voltage and see what that does to the output.
Now on to the attenuators, I am missing a one of the values for the 20 db pad but will try with the closest value I have for now. Will replace with correct value when the assortment of low value SMD resistors I have comes in.
Since it is raining out I decided to finish the board and add the attenuator components. With the attenuator pads out I measured -68.2 dBm on my power meter. I added another diode in series with the existing diode, this dropped the voltage to the oscillator to 1.07 volts. Measuring the output with the additional diode I measured a value of -72.8 dBm. This is more than close enough to the desired -73dBm output level of the Norcal S9 generator.
Only have two crystals in the circuit for now (3.561 and 7.030) will add others as needed. Listening to the output on a receiver. The 50uv gives about a S7 reading, readings for other levels are below S1 but I can hear definite changes in the signal as I change attenuator settings.
Unfortunately I do not have any calibrated test equipment to verify the values I found. But I believe the accuracy should be enough for testing the home-brew equipment I am working on.
Link to dropbox for Eagle files and toner transfer image.
https://www.dropbox.com/sh/p4qqfqab0z5g80k/AACJtjIMUgUTV1FqEuiN-Byta?dl=0
I finished drilling some holes in an Altoids tin and and mounted the circuit board. I also printed a simple instruction card showing the jumper settings for the different signal frequencies and attenuator settings. I sized this to fit inside the top cover of the Altoids tin.