Monday, November 22, 2010

Simple signal generator

With a little bit of inspiration from the blog of M0XPD I have built a simple signal generator. The original design is from NorCal QRP club and can be found here. I´m able to create a S1 or S9 signal (more about the s level here) that I can listen to if I´m going to test a receiver. I can change between 4 different crystals/frequencies. As there is no low pass filtering in the circuit there will also be harmonics. Here is two pictures and you can see that it´s been a while since I built it but haven´t documented it until now.

The box by the way is bought at IKEA. I think it was 7 different boxes in one set and quite cheap. Next test equipment in the blog will use one from that set too.


  1. Hello Erik,
    These IKEA boxes are great. I used old metal sigar boxes myself.
    I studied the NorCal signal generator. It seams to my that it is an excellent design.
    The signal is picked up over a resistor with a low value, so it provides a very low voltage.
    The output voltage is 50 microvolt, which is S9.
    The two attenuators give 20 dB and 14 dB. So the signal is 34 dB lower. This is 1 microvolt.
    I think this is about S3. (in stead of S1)
    Thank you for sharing this great design.
    73, Bert PA1B

  2. Hi Bert,

    Thanks for the comments. M0XPD commented on this so I did 48 dB pad.

    Yes, the IKEA boxes are nice. I think the one I used here is similar to the famous Altoids that I read about. but I do not like to eat mints. :-)