30m Oscillator

I have been interested in building a transmitter for QRSS activities. On 30m the activity is located at 10.140000 MHz to 10.140100 MHz (100 Hz wide sub-band). I happen to have quite a few crystals on hand for 10.140 so I thought it was time to  start building a circuit that could emit some RF.

My initial bread board design is shown below. I built an oscillator and once that
was functional I added simple NPN follower to the circuit. The original oscillator
design is derived from a W7ZOI design for 40m. (I like the oscillator design because
it provides a quite a bit of feedback so it has a reliable start but is stable after
being in key down for 45 minutes.)

It comes up on frequency at 10.138 and is pretty stable. It looks like I will need
to work up an inductor & capacitor pair that I can use to move it up the band
a little bit.

After a few hours of building and testing I translated my changes via pencil on to
the paper schematic and then went back to the computer to update the design in TinyCad.
I also called N0FP to get some help using the AADE filter software so that I could
add a low pass filter to the output of the follower. N0FP also helped me tweak the
bias for the Q2 follower transistor.

Here is a picture of the some test gear. It is nothing special but it is enough to
see what you are building. I was able to adjust L1 to tune out quite a bit of the
harmonic properties. The spectrum analyzer is an inexpensive model that is good to
about 550mhz. The analyzer combined with the 60mhz oscope really helps to visualize
the RF in the project.

The TinyCad schematic above shows the changes to R6 & R7 and then the Chebyshev
low pass filter. Those are the next changes that I will add to breadboard and then
retest the circuit.

Future ideas/goals:

--Move it to a copper board with Manhattan construction for additional stability and

--Add some additional LC to swing it into QRSS sub band.

--Add a PIC 16F628A to generate the QRSS CQ message.

--Use the PIC to generate some visual feedback during operation.

--Investigate rescaling it to another band

--Etch a board for the final project

I had a blast on Saturday building the initial prototype. It was very rewarding to
put the pieces on the breadboard and to see RF start showing up on the scopes. There
is a ton of learning experience that is gained during these projects.

73 de NG0R