PA2OHH Marker Generator tryout

I did finally try out the PA2OHH circuit previously blogged on here:

https://wb9kzy.blogspot.com/2024/07/a-closer-look-at-pa2ohh-marker.html

Here again is the circuit:

I looked through the crystals I have on hand and ended up using a 5.12 MHz crystal

Here it is on the breadboard:

There is a mistake in the top diode polarity in that picture so only the pin 6 output is being looked at - the frequency is nominally 80 kHz (no trimmer was used to get the output more accurate).  See scope captures here:

zoom in on the center spike to see the pulse width

correcting the polarity of the second diode on pin 13 the frequency drops to nominally 16 kHz - that's a division of 5 rather than a binary division of 4.  Unfortunately as can be seen on the photos, the output is not a pure spike, the positive blip is from the pin 6 output being ANDed together with pin 13 using diodes - if a gate had been used the waveform might be cleaner but also the circuit would be more complex.  Here are the scope captures with the corrected diode:

So it does work.  I still need to buy some crystals (hopefully both 6.4 and 3.2 MHz are available) - I will give the circuit a more thorough look when I receive the crystals.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm