LF,
This is now working! I used the QRP 2000 synthesiser (completed with assistance
from G8DQX) and have added a divide-by-100 unit based on the design by G3KAU
with some modifications:
- the original design assumed 10 to 50 W sine wave input. I left out the
attenuator because the synthesiser delivers 2.6 V peak to peak square wave,
which is enough to drive the 4017,
- I was not intending to use anything other than 137 kHz and the power
amplifier requires square wave drive, so I left out the post-divider filters,
- the output from the second divide-by-10 stage is sufficient to drive my Class
E Power Amplifier so I didn't bother with a buffer,
- there are several versions of the 4017 but with different capabilities and
voltage ratings. I used the CD74HC4017,
- and provided a 6 V rail rather than 13.
The unit is now in a die-cast box and I shall shortly be testing it with the PA
into a dummy load.
After that, I need to look at software for driving the synthesiser. For test
purposes I have been using the SI570 programmes referred to in the
documentation but they clearly are not appropriate for transmission.
Many thanks for all your help and encouragement.
73
John F5VLF
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