TS-520S VFO using the Arduino Nano VFO board.

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I've been requested to have a look at a VFO for the TS-520S radio.
Using the Arduino Nano VFO will result in good stability and accuracy.
Here is my first run at this using one of my test rigs.
Pushing the encoder button allows each of the 5 decades to be selected for adjustment (shown by the * ) giving slow to fast tuning.

5.5Mhz output

4.9Mhz output.

I'm not familiar with the TS-520S but it looks like the VFO needs to output 5.5Mhz for .000 reading and 4.9Mhz for .600 reading as this does.
What would be nice is to get a signal from the radio to tell the VFO what the band is so then the display could show the signal frequency directly.
That is something to look into.

So far, the RIT and various mode are not coded in, just the basic VFO.

 

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A test with feeding the VFO into the rear RCA connector seems to work on RX but not on TX as then the set reverts to the internal VFO. A bit more study of the manual is needed to figure out the operation.

 

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I'm playing around with a 16 stage divider fed from the TS520S band selected HET crystals, the resultant frequency is counted by the Arduino Nano then used to set the band. The VFO will display the signal frequency and also limit the VFO range to prevent out of band transmissions.
It does look like it will work after some calibration, but I will still need to test this on the real set.

 

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This is an updated circuit to remove the extra switching. I think it may work ok with the VFO on both TX and RX when selected from the TS520S.

The case no longer fits..

I have not included the filter as yet.
Here is the latest code.
Now, I just need to test it in a radio!!!!

 

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I think the code is done now!
Last night I had fixed a couple of bugs but did not save it as I thought the save prompt was for another reference file, not this one
Sit5ll, this morning, hopefully it is all working.

 

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pcb maybe?