I suggest temporarily setting the Mux board to the side and debugging the Lafferty board in the IG-18; you won't have the convenience of the range switch to manipulate the added AGC paths, but you can address those with jumper connections, band by band. Once you're happy with performance with the distortion performance on all bands, only then introduce the Mux board into operation.
To reiterate, you should establish base-line performance before adding Mux. Otherwise, if performance is disappointing, you won't know where to focus suspicion.
Great work! Good luck!
Steve
Hello Steve!
So, I did build a complete SL18 oscillator, using my own PCB design and building a switch to address AGC cap switching at the same time as dialing the range.
And... it works. I need to test it with a real Audio analyzer to see how it goes, but at least I can see that it works as intended. Amplitude, frequency etc... and doing a FFT on my crappy SDS 1202X-E gives back good numbers. But... now i need to test the MUX board. How can I go to do that and check the actual performance and operation as intended?
Here's a few pics of the completed project.
Attachments
Hi Pizzigri!
That's beautiful work--- my compliments!
So if I understand correctly, you've implemented the AGC redesign, complete with mechanical switching, and so now have a completed AGC IG-18. You're done, but still want to prove out the IC mux concept for follow-on? Kudos!
I reiterate the desirability of characterizing distortion performance of your newly finished unit; it's the target for performance with the mux addition.
I suggest installing the board with with +/- power supply wiring and range-sensing networks. Confirm expected behavior of the mux address inputs with a 'scope; then you should be able to confirm the intended mux path on each range using a multi-meter's resistance function to confirm conduction on each active mux channel.
To address Mafalda's concern in post #161, check for any deterioration of distortion associated with added bias currents. I'm optimistic for results but his concern deserves investigation.
Then replace mechanical switch connections with the mux path. I advise a single band, single path at a time, first with integrator, then envelope detector detector. Check for THD performance as you go.
Good luck!
Steve
That's beautiful work--- my compliments!
So if I understand correctly, you've implemented the AGC redesign, complete with mechanical switching, and so now have a completed AGC IG-18. You're done, but still want to prove out the IC mux concept for follow-on? Kudos!
I reiterate the desirability of characterizing distortion performance of your newly finished unit; it's the target for performance with the mux addition.
I suggest installing the board with with +/- power supply wiring and range-sensing networks. Confirm expected behavior of the mux address inputs with a 'scope; then you should be able to confirm the intended mux path on each range using a multi-meter's resistance function to confirm conduction on each active mux channel.
To address Mafalda's concern in post #161, check for any deterioration of distortion associated with added bias currents. I'm optimistic for results but his concern deserves investigation.
Then replace mechanical switch connections with the mux path. I advise a single band, single path at a time, first with integrator, then envelope detector detector. Check for THD performance as you go.
Good luck!
Steve