I cross posted some of my results.
So I thought I'd post how far I've got.

This is the front end signal conditioning, going into a 74AC74 (Schmitt trigger inverter) that is used to clean the signal up. It feeds a 74HC393 which is a ripple counter. ?I'm only using a divide by 4.
this feeds into pin 11 (which is the TMR21 clk in). ?I've cut the CSW relay feed and move that to one of the TX pins (which I don't use yet).

I have some simple test code that just displays the frequency, it's timing in 16kHz steps.
I have a frequency to memory slot lookup function that covers the amateur bands (with +256kHz margin) in 16kHz steps to 26MHz. Then 160kHz steps above that.
Uses 512 memory slots (16-bit each) but I'm using the program space to store the results.
With the display type set as a #define, the other display code gets optimised out there is plenty of space.
I'm looking at the optimised tune, and will add that, and a nearby search for when you have a memory for something near.

The Pspice of the front end shows it should be good for 5W....225W from 1.5MHz to 55MHz.

Hi,
I've been looking at adding frequency monitoring to the ATU-100 HW.? I have it mainly working (current front end gain is wrong above about 24MHz), so need to tweak some of the network values to get the right voltages and offsets. As part of this I've been wondering about better algorithms, I'll have an experiment with the tune2.c once I've got the freq monitoring sorted.
As part of my research I've been looking at the Icom-AH4, LDG IT-100, MFJ 939.
Interesting, you should mention the steps.? For the inductors, you can measure and tweak, to get them power of 2.
For the capacitors, the AH-4 (and I think the MFJ) uses the same value (so probably same batch, so similar capacitance) 2 in series, as a single, and two in parallel for the smallest 3 settings.? So this should give pretty good binary steps for the bottom 3 bits.? I wondered if it was a temperature thing (for the AH-4) as they would all drift together.
But with what you mentioned, it's an easy way to get pretty good power of 2 values for the bottom 3 bits.

The AH-4 (and SG-237 which I've looked at by don't own, so can't do much checking with) are both remote tuners, and they have separate input and output capacitor banks.
Looking at the schematics, they use fewer bits of smaller capacitors on the antenna side than the input side (as a PI rather than an L).
The SG-237 has 7 bits on the input (51pF...3200pF) but only 4 bits on the output side (12.5pF...100pF) - With 8 bits of inductors.
(Not fully traced the AH-4 board, looks like 8 bits + 3 bits of capacitors + 9 bits of inductors)
Given the limited range on the output, I wonder if the SW=output side range could be significantly restricted.

I started looking at the LDG relay patterns and can already see ways to optimise it (they use bipolar relays, and wait after both the +ve and -ve switching, even if no relays are changing on one phase).? But I only have a 16 channel analyser, so looking to piggy back a monitoring PIC on top of the current one (they use a 28-pin 0.3" DIP PIC, so easy), with this I can output the frequency, relay pattern and Fwd, Rev voltages to a serial port when things change.

Keep up the good work,
Following with interest,
Roger.

Chris, my tuning algorithm isn’t too different than the article you referenced, but I think you will find that the tuning algorithm in the article results in a lot more switches to find a solution. ?It is certainly thorough, but without a way to re-use tunes by frequency matching, it might not be an ideal trade off.

I start out using an optimal table to find a point to start hill climbing, going from the most likely to least likely, rather than running through all the Ls and Cs by 8

Then rather than look in all 8 directions, I only look in 2 directions along one axis and then the other. But identical to the article, I keep reducing by a factor of 2.

I only start walking the diagonals if I haven’t gotten a good match by this point in my 8 way search function.?

I have seen the ‘false’ peek problem with my test points mentioned in the article, but it is very very rare. ?I doubt it’s happening much in the field when you look at all the data. ?I believe it might be related to the component step size bing closer to 3 so sometimes a couple of inductor steps is better than one capacitor step or visa versa. Going to binary component values would fix this problem, but introduced the problem that imprecise components or parasitics on the board would result in reversals values with binary steps of 1. ?

开云体育

Could be either.? I used the code in tune2.c to replace the tune() routine in the ATU100 3.2 firmware

开云体育

Is the Github code pointed to for the ATU-100 or ATU-10?

Seems to be? a conflict here, nATU-100 in the post and ATU-10 at Github.

glenn