1kW auto tuner

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VK5TM
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Re: 1kW auto tuner

Unread post by VK5TM »

Looks good.

I like that the Relay board is seperate, makes it an easy job if you want to do a different version to test something.
Sangoma
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Re: 1kW auto tuner

Unread post by Sangoma »

It makes it very convenient to mount, eithe small for stand alone, or long and thin if inside an amp.
The relay board is anbout the same size as my 160-6m LPF board.
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M0HJO
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Re: 1kW auto tuner

Unread post by M0HJO »

That's class Steve, well done.
Glad to be Here.
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Sangoma
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Re: 1kW auto tuner

Unread post by Sangoma »

Discovered I have a "slight" problem, due to my design of the PCB

Out of habit, and without thinking about it, I made the tracks on the bottom, and the top a ground plane.

To much capacitance, the minimum capacitor that can be switched in is 10pf, which I would expect to give me round about 20 when it is in circuit.
Unfortunately the capacitance without any thing switched in is around 40pf.

The solution is simple, make the board again on single sided board, but I don't feel like unsoldering everything :(

Another thing for the "one day" box!
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M0XXQ
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Re: 1kW auto tuner

Unread post by M0XXQ »

Sangoma wrote: Wed Jul 08, 2020 12:43 pm Discovered I have a "slight" problem, due to my design of the PCB

Out of habit, and without thinking about it, I made the tracks on the bottom, and the top a ground plane.

To much capacitance, the minimum capacitor that can be switched in is 10pf, which I would expect to give me round about 20 when it is in circuit.
Unfortunately the capacitance without any thing switched in is around 40pf.

The solution is simple, make the board again on single sided board, but I don't feel like unsoldering everything :(

Another thing for the "one day" box!
If possible, mask off the PCB leaving only the groundplane areas exposed and use a kitchen sponge, dip it in ferric chloride and wipe it onto the exposed copper, repeat until the copper starts etching away - Might take a while but will save you making a new PCB.
Sangoma
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Re: 1kW auto tuner

Unread post by Sangoma »

I could do that, thing is the router would have finished a new board long before I have finished removing the parts from the old board.

The router does not make as nice boards as etching, but it is far less fuss and more convenient.

I do have etching chemicals, not ferric chloride, but I have not used them for years, having to take over the kitchen and do it early in the morning is usually a problem.

Apart from that, I really want a tuner with memories, like the one I made a few years ago.

I thought my software was slow, turns out all I needed was bigger capacitors across the relay coils, 1uF instead of 100n.

I also stopped because it could not get serial read right, write is easy, but read is not as easy.
Still haven't got it right, seems I have to read a byte from the buffer, add it to a string, clear the buffer, read the next byte etc etc.

I was trying to read a string, which sometimes worked, but not most of the time, just luck if it was timed right.

My next trial is to do it one byte at a time for say 30 bytes, add them all to a string, then search the string for the preamble, read it up to the EOS character, then I will have the command string which is easy to deal with.
(edit) I will also try looking for the preamble as the bytes are retrieved from the buffer, then loading the next bytes until the EOS character is received, but this may not be as effective using the software UART

Its 20 years since I did these things every day, I can't remember what I did last year, let alone then :lol:

It's one thing there is very little information on line for, we used to have info on Beltel/Prestel before the internet came along, there was always some one who knew the answer then. Now programming seems to be assembling blocks.

Couple of years ago I was determined to learn C, but given up on that now, the finished code is only as good as the compiler no matter what it starts as.
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VK5TM
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Re: 1kW auto tuner

Unread post by VK5TM »

I've tried the 'C' thing several times and the further I get into it, the more it looks like over developed spaghetti.
Sangoma
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Re: 1kW auto tuner

Unread post by Sangoma »

VK5TM wrote: Thu Jul 09, 2020 3:44 am I've tried the 'C' thing several times and the further I get into it, the more it looks like over developed spaghetti.

What language do you use, and what IDE and compiler etc?

Its always nice to look at alternatives, in case they suit your way of thinking :)
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VK5TM
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Re: 1kW auto tuner

Unread post by VK5TM »

At the moment I use assembly and MPlab 8.92 (the MPlab X thing is a load of overbloated, buggy crap) for PIC's and if I am really desperate, I'll fire up the Arduino ide, look at it for a few seconds and shut it down again.

Does limit which newer PIC's I can use, but as I don't do anything commercially now, it's no great loss (and I've just realised I've got some samples coming that 8.92 doesn't support, now that's going to be a nuisance :( ).

Also got a couple of ESP32's I need to get my head around (one is for a TFT/Si5351 VFO for an FT7).

Also got SourceBoost C compiler that just went free, but that has problems/bugs and Microchips XC8 but that needs the aforementioned piece of crap software to do anything with (well, I can't get it to work standalone).

EDIT - sometime later: And as if to prove a point, I just fired up MPlabX, clicked open file and it tells me Windows is searching for a shortcut for Scantailor.exe which has absolutely nothing to do with PICs or MPlabX, stupid f@^$%!&g program.
Sangoma
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Re: 1kW auto tuner

Unread post by Sangoma »

Made another board today.

The board is slightly bigger, bur RF wise it is far better then the traditional layout of two rows, one row of capacitors and one row of inductors.

The inductor path is in fact no longer than the other board, but it is a much straighter run, and the inductors positioned better.
The capacitor part had far less tracks and stray capacitance (less than half the other layout.

This one has eight inductors and eight capacitors, the eighth of each will be switched manually on the trial version.
tun2a.jpg
tun2b.jpg
G 3 E J S
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