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Hi Dave? G8PTN.?

So this morning took the driver Mosfet off the board that drives S8 Relay. Replaced the Fet and in Test Mode all working as it should switching between the Capacitor bank and the Inductor bank.? And of course S8 switching correctly.

So I am finally down to the last phase of testing the Bridge out.

Have you a very easy way to test the whole unit out rather than squirt 10 watts of RF into the input.

I've also checked all of the relays switching over and all ok.

All the Outputs on the 16F1938 are short circuit protected apparently so been very lucky. 73s Dave? G4RVH?

I Dave? G8PTN

Just had a thought.? I will test that the Inductance and Capacitance will tune the 50 ohms at a frequency with my NanoVNA on the Smiths Chart.? One stage closer.??

73s Dave? ?G4RVH

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Hi David,
Excellent news that all is now working okay.
It’s probably easier just to go for an RF test with 5 ~ 10W.
I would initially put the ATU in bypass with a 50? dummy load and check that the PWR and SWR readings are as expected.
The auto tuning relies on the PWR and SWR reading for its tuning algorithm.

I also did some manual tune tests with 27?, 50? and 390? using my NanoVNA, but it can be very time consuming, and you need to get close to the target values.

I actually used simulation results to find the theoretical matching values.
73, Dave

Hi Dave? G8PTN

Attached video of both banks of Relays.

Watch the Bottom Middle S8 led go out switching relay banks from L to C.

73s Dave? ?G4RVH

Hi David? G8PTN.

Sim Smith is good to get the matching to be nearer enough. I put my NanoVna onto the ATU tonight actually just to make sure that I could actually see the L's & C's altering the display on my Laptop after Calibration of course OPEN Short Load isolation plus thru the Vna.? Then put a 50 ohms dummy load onto a T BNC on the output of the ATU.? As you said its tickly unless you know what values to poke into the ATU.? It took me 20 minutes to get a match.??

73s David? ?G4RVH

Hi David? G8PTN

You have been very useful guiding me through my difficulties and most grateful of your valuable help.

My ATU was not a kit as you know so had to source all of the parts.? The Chip 16F1938 wasn't that easy because the first one didn't fire up so had to take it off and solder another one on the pcb.

Even the aluminium extrusion box was a swine to cut with a tiny round dremel saw.? But at least I can now see what's going on in the box.

Also by checking with a VN?A your sure all the joints are soldered correctly and the relays all functional.??

Before I bought the NanoVna I had a Polyscope for sweeping Bandpass filters.? It weighed a ton and was massive.? Did you use one.? A beast.

But of course time has marched on and the NanoVNA is a lab in a box.

Oh I did build the Paul Kiciacs N2PK which got me by sweeping filters in real time with the faster ADC

73s? David? ?G4RVH

Hi David,
I am more than happy to help out where possible and hopefully the ATU-100 will work when you put RF through it.
Yes, the enclosures can also take some time. I tend to use the old school method of drilling holes, and then cutting/filing manually.
For projects that don’t need screening, I tend to use ABS enclosures, and I have also printed a few with my 3D printer.
Regarding impedance measurement test gear, I started out with a good old MFJ-259, then an FA-VA5 Analyser from SDR-Kits, and of course the NanoVNA.

The TinySA is another great bit of test equipment to have on hand.
To be honest, I find the construction and experimental side of things is the best part, there is always something to learn and/or understand in more detail.
Anyway, keep up the great work and best wishes to you and your XYL.
73, Dave

Good Morning David? ?G8PTN

Thanks for you kind words. But it sounds like you and I are alike in this radioham hobby,? a labour of love.? Also have the MFJ258 for very quick checking. I have thought of buying? the Tiny SA but tend to use my homebrew QS1R Quick Silver receiver designed by Phil Covington and Zoom right into the signal looking for nasty spurs.? Cathy developed the Software for the QS1R

and also I use her NanoVna software which is fabulous because if you point the mouse onto a desired part of the screen it will give you a Match result L & C.? I do very little operating with a Mike or key these days but have experimented now constantly 24/7 with WSPR to test my aerial systems.? The very best I've ever achieved at my location is with the setup I have now. A 160 foot Doublette fed with homebrew 450 ohms open wire feeders 30 foot long. The results have been staggering.? Been heard in VK literally thousands of times this year with 100 milli-watts and down to South Antarctica but the best was a VK on just 1 milli-watt.? But the most interesting thing is actually monitoring where the aerial is firing and actually ditto with Roy Lewellen Software EZNEC.

ROY has given his Software EZNEC PRO VERSION to all radiohams as a retirement present to us all so grab a free copy.

Kindest Regards to you and your XYL of course.? Great speaking to you David.? ?73s? David? ?G4RVH