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It's only me again? David G4RVH. Before coming away on holiday in the caravan I finished off the ATU-100 pcb.? So went to do a quick test by switching on the unit at the exact same time as switching on the Auto and Bypass and Tune buttons which ground the switches.? Anyhow it did not activate all of the relays to test that all of the 2N7002 Mosfets were grounding all of the relays to switch them all on at the same time.

So thought I would see if anyone can throw some light onto the problem to sort this issue out while I am away.

Much appreciate any help.? I will of course bell the whole circuit through when I return home.? Hoping it's just a quick fix.? Regards to all? 73s David? G4RVH

Hi David,
I tested the “FAST TEST” mode when I first built the ATU100, and it worked as expected.

There are internal pull-ups on all button signals.

With the unit powered up, and without pressing the buttons, the signal end of the switch should measure 5V, indicating it is connected to the PIC.

When the button is pressed the signal end of the switch should measure 0V.

Perhaps, also try the “TEST MODE” by pressing the “Bypass” and “Auto” buttons whilst powering up the unit. This allows you to manually step through the relays.

When all relays are activated, the supply current will be around 0.25A, dependant on the supply voltage.
73, Dave

Sorry for the delay Dave as we have been on holiday in our touring caravan and just returned today.? Been to Tewksbury and Corwen North Wales but thank you very much for pointing me to some tests that I can now carry out.? I will of course let you know how I get on.? Regards david? G4RVH

Hi David,
There should be internal weak pull-ups on all three button signals, there is also an external pull-up on the “TUNE” signal.

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The extract from the code for the internal pull-ups is shown below.

From the datasheet, the typical weak pull-up current is specified as 140uA, with VDD = 5V and VPIN = VSS.
This equates to an equivalent pull-up resistance of around 36k?.

I would therefore expect to see VDD = 5V on all three pins if the buttons are not pressed.
I assume the PIC is working correctly. Without pressing any buttons, does the display show the correct information at power up?

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If I remember correctly it was quite fiddly soldering to the B1 and B2 connections on the bottom side of the PCB.

73, Dave

Hi David.? Gosh so grateful for your guidance on this problem.? The volts on those two little silver soldered pad B1 & B2 is 1.72vdc.

But the resistors I've used are to big so must chance them as don't think there touching the pads enough.? No excuse for age 77 as been using SMD for years now having built a Hermes Transceiver.? The Display is all ok displaying everything on screen? 73s G4RVH

Hi David? ?I've posted 2 jpg files in the files section because somehow cannot attach these 2 jpgs on this page.? 73s? G4RVH

Hoping to add 2 photos for you David to view

73s G4RVH

Hi David,
I hopefully see what the problem is.

Unfortunately, you have connected to the incorrect points for RB1 and RB2.

The connections should be to the pads shown below.

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You have currently connected to the 10nF capacitors associated with the 34k? resistors shown below.

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Also, looking at the display image you sent, it looks like there may be an offset, but that is a minor issue for now.

I don't know if the have a PIC programmer, the offset can be adjusted in the HEX file.

This issue was covered recently in the following thread.

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73, Dave

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Hi David,

I forgot to mention that I also noticed that the 34k resistors for the "RVS" and "FWD" potential divider appears to be 68k on your board.

Perhaps that is intentional?

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An extract from the schematic is shown below, with 68k series and 34k to ground.

R3, R4 = 68k

R20, R21, = 34k

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73, Dave

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Hi David?

Your a Genious,? very well done in spotting my STUPID mistake.? Definitely not intention I can assure you.? So glad you spotted the mistake.?

So as soon as I get time I will drop back onto the project. So after correcting the small SMD resistors hoping to see 5Vdc from ground to the little silver round holes either side of B1 & B2 all being well and then should be able to do the proper test. I will keep you posted but will give the whole board a thourourly good check out and clean with Isopropanol? 73s? G4RVH

Hi David?

Photo of my 10 turn transformer. I must also check those resistors in the diode bridge but it's pelting down up here so not going out to the workshop today

73s G4RVH

You will see that I've purposely used good beefy capacitors.

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73s G4RVH?

Hi David,

I won't bother, but your photo shows a transformer wound with 11 (eleven) windings... Why? look here:? /g/ATU100/message/2535?

You may let is as it is and change the content of cell 31 to '11' or get one turn out from core and let cell 31 with '10'.

Have fun!

Immo, DL5KB

Hell Immo

Thank you for showing me that I had 1 too many turns on my transformer so I will take one turn off no problems.? And yes one too many turns.? Oh dear I must be getting old.? I must be a silly old 77 years old crackpot.? Thankyou

73s? G4RVH

hi David,

my remark should not be a criticism to you or your build nor your age as I‘m at nearly the same age. I built and repaired several of these tuners and recognised a difference between applied power and displayed power. Root cause was the 11th turn on the binocular core. Even ready built ones from china have nearly all 11 turns!!!! So my remark only should help you to get an even better result. nothing more!

Best 73, Immo

Hi Immo.? I am highly delighted that you have pointed the extra turn out to me.? To be quite honest I cannot believe it as every time the wire goes through the hole of a transformer counts as a turn.? I need to go back for a day to school to learn to count again silly me so no need to worry at all Immo.? Pleased you've told me like Dave G8PTN? as he has been helping me also and so glad obviously of any help especially running into problems that require to be sorted out.? Thankyou Immo and David G8PTN kindly.

73s? G4RVH

Hello Immo.

It goes to prove yet again and again that PICTURES paint 1000 words.?

To be quite honest Picture of PCB components paint millions of words as you seen my mistake and also David G8PTN seen that I've put 2 wrong resistors also onto the pcb

73s? G4RVH

Hello again to both David G8PTN and Immo.

I have very good news for both of you. Firstly the 68k resistors WERE 68K but 2 x parallel to give 34k on both 34k resistors so both reading exactly correct.? Anyhow I had soldered to B1 & B2 capacitors and NOT the little silver soldered pads so obviously no 5vdc BUT now soldered to the correct pads.? Switched the unit on with BYPASS TUNE AUTO connected to ground and all the relays switched on after 2 seconds and the Display showing TEST and the PSU showing about 500ma being drawn. So fabulous news and just the transformer to correct now.

Hello Immo

I've taken the Balun transformer off to rewind shortly.? Taken the old windings off because I used a tiny blob of super glue so had to cut the windings out altogether.??

So this project really coming together now I know all the Mosfets are switching all the relays on. Great news.? Yes there definitely was 11 turns on each side of the transformer.? WELL spotted Immo

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73s? G4RVH