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Regarding the relays I've added diodes as well as a very small led across each relay so at least I now know if each of the transistors are working
My next question is? I've used My PicaTune homebrew ATU for years and once it's found a match it remembers for next time so it's not constantly looking for a different match under WINDY conditions or WET conditions. My SG230 I built the AUTO Lock so that once matched in seconds and it's windy or wet outside I just flick the Switch in to LOCK the ATU from retuning. My question is having read people having this same issue with this design would be to have a LOCK switch after the aerial has been matched.? Is this possible in the Firmware and if it is possible would sort the difficult issue of the ATU100 retuning? David? G4RVH |
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Hi David,
The ATU100 should already load the last tuned values from EEPROM for SW (Capacitor IN/OUT selection), L and C when it boots up. However the following points should be noted. If RESET is activated (short press of the TUNE button), the values are reset to 1, 0, 0 for SW, L and C respectively and stored in EEPROM. If AUTO TUNE is set, the tuner will automatically re-tune when transmitting and store the tuned values in EEPROM. 73, Dave |
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Hello David, There is already a smart switch on it. After the tuning operation, to avoid a re-tuning, due to a small swr variation, set the ATU100 to manual tuning: just shortly press the Auto button? and set ATU to manual tuning. A small dot on the display shows the manual or auto status.? Regarding the transistor operation by looking at LED: it doesn't allow to observe relay proper operation since the operation I Is around 15 to 20 mS. Only using an oscilloscope you would know for sure the the relay is properly driven. Regards from Brazil, Paulo Bastos? ? PY1JDX? Em dom., 23 de jun. de 2024 06:47, David Hird via <g4rvh=[email protected]> escreveu: Regarding the relays I've added diodes as well as a very small led across each relay so at least I now know if each of the transistors are working |
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Hi Paulo.? So am I correct in saying as per the manual that if you hold the Bypass and the Auto plus the Tune together it tests all of the relays? ?? ?in other words I could quickly test with a volt meter across all of the coils of the relays that they are switched on proving all of the transistors..? ? ? Regards? David? G4RVH
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Hi Dave.? To be honest looking at the Schematic with the populated PCB below does not make any sense at all with the 15 relays.??
The top 7 relays clearly show the contacts Normally CLOSED The Bottom 7 relays show the contacts normally OPEN and in that position they are connect to nothing as shown with a red cross. S8 relay is shown in the Normally CLOSED position so totally and utterly confused from that drawing.? Regards? Dave? G4RVH |
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Hi David,
I understand the confusion. It looks like the PCB tracking for S1 to S7 is different from the schematic (although functionally the same). This may have been done to ease tracking or is PCB version specific. I have tried to draw a simplified diagram showing the relay contacts, inductors and capacitors based on the schematic and PCB. Enabling relays S1 to S7, enables inductors L1 to L7. Enabling relays S9 to S15, enables capacitors C1 to C7. Enabling relay S8 connects the capacitor bank to the ¡°OUT¡± port. I have not shown the connections to the Stockton Bridge. Hopefully, this will help a little. 73, Dave From Schematic: From PCB: The footprint for the relay from the datasheet is shown attached. |
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Hi David,
So am I correct in saying as per the manual that if you hold the Bypass and the Auto plus the Tune together it tests all of the relays? ?? - Yes, it wil vhech the DC path ?in other words I could quickly test with a volt meter across all of the coils of the relays that they are switched on proving all of the transistors. - Yes you could. But it wont show if the relay contacts are really closure or opening
When you press the three buttons, on power up, it enables the Fast Test Mode: it simply test the DC path from transistors to relays coils, positive voltage and ground.
What was trying to say, is: the Fast Test mode doesn't assure you that the relays contacts are properly allowing the increments (or decrements) of inductance and capacitance, and also the L C (L first and C after) or C L ( C first and L later) configuration, that is what the ¡°search for best tuning¡± algorithm, could still fail due to bad closure or opening relay contact.
I had a failure on my unit, three months ago, the Fast Test Mode Went ok, but the unit was runing an infinite loop, never finishing the search algorithm.
The cause: a leaking drain to source current on a 2N7002.
Latter I¡¯ve also found a leaking diode (emf protection diode).
A simple multi-meter didn¡¯t show the failure, I¡¯ve used a 9V battery to check the reverse current on the diode and the drain to source current leak on the MOSFET.
A better way to properly test the unit is to set the unit to the simple Test Mode ( see bellow the text from the manual):
"When power is applied to the device with the Bypass and Auto buttons pressed, the device enters the simple Test Mode. In this mode, you can manually, step by step, use the Bypass and Auto buttons to change the value of capacitance or inductance. A long press on the Tune button allows you to select which elements will be moved at the moment, and a short press changes the point of connection of the capacitor. In this mode, it is possible to measure input power and SWR in line. The whole process is accompanied by a clear indication."
On this mode you can test, not only the coils but, also the relays contacts. If you connect the output to a 50 ohms load and the input to a nanoVNA, you would be able to measure the capacitor values every step. And similarly, every inductance values. I¡¯ve found the failure on my ATU100 using the Simple test Mode and the nanoVNA changes of impedance values.
An alternative method would be to manually adjust C values, L values and relay S8 contacts, to get the lowest SWR reading for different bands and different antennas or load values.
Best regards,
Paulo Bastos?? -? PY1JDX ? Groups.io Links: |
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Oh WOW thanks to Dave and Paulo,? a very big thank yous to both of you and very appreciated help.? You have both cleared up my head with the diagrams and your explanations and so thrilled of your valid help believe me.??
What a powerful group to be part of for help.? So kind. Infact over the last 40 years built my own complete homebrew station here which like yourselves has been a labour of love in electronics.? I am 77 years old but still love playing with electronics and no joking just having fun building the ATU-100.? I've had power onto the board and the display works perfect with the boot up flash screen plus the Inductance and capacitance also got all of the SMD installed and all of the relays and 1uF plus all the back EMF Diodes installed so just the toroids and air coils to wind.? So not far off testing.? Can't be bothered in this heat but pleased the better weather has arrived? Kind Regards David? G4RVH |
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Hi David? so much easier that you have drawn out the PCB Layout which is obviously correct because the board works.? But the Schematic? really was throwing me altogether.?
Funny you should add the footprint of the relay because I did exactly the same yesterday and I was trying to orientate the footprint to the board and then got even more confused thinking of course that the Schematic was correct but clearly it is NOT.? Thanks again. Of course the reason for me being so particular is for servicing the unit If faults occur and then you definitely require a Pucker Perfect known correct schematic? kind Regards David? G4RVH |
RogerW/GW6HRU