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Michael, I have an AT-10 and love it. My AT also had tuning issues until I resoldered the relay pads. There is a utility on the GitHub webpage that will help. You can read my experience and see the

Hi all, I have purchased a preassembled ATU-10 at AliExpress (HamRadioShop Store). Build quality looks decent, but tuning results are poor especially on 60m and 80m. E.g. tuning stops at SWR 3.0

I'll have a look. Thanks!

A VERY nice example from the aviation industry with 12VDC across relays at 3 cases - no diode, reverse diode at coil, reverse diode at switch http://www.aeroelectric.com/articles/spikecatcher.pdf

The back-emf of the relay coil has to be addressed at the relay coil. The reverse body diode of the transistor is irrelevant for this overvoltage, as it is not imposed on it directly, but trough the

Why do you want to add an additional diode, given that the 2N7002 used for switching has already that diode integrated? 73, Joerg

Hi, Yes, agreed. There is a diode drop from the supply pin, so at 13.8V the relays will have around 13.1V. The relays specified on the schematic have a maximum application voltage of 15.60V. 73, Dave

BTW , there is change of damaging the relays if using with the transceiver power 14v ... or so ... the PIC will work fine , but the relays are getting power directly ...

Hi David, You just need to be careful that the maximum VDSS for the 2N7002 of 60V is no exceeded, otherwise the FET could be damaged. 73, Dave

Hi You can use 0.1uF with diodes in parallel or 1uF with no diodes . In the original design the EMF were measured on the 12V power line. What is happening in the relay's line is not so important.

hi Tim, as I made the translation of the manual, I've left over the description of the EEPROM content in English and German. Look the appended pdf. 73, Immo

Is it wise to place a capacitor as well as a diode in case one has rectification issues with the diodes? I check the schematic of my ICOM AH-4 and it has both diodes and a 0.01uF capacitor. Mike N2MS

Greetings I bought a pre-assembled tuner off ebay last summer, and LOVE it. Works great. On the screen on power up, it says BH8TZB firmware 3.2. I inadvertently got into the setup, and I fear, may

Hi Dave . Yes you can put 4148 diodes across the relay coil, observing polarity. I purchased the full kit with bare pcb just the cpu and a diode was soldered and each part was tested before installing

Hi Jason, The board was supplied with all SMD's fitted. My preferred solution is to have diodes across the relay coils to suppress the back EMF. Also to be noted, the relays have a lower rating than

Hi i too ordered a kit from China , best bet is to check every component before you solder it ! this way you know its real value and it's ok. and replace that 0.1uf with 1uf 100v. 73's jason

Well spotted,you never know what your going to get from china,fake parts covid the list goes on!,simple just dont trust anything chineese,i think thats the best bet!.

Hi Shirley, I have not measured the capacitor value, but it is physically different to the others and since the back EMF is greater, its value is smaller. I will probably just fit a 1uF in parallel or

That's an error on the silkscreen. That capacitor is supposed to be a 1uF like all the others. I'm in the process of building one from a kit, and if you put a 0.1uF part at that spot there aren't

A minor observation on the ATU-100 that I received from China. Although the schematic shows 1uF capacitors across each of the relay coils (to provide some smoothing of the back EMF), one of the relays