Yes, if the relay is non-latched type (usually yellow in colour), it will be reset to off stage when no power is applied. Mine version is ATU-10, it uses latched type (white in colour). It keeps in the previous position when power off. The adv is it uses less power and keep the status, the trade-off is the cost of the relay. Not sure if there is any latched ATU-100 model on the market or you can change it to latched type relay yourself for a trial.

73

de VR2XLQ

在 2022年5月25日週三 上午6:06，Colin Kaminski <colinskaminski@...> 寫道：

The ATU-100 has non-latching relays. It should reset to a pass through configuration when off but I haven’t tested mine.?

The bypass switch is momentary contact. The display shows when you are in tuning mode or bypass mode.?

Colin

K6JTH?

On Tue, May 24, 2022 at 11:38 AM Joe - KF7MIX <joe@...> wrote:

I readily admit that I'm very much an amateur when it comes to schematics, so forgive me one more question:

I notice that if I listen to a band with the ATU-100 in-line but powered off, the RX seems to be just as good as if I connect my antenna directly to the radio. Why is this? Is there danger in transmitting if the ATU-100 is powered off? Thanks for any details you can provide,

73, Joe KF7MIX

On 5/23/22 20:09, Joe - KF7MIX wrote:

Excellent, thank you! I'll get in there and see if I can find that pad. In the schematic, is that a toggle switch? I can't find the schematic symbol online... is it saying that I'd switch that pad to ground to enable bypass (versus a momentary pushbutton)?

Again, thanks,

73, Joe KF7MIX

On 5/23/22 18:20, Colin Kaminski wrote:

Hi Joe,

I have the button but when I was making it I just soldered a wire to the pad marked RB2. It is close to the processor chip on the side of the board close to the controls. I am pretty sure I just ground it with the switch. Here is the schematic.

Colin?

K6JTH