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Hi
I have a new old Futaba T2PHKA radio that draws an impressive 230mA from 8x batteries.
The radio includes a socket on the rear that looks like it should be for plug in 12V. That doesn't seem to work.

Does anyone know what the socket is for?

Charge port for use with individual nicd batteries.

juicedcoupe wrote: ↑Fri Feb 16, 2024 7:40 pm Charge port for use with individual nicd batteries.

OK. Do you know what voltage range should be applied? 15VDC - 20VDC?

I am trying to figure out how to operate with external supply and without batteries.

9.6V (1.2X8)

I did some reverse engineering and confirmed that the charger circuit is only switched in when the radio power switch is off.
Charging is only enabled when the radio is switched off, which makes sense. I have some NiMh cells, but not enough and different capacities/ages. I am going to mount a 12VDC power socket connector in the labeled bulkhead inside the handle. I will drill a plug connector access hole through the top surface of the battery cell holder. I will then be able to plug in any 12V power source I like. Accessing the plug will require at least 2 cells to be removed from the battery box, so there will be no danger of connecting cells to a power supply.
If I decide to do something more I can put the battery box on a connector and 3D print a battery box for some other type of battery it was never designed for, like a LiPo that I don't have. The battery holder just slides out so easy to replace with something else.

I should be able to power this radio from 7.2VDC to 12VDC.

According to the manual, the transmitter needs a 12VDC supply.
Reducing the power supply reduces the measured RF output.

dazz wrote: ↑Sat Feb 17, 2024 5:23 am According to the manual, the transmitter needs a 12VDC supply.
Reducing the power supply reduces the measured RF output.

Alkaline batteries have a higher voltage than equivalent nicd and nimh cells. The charger is designed around it's intended use.

For best performance, it was always recommended to use alkaline batteries.