Futaba T2PHKA 27MHz, AM, 2ch radio socket

[dazz]

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?

[juicedcoupe]

Charge port for use with individual nicd batteries.

[dazz]

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.

[juicedcoupe]

9.6V (1.2X8)

[dazz]

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.

[dazz]

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

[TRX-1-3]

[juicedcoupe]

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.

[Alvin777]

Hi, for a more granular result on at what voltage and amperage would still make it work well, it's best to buy a good power supply that has control knobs (usually they say the Keysight brand is good) wherein you can start with a low voltage and amperage and through trial and error get the sweetspot for voltage-amperage-range.

By the way what's the review on Futaba T2PHKA MJ, is a used one selling for US$26 w/ receiver a good one (assuming it's genuine and not fake, assuming Futaba controllers have been counterfeited- does anyone know? If there are how do you detect the fakes?).

Thank you, God bless R/C trophied champions and all R/C racers alike.

[juicedcoupe]

They are okay, nothing special. If you are after a basic AM radio, it'll do fine.

If the included receiver is one of the newer ones, it is worth more than the transmitter.

If you want a good AM radio, get a 2PL. It does just about anything you can imagine that you'd need, and some things that you never thought of.

Another good option is thr JR XR2i. A little easier to use than the 2PL but only two model memory. Also compatible with Futaba and Hitec receivers.

The Sanwa/Airtronics MX-A is also nice. But I stick with 27mhz to avoid needing Airtronics specific receivers and/or having specific crystals. Everybody's 27mhz stuff works together, just don't mix AM and FM.

[1911Colt]

EGBAX1300.jpg

I'm late, I know, but I just saw this thread