Icom AH4 Support???

[Ken]

I have been combing thru any I/O board info that I can find. Has anyone gotten the AH4 support to work? I see connecting information in the amplifier sections using jpgs but nothing in the area where the AH4 files are. I see pictures in the section but no connections just unmodified board pics. Where are the signals key and start on the board? They need to be connected to the tuner via the DB9. 

[Steve Haynal]

Hi,

I use a AH-4 and AH-705 on my 3 HL2 setups. I use the non-I/O board method which requires some installation and wiring of the rear endplate on the HL2.

 https://github.com/softerhardware/Hermes-Lite2/tree/master/hardware/enclosure/endcaps/kf7o/hl2_40b#atu

73,

Steve

kf7o

[Ken]

Thanks Steve,

I was told that the I/O board was the way to go and to avoid the companion board. So far I have not been able to find the information on the AH4 using the I/O board. I have been pointed to the readme file of the I/O board  but I cannot find the procedure to configure it there. Looks like I will install the Companion board.  BTW, The radio is a lot of fun but definitely not plug and play,,lol

[Heath Petty]

I came across this while searching for a solution to your issue: https://github.com/jimahlstrom/HL2IOBoard/tree/main/zl2te_arduino  It has a library for the AH-4 tuner. It also has documentation on how to build the firmware and install it. The issue is that I didn't see any instructions specific to the AH-4 tuner. I don't have an icom tuner, so any help I could offer would be limited, and others might be in the same boat. 

You are right, the HL2 is not a plug and play radio, but it is very versatile. 

-Heath

[PE1RLZ]

n2adr_basic/main.c describes the following:

// Control the Icom AH-4 antenna tuner.
// Assume the START line is on J4 pin 6 and the KEY line is on J8 pin 2.

According: https://hamoperator.com/HF/AH-4_Design_and_Operation.pdf

START: 

  5. Electrical Interface, The radio should pull up the START line to 13.8 volts. It pulls the START line to ground to assert the signal (start the tuning operation).

According the schematic (https://github.com/jimahlstrom/HL2IOBoard/blob/main/KiCad/HL2IOBoard.pdf) J4 pin 6 is not pulled up to 13.8V. Of course a resistor could be added, but it seems it's all 5V logic around J4. So very likely this could cause hardware damage.

https://github.com/jimahlstrom/HL2IOBoard/blob/main/README.md mentions the TBD62381AFWG in relation to the AH-4, but that should be J6 ??

KEY:

  5. Electrical Interface,  The AH-4 pulls the KEY line to 5 volts through a 22 K ohm resistor/diode combination. The radio also pulls this line to 13.8 volts through a resistor. The AH-4 pulls this line to ground to assert the signal.

According the schematic (https://github.com/jimahlstrom/HL2IOBoard/blob/main/KiCad/HL2IOBoard.pdf) J8 pin 2 is not pulled up to 13.8V.

J8 pin 2 is a protected input (https://github.com/jimahlstrom/HL2IOBoard/blob/main/README.md: Five logic inputs that are protected, and work from plus 3.3 to 20 volts.)

Being pulled up to 5V by the AH-4, this could work. Is pulling up to 13.8V still required?

Any guidance here would be great.

thanks and 73,

pe1rlz

[Steve Haynal]

You may need a leverl shifter. See the original AH-4 support/end pate level shifters for an example.

73,

Steve

kf7o

[PE1RLZ]

When checking the service manual, both START and KEY seem to have pull up voltages from 4.8V (CK206) and 4.5V (CK208) applied by the AH-4.

That would allow the AH-4 do be directly connected. I'll supply 12V to the AH-4 and measure the voltages on START and KEY before connecting.

[PE1RLZ]

Just received my AH-730 which I would expect to be compatible.

Interesting enough I measure on the connector from the AH-730 when supplying 12V:

START: 5V

KEY: 0V

The opposite as described in https://hamoperator.com/HF/AH-4_Design_and_Operation.pdf

I also measure 22K ohm between START and GND. 

It wouldn't surprise me that pulling up KEY to 5V in the HL2 is enough. I 'll use a 22K ohm resistor.

Comments are welcome.

73,

PE1RLZ