Got a very good email from Elliott L, W6EL, who makes the following points (I'm paraphrasing since I don't have permission to paste his actual email publicly.)
1: Extend the standard to include GX16, same pin out as 8p8c
His concern is having an actual coaxial shielded mic line inside the bundle of other signals (specifically headphones), not just having a single shield over the whole bundle which would allow cross-talk between the headphones and mic lines. And building such a cable in a Modular connector is pretty much impossible (I agree with that.)
However, I strongly disagree that GX16 is the correct connector to use. I don't want to make YET ANOTHER INCOMPATIBLE use of that connector. Also, GX16 connectors are a royal PITA to acquire for use on PCBs (as me how I know).
Instead, OHIS already specifies the DE-9 as a Rugged connector option. I believe it addresses his expressed concerns (easy to solder coax to, easy to make custom cables) and addresses my concerns as well (not already a standard in audio, commonly available, still rugged (GX16 is as well)).
I've responded to Elliott with my counter argument and am seeing whether he has any further concerns, or a rebuttal.
2: Vcc spec should include noise tolerance.
He's absolutely right. Specify a ripple limit, and frequency.
3: Headset Level is vague
His concern is that different radios will have different level outputs, and that should be standardized.
I understand his point, and maybe the standard should be more clear on what "headphone level" is. It's currently specified as 0dBV into 16R load. Is this "correct?" Is there a better way to specify this? This is a low-impedance spec; what about high impedance cans that might require more voltage, but less current? What THD?
It's also not clear that that's for max volume. The ACTUAL listening volume is adjusted by the Radio device, not by the User device.
4: PTT voltage and current spec
He's absolutely right. Specify max pull-up voltage, min sink current capability, and max forward voltage drop. Make sure that specification works with BJTs, FETs, Optoisolators, contact switches, and relays.
Got a very good email from Elliott L, W6EL, who makes the following points (I'm paraphrasing since I don't have permission to paste his actual email publicly.)
1: Extend the standard to include GX16, same pin out as 8p8c
His concern is having an actual coaxial shielded mic line inside the bundle of other signals (specifically headphones), not just having a single shield over the whole bundle which would allow cross-talk between the headphones and mic lines. And building such a cable in a Modular connector is pretty much impossible (I agree with that.)
However, I strongly disagree that GX16 is the correct connector to use. I don't want to make YET ANOTHER INCOMPATIBLE use of that connector. Also, GX16 connectors are a royal PITA to acquire for use on PCBs (as me how I know).
Instead, OHIS already specifies the DE-9 as a Rugged connector option. I believe it addresses his expressed concerns (easy to solder coax to, easy to make custom cables) and addresses my concerns as well (not already a standard in audio, commonly available, still rugged (GX16 is as well)).
I've responded to Elliott with my counter argument and am seeing whether he has any further concerns, or a rebuttal.
2: Vcc spec should include noise tolerance.
He's absolutely right. Specify a ripple limit, and frequency.
3: Headset Level is vague
His concern is that different radios will have different level outputs, and that should be standardized.
I understand his point, and maybe the standard should be more clear on what "headphone level" is. It's currently specified as 0dBV into 16R load. Is this "correct?" Is there a better way to specify this? This is a low-impedance spec; what about high impedance cans that might require more voltage, but less current? What THD?
It's also not clear that that's for max volume. The ACTUAL listening volume is adjusted by the Radio device, not by the User device.
4: PTT voltage and current spec
He's absolutely right. Specify max pull-up voltage, min sink current capability, and max forward voltage drop. Make sure that specification works with BJTs, FETs, Optoisolators, contact switches, and relays.