CDM750 Power ON options

[Fire_Doc]

Hi Everyone...

Looking for a solution for powering up a CDM750 when DC power is supplied.

Is it possible, using the CDM750 Accessory Connector/programming, to power the transceiver ON via the same "pulse" method used mechanicaly by pressing the front panel on/off/volume control with DC power supplied to the transceiver at all times?

Looking for momentary pulse... not a latching solution.

ThanX

[fineshot1]

A quick search turned up these two posts. Do not know if this is what you are looking for but if
not perhaps someone else can chime up with a suggestion or two.

http://batboard.dreamhosters.com/viewto ... ba#p471659


http://batboard.dreamhosters.com/viewto ... ba#p433009

[StanComm]

Easiest way to turn a CDM radio into a two wire radio (ditching the Ignition Sense wire entirely) is to connect pins ten and four together on the accessory plug.
That ties a filtered 12 volt line which is used to operate the external horn relay to the Ign Sns input. Only possible issue is that that line can be programmed to be low, the default is high.
Been doing it ever since this beast came out. Doing it this way removes any possible noise spike damage which the Ign. Sns input was noted for.
Just Look at the cludgy hookup Moma /\/\ came out with to fix that problem.
Actually, if you really had to have a separate Ign. Sns line, you'd be better off replacing the 4 amp fuse with a 500 ohm 1/2 watt resistor. It'll get a bit warm if you short the skinny wire to ground but it raises the source impedance so there is no destructive fault current for the noise clipping diodes to have to struggle with. Yea, the sense line only goes to about 6 plus volts but the input switches at about 2 volts so you have plenty of headroom.
One other thing to be wary of here is that you can accidentally program the wrong mode or monitor function to be active at power-on. The fix is to set the radio up as needed and then, using the off/on button cycle the radio power to memorize the settings.

Stan... A CMD Dim Viewer.

[Fire_Doc]

StanComm and fineshot1... thank you for your informative responses. I opted to make a circuit with debounce and diode blocking that tied directly on the the PCB pad of the on/off power switch on the radio head. Diode blocking the existing power circuit and the new one which is driven by an inverting Hi>Lo Lo>Hi 2N2222 that gets a pulse from a sequence of DTMF decode keys. This results in pulse ON... pulse OFF. ThanX again for your input.

[ve3nsv]

Jumping pins 7 & 9 together works also if you aren't using emerg.

[Fire_Doc]

Thank you, ve3nsv. The radio's are out for alignment. I'll try out the pin 7 / 9. I did note that these pins are programmable Tri-state. I'll give it a shot when the radios come back.

[fineshot1]

Thank you, ve3nsv. The radio's are out for alignment. I'll try out the pin 7 / 9. I did note that these pins are programmable Tri-state. I'll give it a shot when the radios come back.

FYI - since 7 and 9 are right next to each other i have used
those little black personal computor board jumpers that were
exactly just the right size.