CDM1250 to Zetron Model 5

[ofire]

I am replacing an older GM300 radio that used a Zetron Model 5 encoder, with a CDM1250. Would like to reconnect the Z5 to new radio, but not sure about the accessory connector pinout connections and the changes/selections needed under the Radio Configuration-Accessory Pin software to make it work. Can anyone give me a little direction on this? Thanks

[SteveC0625]

I am replacing an older GM300 radio that used a Zetron Model 5 encoder, with a CDM1250. Would like to reconnect the Z5 to new radio, but not sure about the accessory connector pinout connections and the changes/selections needed under the Radio Configuration-Accessory Pin software to make it work. Can anyone give me a little direction on this? Thanks

Do you have the programming info for the GM300?

Do you have a decent schematic of the connection between the GM300 and the Zetron so that you know which line goes to which pin on the accessory connector?

Both are going to be necessary for this.

[Bigred]

Steve is correct to check how the pins are connected and programmed. To elaborate, you can pull the 16 pin connector out of the GM300 and plug it into the CDM1250 but here's what to watch out for.

A basic paging encoder only needs ground, PTT and mic input. On a GM 300 ground is pin 7, PTT is pin 3 and mic is pin 2. This is hard written on a GM300 and cannot be changed. On a 1250, ground and mic input are the same so no problem there, but PTT can be assigned to a number of pins but default is pin 3 to match earlier models. Check CPS to make sure.

Now the encoder may also use receive detect to hold off pages until the channel is clear. This was pin 8 usually in a GM300, but others could be used. If this line is used, this is where you need to check the original programming to make sure the 1250 matches. Receive detect could be carrier detect or PL/DPL and you will need to set the new radio the same.

[ofire]

Have the pinout of the accessory connector and the Z5 terminal functions -

Connector Zetron 5 Function
pin#2 - tone output
pin#3 - PTT output
pin#7 - ground
pin#13 - power

I do not have program to read configuration of GM300.

[Will]

Have the pinout of the accessory connector and the Z5 terminal functions -

Connector Zetron 5 Function
pin#2 - tone output
pin#3 - PTT output
pin#7 - ground
pin#13 - power

That looks OK. You may need a series capacitor AND a resistor in the pin 2 'tone' line to isolate the encoder
from the mic circuit. 4.7 K and a 10 uf non polar capacitor work well.
Also makes the encoder adjustment easier
as you are not at the bottom part of the adjustment.

[SteveC0625]

Also, if there is a 15 to 16 jumper on the 16 pin connector, remove it. It is not needed in the CDM and will cause a problem if left in place.

[ofire]

Thanks again. Got the connector pin sorted out; some confusion with CPS settings since I cannot read the old GM300.

Does anyone have suggestion for the correct Function Selections listed under Accessory Pins in the CPS to match the PTT and tone outputs? Or, is it best to use the Accessory Package - Paging Encoder and move the pins around?