Fun with a M1225 & VXR1000U

[KE7JFF]

So I've recently started to build the right cable for interfacing a VHF M1225 with a Vertex VXR1000U vehicular repeater. I've dealt with the fun of a Maxtrac 16 pin connector before so I figure this would be a walk in the park for but it's not. I've used the application notes from Pyramid as my starting point for wiring and configuration but I seem to just can't get each radio to do COR and PTT correctly. If I force PTT by hand I do hear repeated audio so I know some of my work right.

I'll post my wiring and programming notes when I get a chance but does anyone have any advice trying to get the interface right?

[Pump3]

Dont know if this helps or not, you probably have it already but doesnt hurt to post it for reference

[KB2ZTX]

verify your programming in the VXR is correct and the solder in jumpers on the VXR are correct. I have a few of these in service and have no issues at all. You should be able to take one from a maxtract, 1225, CDM and they all work the same.

[KE7JFF]

Yeah I have looked at the service manual and I think in trying to translate the Pyramid notes to the VXR, I got things screwed up in the process.

jsikora: do you have notes on the right wiring and prgramming I could compare? I'm at the point where I need that.

[KB2ZTX]

Yeah I have looked at the service manual and I think in trying to translate the Pyramid notes to the VXR, I got things screwed up in the process.

jsikora: do you have notes on the right wiring and prgramming I could compare? I'm at the point where I need that.

If I get home tonight at a reasonable hour i'll dig around. the picture above of the VXR wiring outputs is all you really need and the pinout from the maxtract mobile 16 pin. I normally use pin 8 or 14 for COR from the motorola. Make sure the vxr is set for COR Low activate. Same with the ptt line from the vxr needs to go low on PTT. I have set up numerous of these for our SAR folks and have no issues at all. I actually have set up a couple back to back as a cheap interop V/U repeater.

[KE7JFF]

Yeah I have looked at the service manual and I think in trying to translate the Pyramid notes to the VXR, I got things screwed up in the process.

jsikora: do you have notes on the right wiring and prgramming I could compare? I'm at the point where I need that.

If I get home tonight at a reasonable hour i'll dig around. the picture above of the VXR wiring outputs is all you really need and the pinout from the maxtract mobile 16 pin. I normally use pin 8 or 14 for COR from the motorola. Make sure the vxr is set for COR Low activate. Same with the ptt line from the vxr needs to go low on PTT. I have set up numerous of these for our SAR folks and have no issues at all. I actually have set up a couple back to back as a cheap interop V/U repeater.

Ahhhh! For some reason I thought I read to set everything to COR High! No wonder! Once I get back to my bench I will change that over.

[Will]

NOTE:

Motorola does not call it COR, it is PL/DPL Detect. Also know as RUS, receiver un-squelch. A combination of PL/DPL Detect AND receiver un-squelch.

In the M1225 this signal is a low going signal on the accessory pin. You will need a pull-up resistor, about 4.7K ohms works well.

No internal mods are required in the radio, it is all on the accy connector.

[KE7JFF]

NOTE:

Motorola does not call it COR, it is PL/DPL Detect. Also know as RUS, receiver un-squelch. A combination of PL/DPL Detect AND receiver un-squelch.

In the M1225 this signal is a low going signal on the accessory pin. You will need a pull-up resistor, about 4.7K ohms works well.

No internal mods are required in the radio, it is all on the accy connector.

Yeah, I know it's called RUS but its just easier to call it COR among us radio folk. I've never heard of the resistor required on the M1225 and I have interfaced the radio before to other devices.

[Will]

I've never heard of the resistor required on the M1225 and I have interfaced the radio before to other devices.

The pull-up resistor is usually in the device the radio is interfaced to... The VXR in your case.

[KB2ZTX]

VXR has a jumper for the resister. No additional items are needed. 1225 will go low and the VXR will key if the jumper is correct.

[KE7JFF]

Okay, I got everything back on the bench and still not working correctly.

I've verified all settings are now low. Now, looking at the manual for the VXU, I don't see where the right jumper for the 4.7K resistor is; I do see mention of it for the audio but thats already set. It sounds like I need to put in my own pull up resistor? Am I reading that right?