MCS2000 to CDM1550, cross band repeater

[buffaloman74]

I am trying to make a bi-directional cross band repeater to go from VHF to 800 mHz conventional. The 800 mHz is MCS2000. The VHF is a Spectra or CDM1550 (whichever is easiest to configure). The CDM series seems to make this very easy if going to another CDM. However, I have yet to be able to make the MCS2000 cooperate. Unless I am missing something the MCS does Not allow you to change any of the acc'y pinouts.

Thanks, Daniel

[wavetar]

You're right, the MCS doesn't make it easy to use in a repeater configuration. It does not provide a COR on the accessory pins. You need to utilize the 5.75-volt biasing voltage present on either of the external speaker leads when active. Use it to trip a simple transistor switching circuit to give you the active low that you need.

Todd

[buffaloman74]

Thanks for your reply Todd. That seems to have resolved the problem.
Daniel

[tsunami_australia]

Just on this (yes old thread I know but extremely handy to what I'm attempting) has anyone found a good cheap commercially available switching circuit for this or just made their own?

Part numbers etc would be handy.

[wavetar]

Just on this (yes old thread I know but extremely handy to what I'm attempting) has anyone found a good cheap commercially available switching circuit for this or just made their own?

Part numbers etc would be handy.

I've always used the NTE291 NPN transistor, running the voltage through a 1k resistor to the base, connecting the collector to ground, and the emitter to the PTT of the other radio. Never had to replace one.

[tsunami_australia]

Thanks for that, I don't know why but I was thinking a bit more advanced...more toward a flipflop... derp.

[motorola_otaku]

I have a Pyramid application note (which they have since taken down from pyramidcomm.com) that showed where you could add a jumper to pin 8 inside the radio to get active low COR. I did to about a dozen UHF VRM650s and it worked great. If someone PMs me a reminder I'll post it from my home PC.

If you want to try your Google-fu it is called AN189.pdf.