Batboard

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

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

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

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.

tsunami_australia wrote: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.

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

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.