channel steering on PM400

IMBEJames · Post by **IMBEJames** » Tue Jun 06, 2006 5:29 pm

I searched for this, but I must have missed something...

I have a PM400 to install on a rescue boat, and where we primarily operate on 1 of 2 or 3 channels, i figured i can keep the radio in the watertight compartment and use a weatherproof switch to supply voltage to the channel steering input pins in the accessory connector.

so, for some reason Im having a brain fart and can't remember what voltage has to be applied to the accessory pins to change channels. also, is it a momentary votage applied to the pin or does it have to be constant?

figured id ask before i blew the thing up.

thanks
-jamie

Al · Post by Al » Tue Jun 06, 2006 7:11 pm

Pins 6, 8, 12, and 14 are channel select 1,2,3, and 4 when you configure them under the accessories tab of the tree display in the CPS. If I remember, they're active low or high(however you program them), and you need to use a BCD coded switch to get the correct combination of active select lines for all channels. If you're only using 2 or 3 frequencies, two switches will give a binary 0, 1, or 2 that can be used on the two low order select lines on the accy connector, and the lines have to be held in the desired states to keep the desired channel selected.

IMBEJames · Post by **IMBEJames** » Thu Jun 08, 2006 4:19 pm

BCD coded switch? Either Im just a little slow, or having one of those days. Im kinda following, but still a little fuzzy. If its going to be a reall comlicated process, i might just forget about the whole thing for now.

I appreciate the help so far...

Al · Post by Al » Thu Jun 08, 2006 4:40 pm

Well, if you're only going to need to select 2 or 3 frequencies, you can do it with two waterproof toggle switches. If you program the accy pins for active low, and connect one side of each switch to the 1 and 2 select lines from the PM400, connect the other side of both switches to radio ground, then you have 4 possible combinations(both switches off, both switches on, 1 on and 1 off, and the opposite combination on and off). That's wired to give you a binary 0,1,2,or 3 at the radio accy connector, which will select freq 1, 2, 3, or 4. Unless you need to be able to select all channels, two switches wired as I've described will do everything you want.