Hi All...
I need to recieve two to three channels of NMEA 0183 and send one channel. I looked around for a level converter chip like a MAX232 but for RS-422, but no luck. Is there an easy circuit or chip to use to convert RS-422 to TTL, ideally with electrical isolation?
Thank you.
You mean a part like the MAX485, or one of its quad versions?
quad TX
http://datasheets.maxim-ic.com/en/ds/MAX3030E-MAX3033E.pdf
quad RX
http://datasheets.maxim-ic.com/en/ds/MAX3093E-MAX3094E.pdf
Yes, very much like that Bob, thank you! I guess you now know what's coming 
Nah, just prescient!
I also ran accross someone who had a line of chips with really good isolation built in. I'll have to find those and post. It was pretty early when I saw them and now I can't remember what company it was 
To get isolation you have to use a chip with built in power supply isol. There are many for RS485, MAX3157 can handle a huge ground difference and they call it isolated but I haven't read the specs to see if that's really the case.
MAX1480/1490 are really isolated and ADUM2486/82/87 are as well I think.
Another way to do it is use simple 5v isolation chips (or optocouplers) and a small isol power supply. Look at ISO7240/1/2/3, ISO7220/1, IL15/16/17, ADUM1210.
Rob