MFJ Deluxe Electronic Keyer Model MFJ-407B

[KG0DB]

Just getting back into radio after a 20+ year absence.  Hope to have the station up and operating this coming week.  Going through some junk boxes I uncovered an electronic keyer described above.  I have no idea what they do or how they work.  Can someone tell me the concept of operation?  My previous CW experience was limited to a Bencher paddle which I thoroughly enjoyed.  To be honest, I don't even know how I wound up with this keyer.  Any information is greatly appreciated.

[K7MH]

Manual is here;
http://www.universal-radio.com/catalog/morse/1324om.pdf

Basically you plug a set of iambic paddles into it and it into the rig.
It is great for an older rig that does not have electronic keying circuitry built into it.
Most all do these days.
Some might use one anyway as it may allow more flexibility with memories, different types of keying and other preferred settings.

[N0GRA]

You actually have one of the best keyers I have ever tried. What makes it special is the Curtis Chip, and the ability to adjust the weight to give a very soft note. At higher speeds, say 25 wpm, it will not matter as you will need to back off on the weight, and the note will by necessity be a little "harder" in order to send at higher speed.