I would add one note of caution with the Kadee under the track magnets. They are rather strong and will pull cars that have steel axels. They also may open some couplers too far to allow for "delayed action" spotting. However, they always uncouple.
Joe
Use both. I'm at the 'about to lay track' stage and I have a yard to put down. It's best then to mark out where your permanenet magnets are to go and where powered ones are to go. Powered magnets should be on the main or anywhere you don't want trains to uncouple as they move along. Fixed magnets are fine for switch yards.
For permanent magnets I have Kadee magnets (item 308 - I think) and these fit under the track. I am routering a pocket for each one under where the track will go. I'll then place cardstock or thin plastic over the top so that when the track is laid and ballasted they will not be seen.
As to powered magnets, I'm thinking of buying Kadee 309's (again I think this is the right part number) and doing much the same but obviously allowing for wiring etc. I would connect these up to my NCE DCC at a later date so I can power them on and off remotely via my handset.
However, don't forget it is possible to make your own powered uncouplers by winding thin copper wire around a couple of bolts, one for each rail. Depends how much time you have and how patience!
Cheers!
It is recommended that electromagnetic uncoupling magnets be used in through tracks, to prevent false uncoupling due to slack action in through trains.
A less expensive alternative is to mount a large under-track magnet on a hinge. When not in use, it hangs vertically well below the ties. Pulling on a cable connected to a knob on the fascia brings the magnet right up to the layer of thin material (in my case, card stock) under the ties, ready to uncouple what YOU want to uncouple - and nothing else. When the cars part or you've run the couplers together for delayed-action spotting, release the cable and the magnet drops out of action.
In this day of DCC controlled widgets, this may seem to be the brute force and ignorance way of doing things. The only thing I can say in rebuttal is that it works.
Chuck (Modeling Central Japan in September, 1964)
Refer to a section of "Workshop" in the January, 2007 Model Railroader. It describes a very inexpensive magnet set available at Ace Hardware stores. The technique is equivalent to Kadee "delayed-action" magnets, and they can be completely hidden under the ties. Suggestion: As this is a fairly permanent installation, set up some test scenarios first to see just how close to curves you can perform the uncoupling and coupling functions. Also, because this magnet arrangement is quite short, you will need something in the way of an above-track marker to let you know just where to position the cars to be uncoupled. I have installed several of these -- they work great!
working on the new pike and before i lay the track i want to install under the track uncoupling magnets. any suggestions on different types or techniques?