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ASSEMBLY INSTRUCTIONS

BEFORE YOU BEGIN CAREFULLY READ THE INSTRUCTIONS AND STUDY THE 

ILLUSTRATIONS.

 Check the package contents and familiarize yourself with each part. 

If any parts are missing, damaged, or defective please contact Kadee

®

 Quality Products 

at the address on the package. 

PACKAGE CONTENTS:

 1 each of the following: coil, steel core, bolt and hex nut, field 

plate divider, upper track mounting plate, bridge rectifier, radial capacitor, 4 each field 
plates, 3 each 2-56 flat head screws, 4 each 0-48 x 3/8” screws, 4 each 0-48 x 1/4” screws.

O T H E R   I T E M S 

NEEDED: These are to be 
provided by the modeler.

 

16 volt DC power source 
(at least 1.5 Amps) or 18 
volt AC power source (at 
least 1.5 Amps)converted 
t o   D C   w i t h   b r i d g e 
rec tifier. The Kadee

®

 

#166 Transformer meets 
power requirements, small 
piece of aluminum foil for 
ballast, #52 and #55 drill 
bits, (Kadee

®

 #780 Tap & 

Drill set) 20 gauge wire, 
Kadee

®

 #165 Normally 

Open  momentary contact 
p u s h   b u t t o n   s w i t c h , 
light bulbs or LEDs of 
appropriate voltage, AMP/
Voltage meter, general 
hobby tools, wood working 
tools for cutting a hole 
into the layout base (see 
text) and tools to cut the 
metal rail if needed and rail 
joiners if you’ve cut the rails. 

GENERAL INFORMATION:

 The #309 uncoupler is a switch on switch off electrically 

actuated magnetic uncoupler. It can be used anywhere our permanent magnetic uncouplers 
are installed (see the “where to place uncouplers” at the end of these instructions). It is 
designed to be mounted under the “ties” of any code size of HO track and will be recessed 
below the layout surface (base). This will necessitate cutting a hole in your layout for the 
coil and field plates to be recessed into, it will need at least 2 inches of depth. 

Since this is electrically actuated (powered) you can place it in your “mainline” without the 

concerns of accidental uncoupling that sometimes happens while moving over or stopping 
over a permanent magnetic uncoupler. When the electric #309 uncoupler is switched on 
(or charged) it still has the “delayed” uncoupling feature as do our permanent delayed 
action uncouplers. Since the uncoupler is under the  ties you can hide it completely from 
view by using a layer of common household aluminum foil between the ties and mounting 
plate then covering it with ballast.

We recommend a 16 volt DC power source, either DC or AC converted to DC through 

a bridge rectifier. 

NOTE: Some inexpensive power packs may not supply the 3 Amps necessary. To 

check the actual voltage measure across the transformers terminals when the uncoupler 
is energize. 

To avoid overheating and to assure reliable operation the uncoupler must have an 

electrical source of at least 3 Amps and no more than 16 volts DC. 

Do not energize 

continuously for more than two minutes, or overheating will occur. 

ASSEMBLY & INSTALLATION:

  It would be best, where possible, to install the #309 

uncoupler while you are building your layout. All uncouplers should be placed on a straight 
piece of track where your two longest models will fit on each side of the uncoupler. We do 
“not” recommend placing an uncoupler on or near a curve, switch, or turn out, both models 
need to be as straight as possible with each other for reliable uncoupling. 

Assemble the uncoupler as the illustration shows (fig. #1). Insert the core into the coil, fit 

two field plates opposite to each other, one bent out one bent inward, as shown, slip the bolt 
through, place the field plate divider into the holes of the field plate, fit the other field plates 
over the bolt and against the coil. Make sure the prongs on the divider are inserted into the 
holes on the field plates and the tabs are fitted into notches of the coil where the lead wires 
are at the bottom of the coil and not under the field plates. Place the hex nut onto the bolt 
and tighten just snug and turn the assembly upside-down and tap it on a flat surface to get 
the plates aligned as even as possible, hold it on the surface and tighten the hex nut firmly. 
Set the top plate onto the divider (between the field plates) and secure with the 2-56 flathead 
screws, tighten just firm, overtightening  will easily strip the plastic holes. 

After you have determined the location where you wish to install the uncoupler you will 

have to cut a hole in the layout surface (base). The hole must be 1 1/16” wide and 2 1/8” 
long and in-line with the track. If your track is already installed then you must remove a 
section of track, at least long enough to accommodate the uncoupler, this also includes 
raised roadbeds. You will need at least 2” depth clearance from the bottom of the ties. As 
illustrated, drill (use a 1/4” drill) a series of holes around the “inside” of the proposed hole, 
overlapping where possible. Carefully use a sharp chisel and carve out the hole, then trim 
and file the edges smooth. (fig. #2)

We recommend using sectional track (9 inch) or flex track to mount the uncoupler to, 

although you can use hand laid track but the procedures will be more challenging and is 
up to the modeler. If your track is already in place you’ll need to remove or cut a section out 
that’s at least 3 1/2” long. To cut the metal rails use a track cutter, razor saw (hack saw), or 
a mini power tool (Dremel® type) with a metal cutting disc attachment (always use proper 
eye protection). File the ends of the rail to remove any burrs, also file the ends of the rail 
remaining on the layout. After the uncouplers installation, use rail joiners to connect the 
pieces together. We recommend soldering the gap left by the saw cuts. If you are using a 
standard piece of 9 inch track then you will not need to cut it any shorter. This also applies 
to 9 inch pieces already laid. It may be more challenging handling the longer pieces of flex 
track (usually 36”), but it still can be done without having to cut the track. (fig. #3)

There are two methods of laying or attaching the track to the #309 uncoupler. It is possible 

to simply lay the uncoupler into the hole in your layout and lay the track over the uncoupler 
without actually attaching them to each other. However, you’ll need to make sure that the 
plates are aligned properly and both the uncoupler and the track are secured so neither will 
get misaligned later on. You can recess the extensions of the upper plate into your layout 
surface so the uncoupler will set flush under the track. If you have raised road bed then 
you’ll have to build up a section to lay the uncoupler into. This is left up to the modeler and 
depends on your skills and the material you have available and your road bed. 

To attach the uncoupler to the track, which is actually easier than leaving both separate, 

you need a #55 and #52 drill (Kadee

®

 #780 Tap & Drill set) for the 0-48 screws. If you are 

going to cover the uncoupler with ballast then you’ll need to place a piece of aluminum foil 
between the ties and the top plate of the uncoupler before you secure them together. Note, 
the top plate has end extensions that should be cut off so you can set the uncoupler into 
a hole in your layout where the track actually sets flush on the surface. Set the track over 
the hole and mark the particular ties that cover the hole, these are the ties you’ll attach the 
uncoupler to. Set the track onto the uncoupler and note where the two assembly screws 
are in relation to the tie locations so you don’t try to drill mounting holes into the screws. If 
you have cut the ends off the top plate then choose two ties, with at least one tie between 
them, and use a #52 (1/16”) drill and drill a hole dead center in the two ties. If you have left 
the end pieces attached to the upper plate, drill a hole into the center most tie and a hole 
in a tie that aligns with the end pieces that misses the original end holes. Set the track 
onto the uncoupler again and carefully align the uncoupler where the outside plates are 
just on the outside of the rail and aligned as straight as possible, hold this in place secure 
enough to mark the top plate through the holes in the ties. Now using the #55 (3/64”) drill, 
drill the holes through the top plate. Set the track onto the uncoupler and secure with the 
self-tapping 0-48 screws. Use the longer 3/8” screw in the center section and the 1/4” 

Under The Ties

 

      DELAYED-ACTION

UNCOUPLER

309

TWO 2-56 SCREWS

MOUNTING 

PLATE

FIELD PLATE

NUT

STEEL 
MAGNETIC 
CORE

COIL

BOLT

FIELD PLATE 

DIVIDER

FIELD PLATE

FIG. 1

1/4" DRILL

1 1/16" WIDE

2  1/8" LONG

3/16"

3/8"

3/16"

3/8"

FIG. 2

USE RAIL JOINERS

3 1/2" LONG

FIG. 3

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