Installing a sound decoder - 5
engine, and vice-versa; if not, you must enlarge the holes until
you can get that amount of movement. Remove the cable for
now, touch up the paint around the openings, and set it aside.
Tender speaker
In 98% of rectangular tenders, you can mount the speaker on
the floor, and many engines have the holes already drilled for
you. If not, you will need to drill holes in it for the sound to go
out. If there is absolutely no way to mount the speaker on the
floor, I have mounted speakers in the coal pile and drilled 40 or
50 holes in the coal for the sound to come out the top, and it
sounded good.
The tender itself makes a great enclosure, and you will be
amazed at how loud it will be if the speaker is mounted so it is
sealed around the opening or holes.
Try and use the largest speaker you have room for, but be sure
it has 8 ohms impedance. Test it first with a 1.5V battery with a
1.2K resistor in series to make sure it makes some static when
you touch the terminals with it.
In a Vanderbilt tender, you may have to build a small baffle of
plastic or cardboard to seal off the ends of the speaker from the
curved tank bottom. Find a location on the frame where you can
drill enough holes for it and not hit any brake parts, then scribe
a circle around it in pencil and drill the holes about 1/8” apart. A
3/16” or 5/32” bit works well, but be sure to anchor the tender
securely when drilling!
After smoothing off the holes, paint them and then you can
mount the speaker. I use any good silicone RTV, since it holds
well, but the speaker can be removed fairly easy if it ever
needs replacement.
Hold the speaker in place and run a bead of RTV around the
speaker and on the tender floor to hold it down, making sure
it is sealed tightly to the floor. This is a good time to reinstall
the tender weight – you want the tender to weigh at least 5
or 6 ounces when finished. Set it aside to cure overnight.
Decoder in the tender
There are a couple of extra challenges encountered when
mounting the decoder in the tender:
(A)
you will need to find a place for the decoder in addition to
the speaker,
(B)
you need to run power from the right rail to the decoder.
Delivering right-rail power can be done in at least three ways:
(1)
You can make pickups on the tender trucks for it
(2)
you can use a wire in the cable from the engine to the
decoder and
(3)
you can reverse the draw bar – soldering the stud to the
engine and drilling the tender for the insulated draw bar
mount.
3: Showing underside of tender and holes for speaker
sound.
3
MRH-Dec 2013
