Friday, July 14, 2017

SP 2424 (Part 3) - Radio Antenna Stanchions

In SP 2424 (Part 1) I covered installing new trucks and in (Part 2) I covered installing the late model roof A/C hatch.  With the hatch in place I can now drill and add the five radio antenna stanchions and string the antenna wire.

SP 2424 with OwlMtModels 4046 Antenna Stanchions installed.

The OwlMtModels 4046 Antenna Stanchions (22 pkg) I'm using are 3d printed at Shapeways and then cast into bronze.  The set has 22 stanchions in it, which is enough to do 4 standard SP cars and two spares, in case the carpet monster decides it's hungry!  The bronze castings can be soldered to very easily with rosin core solder.  There's a small notch in the top of the casting for the antenna wire 0.010-0.012" to rest before the soldering iron touches it, mounting it in place to the stanchion.

Installation on the SP 2424


The SP 2424 was fitted with the SP train radio system, it had 5 streamlined stanchions spaced down the roof of the car.  I started by laying out the center marks for the stanchion holes.  Each hole location is then marked with my carbide scribe tool as a center mark to drill.

Drilling the Holes in the Roof


The roof of SP 2424 with two small center marks for the stanchions pressed in with a Carbide Scribe.

The stanchions are designed to fit MTH Daylight Passenger Cars, but just about any SP passenger car roof can be modifed with the proper drills for mounting of these stanchions.  A clear hole needs to be drilled that is about 0.040" in diameter, followed by a very shallow counter-bore of about 0.06" or 0.0625" about 0.012" deep for the base of the antenna to rest in.

Here's a comparison photo with SP 2424 in the back with SP 2432 in the foreground with the holes for the stanchions.

Shortly after the SP 2424 Antenna was installed I also did the installation on the SP 2432 for a customer.  The SP 2432 is an old Soho car with a brass shell roof.  I installed a strip of styrene inside the roof for the lighting, which had the 0.04" through holes drilled for the Antenna Stanchions.  The roof shell drilled with 0.062" drill to fit the Stanchion base.

Installing the Stanchions


The sprue of 22 stanchions ready for de-spruing and installation.

Side-cutting pliers were used to cut the stanchions from the sprue.  Then standard pliers are used to grip the streamlined flat areas of the sides of the stanchions while pressing the stanchion into the holes and aligning the stanchion to the direction of travel.

Here's a photo of the Stanchions installed without the antenna wire on an MTH Articulated Chair Car.

On the newer installations on plastic cars I've found that it's best NOT to glue the first end stanchion into the roof.  It's tricky to get the first one started and square.  It's easier to pre-solder it while holding it in a vise.  Then transplant it to the car, gluing it to the roof with ACC-type glue.

Soldering the Antenna Wire


Installation of the wire is actually very fast.  There are two ways to install the wire.  One is to pre-flux on the top of the stanchion with liquid flux.  (I sometimes will lightly pre-tin the antenna wire before this.)  Place the antenna wire onto the top of the stanchion, feeling it rest into the small notch in the top of the stanchion.  

Here's a photo after soldering, the notch in the top of the Stanchion is rounded out by the solder.

Then quickly touch the soldering iron to the top of the stanchion and remove it.  About 1/3 of a second is plenty of time with my 15w soldering pencil iron.  You'll hear a quick "Tsst" as the flux burns off and pull the iron away.  I usually have about 1 cubic milimeter of solder on the end of your soldering iron which is plenty for making a good solid joint.

Antenna wire installed with extra hanging over the ends.

I try not to have so much solder that it leaves a 'spike' hanging off the top of the stanchion where I pulled the iron away.  Often I will use some 600-grit sanding stick to lightly dress the top of the antenna wire over the stanchions to remove any excess solder or flux residue.

Wire installed on Stanchion and cleaned up with some very light sanding.

On the first couple of cars that I installed the antenna wire on, I used Tichy Phosphor-Bronze 0.012" wire.  Unfortunately this is only long enough to do about 80% of a 77-C-3 car antenna.  So I had to make a splice.  There are two options for splicing.  Either make them at one of the stanchions or make it in the middle of one of the spans.

Splicing the Antenna Wire

In the above photo, I made a lap-splice in the vestibule end span.  While I found ways to make this work, the simple answer is to use DTA wire which can be bought and is about 11" long.  I did several other cars with 0.010" brass wire with good results.

Other Tricks


Tensioned wire installed on the SP 2424 and painted to match the roof.

During the soldering of the antenna wire to the remaining stanchions I found that it works well to hold the wire beyond the stanchion to be soldered under tension so that the train antenna wire doesn't sag.  The prototype had small insulators at the top of the stanchions and looked much like telephone pole insulators, so the antenna tended to be very straight in the photos I've seen.

Installations on MTH Daylight Cars


One of the MTH Daylight 79-CB-1s was damaged a year or two ago in service at the La Mesa Club.  I'm not sure exactly how it happened, but someone probably grabbed the top of the car not realizing that there was an antenna there.  The result was the rear most stanchion head broke and the steel wire can't really be glued back in place...  These Antenna Stachion parts are the solution to this car's problem too.

In this view we see damage to the plastic stanchions on MTH SP 3302.

I'm very happy with how the new train Antenna Wires came out using the new Stanchions on both the SP 2424 and the SP 3302.  These are much better than the plastic ones that came with the MTH cars.  I'll be using these parts to re-equip all of the MTH cars coming through the shop from now on.

Here's the same car with the new bronze stanchions and wire antenna installed.

Hopefully this will be useful information for everyone that has damaged their passenger car roof antennas despite their best efforts not to break them.

The next time we see the SP 2424 (Part 4), I'll probably be doing more work on the underbody equipment, reconnect the lighting to the new trucks and possibly install a lit marker on the rear of the car.

Happy Modeling!
Jason Hill

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