S-250 Shelter / Ham Shack Conversion

[professor solderflux]

This will start off a new thread following the conversion of my recently acquired S-250 communication shelter into a mobile HAM radio shack. The 2500 mile road trip to bring it from NY to MN is posted under the "road trips" area. http://www.steelsoldiers.com/auxill...2500-mile-road-trip-get-my-s-250-shelter.html

This really isn't a restoration, although I'm trying to make all my modifications look as "military" as possible. The new HAM gear is often used with PC support, or even total PC control (Ham Radio Deluxe), so the modern station set up can run the gamut from tubes and big knobs to keyboards and monitors. I'm a computer kind of guy, but I also like to build test and repair my own circuits, so my station will have a little of both. I plan to use 2 separate IBM computers to support my future radio gear and run 4 or 5 monitors for all the peripheral applications and gadgets that add to the enjoyment and utility of radio communication. (Plus, they look really cool!)

I'm also planning to include a little workstation for testing and repair that will utilize several military surplus Tektronix test equipment modules, I've collected over the last few years. Finally, if you can believe it, I'm also planning to add a bench seat that folds down to a 6 1/2' by 30" sleeping area for overnights (or if Jan locks me out--just kidding, dear). The shelter is mounted on a 4' x 8' trailer with a 3500" axle and bigger trailer tires and Jeep style fenders. There's an area by the tongue for my Subaru 3500W generator, a Jerry can for gas, and a 20' crank-up antenna mast (an army surplus light tower in it's previous life). Depending on how much heat I need and get from the rear mounted AC/Heater, I also have room by the tongue for an LP tank to run a small ventless heater. It DOES get cold in MN!

My first project after getting the shelter home was to determine if the AC/HTR was still going to work after all those years sitting outside. It wasn't the ideal place to put my workshop, but upstairs off my studio was the only place left when we did our addition 10 years ago. Lugging the 163# monster upstairs was a one step at a time deal using a two-wheel dolly. Working from the inside panel, I disconnected the hard to find Amphenol power connector and made a temporary connection to a 115VAC cord--not pretty, but OK for testing. The next thing I discovered was that almost every screw on the exterior was rusted to the point of crumbling. A Phillips head bit would just make a divot. I removed over 50 pan-head screws using a vice grip pliers and holding my breath. Only one broke. Now somebody please tell me why the military would specify an AC unit made entirely of aluminum and stainless steel, and then put it together with corrosive fasteners?!

Once inside, I had all kinds of surprises waiting for me. At the very bottom perimeter of this unit there are three 1/2" holes for water condensation to drain out . Apparently these were very attractive to paper wasps and other little critters from all the nests I found way up inside the unit! The filters prevented them from entering the shelter interior, but I wouldn't have wanted to be around the outside if the unit had been fired up in summer. I spent the next four evenings trying to coax the unit back to life, but after facing rusted control assemblies and missing refrigerant from the sight glass (a demil thing), I decided to keep this as a parts unit and spring for a new crated unit I found online just 3 hours away in St. Paul. I really didn't want two of them, but I can't just requisition a new "#247J / 20-EEE thingy" when I find another bad part either.

The next Saturday I picked up my NOS unit, factory fresh from 1992. One of the things we surplus junkies thrive on, is the bargain basement prices we get (on stuff we already over-paid for as taxpayers). I was not to be disappointed when I saw the original price sticker on the crate at $4020! What a deal. Inside underneath the crate, the padding, and inside the plastic bag was the unit itself, along with a 390 page manual. Makes you wonder what the manual for a Stinger missile comes in at. The unit fit into place perfectly, and included a zippered weather cover for the outside. My only frustration is with the idiot who decided to attach the manual packet and desiccant packs directly to the new unit with gummy OD duct tape. What a MESS! It was stuck so tight in places, I thought it might pull the CARC paint off. A lot of time was spent with a razor blade scraper, turpentine, and elbow grease to get rid of the gummy goo.

Once mounted, I drilled some holes in the holding bracket tray to access the screws that attach the weather cover. Needless to say, I'm replacing them with stainless steel fasteners!

More later...

 

[professor solderflux]

Sorry about the sideways pics, my post preview wasn't working.

 

[StrykerPez]

Will the aluminum shelter provide enough of a ground plane for the antenna?

 

[professor solderflux]

Hi Stryker, When I say mobile shelter, I just mean portable, not to be used while in transport. Once set up, I'll have all the equipment, generator, and shelter linked to a 6' ground rod connection. Beyond that, I'm sure the shelter will possess a ground plane effect of it's own when using a vertical type antenna. I'll also be able to experiment with surface ground plane radials in the form of pipe or cables, when I get to that point.

Any suggestions are appreciated, My first antennas on the mast will probably be a discone at the top, and an inverted V or two coming down from there. I'll probably mount a 2-meter whip on the shelter. After I get into some HF gear things will get more interesting.

 

[HAWKMAN]

These shelters are definately COOL to have fun with. I've got an AN/GRC-46-B shelter that I restore and though it is a bit tight it is very relaxing to fire up the generator and sit inside and listen,( I don't have a license to transmitt)......much fun!!!

 

[professor solderflux]

I know what you mean HAWKMAN, would love to see some pics of your setup!

One of the added benefits, besides using a $20K piece of Military equipment for your hobby is the beefy door. Someone that wouldn't think twice about kicking in a regular entry door on a shed or garage is going to be pretty intimidated by these shelter doors and a good padlock.

You should think about getting a HAM license. Just a couple weeks to study out of the manual, no more morse code requirement, and then you can legally carry a scanner in your vehicle in just about every state.

Of course like any hobby, the money starts to turn up missing from your wallet...

 

[HAWKMAN]

Here you go professor! Hopefully they come out....enjoy!!!!!!

 

[professor solderflux]

Hey thanks for sharing the photos--man, that's a lot of metal! I didn't figure you had the radios with it! Is that a dynamotor on the floor to generate 115VAC? Looks like a jump seat peeking out from behind he door. Do you have lighting and heat as well?

Curious if you got the whip antenna with it, or are you using a long wire, or something else?

Pretty cool, Don at Spruce Mtn. has a couple shelters with all the equipment for a pretty reasonable price, but they come in pretty hefty--my Jeep would croak!

 

[HAWKMAN]

Yea, the weight of that T-135 transmitter alone is crazy. The shelter has two of the dynamotors that suppy power to the teletypes,( 28 VAC to 115 VAC). This set-up I'm told was for the back of an M-37 so a jeep would be groaning from the weight. I do have lights and DID have heat at the begining of the season untill my multifuel heater went south but that's OK as I have plenty of the electric shelter heaters from the larger TRC-117's I've got out back. The antenna is a copper whip that is mounted on the back of the shelter I usually get good reception with this setup.I did try(once) putting wire in the trees as high up as I could but when the thunderstorms got me worried I took them down and only use the original one. I like this shelter set-up cause it's small and easy to move.

 

[professor solderflux]

Prepping, Patching, and Priming - part 1

You can't work in the dark, and without electricity and the doors shut, these shelters are as black as it gets. Power enters the shelter and its' 60 Amp panel through a service panel to the right of the exterior door. The recessed panel has an integral weather shroud, and two imposing connectors (connected in parallel for "daisy-chaining" these things), a covered duplex outlet, and a grounding terminal. The connectors that mate with these plugs carry 115VAC across two sets of wires (to spread the current load across more copper, and thus requiring smaller, more flexible wire), and are a little hard to track down. I did find one for $50 including shipping, and am still waiting for it's arrival from MD. In the meantime, I used the "backdoor" to energize the shelter, so I could use the lights and outlets. I made an electricians nightmare, and wired a short cord with a grounded AC plug on both ends. This goes between the extension cord and the duplex auxilary outlet at the exterior service panel. I also made a bright red sign warning anybody not to unplug the "hot" plug from the shelter. I'll be sure to disassemble this cord when I'm done with it!

Getting started to refurbish the shelter, I realized I had two fronts of attack: INSIDE and OUTSIDE. The outside was still a little cold to work on, but it smelled a lot better than the inside! This shelter is very light-tight, air-tight, and water-tight when all the hatches and vents are closed. While that keeps moisture OUT, it also keeps any moisture that happens to be there IN, as well.

There seemed to be evidence of powdery mildew on almost every metal surface, so one of my first jobs was to wash everything with a solution of hot water, PineSol, and a little bleach. I took the fluorescent lamps out of their holders to clean too, and discovered these neat little brown plastic retaining clips that slide over the socket and two-prong bulb terminals to prevent them from turning, and coming loose. I only discovered their function after snapping two of them, so if anyone knows where to find more, please let me know. I've searched the web, and local places, but no ones ever seen them before. The other neat thing on the fluorescent fixtures, was a bracket on the side to hold a spare bulb. These used a large O-ring to hold the spare bulb to the bracket--love this sort of thing!

 

[professor solderflux]

Prepping, Patching, and Priming - part 2

I had to switch out the 115VAC twist socket for the AC unit, as it's a little different than the standard twist socket available today. I went with a 20 Amp round plug set-up that still prevents plugging the AC unit into an under-rated socket or extension cord. I also had to drill new holes to re-locate the cord and damper control chain to be accessible from the interior. This was already done on the old AC unit that came with the shelter. A little OD paint on the connector fitting, and good as original!

As I started to think about paint color, I found some punctures on the interior knee-wall and floor area. As a matter of fact, the floor was the only part of this shelter that was in rough shape. It has seen a lot of traffic, and clearly shows the supporting cross-members underneath. There were only a couple running indents on the exterior sidewalls to deal with. The aluminum skin is thinner on the sides, and that's the area most likely to be scraped when in motion. I used a fiberglass-reinforced "Bondo" filler to repair these areas, followed with a few coats of glazing putty, and a lot of orbital sanding.

Some other interior niceties were a holding bracket for a sledge hammer (for setting ground rods), and a bracket for a large fire extinguisher. I'm giving both a fresh coat of "safety red" paint.

Back on the OUTSIDE, I primed the patched areas and welded trailer additions with red oxide primer. The mounting for the telescoping antenna mast uses the original brackets for the now-removed 4-pod legs. This way if I ever need to remove the mast and re-attach the legs for use away from the shelter, nothings changed. It's quite impressive looking in the raised position.

 

[professor solderflux]

prepping, Patching, and Priming - part 3

Since these shelters are normally mounted on CUCV or HMMWV carriers, I decided to add a set of Mil-style reflectors on the corners for transport safety and looks. I took note of the stenciled markings so I could re-apply them after painting. At this point this shelter is UGH-ly, with it's lusterless USMC forest green over OD, two colors of Bondo, red oxide primer, OD color mast, cherry red generator, and white trailer wheels.

Time for a make-over...

 

[rlwm211]

S-250 ham shack

Hey, I have one of the s250 shelters. I am the fourth ham to own this since it came out of the military. I have 9 antennas on the unit and I use it for emergency communications work. I have three two meter, an 11 and 10 meter along with provisions for 6 meter hf and a scanner. I also have a complete weather station linked to a laptop inside. Overall there are three laptops all linked and internet capable.
I have a repair station on one side and have a complete soldering, diagnostic setup with materials and spare parts. The entire rig is battery operated and self contained and can run independently for about 12 hours with everything on. It can charge off of 12 volts, or 120 volts. I plan on installing a receiver on the back of my deuce to haul this.
I have the hooch on a heavyduty single axle trailer with 3 landing gear jacks so I can level the trailer in the field. Overall, the complete rig is about 2500#
All of my antennas use the hooch as a ground plane. I have checked them out with an analyzer and they all are very efficent.

 

[Chevytruck]

whats the sledgehammer for?

 

[professor solderflux]

That is outstanding! So many of the features I dreamed up for mine, you've already got in yours! If you don't mind, I'm going to bug you with some questions when I get a little closer to rigging antennas and such. I'm so glad to hear the shelter functions well as a ground plane for the antennas. I have a 2" square tube that runs along the top edge of the forward (tongue-side) wall that I can use for a common mount for the smaller antennas. It's part of the telescoping mast mounting system. I'll have to put a junction box on that wall for the antenna connectors, because the signal entrance panel on my shelter is by the door. That signal box is going to be a pain unless I move (or remove) it because it's huge (26" x 15" x 9") and protrudes into my first 19" radio space.

I've been doing some figuring and sketching for my layout. The neighbors are probably talking with the amount of time I spend in there thinking and measuring--good thing there's no window yet. The curb side will have a fold-out sleeping area, and have a fold-down work bench on the back wall where the current shelter desk is.

I'll post my first sketch of the road side radio area here for a preview of what I'm thinking about. You HAVE to post some good pictures of your interior layout, OK?

Thanks for the stimulus!

 

[professor solderflux]

whats the sledgehammer for?

Pounding in 6-foot grounding rods. Getting them out will be another thing.

 

[kaiser715]

I got an antenna mast just about like that, but it's only about 3-1/2 or 4 feet tall when collapsed. I was working tonight on the brackets to mount it to my S250. (Actually, stuck deciding whether to mount it directly to the shelter, or building the same drop-in mount for each of the 2 trailers. I use my S250 either on my M101A3 or my big flatbed trailer (and also go tent camping sometimes with one of the trailers or the other and not the S250 camper).

I got my Tech about a year ago...just playing in 2m for now.

 

[professor solderflux]

Sound like a good setup Kaiser, I can totally see where acquiring these shelters could be a habit--They are awesome, and can be so different in what they have to work with. Ft. Bragg had a 3 on GL this winter that seemed like they were longer that normal. They looked so new in the photos too, but the physical size was beyond my present towing capacity. The AC unit they had was a 19000 BTU unit that would have taken 3500 Watts just to run by itself!

I got my Tech in February, but I'm so in debt with my shelter project, I don't even have the funds for a 2-meter handheld yet. Later this spring, I hope.

I'm KDØGOP, by the way.

 

[rlwm211]

Hey professor...The majority of my antennas are NMO mounts directly through the roof. They work great and do not leak. I resealed the roof this spring as a PM.
I have 4 SO-239 connections on the right front patch bay on the door itself. I use weather tight covers to protect the connector when it is not in use.

RL Whiting

 

[professor solderflux]

Hey RL,

Sounds like the NMO mounts would be a good option; how did you deal with the 1.5" thick ceiling?

I think I see the connectors on the right/front bay door in your photo. On the rear photos, I see an external speaker box; is that for monitoring when your just outside the shelter? I've seen a couple vintages of this speaker: how does it perform? how much? and where do I find them?

Thanks.