Even more phone info. from Sparks over at SIGNAL CORPS
Archive for November, 2013
The following information was provided by one of my readers. “Switchman” as you will see, has extensive experience in telephony. Read and heed and add another arrow in your quiver.
MSG,
I’m going to apologize up front if any of this info is too elementary. I don’t know how much experience you have around telephony, so I am just going to assume an average layman’s base of knowledge. Tracers (also called toners or tone generators) are most often used to locate specific pairs of wire over long distances. Most also have the ability to provide enough battery to allow voice comms with buttsets across a dead or “dry” pair. Here’s a link to an example tone generator made by JDSU that has the talk battery feature. http://www.electriduct.com/JDSU-TG101-Tone-Generator.html
In the phone business we deal with massive bundles of wire that are often times snarled and resemble a rat’s nest. Even in the best conditions, just trying to find one individual pair of wires out of an 1800 pair cable can be virtually impossible if the color-coded binders have aged and changed colors. There are also relatively ancient cables where the individual pairs are all white. We refer to those as “tone cables” because the only way to find your pair is to put test tone on it at one end and then find that tone on the other end with an inductive probe.
When performing maintenance you often have techs on either end of a cable. One way they can talk to each other is to find a dead pair (no battery on it), then put test tone on it at one end with the toner. The tech at the other end finds the pair with an inductive probe or sometimes even with just a buttset. Once the two techs know they are on the same pair, the toner can be placed in series with a buttset and switched to “talk battery” mode to provide the voltage needed to carry voice over the dead pair. The other end just uses a buttset, you only need one toner to provide battery.
I can’t find specs for the range of voice comms using this method, but these little toners can send test tone over 10 miles. To put a toner in series with a buttset simply connect one lead from the buttset to one lead on the toner, the two remaining leads are used to connect to the pair being used for comms. When being used in this configuration, the end with the toner can “ring” the other end by simply switching to test tone and then back to talk battery. It won’t actually ring the other buttset, but it will generate that same warbling 2 freq test tone on the other end used to locate the pair in the first place.
I hope I haven’t lost you at this point. If there is anything I can clarify about this setup or any other telephony info please let me know. I’ve been working for a “Baby Bell” for 15 years and grew up around it as well.
Switchman
Thanks for the info. Switchman, feel free to contribute at any time. That goes for the rest of you folks out there in the blogosphere that have communications technical experience that is pertinent to our mission (METT-TC). This is not a one man show.
DOL
Dan Morgan
I am going to step back from the high speed, low drag, radio communications arena to talk about a very basic, simple and low tech form of communications: field telephones. I will also incorporate the SOI from the previous article into the discussion.
Why use field phones? They’re not near as sexy as that new multi-band radio with attached can opener, the new cellphone with multiple app. thingies or the the laptop with the 50 gazillionbit hard drive. The answer is: they’re rugged and secure. Again METT-TC prevails. If you have a retreat area and need semi-permenant, secure, nearly bullet-proof communications that cannot be D.F.’d, and require very little maintenance, then a field phone system is right up your alley.The phone system is somewhat labor intensive both to install and to recover, but it doesn’t take a Rocket Surgeon to design. Basically, you run a strand of two conductor wire from one phone location to the other, connect the phones and talk.
The phones:
Several different phones are available and we’ll start with the TA-1. The TA-1 is a simplex phone, you can either talk or listen but not both at the same time (that would be a duplex system). It needs no batteries since it uses the power from your voice to generate the audio signal through a simple carbon mic. To signal the far end phone, squeeze the built in hand generator on the side of the phone and the receiving phone displays a silent, visual indicator and sounds a buzzer. The buzzer can be turned off with the volume control dial on the bottom of the handset. This is my preferred phone for use in the Listening Post/Observation Post (LP/OP). The visual indicator won’t give the position away like the ring or clack of other phones, but it is hard to see at night. With that being said, keep in mind that since the purpose of an LP/OP is early warning, comms usually only go one way, back into the perimeter. If you feel you must talk both ways at night, turn the buzzer as low as possible. To talk, press the push-to-talk lever on the other side from the hand generator. To reset the visual indicator, press the PTT. Range is about 4 miles and the weight is 2.75 lbs. To connect to the phone circuit, strip back 1/2 inch of the insulation on the two line wires and put one under each spring loaded binding post. That’s it, your done.
Things to look for when buying these phone: Rubber insulating boots in good condition over the binding posts at the end of the cord. If you can’t locate any boots, wrap them with electrical tape after installing the wire. If you crank the generator on a wet phone and the exposed terminals are wet, you will most likely get a stout 80 volt shock. (A truly evil mind (John Mosby) can have lots of fun with that). An intact, rubber insulating cap should also cover both the push to signal lever and the push to talk (PTT) lever on the opposite side. The thin diaphragm over both the mouthpiece (transmitter) and earpiece (receiver) should be intact. If you can’t locate suitable diaphragm material, thin plastic (like cheap sandwich bags) will do in a pinch. You should unscrew each plastic cover trim and check that the carbon mic inserts are in place under each diaphragm. If your buying a set, take along a short piece of two lead wire, hook them together and test them out. The phone should come with a metal or plastic container. A good source of field phones, parts and detailed information is: http://signalcenter.com/
For tech manuals go to: http://radionerds.com/index.php/Main_Page
The next phone discussed is the TA/312. A very similar, older version of the 312 is the TA/43. Both require 2 D cell batteries (3vdc) to generate audio and utilize a rotary hand crank magneto for the ringdown signal. If you operate the phones with the SSB-22 switch, you don’t need batteries in the phone (local battery), you can use the batteries in the switch (common battery). The audio level in the earphone and the signal are adjustable. The range is 14 miles wet weather and 21 miles dry. The weight is 9 1/2 lbs, so it’s not something you want to tote around in your ruck. The phone wire is stripped and inserted under the spring loaded binding posts at the top of the phone. The 43/312 has a connector for headphones (if you can find a set). The phone should come in a canvas zipper bag. Check for the same carbon mics in the headset. Also check the battery compartment for ruptured batteries. I would use these phones back at my comms center and in more permanent, built up fighting positions. You can also install a dial tone (DTMF) keypad adapter module to the 312 for use on plain old telepone service (POTS) lines.
As an added note, if you don’t have a lineman’s butt set; when we were in the field and could find a telephone pedestal, I have seen these field phone tied into the pedestal using alligator clips on one end of a short pair of field wires. The alligator clips were moved to different pedestal punch down connections until a dial tone was heard in the headset. Then the hook switch on the phone was clicked in the phone number sequence with short pauses between the numbers, to simulate the old rotary phone dialing clicks and a phone call would be placed. I just saw it happen, because …….I would never do that myself. Yeah, that’s how it went……
Used German Army model FF53M field phones are also in common use. They can be picked up at Army Surplus stores and online. Ours use two D cell batteries, but I have heard of models that use five AAs. Again, the batteries supply audio power and a hand cranked magneto is used for signaling. The case is black Bakelite. They weigh 9 1/2 lbs and have a listed range of 16 miles. I have not tested to see if the German phones are compatible with the U. S. phones but I assume they would. I know….anytime you assume it makes an ass out of u and me.
Switchboard:
The SB-22 Switchboard is used to connect up to 12 phones back to one location in a star configuration. I would use this in my central comms room at the BDOC. Then the phones can be patched together by the switch operator. Attach each set of wires to the modules under the back cover of the switch. Label the wires and label the matching tag above the appropriate patch cord. When a call is received, the appropriate lights will appear as well as the audio signal. The operator then picks up the call based on which indicator lights up. He then places a call to the other party and patches them together. When they hang up the indicators go blank. It uses 4 D cells for audio. The switch has a signaling crank on the front. It requires a special headset with boom mic to operate, but if it is missing, you can substitute a field phone wired into the back with the matching patch cord inserted. With additional modules you can connect military radios and other devices into the system.
Field Wire and Spools:
The two basic types of wire are the wd-1 (two twisted, individually insulated wires) or the WD-1A ( two insulated wires bonded together). Each has four copper and three galvanized steel strands twisted into one wire with a tensile strength of 200 lbs. You can also find 4 pair and 26 pair cable. The wire weighs approximately 62 lbs per mile.
The DR-8 is the smallest and lightest of the military spools. Ir contains 1/4 mile spool of twin lead wire. Notice on the side of the spool two insulated connecting terminals with a small insulated hole beneath each. These are used to connect the free running ends of the wire on the spool to. Then you can later wire your phone directly to the spool with the remaining unused wire left on the spool. This saves cutting your wire into short pieces over time. A hand or chest mounted reel called the RL-39 can be used to play out or reel in the DR-8 spool.
Wire spools and reels come in many larger sizes up to the DR-5 which will hold 2 1/2 miles of 2 conductor wire. It is used with the RL-31 Reel. We used the RL-31 in the back of military and civilian pickups, jeeps and HMMWVs to reel out miles of wire.
Procedures for installing a field phone system.
As listed in the SOI, our retreat has two, two man fighting positions (bunkers) with overhead cover and two LP/OPs (Listening Posts/Observation Posts – the LP/OP’s are not heavily fortified positions, they are instead well camouflaged positions with minimal cover that provide early warning of approaching forces. Listening at night, observation in the day.
The primary comms to our bunkers from the Base Defense Operations Center (BDOC (pronounced bee-doc)) consists of two sets of field phones. One set to each occupied bunker. The same for each occupied LP/OP. The east LP/OP phone is connected directly to the BDOC. The other LP/OP is about 100 meters north of the north bunker and that LP/OP phone is connected directly to another dedicated phone in the north bunker.
So we have a total of 3 phones at the BDOC. One to each of 2 bunkers and one to the east LP/OP. The north bunker has 2 phones, 1 to the BDOC and another to the North LP/OP. For a grand total of 7 phones. You could eliminate 3 phones at the BDOC is you could manage to scrounge up an old SB-22 switch board. You could also wire all the phones together in a “hot loop”. Then if you signaled with your phone using the hand crank, all the phones in the loop would ring at once.
We use one spool of standard army WD-1 wire on a 1/4 mile DR-8 spool for each circuit. When running each circuit, a stake is driven into the ground, near the phone, to loosely tie the wire to. Tying the wire down prevents someone from inadvertently tripping over the wire and pulling all your phones onto the ground. It also provides an anchor point for your reels when you play the wire out. Enough slack is left at the stake to run the free end of the wire to the phone. The wire is then spooled out from each position to the BDOC , where it is again wrapped around a stake. The wire at the spool end is not cut, but the free running end should be running out of the hole at the center of the spool and connected to the terminals on the spool. Then a separate section of wire is also attached to the terminals and the phone, completing the circuit. The spool is left at the BDOC to allow personnel to quickly roll the wire back up toward the far position. Or in an emergency, the wire can be cut at the spool, and the remainder of the wire on the spool is saved. If the bunker or LP/OP is not manned, the phones are disconnected and returned to the BDOC while the wire is left in place. When relieving a sentry, I have used the tied down commo wire to find my way to a position at night with no illumination. It’s probably a good idea to call and give the sentries on duty in the position a heads up prior to using that trick at night. Sentries usually physically check the wire once a day for wire taps, cut wire and attached booby traps. This is known as “walking the wire”. Each time a phone is attached to the wire a test call is made to the BDOC. A unique colored plastic wire tag is attached to each set of wires running from the BDOC to the individual positions. While tags can be attached to each end of the wire if you have multiple phones at each position, in our example we will only tag the BDOC room end. The tags are colored as per the SOI in the previous article. Radio procedures do not apply in a field phone circuit, just use common sense. When we picked up the phone for a call, we usually said something to this effect: BDOC or Mortar Pit, West Tower, Motor Pool, etc.
One last note, if you don’t have access to military field wire, just about any wire will do in a pinch. If it’s TEOTWAWKI, you could use phone line wire. Speaking of phone wire, there is a inexpensive device known as the Ramsey QLRD1 Automatic Telephone Ringdown that will allow phone calls over dead copper phone circuits. Say from your house to your neighbor’s. You will need one device for each end and a 12 volt power source, like a car battery. Plug the phone in and when you pick up the phone it will ring on the other end. It won’t send the signal through a SLIC where the signal is converted from analog to digital. If the power is down, then the SLIC is down. Something else to ponder.
DOL
Dan
Good stuff for all you folks looking to extend the range of your comms.
Readers can find a short exchange of comments at the bottom of the blog regarding the Motorola DTR. I would like to thank the gentlemen for the information provided. A special thanks to Ticom, author of “Musings of a Man In Black: Prometheus”. Read and heed folks.
If you have followed my past articles, including those over at Mountain Guerrilla, you know that I am fond of the Motorola DTR. It is one of the few, rugged, MILSPEC radios that you can run without a license. I do include some caveats and they are:
1. I would use this radio for inter-squad use only. Great for CQB. The DTR inherently has limited range due to it’s 1 watt power output and 900 MHz range.
2. Use it in that application sparingly. When operating in a patrol, I prefer squad hand and arm signals to any radio. Why is that Dan?, you ask. Because I am highly allergic to JDAMs, 30mm Bushmaster rounds and Hellfire missiles. One advantage of the DTR is it’s frequency hopping capability. Motorola is very tight lipped regarding it’s hopset. I do know that it will run ten separate hopsets and will repeat hopsets every 50 cycles. I have no doubt that our buddies over at NSA already have those hopsets. If your dealing with Mosby’s Cannibalistic San Franciscan’s or local law dog’s, don’t worry about it. It can’t be intercepted with any commercial scanner. But, if you’ve managed to draw the ire of the big boys, don’t key any mic (unless you are running a deception). I don’t know how else to put it.
3. As per the comments at the end of the blog, I prefer the DTR-550. The 410 has a fixed stubby antenna which limits range. The 550 and the 650 have removable antennas that can greatly increase range if the proper antenna is constructed and used. The 410 and 650 have the infamous manager functions that can cause havoc if not properly administered. And for you former 18Es, buy the keypads, they’re about $30.00. They can be used somewhat like a DMDG with the DTR.
danmorgan76 