Advanced Field Telephone Techniques – Part 2, by Tunnel Rabbit

Remotely Operating Transceivers Via Field Phones

If one could potentially be DFed, then we should operate a transceiver remotely, and should do for this purpose at a distance of no less than 500 meters away from a base station. 500 meters was once the standard for an adequately small enough area that was considered as a good ‘fix’ on a location identified by using radio direction-finding techniques in the 1990s. It was an area size small enough for an effective artillery bombardment.  Drones can be used to pinpoint a location, yet there can be user error.  There are ways to confuse drones, and drone operators using unconventional low-tech electronic warfare techniques.

The EE-8, and the popular TA-312 (pictured), or most any other field phone operated by two D batteries could operate a transceiver from many miles away.  If not 5 miles away, the further away, the better.  And we could use a low-power transmitter on a directional antenna to link to a repeater on a directional or omnidirectional antenna to further reduce the risk.  This demonstration shows us just how easily it can be done using most field phones, and a common, inexpensive transceiver:

FIELD PHONE OPS: Remoting a VOX Radio Using a TA-312

Remote Transmission Using VOX and Voice ‘Receiver’ Interface

Field phones can also be used to operate a radio remotely by using the VOX function of the transceiver without using a plug, or jack. We can also use some commercial phones for this task as well. If the buzzer or commercial phone receiver is placed directly on the surface of the transceiver in front of the microphone, the VOX function can operate and cause the transceiver to transmit, because when the PTT switch on the field phone handset is depressed, the piezoelectric buzzer acts as a tiny speaker. Polarity does not matter, just connect the buzzer to a wire pair.  The transceiver hears the voice signal and transmits if the VOX setting is appropriately set to be sensitive enough to hear the tiny speaker.

Vintage commercial phone handset earpieces can also be used, and these are best as they have a much better audio quality that could greatly improve the quality of the transmission. However, the piezoelectric buzzer, used as a tiny speaker, is the lowest in price.  However, we can not hear the reply over the field phone, but must listen to the reply over a receiver at our location. This is not ideal, yet it can be useful in some situations.

One Way Over Wire Voice Communications

If we are short on field phones, yet wish to use them to avoid become a target for DFing drones, then we can use this setup to talk from a base station to a LP/OP, using only one field phone to a LP/OP that replies with a transceiver.  In these threat conditions, we would like to avoid transmitting from a base station if at all possible.  For this purpose, a piezoelectric buzzer is the best choice as a substitute for field phone, as it can acts as a ringer and a speaker (receiver) that the LP/OP end can listen to.

The buzzer act as a ringer to signal that there is an incoming call, and gently chirps. If it is too loud, place it in a container, and connect a 12vdc LED mirco light. These can be ‘grain of wheat’ in size.  This will flash when the field phone hand crank is operated, and at the same time as the buzzer chirps. Both the buzzer and the lamp my also be used on a field phone to eliminate the bell-type ringer. LEDs can be used in place of the mechanical ringer for silent operation at a LP/OP. Simply disable the mechanical ringer and install the led at the terminal posts.  It will flash as line voltage pulses with the cranking of the magneto/generator. Many piezoelectric buzzers and 12vdc LED lamps can be used on the line, or many separate lines, that go to many different LP/OPs, or individual homes in the area and in many rooms of these homes.

Each location can be connected to one field phone at a base station that can call and talk to all locations simultaneously. In addition, we can from a base station, signal with a very loud general alarm (85Dbd or greater buzzer) to all locations using the same buzzers mentioned by applying 12vdc to the line with a momentary switch.  These buzzers are very loud and can awaken a person in the same room as is the buzzer. These buzzers can be placed in several rooms of a home where people could be sleeping, or working.  After the general alert is sounded, these persons can listen to voice communications on the same buzzer. If one must, speaking loudly, or shouting into the buzzer, the entire ‘party line’, including the field phone at the base station, can hear the voice.

Operational Details

The hand crank on a field phone is a magneto-type generator that produces 60 to 90 VAC (Volts Alternating Current), yet it can operate simple DC (Direct Current) powered devices as well, such as the buzzer and small LED lamp. The power requirement to operate these devices is exceptionally low, yet there is a limit to the number of these devices that can be operated by a field phone.  These buzzers can also be used in-line as an auxiliary ringer for a field phone that can be placed in bedrooms and other parts of the building.   When the field phone magneto is cranked, the buzzer chirps.  After the user is done ringing, anyone can listen into the conversation on the ‘party line’ by simply placing the buzzer to their ear.

These buzzers are multipurpose and can be used in many ways to extend the use of a field phone system.  Even used them as noise makers on a trip wire, and located remotely at the base station using inexpensive WD-1 field wire. The base station can also use a momentary switch to signal using a simple code of dits and dahs sounded by the same buzzer.  A predetermined series of dits and dahs can indicate a shift change, a summons for meals, or a meeting.

When speaking from a field phone, the transmitter element in the phone handset is amplified using 3 vdc from two D cell batteries.  The phones can operate on as little as 1/2 volt DC. if within close proximity. One set of D batteries might last up to one year if seldom used. The field phone operates using both AC and DC currents. When cranking the magneto to ring another phone, be sure not to place your hand on the terminals where the field wire connects, lest we might receive a shock.

Avoid using what is referred to a “Patrol Hot Loop” method of wiring phones in series as the entire phone system can be disabled with a single break in the line. We could however use metal fence line as a ground wire and single strand of positive line to conserve our supply of wire.  And we can use electric fence wire as our hot or positive wire lead when that wire is suspended by electric fence insulator. Using direct ground for a return signal is unreliable in most terrain, and seasons.

This is the kind of vintage telephone that can be a donor of the receiver (ear piece) part of the handset.

This is the piezo buzzer that acts as a tiny speaker when used with a field phone. I paid about $1.00/ea.

12 vdc LED lamp bulbs.  I recommend red in color.

Some Field Wire Advice

WD-1 field phone wire uses steel conductors, whereas WD-1A is mostly a few strands of steel with a copper wash. The copper line in WD-1A has better conductivity (less resistance), and thus less voltage loss than WD1. This can be significant if many miles of wire are used.  WD1a can be used for longer runs without the need for a repeater. As distance increases, the voice at the far end becomes weaker.  Steel was used for strength and it is less expensive.

WD-36 is ultra-light and compact ‘assault wire’ that uses insulated strands of aluminum wire. It does not have a high tensile strength and is best used where it will not be exposed to damage. A 1/2-mile spool in donut form of WD-36 wire is about one third the volume, and less than 1/3 the weight of 1/2-mile of WD1a wire in donut form, and therefore is man portable, and can be quickly deployed or using a DR-8 spool, quickly retracted after an assult, or during a retrograde action. Approximately 3/4-mile of WD36 can be on a DR-8 spool, whereas only 1/4 mile of WD1, or 1/3-mile of WD1a can be on a DR-8 spool.]

WD-1A for semi-permanent installations would be my first and second choice when long runs approaching 1 mile or more would be used.  WD1 wire is arguably is more durable, yet the available stocks of it are now ‘long in the tooth’, and the insulation on this wire could be prone to failure. If stored correctly, both types of wire can be in very good condition. Newer production WD1a can easily be found on eBay.  Because of the age and condition of surplus military field wire, it is best to install it above and off the ground where is it less exposed water infiltration. New commercial wire that uses copper strands can be a direct bury type, and lighter gauge copper can be used as copper is 8 times better at conducting than steel.

Shop surplus outlets that are close by in location to reduce the shipping cost. Some surplus wire is much less expensive than newer production Wd1a that is often still found in plastic and cardboard boxes that are in excellent condition. The newer production wire might still be suitable for burial.

WD-1a has a very high tensile strength and therefore it can be used in a variety of ways to substitute for clothes line, or general purpose cordage, to tangle foot wire and other obstacles, trip wire at night, or even to vehicle interdiction that wraps around drive shafts and wheels. It can also be used as wire for alarms operated by trip wire. If we are using this wire, we should also have a hand crank and harness to retrieve and relocate our limited supply of wire.

Signal Center is the best source of information about field wire on the internet.  If you want good quality wire, this is the place.


The untold advantage of WD-36 is that one can store up to a mile of wire and two field phones in a single 6-gallon plastic bucket. A 1/2 mile ‘donut ‘ of WD1a does not fit into a bucket. A DR-8 spool that contains 1/4 mile of WD1, or .5Km or 1/3 mile of WD-1a  does fit into a 6-gallon bucket, along with two TA-1 or TA-312 field phones. Keep new D batteries in their original container, and place plenty of desiccant in the bucket.  The handset elements will degrade when exposed to high humidity.  Keep them dry.  A Mylar bag would provide additional protection from moisture, but is not needed as a Faraday cage.

Field phones that are not connected are EMP/CME proof.  You would now have a ‘good to go’ package that provides rock solid reliable comms for a decade or more, that is actually secure.  Bury the wire, deep enough, and it will also be EMP resistant.