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Basic Countermeasures Equipment


This differential antenna detector covers from 10 to over 1,000 MHz and solves many of the problems encountered in very high level signal locations such as metropolitan areas. The level of radio frequency (RF) radiation from computers and other electronic equipment can also be observed with this unit. Supplied with amplifier/indicator assembly, RF head, two antennas, head extension rods and cables, special 2,000 ohm headset and carrying case. Uses two 9-volt batteries and incorporates internal battery test circuits.

The 2055HA is designed to detect low level radio frequency (RF) radiation from transmitters, receivers, computers, etc. One of the two antennas detects towards positive while the other detects towards negative, therefore, if the source of RF energy is away from the two antennas (i.e. 20 feet or more) both antennas receive essentially the same amount of energy and the meter remains at zero. As the ratio of the distance between the RF source and the antennas decreases, one antenna receives more RF than the other and the meter swings on that direction. This effect is known as near field or differential detection.

The 2055HA covers frequencies ranging from lower than 10,000 Hz (10 Khz) to over 1,000 MHz or 1 GHz. The system consists of: amplifier/indicator assembly, RF head assembly, head extension rods, head extension cable, two multi-section antennas, two right angle BNC connectors, special 2,000 ohm headset, carrying case and instructions.

TO OPERATE: Insert the RF head assembly into the BNC connector on the top of the amplifier/indicator assembly and position so the two cover screws face the operator. Connect the two antennas with right angle adapters to the RF head and position so they are parallel. If the frequency of interest it above 500 MHz, collapse both antennas fully. For frequencies between 100 and 500 Mhz, extend both antennas one section. For frequencies below 100 Mhz extend both antennas two sections.

Insert the 2K ohm headset supplied into the HEADSET-2K jack. Do NOT use a low impedance headset (it simply won't work). The headset is worn with the gray stethoscope tube under the chin and the sound output holes facing slightly forward (roughly 30 degrees) or with the ear hook. Turn the unit ON and place the TONE/AUDIO switch in the TONE position. Zero the Meter with the ZERO SET control at the top of the unit. press the + BATTERY Test button. The meter will swing to the right and a reading in excess of + .8 indicates satisfactory battery conditions Pressing the - button causes the meter to swing to the left and again, a reading in excess of - .8 indicates a satisfactory battery condition.

Pass the antennas over the test areas If a source is located, the Meter will swing in the direction of the source and pass through zero when the source is perpendicular to the two antennas. Since the tone heard through the headset has a pitch proportional to the meter readings it is not necessary to observe the meter while searching for the source.

The lowest pitch tone indicator zero and the tone increases in pitch on either side of zero. The RF head can be extended with the extension handles and cable. Plug the cable BNC connector into the BNC jack at the bottom of the RF head. Plug the mini-plug into the jack located to the left of the BNC plug on the amplifier/indicator assembly.

The 2055HA say also be used as a single antenna RF detector by removing the left antenna and zeroing the unit. The meter will swing only to the right when a source is located If the meter goes beyond full scale to the right, the zero may be suppressed to the left of center as required. The TONE/AUDIO switch causes either a tone proportional to the meter reading (TONE) or demodulated AM audio (AUDIO) to occur at the headset. the DC output of the op-amp is accessible through the RECORDER jack. This output is designed to drive a strip chart recorder.

Should either battery become weak (i.e. below .8), replace both batteries by removing the top and bottom screws from the amplifier/ indicator assembly and carefully lifting off the back cover. Alkaline batteries are always preferred. While the back cover is off, note the three screw-driver adjust potentiometers The one in the upper center above the upper integrated circuit is the rough zero. The control to the right (as viewed from the back) of the integrated circuit is the gain control, The control below and slightly to the right of the gain control is the base tone adjustments To re-enter the position of the ZERO SET control, set that control to mid-range and adjust the rough zero control for zero indication on the Deter. To adjust the base tone, zero the meter and set this control for a tone output of roughly 5 to 20 Hz. As with any piece of electronic equipment, remove the batteries during periods of prolonged storage.

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