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The device was used for navigation, but also for locating miniature
transmitters, such as the ones used for the detection of schools of tuna fish.
The device is housed in a heavy metal enclosure – common for most
OAR direction finders – and is suitable for the
reception of up to 10 crystal-controlled channels between 26 and 28 MHz.
A fairly large loop antenna – constructed from two perpendicular loops –
should be mounted outside, for example in a mast on the deck of a ship,
or on the hull of an airplane. The direction to the transmitter was
shown on a CRT display.
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The ADF-210 could also be mounted within a vehicle, for use on land.
In the Netherlands, for example, it was used in the early 1970s
by the Radio Monitoring Service (RCD)
for locating illegal transmitters
in the 11 metre CB-band, which was prohibited in the Netherlands.
The major drawback
of the ADF-210 however, was that it only had room for 10 channels,
whilst CB radios typically had 23 channels, or 28 if the so-called
A- or Alpha-channels were counted as well.
It was replaced a few years later by the ADF-928, which covered
the original 28 channels of the 27 MHz CB band in AM, and finally –
in the mid-1970s – by the more versatile ADF-940,
which had a scanner and covered all 40 channels of the expanded 27 MHz
(CB) band in AM and FM.
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The following models of the OAR ADF direction finder are known.
Note that the 900-range was probably reserved for specials
and that the last two digits indicate the number of channels.
No information about these variants is publicly available at the moment.
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At the time, the CB-band consisted of 23 AM-modulated channels, plus
five so-called A-channels or alpha-channels that were used
for radio controlled models [7].
➤ Wikipedia
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© Crypto Museum. Created: Thursday 17 December 2020. Last changed: Thursday, 17 December 2020 - 21:13 CET.
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