[ARC5] Type 185 Radio Receiver?

[Mike Morrow]

Tim wrote:

> I'm guessing a portable NDB Nav receiver...

It certainly was NOT a Non-Directional Beacon (NDB) receiver.  For navigation, a non-directional beacon requires a directional receiver on the aircraft, and a non-directional receiver on the aircraft requires a directional beacon on the ground.

NDBs have no value to navigation unless the aircraft has some sort of radio direction finder on board.  An RDF or ADF set would be very unlikely on any aircraft using one of these simple battery-powered beacon receivers.  Those were designed to work with LF/MF Four-Course A-N Adcock Directional Beacons, nicely described here:

 https://en.wikipedia.org/wiki/Low-frequency_radio_range

These range beacons established the airways in use nationwide.  A pilot could tell if he were flying on one of the four beams to the beacon by flying a course that created a continuous 1020 Hz tone in his earphone.  If he was off the beam either A or N would be heard.  These beacons established the directional information on four beams separated by approximately 90 degrees that were transmitted from the beacon site.  The simple non-directional aircraft receiver conveyed this directional information using ONLY audible A-N-Continuous tone signals.  Most US Adcock DBs were converted to NDBs by the early 1960s as VOR navigation became universal.

In its prime, the simple beacon band receiver was the most useful radio set on any aircraft that carried radio.  The pilot could fly directional ranges, listen for airport tower information on frequencies like 278 kHz, and get weather and other information broadcast on these LF/MF frequencies.  That's why there were so many such non-directional receivers made from the early 1930s through the late 1950s.

So, the Type 185 was designed to provide the pilot with audible navigation information from Directional Beacons, not NDBs.

Mike / KK5F