I recently picked up a Mitchell Airboy Sr aviation radio, marked
Navigation Receiver and Trans
Model No. AT-92-50
Mfg by Mitchell Industries Inc
Mineral Wells, Texas

It's a small, lightweight red box about 6" by 4" by 4" with a carrying handle on top. Front panel is chrome, black and white. This is a late 40's design with a tunable 4-tube superhet receiver covering the 200-400 kHz beacon band, and the .55 - 1.5 MHz AM broadcast band. The transmitter section has two tubes and is crystal controlled (it came with crystals for 122.1 and 122.5 MHz); apparently the final amplifier is plate modulated by a carbon microphone which plugs into the front panel. The whole rig is powered by 2 "D"
flashlight batteries and 2 67.5 volt "B" batteries.

It's such a strange and cute radio that I'd like to
find out more about it.
Also, it intrigues me that the Airboy transmits on VHF while its receiver only covers the low-frequency beacon band ... is it true that right after WWII a private pilot could call the tower on VHF and listen for a reply on a lf beacon frequency?

Thanks for any help you can provide.

Marco Casagrande (I0YAZ)
Rome-Italy

:I recently picked up a Mitchell Airboy Sr aviation radio, marked
:Navigation Receiver and Trans
:Model No. AT-92-50
:Mfg by Mitchell Industries Inc
:Mineral Wells, Texas
:
:It's a small, lightweight red box about 6" by 4" by 4" with a carrying handle on top. Front panel is chrome, black and white. This is a late 40's design with a tunable 4-tube superhet receiver covering the 200-400 kHz beacon band, and the .55 - 1.5 MHz AM broadcast band. The transmitter section has two tubes and is crystal controlled (it came with crystals for 122.1 and 122.5 MHz); apparently the final amplifier is plate modulated by a carbon microphone which plugs into the front panel. The whole rig is powered by 2 "D"
:flashlight batteries and 2 67.5 volt "B" batteries.
:
:It's such a strange and cute radio that I'd like to
:find out more about it.
:Also, it intrigues me that the Airboy transmits on VHF while its receiver only covers the low-frequency beacon band ... is it true that right after WWII a private pilot could call the tower on VHF and listen for a reply on a lf beacon frequency?
:
:Thanks for any help you can provide.
:
:Marco Casagrande (I0YAZ)
:Rome-Italy
:

That's exactly how it worked in the very early day's of aircraft radio. Listening was done on 278 KC. and before VHF transmitters the radio transmitted on 3105 KC and again listened on 278.

::I recently picked up a Mitchell Airboy Sr aviation radio, marked
::Navigation Receiver and Trans
::Model No. AT-92-50
::Mfg by Mitchell Industries Inc
::Mineral Wells, Texas
::
::It's a small, lightweight red box about 6" by 4" by 4" with a carrying handle on top. Front panel is chrome, black and white. This is a late 40's design with a tunable 4-tube superhet receiver covering the 200-400 kHz beacon band, and the .55 - 1.5 MHz AM broadcast band. The transmitter section has two tubes and is crystal controlled (it came with crystals for 122.1 and 122.5 MHz); apparently the final amplifier is plate modulated by a carbon microphone which plugs into the front panel. The whole rig is powered by 2 "D"
::flashlight batteries and 2 67.5 volt "B" batteries.
::
::It's such a strange and cute radio that I'd like to
::find out more about it.
::Also, it intrigues me that the Airboy transmits on VHF while its receiver only covers the low-frequency beacon band ... is it true that right after WWII a private pilot could call the tower on VHF and listen for a reply on a lf beacon frequency?
::
::Thanks for any help you can provide.
::
::Marco Casagrande (I0YAZ)
::Rome-Italy
::
:

::I recently picked up a Mitchell Airboy Sr aviation radio, marked
::Navigation Receiver and Trans
::Model No. AT-92-50
::Mfg by Mitchell Industries Inc
::Mineral Wells, Texas
::
::It's a small, lightweight red box about 6" by 4" by 4" with a carrying handle on top. Front panel is chrome, black and white. This is a late 40's design with a tunable 4-tube superhet receiver covering the 200-400 kHz beacon band, and the .55 - 1.5 MHz AM broadcast band. The transmitter section has two tubes and is crystal controlled (it came with crystals for 122.1 and 122.5 MHz); apparently the final amplifier is plate modulated by a carbon microphone which plugs into the front panel. The whole rig is powered by 2 "D"
::flashlight batteries and 2 67.5 volt "B" batteries.
::
::It's such a strange and cute radio that I'd like to
::find out more about it.
::Also, it intrigues me that the Airboy transmits on VHF while its receiver only covers the low-frequency beacon band ... is it true that right after WWII a private pilot could call the tower on VHF and listen for a reply on a lf beacon frequency?
::
::Thanks for any help you can provide.
::
::Marco Casagrande (I0YAZ)
::Rome-Italy
::
:
Very true. For many years after WWII, the Low frequency navigation system continue to function while the VHF Omni directional systems were being built and taking over more air routes. Many fields had a LF navigation system and a pilot could recieve on LF and transmit on AM VHF. The old saying was one for the run and five for hive. Meaning 121.1 was airway frequency and 121.5 was a standard tower frequency. Both were monitored by towers and traffic centers.

::I recently picked up a Mitchell Airboy Sr aviation radio, marked
::Navigation Receiver and Trans
::Model No. AT-92-50
::Mfg by Mitchell Industries Inc
::Mineral Wells, Texas
::
::It's a small, lightweight red box about 6" by 4" by 4" with a carrying handle on top. Front panel is chrome, black and white. This is a late 40's design with a tunable 4-tube superhet receiver covering the 200-400 kHz beacon band, and the .55 - 1.5 MHz AM broadcast band. The transmitter section has two tubes and is crystal controlled (it came with crystals for 122.1 and 122.5 MHz); apparently the final amplifier is plate modulated by a carbon microphone which plugs into the front panel. The whole rig is powered by 2 "D"
::flashlight batteries and 2 67.5 volt "B" batteries.
::
::It's such a strange and cute radio that I'd like to
::find out more about it.
::Also, it intrigues me that the Airboy transmits on VHF while its receiver only covers the low-frequency beacon band ... is it true that right after WWII a private pilot could call the tower on VHF and listen for a reply on a lf beacon frequency?
::
::Thanks for any help you can provide.
::
::Marco Casagrande (I0YAZ)
::Rome-Italy
::
:
Very true. For many years after WWII, the Low frequency navigation system continue to function while the VHF Omni directional systems were being built and taking over more air routes. Many fields had a LF navigation system and a pilot could recieve on LF and transmit on AM VHF. The old saying was one for the run and five for hive. Meaning 121.1 was airway frequency and 121.5 was a standard tower frequency. Both were monitored by towers and traffic centers.