RAN Technology

W9RAN Field Radio

Technical 0 Comments 05/11/2019 

Vintage light aircraft radios repurposed

Posted By: Robert Nickels (ranickels)

In the early days of aviation radio, transmissions originated from the ground using the longwave transmitter also used for homing,  and pilots acknowledged by wagging their wings.  It didn't take long to realize the benefits of having transmitting capability onboard the plane as well, and the first generation of aircraft radio used the low HF band.    Given today's crowded airspace it is hard to imagine every aircraft sharing the same frequency - 3105 kHz - to talk to the tower while still listening for replied on the longwave band.   For light aircraft, power output seldom exceeded a few watts, which with a fairly inefficient loaded longwire antenna meant a limited range, but that was sufficient.   Airlines and those flying longer distances drew power from a vibrator supply or even a dynamotor, but the most common setup used A and B batteries, just like some home radios still did, which were readily available.   

I acquired this near-mint set at the Cedar Rapids hamfest last summer.  The Ranger model 210 transmitter could put out 2 watts from it's battery pack power supply on either 3105 or by doubling, 6210 kHz which was the alternate frequency for daytime use.   The model 117 reciever also ran from batteries and tuned the radio range band, 200 to 400 kHz to hear transmissions from the tower, weather, and homing beacons.    A RAN Technology converter brings the 75 meter band down so the LF band receiver can be used as a tunable IF and a 5 watt audio amplifier provides loudspeaker volume instead of requring headphones.   Instant heating 1.5 volt battery tubes are used in both transmitter and receiver, along with a boost-type DC-DC converter to produce the 150 volts B+ instead of B batteries.  A previous owner had rewired the units for self-bias to eliminate the need for a C battery as originally required.    The battery pack would have  fit into a small box and carried onboard and replaced when necessary (hopefully before going dead during a flight!)    The transmitter uses a carbon microphone and is crystal controlled on 3885 kHz, with 2 watts output.  The normal airplane antenna would have been a longwire running to the tail with a loading coil resonator, but provision was made for a trailing wire antenna as well.   The receiver would have had it's own low-frequency antenna for flying the radio range and receiving the tower. 

I decided the pair would make a neat 75 meter AM Field Radio, and fitted them into a custom made plywood box that could be easily transported (to places like the Dayton Hamvention, for the WWII military radio net).   The removable lid has a 5" speaker and a storage compartment on the rear allows storage of the mic and Li-Ion battery pack.

Listen to a bit of K5UJ calling CQ as a receiving test:  Listen

The Ranger was an obscure manufacturer but big names including GE,  Lear,  Raytheon, Bendix, Philco,  RCA, and Motorola produced similar radios.   Most recognizable after WWII was the Aircraft Radio Corp., producers of the wartime "Command Sets".   A portable lightplane radio like this was often used when the ferry pilots (often women) flew the warbirds from the aircraft plant to a nearby base where the command sets and other radio equipment would be installed.   Having seen the RCA AVT-112/AVR-20 packaged in a wooden case for this purpose was the inspiration for making my own version.

I was fortunate to receive both manuals with my Rangers, but with a little effort the schematic and interconnections for most of these simpler aircraft radios can be figured out and it is a lot of fun to put such a cool piece of vintage radio equipment back on the air in a useful way.

   EFJ transmitter sales data from former employees....  READ MORE
- Robert Nickels (ranickels),  09/16/2020 
   Like most hams, I remembered seeing the FPM-200 at an astronomical price in the 1962 Allied Radio catalog and wondering just how rich would a person have to be to own one?    For my 11 year old self, such things may as well have been on another planet, but well...things change.I'd seen only one FPM-200 sold (to a guy ahead of me at a hamfest) and in the pre-eBay era most rare ra...  READ MORE
- Robert Nickels (ranickels),  09/12/2020 

why 50 ohms?

The Forgotten Impedance
Category: Technical
 Why do we use 50 ohm cables?    If you're like most hams the answer is:  "I dunno!"In fact, it's a compromise (like most things in life) - between lowest loss when handling power and voltage breakdown, as Belden engineer Steve Lampen explains hereA pdf copy can be found below as well.   And now you know!...  READ MORE
- Robert Nickels (ranickels),  09/06/2020 

"Crystal Plugs"

DIY version by "RAN Crystals"
Category: Crystal Replacement
Crystal sockets were popular for pluging in ... crystals, of all things!   But they were also used for other purposes, such as the antenna relay connection on some EF Johnson transmitters.    If you want to connect a VFO to a transmitter with just a crystal socket, for example, you're going to have to either carve up an old FT-243 type crystal or if you want to outboar...  READ MORE
- Robert Nickels (ranickels),  09/01/2020 

A visit to the D J Everett III Radio Room

Honoring the legacy of a small town radio station owner
Category: Historic
Many successful career people are grateful for mentoring they received on the way to the top. But few have honored a memory as passionately as has been done by Beth Mann.   She's the owner of Ham Broadcasting which owns five stations in western Kentucky but the story is about her mentor, the late DJ Everett III who started WKDZ in Cadiz Kentucky in 1966.   Everett worked as...  READ MORE
- Robert Nickels (ranickels),  08/14/2020 
   Bob Heil's favorite radio is the Moseley CM-1 which the developer, John Clemmons, told Carl Moseley stood for Clemens Manufacturing number 1.   "No", Mr. Moseley said, "That stands for Carl Moseley number 1!"As that may be, there's yet another CM-1 receiver and it was made by the Multi Products Company of Oak Park, Michigan.As wikipedia states:  "CON...  READ MORE
- Robert Nickels (ranickels),  08/13/2020 
    Jay Miller KK5IM recently wrote an article in Electric Radio magazine about fulfilling his dream of building a homebrew "AM Kilowatt" transmitter (375 watts output by today's standards).     His crystal-controlled exciter that drive the 813 was based on his Novice transmitter, which was built by his grand-uncle back in the 1960s when Novice class hams were l...  READ MORE
- Robert Nickels (ranickels),  07/09/2020 

Bias control of Class E amplfiers

Previously undocumented phenomenon
Category: Technical
Micro SDR innovator Guido PE1NNZ has implemented polar modulation using an Arduino MCU and a class E PA.   For more informartion on this fascinating project, join the discussion group at https://groups.io/g/ucxInitially, Guido's design implemented the polar or EER modulation scheme using modifications to the QCX CW transceiver hardware in the traditional way as described by Leonard K...  READ MORE
- Robert Nickels (ranickels),  06/20/2020 
    I'm always intrigued by the odd and unusual ham gear that I remember seeing in catalogs as a kid but have seldom seen after hundreds of hamfests and uncountable for sale listings.   One such is the Lysco mobile transmitter which was produced by the Lysco Manufacturing Company of 1401 Clinton St. Hoboken NJ between 1949 and 1953.   Despite being a very cute and co...  READ MORE
- Robert Nickels (ranickels),  06/06/2020 

Class E Notes

the result of experiments with high efficiency class E amplifiers
Category: Technical
 There is a lot of misunderstanding about how a Class E amplifier works.     As the result of studying the literature and experimenting, I thought I'd share what I have learned over the past several years.   Below is an example of a test amplifier I used to optimize my 2 watt wspr transmitter boards.   It can be visualized as two circuits - the...  READ MORE
- Robert Nickels (ranickels),  06/06/2020 

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