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.

   Some pieces of vintage ham gear are not really unique, but are so rare as to almost never be seen.   The Multi Elmac PS-500 power supply is an example, it was sold as an AC power supply for the A54 and A54H transmitters in the mid-50s. There's nothing special about it - just a big transformer with 5 volt rectifier, 6.3 volt filament, and 500 volt secondaries.  Two nice chok...  READ MORE
- Robert Nickels (ranickels),  11/14/2019 

My experience with the Nouveau 75

a new AM QRP transceiver from the 4SQRP group
Category: Technical
Mini-review of the Nouveau 75 by W9RANI like it, warts and all!OK, maybe not quite that "mini"...here's a few of my impressions of this innovative kit from the 4 State QRP Group.I've been interested in amplitude modulation of a class E PA for some time and after Dave Cripe said to stay tuned for the next 4SQRP offering, I wasn't too surprised to see what it was, and bought on...  READ MORE
- Robert Nickels (ranickels),  11/12/2019 
   International Crystal Company of Oklahoma City was certainly best known for its crystals but the company was also a not-insignificant player in the CB radio manufacturing business, and also had a pretty extensive line of experimenter kits.   The kits typically had one to three tubes on a PC board and provided a single function, such as an RF amplifier, or transmitter, although some were ...  READ MORE
- Robert Nickels (ranickels),  08/02/2019 
   Equipment manuals and handbooks of the 1950s and 60s were filled with complex oscilloscope screens and discussion of ripple and as a result proper alignment of a phasing rig eluded most hams.    But a clever New Zealand ham, Fred Johnson ZL2AMJ was able to see what everyone else had missed, and published a short note in the NZ ham magazine in 1972 that makes the process simple and r...  READ MORE
- Robert Nickels (ranickels),  07/20/2019 
    Finding myself in need of a tool to remove a bad bearing on a blower from a linear amplifier I first tried the usual automotive type gear puller but it wasn't able to get underneath this small 5/8" OD bearing.   So I improvised a tool that took 10 minutes to make, cost a few cents, and had the job done in no time at allThe secret is wedges sold at the home improvement stor...  READ MORE
- Robert Nickels (ranickels),  07/16/2019 
   Watch the video  trailer for the 2019 monster movie that relies on a 1950s vintage Hammarlund SP-600 and Collins 30L-1 amplifier....  READ MORE
- Robert Nickels (ranickels),  04/20/2019 
   I find the show-biz association of the founder of Allied Radio, Simon Wexler, to be rather fascinating.  What started out as a supplier of crystal set parts led to a family that became a major force in the entertainment industry and in Chicago business...including many recognizable names:"Allied Radio (now known as Allied Electronics) is a company with a long history. On August 6, 1...  READ MORE
- Robert Nickels (ranickels),  04/14/2019 

Hazard E. Reeves - audio pioneer and defense contractor

Making crystals in midtown Manhattan during WWII
Category: Historic
 Hazard E. Reeves (1906-1986) may not be a household name, but his work is well known to every moviegoer.   He was an American pioneer in sound and sound electronics, and introduced stereophonic sound for motion pictures. He met Fred Waller at the 1939 World's Fair and saw the potential of Waller's "Vitarama" system which he invested in and which soon became the mo...  READ MORE
- BRADLEY STONE (NB9M),  04/12/2019 
    In his book "In Touch with Leo", the success and growing backlog of CB-100 orders is what drove Leo to his banker, Lou Ross, who asked him why he didn't anticipate the number of orders and required capital.  Leo responded "Lou, never on God's green earth could I have believed such an influx of orders!".    More funding was needed than the bank ...  READ MORE
- Robert Nickels (ranickels),  03/18/2019 

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