RAN Technology

WWII Command Set radio checkout in a P-47 Thunderbolt


Ham Radio Information 0 Comments 02/18/2019

Radio Mechanic Jones...bring your screwdriver, you have a lot of Dzus fasteners in your future!

Posted By: Robert Nickels (ranickels)
Post Date: 02/18/2019

PREFLIGHT RADIO INSPECTION FOR FIGHTER AIRCRAFT is a WWII film made for newbie Army Air Force Radio Mechanics. The film shows a P-47 Thunderbolt's SCR274 radio being checked out on the ground, part of the routine pre-flight for any fighter aircraft. What's really interesting about it, is that the film really goes into great detail on the inspection including showing the various forms that would be filled in during a check, and the entire process by which planes were approved for flight by radiomen. The various steps of check out are shown, with examination of the receivers, transmitters, headsets, and even making sure that the instruction book is in place.    The film shows a complete inspection and operational checkout of the SCR274 "Command Set" radio including all LF and HF radios, antenna, and modulator.

At the 10 minute mark the film switches from focusing on the SCR274 to an aircraft equipped with an SCR-522, which can provide two-way radio-telephone communication between aircraft in flight and between aircraft and ground stations. At the 13:00 mark, a P-38 Lightning is checked out. This aircraft has a SCR-522 on board, with the radio set behind the pilot. An early model P-51 is shown with an SCR274 at the 13:20 mark. Operation of the SCR-522 may take place on any one of four crystal-controlled channels lying within the frequency range of 100 to 156 megacycles. Remote control only is provided. Radio set SCR-522 operates from a 28-volt source and uses dynamotor PE-94-A ; radio set SCR-542 operates from a 14-volt source and uses dynamotor PE-98- A. Radio sets SCR-522 and SCR-542 differ only in the primary power supply voltage and the dynamotor unit used.

If you've never seen how these famous radios were actually installed, this is a must-see!  And make sure a copy of the instruction manual is onboard, just in case...


    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 
  

Spectral Purity using Epson Programmable Oscillators

Do harmonics matter if there's no way for them to be heard?
Category: Crystal Replacement
 In the 5 or so years I've been using the Epson oscillators I've looked at the spectral output many times.   Without a doubt the harmonic output from the Epson oscillator is high as would be expected  from a square wave device.   The question to me has always been "does it matter"?PLL controlled digital oscillators have long been used as LOs in recei...  READ MORE
- Robert Nickels (ranickels),  03/12/2019 
  

The Foxhole Radio

aka "Razor Blade and Safety Pin Radio"...from the Boy's Fun Book
Category: Vintage Radio
 When I was a kid, my dad gave me a thin hardcover book called "Boys Fun Book - Things to Make and Do".   It was printed during WWII on very thin paper as a wartime conservation measure, but was chock-full of interesting projects, ranging from hobbies and magic tricks to sports, puzzles, camping...and the chapter I was drawn to:  "Unusual Radios You Can Build You...  READ MORE
- Robert Nickels (ranickels),  03/08/2019 
   As anyone who likes building radios knows, it's getting harder and harder to buy RF components.   One of the last casualties was the 3-section pi-wound RF chokes made by Hammond, a company that has done more than most to support the vintage radio and audio hobbies.    The Toko variable inductors long favored by QRP enthuisiasts have become all but unavailable, and vari...  READ MORE
- Robert Nickels (ranickels),  03/02/2019 
   The following obituary appeared in the Freeport Journal-Standard on Febr. 9, 2019.      I attended a lecture by Mr. Anderson in the late 1990s after moving to Freeport and working for Honeywell where despite being a supplier to DEC, few realized the local connection existed to the founder of what once was the second-largest computer company in the world.   Mr. Anderso...  READ MORE
- Robert Nickels (ranickels),  02/09/2019 
  

The Case of the Phantom Voltage

“When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.”
Category: Technical
A Heathkit HW-12 gave me a troubleshooting challenge the likes of which I've not seen before - or even heard of!A few days ago the transmitter wouldn't produce output, and in checking voltages and I measured -75 volts on the ALC line which should be -20.   But it corrected itself and I figured it must have been a solder splash or something that cleared by itself.  That theor...  READ MORE
- Robert Nickels (ranickels),  02/08/2019 
  

The Solvay Conference, 1927

The Smartest Photograph Ever Take
Category: Historic
The Solvay Conference, founded by the Belgian industrialist Ernest Solvay in 1912, was considered a turning point in the world of physics. Located in Brussels, the conferences were devoted to outstanding preeminent open problems in both physics and chemistry. The most famous conference was the October 1927 Fifth Solvay International Conference on Electrons and Photons, where the world’s most...  READ MORE
- Robert Nickels (ranickels),  12/27/2018 
   Put yourself in 1963...A stamp was a nickel, bread was 22 cents a loaf, and you could buy 3 gallons of gas for a buck.   The average wage in the US was $84 a week.  If you were a ham, you might have been able to build and trade your way up to a really nice AM/CW station - maybe a Valiant or DX-100 transmitter with an NC-300 or HQ-170 receiver - a huge improvement over the S-38 you s...  READ MORE
- Robert Nickels (ranickels),  12/17/2018 
  

Astro...Don Stoner's legacy

How many of these rare transceivers have you seen?
Category: Vintage Ham Radio
A recent post on the Cubic-Astro mail reflector noted the similarities between the rare CIR Astro 200 and the much more common Cubic Astro 150 transceivers.   And therein lies an  interesting story...I have done a little research on the CIR Astro 200, and the commenter was right - it is the progenitor of the Astro line we are much more familiar with as a result of Swan (already owne...  READ MORE
- Robert Nickels (ranickels),  12/09/2018 
  

The DX-60 Family

what hath Benton Harbor wrought?
Category: Vintage Ham Radio
When an engineer at Heathkit in 1962 turned his attention to designing a replacement for the somewhat flawed DX-40 novice transmitter, little would he have expected the DX-60 to remain in the Heathkit catalog for 14 years.    From the new solid-state power supply to the streamlined apeperance and dependable performace, the new transmitter was instantly popular with novices who had t...  READ MORE
- Robert Nickels (ranickels),  12/09/2018 

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