Detailed write-up on this version of the Super Pro SP-600 that tunes from 540kc down to 10kc. Circuit description, operation, performance using both loop antenna or long wire antenna. Details on maintaining the SP-600-VLF including the how to fix the infamous "slipping" tuning dial (works for the HF SP-600 too.) The unusable Hammarlund manual is critically reviewed and concludes that the manual's alignment procedure was never used by commercial technicians for SP-600-VLF alignment. Instead, a new complete alignment procedure is presented that follows a conventional and easy approach to performing a sweep alignment of the SP-600-VLF's IF section with full details and photos showing the oscilloscope images. 2022 NDB log and now a 2024-25 NDB log. I've owned and used my SP-600-VLF for over a decade so there's lots and lots of detailed information presented with lots of photos.
 

Comprehensive history of this "ultra-rare" US Navy 1933 TRF with Tracking BFO Long Wave Receiver. History of the Hygrade Sylvania Corporation. This article is in a journal format that documents the restoration process. Challenges included a severely damaged chassis and a major bend of the front panel. Equally challenging was the total lack of documentation, no schematic, no manual. Lots of photos show how the project progressed from a non-functional derelict into a fully operational LW receiver. Reception Test Logs. Comparison of the RAG versus the RAK receiver. Write up on the CHS-20032 Power Unit and getting it to actually power up the RAG-1.
 

Navy Department-RCA  -  RAA-3 - Shipboard Long Wave Superheterodyne Receiver from 1935

Comprehensive history of the U.S. Navy's first superheterodyne long wave receiver. Includes a comprehensive history of the origins of RCA and their relationship with the US Navy. Also, origins of Radiomarine Corp, RCA Manufacturing Company, Inc and RCA-Victor. Continuing Restoration of RAA-3 SN: 64 - a journal-type write-up of the "ground-up" restoration of this behemoth of a Navy receiver. Weighing 465 pounds and comprising three individual sections, this ultra-rare receiver was stored outside, wrapped in a tarp. A real restoration challenge that's still on-going. Lots of photos.
 

Expanded and rewritten in 2024, the new SP-600 write-up contains all of the old "Rebuilding the SP-600" information but now there's much more information. New sections include the History of the design, Circuit description, Manual overview, a 2024 newly written Sweep IF Alignment procedure (since the manual's sweep alignment only consists of two sentences,) 2024 "Revisit to the Bench" for a SP-600JX-21 that includes a front panel repaint. 46 photographs are now in this write-up. Also, the old (and now rewritten) sections for Overview of the task, Rebuilding the RF Platform, Replacing Capacitors in IF, Xtal Osc, Conversion Osc, Chassis, Miscellaneous Electronic Work, Rebuilding the Carrier Level/Audio Level Meter, Cosmetic Restoration, Panel, Cabinet, Alignment, Expected Performance, Collector Gallery Photos, Lots of photos

Comprehensive look at the entire series of 32V transmitters. Includes 32V-1, 32V-2 and 32V-3 plus descriptions of early and late production variations. Operational idiosyncrasies and mechanical complexities. 32V-2 Pi-L network problems and solutions. Is the 32V-3 the best of the lot? Details on how to remove the 32V series front panels (it's more complicated than you'd think,) rebuilding the MC slide rule dial assembly with lots of photos. Restoration write-ups on the 32V-1, 32V-2 and the 32V-3. Lots of photos and information.
 

Just a little history and just a few circuit descriptions. This write-up is mostly about KWS-1 SN:616 and 75A-4 SN:850, a pair that I've owned since 1970 and how I've kept them running for over half-a-century. The KWS-1 SN:616 section has RTTY operations, AM operations, Frequency Drift, 80M oscillation and other information. The 75A-4 section covers the SN:850 refurbishment that discovered problems that had been in the receiver circuitry for 50+ years. A short description of working on the 4:1 reduction knob. Additionally, 75A-4 SN:4470, a 1990s find, is covered in a refurbishment that only required a few things. Collins Service Bulletins, non-Collins mods from the 1970s and other mayhem. Lots of photos and information.
 

Comprehensive look at all of the different receivers that comprise the 51J Series, including the 51J-1, 51J-2, 51J-3, 51J-4 and the R-388/URR. Production history, variations, circuit changes, alignments and more. Details on some of the rare variants in the 51J Series. Info on the 51J-5 receiver. Info on the 51S-1 receiver. The 354A-1 Mechanical Filter Kit. Detailed info on the Beckman/Berkeley Frequency Measuring System that used the 51J-4 receiver. Lots of photos of different light-gray panel 51J-4 "Lab Receivers" and info on the "Collins Fix" for the 51J-4 6kc mechanical filter audio. Detailed rebuilding information on the 51J-2, R-388 and 51J-4. 70E-15 "M" PTO suggestions and link to Bill Orr's 1969 Ham Radio magazine article on the R-388 PTO. Lots of photos and information.

Part One - Detailed profiles on each 51J model, including the many variations, Beckman versions, Laboratory Light-gray Panel versions, Collins and Military Cabinets

Part Two - "Oddities" in the 51J Series, 70E-15 "M" and "CR" details, BFO Inversions, Loudspeakers, How Collins Radio and the 51J were responsible for the RACAL RA-17, General rebuilding info, Common problems, Providing Break-in, Fixing the 70E-15 "M" PTO, Rebuilding write-ups on the 51J-2 and a Basket Case R-388 receiver.

Part Three - Detailing a R-388 installed in a CY-1206/G Receiver Case, Refurbishing a Collins Lab Light-Gray Panel 51J-4, Rebuilding a R-388 with vintage installation of the 354A-1 Mechanical Filter Kit, Restoring the 51J-1
 

Comprehensive write-up on Radio Engineer Glenn Browning's 1935 design of a relatively easy-to-build, seven or eight tube, bandswitching, hams-bands only, superheterodyne receiver kit. Details on the 1935 Browning 35 general coverage short wave receiver version, the TOBE Amateur Communication Receiver version and the 1936 TOBE SPECIAL version. History of Radio Kits from 1920s to 1960s. Problems only found in kit-built electronic devices. Biographies of Glenn Browning and Tobe Deutschmann. Two very long restoration write-ups (OCD type) on the TOBE SPECIAL, an eight tube receiver using all metal octal tube and air trimmers that was in just about the best state of preservation possible. And, on the TOBE Amateur Communication Receiver, a seven tube receiver using all glass tubes that was almost totally destroyed by a history of endless repairs and modifications. Lots of restoration details and photographs. Post-restoration performance comparisons. Lots of photographs - over 40 photos.
 

Detailed write-up on Austin A. Howard's Howard Radio Company of Chicago. The Howard company history involved not only Austin Howard but also McMurdo Silver, Bill Halligan and many others. Six Howard-built Ham Receivers are profiled in this write-up. The large Howard 450A Communication Receiver is one of Howard's most elaborate receivers and certainly has an impressive "bench presence." Full restoration on the 450A. The Silvertone 5656A Communication Receiver is another impressive receiver built by Howard Radio for Sears-Roebuck. Full restoration on the 5656A. Also, the Silvertone 5752 STANDBY and the Howard 437A. Then,...the surprise,...the Hallicrafters SX-9 and Hallicrafters 5-T, both built in 1935 by Howard Radio when Hallicrafters still had to have their radios built by contractors. Full story on that. Lots of photos.
 

Patterson Radio Company - PR-10 Receiver & PR-10 Preselector

Comprehensive history of Patterson Radio Company and 1930s Los Angeles radio manufacturing. Detailed circuit analysis, red-lined corrected schematic, frequency calibration chart (so you know where your PR-10 is tuned.) Restoration details on Velvet Tuning rebuild and more. Collector Photo Gallery. Lots of photos and information.
 

Signal Corps R-274  Hallicrafters' "Super Pro" Receiver

Comprehensive history of Hallicrafters' Super Pro, the R-274 receiver, circuit description, performance analysis, detailed comparison between the R-274 and the Hammarlund SP-600, pros and cons of each receiver. You can VOTE for your favorite "Super Pro" - either Hallicrafters' or Hammarlund's. Voting results are shown (you might be surprised at the results.) Lots of photos and information.
 

Comprehensive history of RACAL Engineering Ltd (and the various other names the company was known by.) The RA-17 and the Wadley Loop, RA-17 versions (over 40 different versions,) the RA-117 design, RA-117 versions (a lot of them,) the RA-6117 (made in the USA,) the RA-6217 RACAL's first Solid-State receiver. Adding remote standby to the RA-6117, How to set correct power transformer primary voltage, Receiver performance. RA-237-B Low Frequency Converter set up and operation with the RA-17C-12 receiver. Performance and NDB reception log. Lots of photos (Ray Brown, Jock Cunningham, Dr. Trevor Wadley, Ernest Harrison) and lots of information.

Profiling the Viking 1 transmitter kit with detailed refurbishment with lots of photos, includes details on Johnson Mod B for significant improvement in audio and modulation for the transmitter. The Ranger and the Desk KW are older write-ups that I've updated, edited and expanded. Details on the KW Matchbox. A detailed article on how to install a Viking Ranger Meter into a Viking Navigator and get rid of that worthless original iron vane meter that was never accurate and was constantly banging the needle against the stops. The Viking Ranger meter doesn't just "drop in" but the installation is shown with details and the end result is,...The Viking Navigator Deluxe.  

Comprehensive history of how the famous U.S. Navy RAO receiver that was built by National Company Inc. and by Wells Gardner & Co. developed from National's "Moving Coil" receivers - better known as "coil catacomb" receivers. Detailed information on each version of the RAO receivers, information on the RAO accessories including details on the USN RCX panoramic adaptor used with the RAO-7. Excruciating OCD details on two RAO restorations, Wells Gardner & Co. RAO-3 and National Company, Inc. RAO-7. Lots of photos and lots of information.  

Comprehensive look at these long-lived receivers and transmitters that were built all through the 1930s by Aircraft Radio Corporation and by Western Electric Company. The RU-16 and GF-11 are the 1941 versions built just before WWII. Details on the circuits used and how the equipment was installed in single-seater aircraft and larger airplanes. Details on all of the ancillary pieces that are necessary for the operation of the receiver alone or both the receiver and transmitter. Section on rebuilding the metal tub capacitors used in both units. Performance details. Lots and lots of photos plus lots of detailed information.

Comprehensive history of the Radio Compass from its beginnings in 1920 up through the 1950s. Detailed look at pre-WWII Airway Navigation and its development. Profiles of "Homing" gear, such as, USN RU-type receivers, USN ARB receivers with the ZB-3 Homing Adapter. Detailed look at Search & Rescue using "True" direction. Profiles of "True" DF gear, such as, USN DZ-2 complete set-up with dual loop compass, Bendix DW-1 amplified loop. Ground-based DF gear profiling the British mobile DF hut B/C DF No.2 with the R106 (HRO,) the elaborate AN/PRD-1 portable DF receiver (used extensively in early part of Vietnam.) Radiomarine Corp. AR-8711, a late-1940s DF receiver for cabin cruisers.

A comprehensive look at the history and the circuit design of this 1940 Aircraft Transmitter. The write-up features a "day-by-day" and "problem by problem" journal that illustrates what's involved in getting a WWII-era aircraft transmitter to the point where it can actually be used "on the air." Detailed information on using a homebrew ART-13 AC Power Supply to power the ATD. Much more detailed information on servicing the ATD Dynamotor for use in powering the ATD with the authentic equipment. Plans on an "easy to build" +28vdc power supply that can provide 80 AMPs of current and only weighs 15 pounds! How to interface the ATD with a linear amplifier to increase the RF power output. Lots of photos.

Producing the GPR-90 receiver wasn't TMCs primary business focus. TMC's output of commercial-military radio electronic equipment was vast,...staggering in the enormous quantity of different equipment they produced. Their one "ham receiver" was the GPR-90 but its "spin-offs" form an impressive collection of commercial-military radio receivers. Covered are the GPR-90 ham receiver and its military versions, then the military-commercial GPR-90RX, GPR-90RXD and the GPR-92. Various accessories, including the GSB-1 SSB adapter for the GPR-90 and the commercial-military MSR-type SSB adapters are covered. Detailed circuit descriptions, a detailed analysis of the Internet reviews of the GPR-90, reworking a GPR-90RXD and its matching MSR-6 SSB adapter. A performance review of the GPR-90RXD operated with the MSR-6. Lots of info and lots of photos. Lots of info and lots of photos.

A detailed look a the British WWII Mobile Radio D.F. Station B/C No.2, a radio hut that was installed on a half-ton trailer and used in the field for locating enemy radio transmitting stations. The write-up profiles the two receivers that were used in the hut, the Reception Set R106, a National Company HRO-M receiver that was British-modified for the installation, and a Reception Set R.107, a British Army Receiver that was also used in the hut. Both Reception Sets have detailed circuit descriptions, individual write-ups on their refurbishment and a performance evaluation. Lots of information and lots of photos.

Full-Length Articles on Rebuilding Vintage Radio Communication Equipment

Rebuilding the R-390A/URR Receivers

Part One - History of the R-390 and R-390A, description of each module and basic rebuilding information, Main Frame, RF Deck, IF Deck, AF Module, PS Module, PTO, Lots of photos

Part Two - Front panel restoration, Meters, Contractor list by year, Alignment Suggestions, Performance expectations, Diversity R-390As, R-390A "Built from Parts," (2) 1967 EAC versions,

Part Three - Restoration & Recreation - detailed restoration/recreation profiles of the Arvin Industries R-725 version, the Army Security Agency R-390A, the Black Panel NSA R-390A, the USMC OD Panel R-390A

Part Four - Restoration of other R-390A family receivers - includes R-389 (LF version,) Refurb of R-648 (Airborne R-390A,) R-392 (GRC-19,) Misc. Info., plus LS-206, Security Dial Cover, CV-979 cabinets
 

Part One - History of the ATC and ART-13, Accessories, Testing Prospective Purchases, Powering the ART-13 with a Dynamotor, PP-1104-C High Current Power Supply details

Part Two - Powering the ART-13 with a homebrew AC Power Supply, Four AC Power Supply Plans with Schematics, Updates to AC power supplies, Mechanical Servicing of the Autotune

Part Four - Refurbishing a Collins ATC that SAAMA MWO'd into ART-13, Operating the ART-13 on the air, Operating on 630 Meters, Details on the CU-32 Low Frequency Loading Coil (tuner), Lots and lots of photos
 

Part One -  Rebuilding and Retrofitting the DM-28 Dynamotor into the Single Ended Tube Versions of the BC-348 (Q, N or J only,) with schematics

Part Two -  Rebuilding and Retrofitting the DM-28 Dynamotor into the Grid Cap Versions of the BC-348 (all other versions,) Retrofitting the DM-24 into the BC-224 versions, with schematics

Part Three -  Performance Expectations for Single Ended and Grid Cap Versions, AC power supply Enhancement with designs and schematics, Wrinkle Finish painting, Duplicating Inspection Stamps
 

Details on getting the T-195 into operation. Includes hints on following the 27 steps shown in the manual that are the "guide" to finding the problems and getting the T-195 operational. Manual glitches are listed. Microphones profiled. R-392 is profiled with general information on operating the receiver "stand-alone" or in conjunction with the T-195 to become the GRC-19. Power supply problems are covered with a link to how to build a +28vdc 80amp power supply that only weighs 15 pounds and operates the GRC-19 with no problems. Lots of info and lots of photos.
 

History of the design, Circuit description, Testing and Repair of the three decks, Testing and Repair of cabinet harness, Powering Up the T-3, Operating the T-3, profile on the BC-939 Antenna Tuner, profile on the SWR Bridge/Watt Meter, Lots of photos
 

Successfully Operating the BC-375 on the Ham Bands Today

Detailed information on how to power the BC-375 to avoid problems that include "FMing," non-symmetrical modulation, low power output and more. How to perform "dynamic neutralization" to eliminate audio distortion due to parasitic oscillations. Interfacing the BC-375 with the BC-348 receiver. Plans for an "Easy to Build" +28vdc 80amp power supply that only weighs 15 pounds. Where to buy "newly built" 211 tubes at a reasonable price. Operating the BC-375 on 630 meters CW. Includes set-up data.
 

Radio Telegraphy and Real Machine RTTY - Photo Galleries

Telegraph Keys 

Part One - Hand Keys, includes Spark Keys, Boston Keys, Early Radio Keys, Leg Keys, Flame-proof Keys, Recently Made Keys, "British-style" Morse, Land Line Telegraph Equipment, Sounders, Keys, Relays, KOBs

Part Two - Semi-Automatic Keys or Bugs, History of Vibroplex showing many early models, Mecograph, ATOZ, J-36 versions, Speed-X Radio Mfg, Speed-X Mfg, Speed-X E.F. Johnson, McElroy Mfg, Buzza, Kenco, Speed Bug, Dow-Key, 73 Bug and more - Learning Tools, records, oscillators, Instructographs

Teletype Corporation Machines - Model 19ASR, Model 28KSR Compact, Model 15KSR, Model 28KSR, WA7YBS RTTY Station, Lots of Terminal Units both Military and Civilian, ITTY - Internet teletype, WA7YBS homebrew TU updates

Radio Equipment from 1909 up to 1960+ - Photo Galleries