AB0CW's Amateur and Antique Radio Page

Welcome to the homepage of AB0CW, Mark B. Dittmar, in Westminster, Colorado.

I have been an amateur radio operator for 25 years. I first got my novice license back in 1977 in Ohio with the call WD8PCE. My main interests in amateur radio revolve around operating, maintaining, and restoring vintage gear, aka "boatanchors", as well as building homebrew equipment, both tube and solid state. I operate 95% HF CW, mostly in the 80 and 40 meter CW portions of the amateur bands. Other radio-related interests include antique broadcast band receivers, early wireless, LF/Part 15 operation , and "natural radio" ( 10 khz and below ). On these pages you will find a bunch of photos of my gear, along with shematics/design info of some of my homebrew stuff, and various commentary/ramblings.

My boatanchors are not particularly "collectible" or rare; they have, however, given me many years of operating enjoyment. I hope you find something here that interests you.

Thanks for checking out my site!

73,

Mark Dittmar, AB0CW

The picture above is a Wireless Specialty Apparatus Co 1/2 kw quenched spark gap transmitter type CR-654A, circa 1917

My Homebrew Vacuum Tube Amateur Radio Equipment ("Glowbugs")

• 1929 MOPA ( Master Oscillator Power Amplifier ) 80 meter transmitter using a pair of 27 triodes to an 865 tetrode
• A 40 meter MOPA transmitter using a '10 triode TNT oscillator driving an 860 PA, from March 1931 QST
• Shunt Fed Hartley Oscillator using a single type 10 triode
• A 6L6 crystal-controlled transmitter for 80 - 30 meter CW
• An 80 meter MOPA transmitter using three 2A5 pentodes
• An 809 RF final amplifier for the 2A5 transmitter
• A battery powered regenerative receiver using three type 30 triodes
• A two tube regenerative receiver using 6SN7 tubes
• The Grimes Inverse Duplex ( see article below and the schematic here   )  picture 1  picture 2  
• Replica Spark Gap Transmitter ( circa 1919 design )
• Westinghouse 861 Power Triode

Pix of other amateur's breadboard/glowbug rigs

• W0HIO's "Little Receiver", a 7-tube high-performance superhet with xtal filtering: schematic 1,  schematic 2,  power supply,  picture 
• A late 1930s homebrew rack transmitter ( shades of Frank C. Jones )
• Ed Swynar, VE3CUI's fine "1929" style homebrew gear
• W9QZ's 1929 amateur radio station
• NA4G's homebrew firebottle gear
• W7FG's Hartley

Vintage Communications Equipment ( "Boatanchors" ) and Test Gear

• AB0CW's ham shack
• Patterson PR-15 communications receiver
• Hallicrafters HT-44 CW/AM/SSB Transmitter and SX117 ham band receiver
• Hallicrafters SX101A 80-10 m ham band receiver
• Hallicrafters HT37 80-10 m CW/AM/SSB transmitter
• Navy RAL-7 regenerative receiver, ARC-5 command set, and BC221 frequency meter
• Navy RBM-4 medium wave ( 200 khz to 2 Mhz ) receiver
• Navy TCS-12 1.5-12 Mhz transmitter and receiver set
• Harvey-Wells TBS-50D Bandmaster Deluxe transmitter
• Scott RCH receiver
• Hallicrafters S-20R
• Hallicrafters SX-15 receiver
• Hallicrafters SX-16 receiver
• National NC-303 receiver
• Canadian Wireless Set 52 ( receiver )
• National NC173 ham band receiver
• RMCA AR-8505 HF receiver
• Signal Corps BC342 HF receiver
• Hammarlund HQ140X general coverage receiver, w/matching speaker, and Heath HD11 Q-multiplier
• WRL Globe Chief 90 CW transmitter, with WRL 755A VFO
• RMCA AR-8507 Low Frequency Receiver
• miscellaneous vintage test gear

Vintage Broadcast Receivers

Early Battery Sets ( 1920s )

• Pfanstiehl Model 10C, "overtone", battery set, ca. 1924, w/ schematic
• Crosley 51, regenerative, battery set, ca. 1924
• Crosley 52SD ( "special deluxe")
• Freed-Eisemann NR-7 neutrodyne
• Garod RAF neutrodyne, ca. 1923
• RCA Radiola III
• Kolster 6D
• An unknown crystal set ( I know, it's not a battery set )
• An OLD homebrew loose coupler ( ca. early 20s? )
• several early homebrew sets, regenerative and TRF

Early AC sets ( 1920s )

• Crosley 706 "showbox", ca. 1928
• Atwater Kent 37, ca. 1927
• RCA Radiola 17 and 100A speaker, ca. 1927
• Kolster K-24 floor model, 1929
• Eveready Model 3

Other AC sets/Miscellaneous tube radios

• Crosley 24-AU tombstone and RCA 106 tapestry speaker
• Zenith "Wavemagnet", ca. 1942
• Air King "skyhawk", model 21-XX, ca. 1940 (?)
• Philco Model 50 cathedral
• Crosley Model 167 cathedral
• Atwater Kent 427
• Grunow "All Wave" model 1191 ( chassis 11G )
• Philco model 39-7 wood table radio
• Philco model 42-358 Wood Console
• RCA Victor model T7-5 wood tombstone
• Sonora RKRU 215 radio/phono ( ca. 1946)
• Bendix 75P6U AM/FM bakelite
• RPC "Western Air Patrol" farm set

Speakers and Reproducers

• RCA 106 tapestry speaker, floor model
• GGH Majestic horn speaker and Peerless Reproducer
• RCA 100A "napolean hat"
• Stewart Warner Unknown

Other Homebrew Gear

• A stereo amplifier based on a single 829B vacuum tube, from W0HIO

A Series of Construction Articles written for "THE FLASH", a publication of the Colorado Radio Collectors Club

• March/April 2000 "Building the Klase Regenerative Receiver"
• May/June 2000 "One Valve 12 volt regen for the AM BCB"
• July/August 2000 "Farm Radio Power Supply"
• September/October 2000 "Build an Active Antenna for the AM BCB" Page 1,  Page 2
• November/December 2000 "The detector and two-step regenerative receiver"  Page 1,  Page 2,  Page 3,  Page 4,  Page 5
• January/February 2001 "The Grimes Inverse Duplex"  Page 1,  Page 2,  Page 3,  Page 4,  
• March/April 2001 "A Look Back at Spark Radio, Part 1" Page 1,  Page 2,  Page 3  
• May/June 2001 " A Look Back at Spark Radio, Part 2"

Miscellaneous Early Wireless

• The modern amateur wireless station
• Halcun Spark Transmitter advertisement
• Fischer 1 kw spark gap
• Early 1/2" Electroimporting Company (?) spark coil
• Early (1924) ARRL Membership Certificate  Note: signature of Hiram Percy Maxim (T.O.M) on this
• 1910 bicycle mobile spark set, from Modern Electrics
• Shipboard arc converter installation, ca. 1922
• Shipboard spark set installation, ca. 1922
• "impulse" type spark set installation, ca. 1922

The Nerd Prince WD8PCE, pounding brass ca. 1977

Last Updated 11/26/2003 by Mark

Comments ? MAIL TO: ab0cw_remove.spam@qsl.net Delete the _remove.spam in this address to e-mail me!