• Country
• United States of America (USA)

• Manufacturer / Brand
• Shamrock Manufacturing Co.; Newark, NJ

• Year
• 1925

• Category
• Broadcast Receiver - or past WW2 Tuner

• Radiomuseum.org ID
• 57839

Click on the schematic thumbnail to request the schematic as a free document.

• Number of Tubes
• 3

• Valves / Tubes
• UV201

• Main principle
• TRF (Tuned-Radio-Frequency but use of regeneration unknown); Reflex

• from Radiomuseum.org
• Model: Shamrock Harkness - Shamrock Manufacturing Co.;

• Notes

• In this kit the 6 ohm rheostats are designed for UV201 tubes. Acme T2 audio transformers are used. Federal tube sockets are used. This kit contains the parts to build the Harkness Counterflex receiver.  The tuners are marked Shamrock T1 and T2 but are Harkness designed. The center condenser is the Counterdon for neutralization. C Battery bias is a later improvement. There are several articles on the Harkness Counterflex in  the 1924-25 Radio in the Home periodical. Harkness was a co-editor. Shamrock offered an instruction book by mail.

• Price in first year of sale
• 39.00 $

• External source of data
• Ernst Erb

• Source of data
• Radio Collector`s Guide 1921-1932

• Literature/Schematics (1)
• Radio Digest 4-11-1925

• Other Models

• Here you find 21 models, 7 with images and 2 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Shamrock Manufacturing Co.; Newark, NJ