2021638

Information

• Patent Grant
• 2021638

• References
• Source

• Patent Number

  2,021,638

• Date Filed

  Not available

• Date Issued

  Tuesday, November 19, 1935
  90 years ago

• CPC

  • H03F3/64 - with tubes only
  • H04B3/36 - Repeater circuits

• US Classifications

  • 379 - Telephonic communications