SPARC 900MHz

 Posted on 2025-02-25

W3IHM, Sam, presented the 900MHz band at the SPARC member meeting.

History

  • 1926 - first regulation of amateur radio
    • before 1926, ban on anything belowe 200m
      • amateurs could do anything they want above 1.5MHz
  • First regulations defined bands
    • harmonically related
  • Amateurs imposed legislation for technical reasons
  • 900MHz has been available to hams since 1926
  • People wanted broadcast interference from ham radio gone in mid 1920s
  • 1930s - allow anything above 110MHz
  • 1935 - people were getting up to 3200MHz with magnetrons (spinning electron)
  • Commercial broadcastsers pushed hams into bands and out of lower bands in 1920s when we started figuring out propagation in the ionosphere, and they wanted to broadcast around the world.
  • war-1940 - we’re allowed above 300MHz
  • 1941 - all ham radio is shutdown for war
  • 1947 - military is reluctant to give back bands
    • bands shifted around a little
    • allowed up to 300GHz
  • 1952 - added 15M
  • 1979 - added WARC bands (12, 17, 30)
  • 1986 - 33cm
  • 2002 - 60M
  • 2016 - 2200M, 630M
  • Will we get 8M, 5M, and 4M like other parts of the world?

Characteristics

  • 900MHz-928MHz
  • Feed line loss is double that of 440MHz
  • Antenna loss
  • Atmospheric loss
  • Simplex is pretty dismal
  • Bounces well, like off airplanes
    • Once got Harrisburg to Philly bouncing off an airplane
    • Hit repeaters with Yagis and bounces
  • It’s a shared band with some other services.

Possibilities

  • Commercial radios with other software and surgery
  • Harris radio - expensive software
  • EF Johnson - free software, but needs surgery
  • Alinco had something, but not available
  • Kenwood TK981/481
  • Retevis RT10 - 1W $80
  • Listen with Quansheng, but filters won’t transmit.
  • Baofeng with dirty harmonics might TX on 900MHz
  • Baby monitors?
  • SDR dongle
  • Transverters

Shared Bands

  • Power meters are everywhere in the middle of the band, and the noise causes the FM squelch to stay closed.
  • Everyone’s trying to use the slivers on the end to avoid interference.
  • Amplifiers can overcome the noisy power meters.
  • Surplus amplifiers and antennas can be cheap.
  • K3LV has a repeater in the area.
  • Use it or lose it (already to the power meters).
  • Power meters may go away after a while to move up to 2.4GHz
  • Lots of competition for 900MHz - 2GHz - goes through the atmosphere easily.
900mhz  meeting  sparc