985 Workbench: 2024-07-22

My Week in Radio

  • Great to see everyone at the breakfast, especially Luke’s loose couplers.
  • POTA after the breakfast at Marsh Creek with Vic, KC3TYX
    • 20m was the place to be, but 2 of us operating, so we had to take shifts with our own radios.
  • Prime Day Shopping
    • microcord
    • TYT HT for 10w crossband repeater
      • I’m using it now as the repeater
      • Less tethered to the outside antenna
      • Top of the radio/sma is 50C after repeating for an hour on power
    • TinySA
    • Raspberry Pi Zero W kits
  • APRSDroid: phone & radio
    • email gateway
    • POTA spotting

Notes from Others

  • solarham.com
  • Reading Ham Fest coming up
  • VE session at Stateline Radio Club

Questions

  • KC3WWC: What’s cool about APRS?
    • APRS weather station
    • PWS monitor app to find weather stations near me
    • Other gateway frequencies?
    • Check with CCAR/ARES/RACES nets for their uses.
  • KC3WWC: In Galenium detector, how does one know when the cat whisker is right?
    • Joe, W3GMS
      • put on headphones
      • move spring arm with stiff wire (cat whisker)
      • touch it to the galenium
      • move around to find the hot spot where it’s louder
      • germanium diode conducts at very low voltages, so easy
      • loose couplers don’t work so well in a crystal set, since it’s lossy
      • spark era - 1913
      • before galenium, there was a tube with metal filings, a “coherer”.
        • activate a buzzer
        • tap that would fall and reset the coherer
      • after galenium, then audion tube
      • imperative to have a very big antenna to capture as much signal as possible.
      • drive diode into forward current
      • Heathkit made a collectible kit
        • tightly coupled
        • voltage increase in the second coil
        • higher Q, so could be made more selective
      • Luke, KC3SCY, counted 20 different stations one night
    • Chuck, NA3CW
      • fox-hole radio: rusty razor blade, lead pencil, coil, safety pin, oatmeal box, wire
      • galena: ore of lead sulfide
      • immerse the galena in base of lead solder
      • grope around quietly to find magic spot where it works best
      • same thing with foxhole radio
      • uses oxide for detecting, not stainless
      • galena has 0.4V drop, like germanium diode
    • Ron, WA3VEE
      • has a marconi cat whiskey receiver
      • 0.4V can be converted to dBm, and it’s a pretty large signal required
      • predates any amplification
  • WA3VEE: What is the most important measure of solar activity we need to consider?
    • most profound affect on propagation?
    • KC3RFP: a-index (9 or lower) k-index (5 or lower)
    • Tamitha Skov website and youtube

See also