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website/content/posts/ham.md
Mira 5d3e1a74bc oh boy
2026-01-04 14:04:14 -05:00

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You're telling me a Ham Fisted this Metaphor?

Amateur Extra

Rules and Shit (E1)

  • PRB-1 is an FCC document that basically says that localities can't fuck with ham radio equipment (within reason)
    • your HOA can't legally do anything about your massive fucking Antenna but they're damn well gonna try

TV (E2B)

  • Cable TV uses the same frequency range as the Amateur 70cm band, so you can fit Fast-Scan TV into the same channels
    • what the fuck does this mean (E2B08)
  • Transmitting on Channel 2 (VHF TV) is illegal for amateurs
  • Upper Sideband (USB) modulation with a sound card is only used for SSTV
  • NTSC runs at 525i, 483 of which are visible, the rest is for vsync and other meta stuff
    • so basically 480i with extra metadata

Modes and Procedures (E2D)

  • MSK144 is designed for Meteor Scatter
    • Contact can be made on VHF up to 1300mi using Meteor Scatter
  • APRS (Automatic Packet Reporting System) sends packet data, ie locations/text/weather
  • WSPR (Weak Signal Propagation Reporter) is for testing propagation
  • Hellschreiber is for some sort of Fax Machine?

Propagation (E3)

  • Trans-equatorial propagation can be afternoon or evening
    • Afternoon
      • 4000-5000 miles
      • limited to 60MHz
      • High signal strength, but moderate distortion due to multipath bs
    • Evening
      • Peaks at 7PM-11PM
      • Up to 220MHz, sometimes even 432MHz
      • quenched(tf does that mean?) by moderate to severe geomagnetic disturbances
      • depends on high solar activity
  • Sporadic-E Propagation
    • is what happenes to my endocrine system when I'm on a family trip
    • is when signals sometimes bounces off the E layer, which gives you less range
      • usually the bouncing happens higher (in the F layer), which gives you more range Happens around solstices, especially summer

Measuring Stuff (E4A,B)

  • Frequency Counters depend on the accuracy of the Time Base
    • aka a Reference Frequency
  • Standing Wave Ratio
    • checks for impedance mismatch
    • measures ratio of peak to trough in a standing wave(?)
      • how do you get a standing wave here?
    • can be measured by an Antenna Analyzer, Directional Wattmeter, or Vector Network Analyzer

Receiving Stuff (E4,C,D,E)

  • Intermodulation happens when you have two signals with different frequencies passing through a "nonlinear system" (what?), which I guess causes constructive? destructive? interference
    • everything is at least a little nonlinear (again what the fuck does that mean)
    • seems like the base frequencies and all their harmonics join in on the interference, I think it's like some sort of clusterfuck of a beat frequency?
    • Here's the graph of 270 and 275MHz signals getting intermodulated
    • okay so plugging f\left(k,x\right)=\sin\left(2.7\cdot kx\right)+\sin\left(2.75\cdot kx\right), f\left(1,x\right)+f\left(2,x\right)+f\left(3,x\right)+f\left(4,x\right)+f\left(5,x\right)+f\left(6,x\right)+f\left(7,x\right) into desmos looks nothing like this graph so

Circuit City (E5,6,7)

  • Microwave freqs need short connections to reduce phase shift
    • what?
  • Emitter Follower/Common Collector Amplifier
    • has the RX and TX signals in phase
    • Has a gain close to 1 (doesn't amplify voltage, but boosts current?)
    • ....I'm not actually sure how this works and I'm too sleep to look it up
  • Op-amp
    • Voltage amplifier
      • in theory, infinite input impedance, 0 output impedance
  • Parasitic Inductance is a thing that fucks with Capacitors
    • physically bigger capacitors have more of this, tends to cause issues for RF
  • Two types of Semiconductors
    • N-Type is negative since it has extra electrons
    • P-Type is positive since it doesn't have enough electrons

Digital Signals (E8)

  • Audio Freq Shift Keying (AFSK) sends beep boops into a transmitter which sends them as AM/FM/SSB/what have you
    • if the beep boops are too loud going into the transmitter, shit goes wrong with the Carrier Frequency (Overmodulation)
    • This does AoE damage to the band and pisses off everyone whose signal you just interfered with
    • tl;dr It's like talking in a room, if you're too loud you'll piss off everyone in the room next to it (okay the metaphor is dogshit but)
    • you also need to turn off Automatic Level Control/reduce gain to prevent distortion
  • 8-Bit ADC can quantize signal down to 8 bits
    • I honestly don't know what you expected

Antennas (E9)

  • Two \frac14\lambda vertical antennas can be used for directionality
    • \frac12\lambda apart in phase yields a figure-8 radiation pattern broadsidei to the axis
    • if they're out of phase, it's the same pattern along the axis
    • \frac14\lambda apart in phase 90\degree out of phase is a cardioid
  • 160m and 80m Antennas need directivity due to atmospheric noise
    • At low HF frequencies, ligthning and other stuff generates RF interference that travels far (due to ionosphere refraction)
    • tl;dr Antenna gain isn't gonna do shit to fix the SNR wrt atmospheric noise
  • An Isotropic Antenna is the spherical cow of the radio world
  • Yagi Antennas
    • can use a Beta/Hairpin matching system to change the impedance
      • involves using a loop (sometimes shaped like a hairpin) across the terminals of the antenna, which makes the coil act as an inductor
      • This improves antenna performance by reducing reflections of RF energy back down the TX line
    • Pennant Antenna is a single-turn terminated loop?
      • tf does this look like
      • Creates a cardioid radiation pattern
    • Folded Dipole Antenna
      • \frac12\lambda with a wire in parallel connecting both ends
        • how is this different than a pennant
        • it's literally just a 1\lambda wire folded in half
        • I can't find a copyright free pic but just imagine the schematic looks goofy
    • Gamma Matching is when a you (impedance?) match a coax cable to an antenna by connecting the shielding to the center of the antenna and putting the coax conductor some fraction of the wavelength away
      • if your impedance is less than 50ohms,this should do the trick?
      • I'm gonna be honest I barely understand what impedance is, forget impedance matching
      • anyway Yagi Antennas rarely have 50ohm impedance so like gamma matching is good for those

Technician

  • nvm I passed this by grinding hamstudy
    • nearly passed the General one too at the same time so uh
  • callsign format
    • standard 2x3
      • K\w\d\w\w\w
    • vanity 1x3
      • K\d\*\*\*