KA7OEI's blog

Recent posts indexed from this public source.

• The Comcraft CTR-144 FM transceiver - A "multi-mode" solid state 2 Meter transceiver from the early 1970s.
• The Morrow CM-1 receiver - A relic of the cold war's effect on amateur radio
• A new push-pull switch/potentiometer for the Heathkit HM-102 VSWR/Wattmeter
• Making LED headlights RF-quiet
• Replacing the relays in the Yaesu FT-480R (FT-280)
• A (simple) WWVB loop amplifier for radio-controlled clocks
• Repairing a ("smoked") MFJ-998 1.5kW automatic antenna tuner
• Modifying the MFJ-5008 parabolic ultrasonic receiver for better sensitivity and wider frequency response
• Impedance matching (auto) transformer and common-mode choke for the JPC-7 dipole and other electrically-short (loaded) dipoles and verticals
• How I prevented QRM to HF reception from my solar charger and AC inverter at Quartzfest
• Neon bar-graph VSWR/Power meter using the ИН-13 (a.k.a "IN-13") "Nixie" - Part 3 (of 3)
• Adding ALC and overdrive protection to the MFJ ALS-500M "500 watt" amplifier
• A "sharp" 160 meter receive-only band-pass filter
• DXing distant SolarEdge PV optimizer modules (or long-distance propagation of PV system QRM)
• Exploring the Ameco PCL-P Nuvistor cascode preamp/preselector
• Reducing RF susceptibility for the HamGadgets "Ultra Pico Keyer" - and mimizing RF issues on portable HF stations in general
• A 15 (and 10) meter high-pass filter for Field Day
• The construction of a hybrid ring combiner: Using the same duplexer, feedline and antenna for two repeaters/links/transmitters
• Refurbishing a CIR Astro 200 HF amateur band transceiver
• Using a PIR to reduce wear and tear on a Nixie clock
• Repairing a NanoVNA "V2" with nonsensical readings ("Blown up" input)
• Ali Express "SDR TX/RX Switch" - A design NOT well thought out...
• A short-term capacitor-based "UPS" for mini (NUC-type) PCs
• Charging LiFePO4 batteries from a vehicular electrical system - the problems and a solution.
• Frequency response of the RX-888 SDR at the high and low ends (Above 30 MHz, below 1.5 MHz)
• The "Universal TCXO" - better stability for the Kenwood TS-590, TS-570, TS-480 (and other radios) using the QRP Labs ProgRock 2
• Hiking and POTA (Parks On the Air) operation from Arches National Park (US-0004)