corpus.blog
41554 blogs · [ { "id": "01a0bb69-63b2-71b0-adc6-6564e5e657b2", "title": "Revisiting the 20 meter \"helical resonator\" band-pass/notch filters", "url": "https://ka7oei.blogspot.com/2019/05/revisiting-20-meter-helical-resonator.html", "published_at": "2019-06-01T02:57:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e6131929", "title": "Applying outboard AGC and filtering to RTL-SDR dongles to maximize usable dynamic range on HF", "url": "https://ka7oei.blogspot.com/2019/04/applying-outboard-agc-in-front-of-rtl.html", "published_at": "2019-04-15T23:55:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e64de848", "title": "Quieting an insanely (RFI) noisy LED floodlight", "url": "https://ka7oei.blogspot.com/2019/03/quieting-insanely-rfi-noisy-led.html", "published_at": "2019-03-11T16:57:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e6613f5d", "title": "A 2 meter and 222 MHz low-pass filter for the SocoTran ST-7900D", "url": "https://ka7oei.blogspot.com/2019/02/a-2-band-filter-for-st-7900d.html", "published_at": "2019-02-15T01:29:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e7257316", "title": "A hiliariously bad multi-band radio: The SocoTran ST-7900D", "url": "https://ka7oei.blogspot.com/2019/02/a-hiliariously-bad-multi-band-radio.html", "published_at": "2019-02-02T01:50:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e7271a95", "title": "A transmit converter (and amplifier) for 630 and 2200 meters", "url": "https://ka7oei.blogspot.com/2019/01/a-transmit-converter-and-amplifier-for.html", "published_at": "2019-01-19T20:19:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e7805ec3", "title": "Electrically driving a mechanical speedometer from a remote wheel sensor using a motor and PID loop", "url": "https://ka7oei.blogspot.com/2019/01/electrically-driving-speedometer-with.html", "published_at": "2019-01-07T20:41:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e7ef1fb7", "title": "Tesla Powerwall RF sensitivity to RF transmissions - and how to deal with it.", "url": "https://ka7oei.blogspot.com/2018/11/tesla-powerwall-rf-sensitivity.html", "published_at": "2018-11-14T18:29:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e84580fb", "title": "A quick (and probably incomplete) guide to getting kiwirecorder and kiwiwspr (now wsprdaemon) running on Linux", "url": "https://ka7oei.blogspot.com/2018/10/a-quick-and-probably-incomplete-guide.html", "published_at": "2018-10-18T20:16:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e8aa3122", "title": "Reducing RFI from the Tesla Powerall 2", "url": "https://ka7oei.blogspot.com/2018/10/reducing-rfi-from-tesla-powerall-2.html", "published_at": "2018-10-05T21:13:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e93f08c3", "title": "A simple 8-channel receiver voting controller for enhanced repeater coverage and usability", "url": "https://ka7oei.blogspot.com/2018/09/a-simple-8-channel-receiver-voting.html", "published_at": "2018-09-26T21:32:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e95d127e", "title": "Preventing a GFCI from tripping on transmitted RF", "url": "https://ka7oei.blogspot.com/2018/08/preventing-gfci-trip-on-rf.html", "published_at": "2018-08-24T17:18:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564e9b1e04f", "title": "A limited attenuation high-pass filter for the KiwiSDR", "url": "https://ka7oei.blogspot.com/2018/06/a-limited-attenuation-high-pass-filter.html", "published_at": "2018-06-19T02:42:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564ea55a886", "title": "A \"floaty thingie\" for keeping NiHM cells topped off", "url": "https://ka7oei.blogspot.com/2018/05/a-floaty-thingie-for-keeping-nihm-cells.html", "published_at": "2018-05-31T19:22:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564eb166505", "title": "Pine needle what? (Keeping your coniferous antenna supports alive!)", "url": "https://ka7oei.blogspot.com/2018/04/pine-needle-what.html", "published_at": "2018-04-24T17:38:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564eb283eaf", "title": "Better frequency stability for the QRP Labs \"ProgRock\" synthesizer", "url": "https://ka7oei.blogspot.com/2018/02/better-frequency-stability-for-qrp-labs.html", "published_at": "2018-02-21T04:50:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564eb515c7e", "title": "Managing HF signal dynamics and preventing overload with the RTL-SDR (and KiwiSDR) receivers", "url": "https://ka7oei.blogspot.com/2018/02/managing-hf-signal-dynamics-on-rtl-sdr.html", "published_at": "2018-02-15T20:26:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564eb86b556", "title": "Un-Bricking an RTL-SDR Dongle after an EEPROM write", "url": "https://ka7oei.blogspot.com/2018/02/un-bricking-rtl-sdr-dongle-after-eeprom.html", "published_at": "2018-02-09T01:35:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564ebc75d6d", "title": "A simple crystal oven/heater that uses no power resistors", "url": "https://ka7oei.blogspot.com/2018/01/a-simple-crystal-ovenheater-that-uses.html", "published_at": "2018-01-14T01:21:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564ecb77755", "title": "A quick fix for a Yaesu FT-757GXII blank display", "url": "https://ka7oei.blogspot.com/2018/01/a-quick-fix-for-yeasu-ft-757gxii-blank.html", "published_at": "2018-01-04T17:10:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564ed1db921", "title": "Does the Tesla Powerwall 2 produce RFI (Radio Frequency Interference)?", "url": "https://ka7oei.blogspot.com/2017/12/does-tesla-powerwall-2-produce-rfi.html", "published_at": "2017-12-20T18:10:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564ed2d5686", "title": "KA7OEI now QRV on 630 and 2200 meters", "url": "https://ka7oei.blogspot.com/2017/12/now-qrv-on-630-and-2200-meters.html", "published_at": "2017-12-06T20:33:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564edf6fcdc", "title": "Containing RF noise from a sine wave UPS", "url": "https://ka7oei.blogspot.com/2017/12/containing-rf-noise-from-sine-wave-ups.html", "published_at": "2017-12-01T19:10:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564eebf6943", "title": "Matching the 2 and 6 meter cycloid dipoles to 50 ohms", "url": "https://ka7oei.blogspot.com/2017/11/matching-2-and-6-meter-cycloid-dipoles.html", "published_at": "2017-11-21T19:24:00+00:00" }, { "id": "01a0bb69-63b2-71b0-adc6-6564ef1c5470", "title": "An alternate PA transistor for the QRP Labs Ultimate 3S beacon for more output power", "url": "https://ka7oei.blogspot.com/2017/11/an-alternative-pa-output-transistor-for.html", "published_at": "2017-11-14T20:31:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f39adf0e8d", "title": "A (semi)-typical suburban E-field whip receive system for the 630 and 2200 meter amateur bands", "url": "https://ka7oei.blogspot.com/2017/11/a-semi-typical-suburban-e-field-whip.html", "published_at": "2017-11-01T20:58:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f39b151d53", "title": "A 10 MHz OCXO (Oven-controlled Crystal Oscillator)", "url": "https://ka7oei.blogspot.com/2017/10/a-10-mhz-ocxo-oven-controlled-crystal.html", "published_at": "2017-10-17T19:46:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f39b73791b", "title": "Fixing my failed \"Kill-A-Watt\" meter - and a bit about capacitive dropper power supplies.", "url": "https://ka7oei.blogspot.com/2017/10/fixing-my-failed-kill-watt-meter-and.html", "published_at": "2017-10-05T17:40:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f39c0eff06", "title": "When Band-Pass/Band-Reject (Bp/Br) duplexers really aren't band-pass", "url": "https://ka7oei.blogspot.com/2017/09/when-band-passband-reject-bpbr.html", "published_at": "2017-09-27T15:34:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f39d08bf0e", "title": "Using an inexpensive MPPT controller in a portable solar charging system", "url": "https://ka7oei.blogspot.com/2017/09/using-inexpensive-mppt-controller-in.html", "published_at": "2017-09-12T19:40:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f39dfc5cf7", "title": "Monitoring the \"CT\" MedFER beacon from \"Eclipse land\"", "url": "https://ka7oei.blogspot.com/2017/08/monitoring-ct-medfer-beacon-from.html", "published_at": "2017-08-28T23:16:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f39e86e32b", "title": "Analyzing \"fake\" solar eclipse viewing glasses - how good/bad are they?", "url": "https://ka7oei.blogspot.com/2017/08/analyzing-fake-solar-eclipse-viewing.html", "published_at": "2017-08-15T21:17:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f39f12277c", "title": "A 173 mile (278km) all-electronics, FSO (Free Space Optical) contact: Part 1 - Scouting it out", "url": "https://ka7oei.blogspot.com/2017/07/a-173-mile-278km-all-electronics-fso.html", "published_at": "2017-07-20T20:54:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f39f4900e0", "title": "Odd differences between two (nearly) identical PV systems", "url": "https://ka7oei.blogspot.com/2017/06/odd-differences-between-two-nearly.html", "published_at": "2017-06-21T20:46:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f39f99a5e3", "title": "Adding a useful signal strength indication to an old, inexpensive handie-talkie for transmitter hunting", "url": "https://ka7oei.blogspot.com/2017/06/adding-useful-field-strength-indicator.html", "published_at": "2017-06-13T19:29:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a090c881", "title": "Teasing out the differences between the \"AC\" and \"DC\" versions of the Tesla PowerWall 2", "url": "https://ka7oei.blogspot.com/2017/05/teasing-out-differences-between-ac-and.html", "published_at": "2017-05-17T17:56:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a1481a77", "title": "An RV \"Generator Start Battery\" regulator/controller for use with a LiFePO4 power system", "url": "https://ka7oei.blogspot.com/2017/04/an-rv-generator-start-battery.html", "published_at": "2017-04-29T22:12:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a1664dc5", "title": "A daylight-tolerant TIA (TransImpedance Amplifier) optical receiver", "url": "https://ka7oei.blogspot.com/2017/04/a-daylight-tolerant-tia-transimpedance.html", "published_at": "2017-04-19T21:49:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a1f9f069", "title": "A (somewhat convoluted) means of locking a \"binary\" (2^n Hz) frequency to a 10 MHz reference", "url": "https://ka7oei.blogspot.com/2017/03/a-somewhat-convoluted-means-of-locking.html", "published_at": "2017-03-31T22:45:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a24abe29", "title": "The 1J37B as a replacement for a 1L6?", "url": "https://ka7oei.blogspot.com/2017/03/the-1j37b-as-replacement-for-1l6.html", "published_at": "2017-03-21T21:52:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a2fe9d65", "title": "Fun with self-oscillating TV flyback transformer circuits, arcs and high voltage", "url": "https://ka7oei.blogspot.com/2017/02/fun-with-self-oscillating-tv-flyback.html", "published_at": "2017-02-24T16:49:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a3bda07d", "title": "A novel APD-based speech bandwidth optical receiver", "url": "https://ka7oei.blogspot.com/2017/02/a-novel-apd-based-speech-bandwidth.html", "published_at": "2017-02-12T04:24:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a3f22a17", "title": "A microcontroller-based A/B Battery replacement for the Zenith TransOceanic H-500 radio, with filament regulation", "url": "https://ka7oei.blogspot.com/2017/01/an-ab-battery-replacement-for-zenith.html", "published_at": "2017-01-26T02:52:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a4a46573", "title": "A low power PSK31 transmitter using a Class-E power amplifier and envelope modulation", "url": "https://ka7oei.blogspot.com/2017/01/a-low-power-psk31-transmitter-using.html", "published_at": "2017-01-12T22:00:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a517d2bf", "title": "A simple push-pull audio amplifier using russian rod tubes and power transformers", "url": "https://ka7oei.blogspot.com/2016/12/a-simple-push-pull-audio-amplifier.html", "published_at": "2016-12-31T23:20:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a6107406", "title": "On the winding of power chokes and transformers: Part 3 - The plate (high voltage) transformer", "url": "https://ka7oei.blogspot.com/2016/12/on-winding-of-power-chokes-and.html", "published_at": "2016-12-19T23:42:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a652766d", "title": "Repairing the power switch on the Kenwood KA-8011 (a.k.a. KA-801) amplifier", "url": "https://ka7oei.blogspot.com/2016/12/repairing-power-switch-on-kenwood-ka.html", "published_at": "2016-12-10T01:19:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a7247469", "title": "On the winding of power chokes and transformers: Part 2 - A filament transformer", "url": "https://ka7oei.blogspot.com/2016/11/on-winding-of-power-chokes-and.html", "published_at": "2016-11-28T17:23:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a7960a49", "title": "\"TDOA\" direction finder systems - Part 1 - how they work, and a few examples.", "url": "https://ka7oei.blogspot.com/2016/11/tdoa-direction-finder-systems-part-1.html", "published_at": "2016-11-15T01:44:00+00:00" }, { "id": "01a0bb6d-8850-72eb-8866-21f3a7c275bb", "title": "On the winding of power chokes and transformers: Part 1 - A power choke", "url": "https://ka7oei.blogspot.com/2016/10/on-winding-of-power-chokes-and.html", "published_at": "2016-10-25T03:41:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-3675694e17a5", "title": "Automatic volume tracking for a TV", "url": "https://ka7oei.blogspot.com/2016/09/automatic-volume-tracking-for-tv.html", "published_at": "2016-09-29T04:44:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-367569c20c00", "title": "The solar saga - part 2: Getting the system online", "url": "https://ka7oei.blogspot.com/2016/08/the-solar-saga-part-2-getting-system.html", "published_at": "2016-08-23T04:21:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756a7f277d", "title": "A latching low-voltage disconnect for 12 volt lead acid and lithium batteries (non auto-resetting)", "url": "https://ka7oei.blogspot.com/2016/08/a-low-voltage-disconnect-for-12-volt.html", "published_at": "2016-08-09T23:52:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756b43c373", "title": "Fixing the squealing auto-tuner motors in the Kenwood TS-450", "url": "https://ka7oei.blogspot.com/2016/07/fixing-squealing-auto-tuner-motors-in.html", "published_at": "2016-07-15T23:53:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756c43370b", "title": "A 1:1 balun was the best overall choice for feeding the horizontal loop...", "url": "https://ka7oei.blogspot.com/2016/06/a-11-balun-was-best-choice.html", "published_at": "2016-06-12T19:30:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756cdad5ab", "title": "Audio breakup on the JBL 4315B speaker", "url": "https://ka7oei.blogspot.com/2016/05/audio-breakup-on-jbl-4315b-speaker.html", "published_at": "2016-05-31T19:27:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756d19c355", "title": "Combatting scintillation effects on optical voice links", "url": "https://ka7oei.blogspot.com/2016/04/combatting-scintillation-effects-on.html", "published_at": "2016-04-19T00:14:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756d71dab7", "title": "The solar saga - part 1: Avoiding interference (Why I did not choose microinverters!)", "url": "https://ka7oei.blogspot.com/2016/03/the-solar-saga-part-1-avoiding.html", "published_at": "2016-03-03T00:41:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756db547a2", "title": "Using \"Ultracapacitors\" as a power conditioner and ballast for transient high-power loads (or \"How to run your HF rig from D-cells\" - sort of...)", "url": "https://ka7oei.blogspot.com/2016/02/using-ultracapacitors-as-ballast-for.html", "published_at": "2016-02-06T19:06:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756e40bd2c", "title": "Homebrew Drake TR-3 power supply", "url": "https://ka7oei.blogspot.com/2016/01/homebrew-drake-tr-3-power-supply.html", "published_at": "2016-01-19T21:58:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756eb3f747", "title": "Adding FM transmit to the mcHF transceiver", "url": "https://ka7oei.blogspot.com/2015/12/adding-fm-transmit-to-mchf-transceiver.html", "published_at": "2015-12-31T04:04:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756eef5df0", "title": "Minimizing VHF (and HF) RFI from electronic ballasts and fluorescent tubes", "url": "https://ka7oei.blogspot.com/2015/12/minimizing-vhf-rfi-from-electronic.html", "published_at": "2015-12-18T00:55:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756f43158b", "title": "FM squelch and subaudible tone detection on the mcHF", "url": "https://ka7oei.blogspot.com/2015/11/fm-squelch-and-subaudible-tone.html", "published_at": "2015-11-20T20:42:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756f4e87bd", "title": "Repairing the TUNE capacitor on the Heathkit HL2200 (SB-220) amplifier", "url": "https://ka7oei.blogspot.com/2015/11/repairing-tune-capacitor-on-heathkit.html", "published_at": "2015-11-10T05:11:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36756ffacd37", "title": "Adding FM to the mcHF SDR transceiver", "url": "https://ka7oei.blogspot.com/2015/11/adding-fm-to-mchf-sdr-transceiver.html", "published_at": "2015-11-01T18:37:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-3675701b77c4", "title": "6 meter cycloid dipole for circular polarization", "url": "https://ka7oei.blogspot.com/2015/10/6-meter-cycloid-dipole-for-circular.html", "published_at": "2015-10-28T01:09:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-367571164d1e", "title": "Gate current in a JFET: The development of a very sensitive, speech-frequency optical receiver.", "url": "https://ka7oei.blogspot.com/2015/09/gate-current-in-jfet-development-of.html", "published_at": "2015-09-30T19:40:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-3675713f78ae", "title": "The most sensitive repeater on Earth?", "url": "https://ka7oei.blogspot.com/2015/09/the-most-sensitive-repeater-on-earth.html", "published_at": "2015-09-12T22:48:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-36757219690e", "title": "A PIC-based audio source for locking a VHF oscillator", "url": "https://ka7oei.blogspot.com/2015/08/a-pic-based-audio-source-for-locking.html", "published_at": "2015-09-01T05:50:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-3675724e6017", "title": "A PIC-based audio comb filter to remove AC mains hum", "url": "https://ka7oei.blogspot.com/2015/07/a-pic-based-audio-comb-filter-to-remove.html", "published_at": "2015-07-29T23:01:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-367572ef1516", "title": "Adding a waterfall display to the mcHF transceiver", "url": "https://ka7oei.blogspot.com/2015/05/adding-waterfall-display-to-mchf.html", "published_at": "2015-06-01T05:09:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-3675739c0f3b", "title": "It should have not been BPL that worried us! (And using a separate receive antenna at HF)", "url": "https://ka7oei.blogspot.com/2015/04/it-should-have-not-been-bpl-that.html", "published_at": "2015-04-20T18:49:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-367573a864ac", "title": "Update on the mcHF - Adding more features (Part 2) - Implementing audio filters and fractional I/Q phase adjustments", "url": "https://ka7oei.blogspot.com/2015/03/update-on-mchf-adding-more-features.html", "published_at": "2015-03-10T21:17:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-367573b90fe7", "title": "Using the \"RTL.SDR\" dongle (with HF port) as found on Ebay", "url": "https://ka7oei.blogspot.com/2015/03/using-rtssdr-dongle-with-hf-upconverter.html", "published_at": "2015-03-08T06:37:00+00:00" }, { "id": "01a0bb71-5759-70b9-a9b5-367573fa572d", "title": "A \"quiet\" 5 volt USB car power supply", "url": "https://ka7oei.blogspot.com/2015/02/a-quiet-5-volt-usb-car-power-supply.html", "published_at": "2015-02-20T22:25:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a7c109dc4", "title": "Updated version of the \"Simple\" PWM LED/Laser modulator", "url": "https://ka7oei.blogspot.com/2015/01/updated-version-of-simple-pwm-ledlaser.html", "published_at": "2015-01-31T00:23:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a7cb8b887", "title": "Update on the mcHF transceiver - Adding features to the original code", "url": "https://ka7oei.blogspot.com/2015/01/update-on-mchf-transceiver-adding.html", "published_at": "2015-01-27T20:26:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a7d819947", "title": "Noisy fan on my Owon DS7102V Digital Oscilloscope", "url": "https://ka7oei.blogspot.com/2014/12/noisy-fan-on-my-owon-ds7102v-digital.html", "published_at": "2014-12-24T22:19:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a7da7ad9e", "title": "My first coherer", "url": "https://ka7oei.blogspot.com/2014/11/my-first-coherer.html", "published_at": "2014-11-23T21:40:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a7decdd12", "title": "The \"Pointless\" 10 meter DSB QRP transmitter", "url": "https://ka7oei.blogspot.com/2014/10/the-pointless-10-meter-dsb-qrp.html", "published_at": "2014-10-15T21:30:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a7e557989", "title": "What to do if your IFR 1200 Service Monitor display just shows \"@\" signs on the display - and if your deviation meter goes non-linear...", "url": "https://ka7oei.blogspot.com/2014/10/what-to-do-if-your-ifr-1200-service.html", "published_at": "2014-10-02T01:01:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a7eec6b30", "title": "Assembling the mcHF transceiver boards - getting ready.", "url": "https://ka7oei.blogspot.com/2014/09/assembling-mchf-transceiver-boards.html", "published_at": "2014-09-17T23:21:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a7fd4e3af", "title": "YAFP - The mcHF SDR HF Transceiver", "url": "https://ka7oei.blogspot.com/2014/08/yafp-mchf-sdr-hf-transceiver.html", "published_at": "2014-08-20T02:07:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a80d459f7", "title": "Completely containing switching power supply RFI", "url": "https://ka7oei.blogspot.com/2014/08/completely-containing-switching-power.html", "published_at": "2014-08-19T04:40:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a81555195", "title": "Replacing the filters in the Drake SP75 Speech Processor", "url": "https://ka7oei.blogspot.com/2014/07/replacing-filters-in-drake-sp75-speech.html", "published_at": "2014-07-19T19:38:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a8174c356", "title": "A 100 watt \"Helical\" resonator bandpass/notch filters to increase isolation of 20 meter stations during Field Day", "url": "https://ka7oei.blogspot.com/2014/06/a-helical-resonator-to-help-isolation.html", "published_at": "2014-07-01T05:52:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a8233dba2", "title": "How USB car power adapters can ruin 2 meter mobile reception!", "url": "https://ka7oei.blogspot.com/2014/05/how-usb-power-adapters-can-ruin-your-2.html", "published_at": "2014-05-26T20:59:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a82639785", "title": "Making a cheap Chinese battery tester more accurate and useful", "url": "https://ka7oei.blogspot.com/2014/04/making-cheap-chinese-battery-tester.html", "published_at": "2014-04-03T02:52:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a834cc3b0", "title": "Examining the Glencom VC510 UHF to L-Band Upconverter", "url": "https://ka7oei.blogspot.com/2014/03/examining-vc510-uhf-to-l-band.html", "published_at": "2014-04-01T04:51:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a83e1b305", "title": "Analysis of a repeater's antenna pattern", "url": "https://ka7oei.blogspot.com/2014/02/analysis-of-repeaters-antenna-pattern.html", "published_at": "2014-02-17T22:52:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a84d9d392", "title": "Low Pass filter for MF/LF (630 meter and 2200 meter) reception", "url": "https://ka7oei.blogspot.com/2014/02/low-pass-filter-for-mflf-reception.html", "published_at": "2014-02-09T01:38:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a85b6a03f", "title": "First foray into the world of Arduino", "url": "https://ka7oei.blogspot.com/2014/02/first-foray-into-arduino.html", "published_at": "2014-02-03T06:09:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a85bf7be0", "title": "A Stand-alone ICSP Interface/programming board for 8 and 28 pin AVR microcontrollers", "url": "https://ka7oei.blogspot.com/2014/01/icsp-interfaceprogramming-board-for-8.html", "published_at": "2014-01-22T04:19:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a86b8ad65", "title": "RIP Gretchen cat", "url": "https://ka7oei.blogspot.com/2014/01/rip-gretchen-cat.html", "published_at": "2014-01-07T22:35:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a8768265c", "title": "A simple inverter for driving neons/nixies using Radio Shack parts", "url": "https://ka7oei.blogspot.com/2013/12/a-simple-inverter-for-driving.html", "published_at": "2014-01-01T06:57:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a87e55a32", "title": "Improving the bass response of a (cheap) subwoofer amplifier system by *reducing* its bass response", "url": "https://ka7oei.blogspot.com/2013/11/improving-cheap-subwoofer-amplifier.html", "published_at": "2013-11-24T19:14:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a88030436", "title": "Attention-getting brake light \"modulator\" for a motorcycle.", "url": "https://ka7oei.blogspot.com/2013/11/attention-getting-brake-light-modulator.html", "published_at": "2013-11-11T17:49:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a889e3aaa", "title": "Fun with the Microchip PICKit 3 and the Sure Electronics DB-UD11111 ZIF adapter", "url": "https://ka7oei.blogspot.com/2013/10/fun-with-microchip-pickit-3.html", "published_at": "2013-10-29T22:26:00+00:00" }, { "id": "01a0bb74-ca5b-718d-8701-625a895d847c", "title": "Repair of the speedometer on a Polaris Sportsman 500 4-wheeler", "url": "https://ka7oei.blogspot.com/2013/10/repair-of-speedometer-on-polaris.html", "published_at": "2013-10-28T23:34:00+00:00" }, { "id": "01a0bb74-ca5c-720a-bb28-55c574078346", "title": "Sleuthing the source of a SARSAT signal?", "url": "https://ka7oei.blogspot.com/2013/10/sleuthing-source-of-sarsat-signal.html", "published_at": "2013-10-16T22:41:00+00:00" } ] posts Claim your blog
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ka7oei.blogspot.com

ka7oei.blogspot.com

2019

Revisiting the 20 meter "helical resonator" band-pass/notch filtersoriginal ↗
1 Jun 2019
Applying outboard AGC and filtering to RTL-SDR dongles to maximize usable dynamic range on HForiginal ↗
15 Apr 2019
Quieting an insanely (RFI) noisy LED floodlightoriginal ↗
11 Mar 2019
A 2 meter and 222 MHz low-pass filter for the SocoTran ST-7900Doriginal ↗
15 Feb 2019
A hiliariously bad multi-band radio: The SocoTran ST-7900Doriginal ↗
2 Feb 2019
A transmit converter (and amplifier) for 630 and 2200 metersoriginal ↗
19 Jan 2019
Electrically driving a mechanical speedometer from a remote wheel sensor using a motor and PID looporiginal ↗
7 Jan 2019

2018

Tesla Powerwall RF sensitivity to RF transmissions - and how to deal with it.original ↗
14 Nov 2018
A quick (and probably incomplete) guide to getting kiwirecorder and kiwiwspr (now wsprdaemon) running on Linuxoriginal ↗
18 Oct 2018
Reducing RFI from the Tesla Powerall 2original ↗
5 Oct 2018
A simple 8-channel receiver voting controller for enhanced repeater coverage and usabilityoriginal ↗
26 Sept 2018
Preventing a GFCI from tripping on transmitted RForiginal ↗
24 Aug 2018
A limited attenuation high-pass filter for the KiwiSDRoriginal ↗
19 Jun 2018
A "floaty thingie" for keeping NiHM cells topped offoriginal ↗
31 May 2018
Pine needle what? (Keeping your coniferous antenna supports alive!)original ↗
24 Apr 2018
Better frequency stability for the QRP Labs "ProgRock" synthesizeroriginal ↗
21 Feb 2018
Managing HF signal dynamics and preventing overload with the RTL-SDR (and KiwiSDR) receiversoriginal ↗
15 Feb 2018
Un-Bricking an RTL-SDR Dongle after an EEPROM writeoriginal ↗
9 Feb 2018
A simple crystal oven/heater that uses no power resistorsoriginal ↗
14 Jan 2018
A quick fix for a Yaesu FT-757GXII blank displayoriginal ↗
4 Jan 2018

2017

Does the Tesla Powerwall 2 produce RFI (Radio Frequency Interference)?original ↗
20 Dec 2017
KA7OEI now QRV on 630 and 2200 metersoriginal ↗
6 Dec 2017
Containing RF noise from a sine wave UPSoriginal ↗
1 Dec 2017
Matching the 2 and 6 meter cycloid dipoles to 50 ohmsoriginal ↗
21 Nov 2017
An alternate PA transistor for the QRP Labs Ultimate 3S beacon for more output poweroriginal ↗
14 Nov 2017
A (semi)-typical suburban E-field whip receive system for the 630 and 2200 meter amateur bandsoriginal ↗
1 Nov 2017
A 10 MHz OCXO (Oven-controlled Crystal Oscillator)original ↗
17 Oct 2017
Fixing my failed "Kill-A-Watt" meter - and a bit about capacitive dropper power supplies.original ↗
5 Oct 2017
When Band-Pass/Band-Reject (Bp/Br) duplexers really aren't band-passoriginal ↗
27 Sept 2017
Using an inexpensive MPPT controller in a portable solar charging systemoriginal ↗
12 Sept 2017
Monitoring the "CT" MedFER beacon from "Eclipse land"original ↗
28 Aug 2017
Analyzing "fake" solar eclipse viewing glasses - how good/bad are they?original ↗
15 Aug 2017
A 173 mile (278km) all-electronics, FSO (Free Space Optical) contact: Part 1 - Scouting it outoriginal ↗
20 Jul 2017
Odd differences between two (nearly) identical PV systemsoriginal ↗
21 Jun 2017
Adding a useful signal strength indication to an old, inexpensive handie-talkie for transmitter huntingoriginal ↗
13 Jun 2017
Teasing out the differences between the "AC" and "DC" versions of the Tesla PowerWall 2original ↗
17 May 2017
An RV "Generator Start Battery" regulator/controller for use with a LiFePO4 power systemoriginal ↗
29 Apr 2017
A daylight-tolerant TIA (TransImpedance Amplifier) optical receiveroriginal ↗
19 Apr 2017
A (somewhat convoluted) means of locking a "binary" (2^n Hz) frequency to a 10 MHz referenceoriginal ↗
31 Mar 2017
The 1J37B as a replacement for a 1L6?original ↗
21 Mar 2017
Fun with self-oscillating TV flyback transformer circuits, arcs and high voltageoriginal ↗
24 Feb 2017
A novel APD-based speech bandwidth optical receiveroriginal ↗
12 Feb 2017
A microcontroller-based A/B Battery replacement for the Zenith TransOceanic H-500 radio, with filament regulationoriginal ↗
26 Jan 2017
A low power PSK31 transmitter using a Class-E power amplifier and envelope modulationoriginal ↗
12 Jan 2017

2016

A simple push-pull audio amplifier using russian rod tubes and power transformersoriginal ↗
31 Dec 2016
On the winding of power chokes and transformers: Part 3 - The plate (high voltage) transformeroriginal ↗
19 Dec 2016
Repairing the power switch on the Kenwood KA-8011 (a.k.a. KA-801) amplifieroriginal ↗
10 Dec 2016
On the winding of power chokes and transformers: Part 2 - A filament transformeroriginal ↗
28 Nov 2016
"TDOA" direction finder systems - Part 1 - how they work, and a few examples.original ↗
15 Nov 2016
On the winding of power chokes and transformers: Part 1 - A power chokeoriginal ↗
25 Oct 2016
Automatic volume tracking for a TVoriginal ↗
29 Sept 2016
The solar saga - part 2: Getting the system onlineoriginal ↗
23 Aug 2016
A latching low-voltage disconnect for 12 volt lead acid and lithium batteries (non auto-resetting)original ↗
9 Aug 2016
Fixing the squealing auto-tuner motors in the Kenwood TS-450original ↗
15 Jul 2016
A 1:1 balun was the best overall choice for feeding the horizontal loop...original ↗
12 Jun 2016
Audio breakup on the JBL 4315B speakeroriginal ↗
31 May 2016
Combatting scintillation effects on optical voice linksoriginal ↗
19 Apr 2016
The solar saga - part 1: Avoiding interference (Why I did not choose microinverters!)original ↗
3 Mar 2016
Using "Ultracapacitors" as a power conditioner and ballast for transient high-power loads (or "How to run your HF rig from D-cells" - sort of...)original ↗
6 Feb 2016
Homebrew Drake TR-3 power supplyoriginal ↗
19 Jan 2016

2015

Adding FM transmit to the mcHF transceiveroriginal ↗
31 Dec 2015
Minimizing VHF (and HF) RFI from electronic ballasts and fluorescent tubesoriginal ↗
18 Dec 2015
FM squelch and subaudible tone detection on the mcHForiginal ↗
20 Nov 2015
Repairing the TUNE capacitor on the Heathkit HL2200 (SB-220) amplifieroriginal ↗
10 Nov 2015
Adding FM to the mcHF SDR transceiveroriginal ↗
1 Nov 2015
6 meter cycloid dipole for circular polarizationoriginal ↗
28 Oct 2015
Gate current in a JFET: The development of a very sensitive, speech-frequency optical receiver.original ↗
30 Sept 2015
The most sensitive repeater on Earth?original ↗
12 Sept 2015
A PIC-based audio source for locking a VHF oscillatororiginal ↗
1 Sept 2015
A PIC-based audio comb filter to remove AC mains humoriginal ↗
29 Jul 2015
Adding a waterfall display to the mcHF transceiveroriginal ↗
1 Jun 2015
It should have not been BPL that worried us! (And using a separate receive antenna at HF)original ↗
20 Apr 2015
Update on the mcHF - Adding more features (Part 2) - Implementing audio filters and fractional I/Q phase adjustmentsoriginal ↗
10 Mar 2015
Using the "RTL.SDR" dongle (with HF port) as found on Ebayoriginal ↗
8 Mar 2015
A "quiet" 5 volt USB car power supplyoriginal ↗
20 Feb 2015
Updated version of the "Simple" PWM LED/Laser modulatororiginal ↗
31 Jan 2015
Update on the mcHF transceiver - Adding features to the original codeoriginal ↗
27 Jan 2015

2014

Noisy fan on my Owon DS7102V Digital Oscilloscopeoriginal ↗
24 Dec 2014
My first cohereroriginal ↗
23 Nov 2014
The "Pointless" 10 meter DSB QRP transmitteroriginal ↗
15 Oct 2014
What to do if your IFR 1200 Service Monitor display just shows "@" signs on the display - and if your deviation meter goes non-linear...original ↗
2 Oct 2014
Assembling the mcHF transceiver boards - getting ready.original ↗
17 Sept 2014
YAFP - The mcHF SDR HF Transceiveroriginal ↗
20 Aug 2014
Completely containing switching power supply RFIoriginal ↗
19 Aug 2014
Replacing the filters in the Drake SP75 Speech Processororiginal ↗
19 Jul 2014
A 100 watt "Helical" resonator bandpass/notch filters to increase isolation of 20 meter stations during Field Dayoriginal ↗
1 Jul 2014
How USB car power adapters can ruin 2 meter mobile reception!original ↗
26 May 2014
Making a cheap Chinese battery tester more accurate and usefuloriginal ↗
3 Apr 2014
Examining the Glencom VC510 UHF to L-Band Upconverteroriginal ↗
1 Apr 2014
Analysis of a repeater's antenna patternoriginal ↗
17 Feb 2014
Low Pass filter for MF/LF (630 meter and 2200 meter) receptionoriginal ↗
9 Feb 2014
First foray into the world of Arduinooriginal ↗
3 Feb 2014
A Stand-alone ICSP Interface/programming board for 8 and 28 pin AVR microcontrollersoriginal ↗
22 Jan 2014
RIP Gretchen catoriginal ↗
7 Jan 2014
A simple inverter for driving neons/nixies using Radio Shack partsoriginal ↗
1 Jan 2014

2013

Improving the bass response of a (cheap) subwoofer amplifier system by *reducing* its bass responseoriginal ↗
24 Nov 2013
Attention-getting brake light "modulator" for a motorcycle.original ↗
11 Nov 2013
Fun with the Microchip PICKit 3 and the Sure Electronics DB-UD11111 ZIF adapteroriginal ↗
29 Oct 2013
Repair of the speedometer on a Polaris Sportsman 500 4-wheeleroriginal ↗
28 Oct 2013
Sleuthing the source of a SARSAT signal?original ↗
16 Oct 2013
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