Feedline eliminator test transmitter – first look
The Raspberry Pi Zero brings nearly off the shelf gear to the task of generating an RF test signal from a completely wireless, small, self powered device about the size of a D cell.
Search Results for: transmitter
Higher Fidelity OpenWebRX 1.0.0
Some simple tweaks to a few text files try to make OpenWebRx more compatible with wider AM and FM RF bandwidths.
Anatomy of a low frequency aviation radio beacon
Aviation LF/MF beacons provide the opportunity to admire electrically-small antenna design on a macroscopic scale.
Demo of TDoA using the SDR.hu network
Quick demonstration of Time Difference of Arrival (TDoA) technique to correlate a common transmitted signal on multiple receivers to find the transmitter’s location.
BOB, the battery operated “beacon” for APRS
I built a prototype APRS beacon, dubbed Thor Hammer (big), to test back-packable APRS 2m beacon concepts.
Electrically isolated end-fed vs. center-fed dipole radiation
Testing confirms an end-fed dipole can energize the radiator nearly as well as a center-fed without need of additional counterpoise or other extraneous conductors.
Energizer lithium vs. alkaline batteries
Some APRS beacon tests provide data directly comparing the energy performance of Energizer alkaline and lithium AA cells.
Wireless near-field sensor
Careful selection of quality probes joined with the Raspberry Pi offerings yields a wireless E and H field sensor for accurate antenna analysis.
Of end-feds and feed-lines
Simulations suggest end-fed and center-fed half-wave dipoles share sensitivity to various feedline lengths, but in differing and manageable ways.
HT Antenna Comparisons
Does one really need to upgrade the antenna that came with your HT? Presented are EIRP measurements of various aftermarket HT aerials to help understand the trade space.
WWV @ 25MHz?
WWV apparently switched on its 25 MHz transmitter for a short while to give the old timers something to talk about… WWV’s 25 MHz Signal Back on the Air Have a listen while you can. John
Counting Kilowatt-Hours
Monitor your home’s power use with the Efergy E2 wireless clamp-on style whole house power monitoring system.
Superbowl HDTV Antenna
Build the venerable Hoverman TV antenna and watch digital broadcast high definition HDTV television this weekend. This version of a HDTV antenna uses amateur radio antenna building techniques to make a lightweight structure.
‘UHF’ Connector Test Results
Real measured data reveal the UHF (PL259 and SO239) connectors have real limitations.
Pretty Lousy? (PL) 259 Connectors
The PL259/SO239 (aka UHF) connectors have harsh critics and religious defenders. Questionable measurement techniques complicate matters. Let’s clear things up.
Magnetic Mount Antennas Don’t Suck
Magnetic Mount Antennas get a bum wrap it seems and for poor reasons and misunderstanding on how antennas work. Here is a way to see they are not so bad afterall… at least electrically.
SO2R Antenna Band Filtering
Band-pass filtering is a very good idea for SO2R.
EasyPal – Image Transfer Made Easy
EasyPal appears to be a great way to manage and transfer computer images via SSB in the HF bands.
Alternate Power Bonus for Field Day
Use Solar Power to get your Alternate Power Field Day bonus points using this example.
Field Day 802.11 Wireless Network
Use 802.11 in your Field Day network for flexible multi-mode success.
QRPeanut Can Transceiver
When QRP and Peanut Cans collide…
Morse Abbreviations
Procedural Signals (Prosigns) for Morse Code These are letters strung together in one continuous symbol. CQ – Calling any station (does any ham *not* know this one?) AR – end of message K – go, invite any station to transmit KN – “(” go only, invite a specific station to transmit BK – invite receiving … Read more
CW Common Abbreviations
Morse code is cool enough by itself, but these abbreviations help to make it even more efficient.