Category: Electronics
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10 Meter Vertical Dipole
I recently built some coaxial vertical dipoles for the 6 meter band to use with my converted Maxtrac radio on FM. I designed a 50mm coil form with holes in the ends to capture the coax. 2 inch (~50mm) diameter PVC pipe would work also. I learned about this easy to build coaxial dipole from…
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Batteries America EMS-20-28 Charger Repair
I recently came across an aftermarket rapid battery charger for an old Alinco DJ-280 220 MHz Handie-Talkie. When I plugged it in, there were no signs of life. So, I looked inside and found a very crispy 1/2 watt resistor in circuit with an NPN transistor. I had to guess at the value of the…
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Fun with (IoT?) Displays
At one of the repeater sites there is a remotely addressable power control system. Right now we’re running on emergency generators after a fire took out the power distribution system to the mountain. I thought it might be useful to have a remote display that would reflect the site status. Towards that end, I wired…
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Convenient Workbench Power
The super convenient under-shelf Anderson Powerpole distribution panel that I made some time ago started to show signs of wearing out. The connectors had become loose inside the PLA. So, I designed a new version that’s similar to a standalone tabletop Powerpole distribution strip that I built recently. Instead of having flush mounted Powerpole connectors,…
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LED S-Meter for /\/\otorola
I have been using Motorola CDM-750/1250/1550 radios to build digital and analog repeaters, full duplex links, and digital hotspots for some time. Quite a few of the radios I have do not have a front panel display. However, they do have a 16 pin accessory jack that has all of the usual signals including TX/RX…
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Dire Wolf & YAAC for APRS
I had an old Icom ID-880H lying around. The ID-880H has something many radios lack, a Data port! That gave me an excuse to buy another Masters Communications Radio Adapter kit! The DRA-50 is very similar to the RA-35/RA-42 interfaces that I’ve used before. The DRA series of adapters are designed to be used in…
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K3NG Electronic Keyer
Recently, someone mentioned they were looking for a code practice keyer during one of our HF nets. I have a few older keyers in my collection including a CMOS keyer that I built from a QST article back in the early 80’s or so and a Logikey K-1. I had recently built a very simplistic…
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Malahit/N7DDC ATU-100 EXT Antenna Tuner
This is a 100 watt HF/6m Antenna Tuner kit sold through the usual consumer sites like Amazon, Ebay, and AliExpress. It was apparently designed by N7DDC. I happened to run across this tuner kit while looking for something else on Amazon. At $30 or so, it was cheap enough to take a chance on and…
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Automatic Power Off
I have used an APO-3 automatic power off unit in my vehicles for many years. I recently needed to add a second one for my rear-facing dash camera in my truck and wondered what it would take to design and build one myself. I decided to use an Arduino Nano as the microcontroller since I…
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3D Printed Dipole Support
for portable or fixed use I had some left over aluminum tubing from other antenna projects and thought it would be useful to build a 10 meter dipole out of it. I needed a way to attach the elements to a block of wood and attach the block of wood to a TV antenna mast.…