NJ6N’s Amateur Radio & Electronics Blog
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SVXLink Interfaces
I’ve been running the svxLink application written by Tobias, SM0SVX for some time now. I installed it on our local VHF repeater back in 2018 using a Raspberry Pi 3B+, and an audio/PTT isolation board. I’ve been looking for new, improved or simplified interfaces to interconnect svxLink with repeater controllers and simplex node radios. Some…
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Ham Clock
Some time ago, I bought all of the parts to build a HamClock. Ed, WA6ED mentioned this project on the 40 meter net a while back. I finally got around to building mine in September, 2020. HamClock runs on Linux (Raspberry Pi, single board computers), or Arduino platforms. The Arduino version was written for an…
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Raspberry Pi Notes
Keyspan USB RS232 Adapter To use a Keyspan USA-19 USB to RS232 adapter, you need to install “firmware-linux-free”: e.g.: apt-get -y install firmware-linux-free Install seeed-voicecard seeed voice card source code and linux kernel drivers git clone https://github.com/HinTak/seeed-voicecard/ cd seeed-voicecard sudo ./install.sh sudo reboot Installing Google AIY Voice Kit on Raspios git clone https://github.com/google/aiyprojects-raspbian.git …
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TM-731A Battery Replacement & Backlight LED Modification
I recently repaired a Kenwood TM-731A 2m/70cm mobile radio. It appeared that the backup battery was dead since it would no longer retain any memories after power was removed. Checking the battery, it was indeed dead. I replaced that but noticed the board was coated with what could have been electrolyte leaking from the dead…
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Remote control for the Repeater Site
Howard, KG6GI and I installed the first D-STAR repeater system for the SOARA club in early 2007. During the process, we realized that we needed a way to remotely disable this new repeater system should anything go wrong, and to meet our FCC obligations. Howard had already obtained a network connected relay and opto-isolated input…
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Repairing Maggiore R1 Repeater
The SOARA 224.100 Repeater became intermittent and stopped transmitting a few months ago. I finally made an appointment with the Laguna Beach water district to visit the site on May 28th. Once on site, I quickly determined that the repeater had no power output. Keying the repeater did engage the transmitter, but nothing was heard…
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TM-742AD no TX audio
I noticed an old TM-742AD in a friends garage recently. It had been disassembled and had a label on it that read “Defective Unit” – that piqued my interest! I brought the radio home and put it on the bench. The radio powered up but all of the memories were reset to default frequencies so…
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FT-911 low-audio repair
My Brother recently took his old FT-911 23cm handie talkie out of storage and powered it up. The radio worked, but the output audio was very low. Tracing the audio path, I found sufficient audio at the output of the LM386 audio amplifier and the only component between the speaker and that was an electrolytic…
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Alpha Delta Coax Switches
I have one primary HF antenna, a Hustler 6BTV (6 band trap vertical). I was using an Alpha Delta 4-port coax switch to switch the antenna between my K3, K2, and coax that I use on the workbench. This morning when I listened for the SOARA 40 meter net, signals were very weak. SWR was…
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Tivo Power Supply Repair
I’ve got a very old Tivo, an HRI-250. Last week we had a major power outage that lasted 12 hours. When the power came back on, my Tivo did not. It had been having some over-heating problems, so I wasn’t surprised. Investigating further, I found that I was missing some of the supply voltages. The…
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