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A simple 8-channel receiver voting controller for a repeater
One of the often-overlooked means of improving the coverage of an amateur radio repeater is the use of multiple receivers in a voting configuration. It's often the case that a user can hear the...
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Reducing RFI from the Tesla Powerall 2
This is a follow-up of a previous article: "Does the Tesla Powerwall 2 produce RFI (Radio Frequency Interference)?". Figure 1:A typical Powerwall 2 installation.Left to right: Utility meter/original...
View ArticleA quick (and probably incomplete) guide to getting kiwirecorder and kiwiwspr...
What follows is likely to be quite incomplete - but it contains the major steps in installing the kiwirecorder and kiwiwspr packages on a Linux machine. I did my installation on Ubuntu, but similar...
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Tesla Powerwall RF sensitivity to RF transmissions - and how to deal with it.
This article is about my experience in causing RF interference to a powerwall, but I have written on two other articles about HF amateur radio operation along with having a Tesla Powerwall - these...
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Electrically driving a speedometer with a remote wheel sensor and a motor...
A friend of mine [Dan] is building a side-by-side 4 wheeler more or less from scratch using a motorcycle engine and transmission, an instrument cluster from a motorcycle, a home-built transfer case,...
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A transmit converter (and amplifier) for 630 and 2200 meters
There is a dearth of commercial equipment "out there" designed to allow operation on the new (to U.S. Amateurs) 630 and 2200 meter bands.Figure 1:Complete (except for antenna and matching) 630 and 2200...
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A hiliariously bad multi-band radio: The SocoTran ST-7900D
Spoiler: DO NOT get one of these radios, and if you have one, don't use it again until you read this!A couple of days ago an "interesting" mobile transceiver crossed my path - the SocoTran ST-7900D....
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A 2-band filter for the ST-7900D
In an earlier post I described a "hilariously bad" radio - the Socotran ST-7900D (a.k.a. the "KT-7900D"). This radio, right out of the box, could not legally be used by U.S. amateurs on three of its...
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Quieting an insanely (RFI) noisy LED floodlight
A friend of mine recently installed some inexpensive Chinese-made floodlights to illuminate his backyard, but was dismayed to discover that when they were on, his 80, 40 and 20 (shortwave - 3.5-14.5...
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Applying outboard AGC in front of RTL-SDR dongles to improve usable dynamic...
Figure 1:An"RTL-SDR.com" USB-based receiver - one of the better, "cheaper" options out there.This unit has been programmed and marked with its own, unique (to the system)serial number.Click on the...
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Revisiting the 20 meter "helical resonator" band-pass/notch filters
In my June 30, 2014 blog entry (linked here) I described simple band-pass and band-stop filters that could offer a degree of isolation between two 20 meter stations - for operations that might occur...
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Using the same feedline for HF/6 meters and 2 meters/70cm (a diplexer)
Yesterday, a work party went to the remote HF station of the Utah Amateur radio club to install a new antenna for the lower HF bands. At the site was an existing G5RV-type antenna which provided...
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Revisiting the limited attenuation filter for the KiwiSDR
In the June 18, 2018 entry of this blog (see that page here) I described a device that reduced the lower-frequency (below approximately 10 MHz) by approximately 12dB while leaving higher-frequency...
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A LiIon Pack for the Yaesu FT-530 (e.g. Updating a NiCd/NiMH HT battery pack...
Since the mid 1990s my "go to" handie-talking has been the venerable Yaesu FT-530. Reasonably popular at the time, this radio has endured, possessing pretty much all of the features that I would want...
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Shunt regulation of series-connected lead-acid batteries to equalize the voltage
There are many instances where series lead-acid batteries are connected - including:12 volt systems using two 6 volt "golf cart" batteries in series24 or 48 volts in a UPS (Uninterruptible Power...
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Characterizing the Mini-Circuits ZFSC-4-3, ZFDC-20-3, ZFSC-4-1-BNC+ and...
Figure 1:The collection of devices to be tested - plus a few 50 ohm terminators.Click on the image for a larger version.Rummaging through a box of RF stuff I ran across several multi-port devices made...
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Homebrew construction of 2 and 4 port splitters/combiners for the LF-MF-HF...
Note: This is a follow-up of a previous article,"Characterizing the Mini-Circuits ZFSC-4-3, ZFDC-20-3, ZFSC-4-1-BNC+ and ZFSC-2-1+ well below their designed frequency range" - link. Comment:All of the...
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Automatically re-connecting low-voltage cut-outs for 12 and 24 volt battery...
In a previous post I described a simple circuit that provided a low-voltage cut-out that could be used in a battery-operated system - see the article "A latching low-voltage disconnect for 12 volt...
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Using TV-type 75 ohm splitters and taps in 50 ohm systems on the amateur HF,...
I recently posted several articles about using commercially-available splitters link - and making one's own splitters - link - particularly for the HF frequencies and below (e.g. 30 MHz, down to a few...
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Improving the stability and performance of the FiFi SDR receiver
At the Northern Utah WebSDR link, among one of the several receiver configurations is that where a "SoftRock" receiver is used with a sound card. This combination works very well - far exceeding in...
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