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Observations, analysis and field use of the JPC-7 portable "dipole" antenna
Figure 1:The JPC-7 and its original set of components in the case. Onthe left is a zippered section with the balun, strap, feedpointand mounting hardware for the elements. On the rightcan be seen the...
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A simple VHF notch cavity from scraps of (large) Heliax
In a previous post I discussed how a band-pass"cavity" could be constructed from a chunk of 1-5/8" Heliax (tm) cable (a link to that article is here). This is the follow-up to that article.Figure 1:...
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"TDOA" direction finder systems - Part 2 - Determining signal bearing from...
Note:This is a follow-up to a Part 1 blog post on this topic where we discuss in general how "rotating"(or switched) antennas may be used to determine the apparent bearing of a transmitter. It is...
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Remote (POTA) operation from the Conger Mountain BLM Wilderness Area (K-6085)
It is likely that - almost no matter where you were - you were aware that a solar eclipse occurred in the Western U.S. in the middle of October, 2023. Wanting to go somewhere away from the crowds -...
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Reducing RFI (Radio Frequency Interference) for a POE (Power Over Ethernet)...
One of the (many) banes of the amateur radio operator's existence is often found at the end of an Ethernet cable - specifically a device that is being powered via "Ethernet": It is often the case that...
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Repairing a dead Kenwood TS-850S
Recently, a Kenwood TS-850S - a radio from the mid-early 1990s - crossed my workbench. While I'm not in the "repair business", I do fix my own radios, those of close friends, and occasionally those of...
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Using an external clock with the RX-888 (Mk2)
The RX-888 (Mk2) and external clockingFigure 1:The RX-888 with external clock input (right)The enable/disable switch is barelyvisible behind the USB connector.Click on the image for a larger...
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Analysis of interference from a SolarEdge PV (solar) electric system.
Comment:This article - while it centers about the investigation of a SolarEdge PV (PhotoVoltaic) system - the discussions of techniques and strategies should be generally useful when investigating...
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Repairing a dead RX-888 (no A/D converter clocking)
On this blog I have posted three previous entries related to the RX-888 (Mk2) which may be of interest to the reader:Figure 1 - The (stock) RX-888Using an external clock with the RX-888 (Mk2) - link -...
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Observations, analysis and modifications of the JPC-12 vertical antenna
The JPC-12antenna (possibly made by BD7JPC) is relatively inexpensive a portable vertical antenna - made in China, of course - that may be found for sale at quite a few places under a few different...
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Reducing QRM (interference) from a Renogy 200 watt portable solar panel system
Figure 1: Renogy 200 watt folding panel, in the sunClick on the image for a larger version.A year or so ago I got a 200 watt foldable solar panel system. This unit - made by Renogy - consists of two...
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Rewinding the stainless steel for silver-plated copper coils on the JPC-7 and...
Portable antennas (verticals, loaded dipoles) typically use coils on the lower HF bands to make them electrically "larger" - but what about losses in those coils?While it's "traditional" to use copper...
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Neon bar-graph VSWR/Power meter using the ИН-13 (a.k.a "IN-13") "Nixie" - Part 1
Figure 1: Power/VSWR meter using ИН-13 (a.k.a. "IN-13") neon bar-graph indicators.Click on the image for a larger version.Several years ago I bought some Soviet-era neon bar-graph displays - mainly...
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DRAFT - Neon bar-graph VSWR/Power meter using the ИН-13 (a.k.a "IN-13")...
Figure 1: Power/VSWR meter using ИН-13 neon bar-graphindicators.Click on the image for a larger versionIn Part 1 I laid out the requirements of the ИН-13-based neon bar-graph VSWR/power meter....
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Hiking and POTA (Parks On the Air) operation from Arches National Park (US-0004)
Figure 1:Double-O ArchClick on the image for a larger version.Earlier this month I had the opportunity to spend nearly a week in Arches National Park in south eastern Utah. As the name implies, there...
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The "Universal TCXO" - better stability for the TS-590 (and other radios)...
Figure 1:The TS-590G into which the ProgRock was installed.A useful accessory for many amateur transceivers is a TCXO - a device, often offered as an option, that improves the absolute frequency...
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Frequency response of the RX-888 SDR at the high and low ends (above 30 MHz...
Figure 1:The RX-888 Mk2.The RX-888 Mk 2 (hereafter referred to as the RX-888 or '888) is a versatile device, essentially providing a means by which "all of HF"(0-30 MHz - or even 0-60 MHz) may be...
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Charging LiFePO4 batteries from a vehicular electrical system - the problems...
Figure 1:The Renogy RNG-DCC1212-20 - an isolatedand current-limited battery charger, intendedfor use with vehicle electrical systems.Click on the image for a larger version.There are times - usually on...
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A short-term "UPS" for mini (NUC-type) PCs
The problemFigure 1:A "Beelink" small form-factor PC. This unit sports a Ryzenprocessor. and runs from an external 19 volt supply.Click on the image for a larger version.Very small computers...
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Ali Express "SDR TX/RX Switch" - A design not well thought out...
Figure 1: Front panel of the SDR switchI've you've been following this blog, you'll note that I've used SDRs (Software Defined Radios) a bit - particularly for reception. Transmitting in the vicinity...
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Repairing a NanoVNA "V2" (Blown up input)
Figure 1: The SAA-2N, a variant of the Version 2. As noted in the textI chose this version as it had N connectors and was well suitedfor my specific needs and has served well for several years.Click...
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Using a PIR to reduce wear and tear on a Nixie clock
"Does a lit-up Nixie tube in a forest wear out even if there's no-one to see it?"Figure 1:The "Black'n'wood" Nixie Clock (blue back-light turned on)with the PIR (Passive InfraRed) sensor to the...
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Refurbishing a CIR Astro 200 HF amateur band transceiver
The Astro 200The CIR Industries Astro 200 is a compact, synthesized 100 watt HF transceiver from the mid-late 1970s that covers the 80, 40, 20, 15 and 10 meter bands. Intended for both home and mobile...
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The construction of a hybrid ring combiner: Using the same duplexer, feedline...
Two transmitters, one antennaThere are occasions when it is desirable to combine two transmitters and receivers onto a single antenna - perhaps at a busy repeater site where more than one link is...
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A 15 (and 10) meter high-pass filter for Field Day
QRM from a transmitter to receivers on lower bandsA friend of mine belongs to a club in a town north of me and he was describing an issue that they've been having for the past several years during ARRL...
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