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A circularly-polarized, "omnidirectional" antenna
The idea of s circularly-polarized omnidirectional antenna is a bit hard for some folks to wrap their heads around, but they are quite common: Antennas used on GPS receivers are circularly-polarized...
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Avoiding "blowed up" speakers!
Several years ago I finally got around to installing my dual-band FM transceiver in my car permanently and in so-doing, I put a speaker in a location under the dash where one might have been had it not...
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Quieting high-current switching power supplies used in the ham shack.
Over the years I have acquired several switching supplies that I use in the shack and in portable operation such as field day. These power supplies (two Samlex model 1223's and a Radio Shack #22-510)...
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Generating low-distortion audio sine waves using a PIC and DDS techniques
Over the years I have collected a number of service monitors (see the posting about the IFR-1000 and Cushman CE-50A) but the one that I use most often is a rather strange bird, a Wavetek/Schlumberger...
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Sleuthing the source of a SARSAT signal?
It was August 11, 2006 - a late Friday afternoon - and I received a telephone call from Gordon, K7HFV and with him on the line was John, WA7UUJ with an unusual request: The FCC's Denver field office...
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Repair of the speedometer on a Polaris Sportsman 500 4-wheeler
Last year, a friend of mine had the battery go bad on his 1999 Polaris Sportsman 500 4-wheeler. Aside from the inconvenience of having to pull-start it, it seemed to work OK.Sort of.Soon, it was...
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Fun with the Microchip PICKit 3 and the Sure Electronics DB-UD11111 ZIF adapter
For many years now I've been using my old, trusty Picstart Plus programmer for my PIC-based projects. Having used PICs since about 1990 - and having a reasonable suite of development tools, including...
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Attention-getting brake light "modulator" for a motorcycle.
Figure 1:Figuring out how to remove the tail light. It requiredremoving the bracket and license-plate holder just toget to the bolts that hold the light in place.Click on the image for a larger...
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Improving the bass response of a (cheap) subwoofer amplifier system by...
Several weeks ago I happened to be at a local electronics type store (I'll admit it, it was Radio Shack!)and they had on clearance - for a pretty good price - a nice-looking set of computer speakers...
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A simple inverter for driving neons/nixies using Radio Shack parts
I was visiting a friend of mine a few weeks to who was helping me repair the Model H horn on my old Atwater Kent 20C receiver. This radio and horn lives in my office at work and one day, I heard a...
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RIP Gretchen cat
In the summer of 2001, in the courtyard of the apartment complex where my older brother lived at the time a feral mother cat had a litter of 4 kittens: Two males and two females. When they were about...
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A Stand-alone ICSP Interface/programming board for 8 and 28 pin AVR...
Several weeks ago I got an "Ultimate 3" transmitter kit from Hans, G0UPL (See the web page http://hanssummers.com for more information) and built it with no problems. As is often the case with a...
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First foray into the world of Arduino
Before Christmas I was ordering a few things from Amazon and was somewhat surprised when I was unable to check out with a few smaller items that completed the order. Puzzled, I dug around and...
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Low Pass filter for MF/LF (600 meter) reception
About a month ago I fired up the SDR-14 (a wide-bandwidth software-defined "receiver") to "listen" to some longwave signals from some (relatively) high-power stations back east. These stations had...
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Analysis of a repeater's antenna pattern
Back in 1997 the antennas on the Utah Amateur Radio Club's 146.760 repeater were relocated and replaced - this, because the original, guyed tower on which the antenna was located was being replaced by...
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Examining the Glencom VC510 UHF to L-Band Upconverter
This is a curious little device - of which several have fallen into my hands.Often available on EvilBay for fairly cheap, these are in some nice, die-cast Hammond (tm) aluminum boxes approximately...
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Making a cheap Chinese battery tester more accurate and useful
A few months ago I was ordering some stuff on EvilBay from a vendor and noticed, for only $5 or so, what looked like a nice, little battery tester with an LCD readout showing voltage."Only $5 - I'll...
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How USB car power adapters can ruin 2 meter mobile reception!
For decades now, the ubiquitous power adapter found in vehicles has been the "Cigarette Lighter Plug" - a 12 volt receptacle found in pretty much every vehicle made - for more than more than half a...
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A "Helical" resonator to increase isolation of 20 meter stations during Field...
As with many groups, the Utah Amateur Radio Club (UARC) operates both a CW and SSB station on 20 meters during Field Day. Being that 20 meters is typically one of the "prime" bands where most of the...
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Replacing the filters in the Drake SP75 Speech Processor
A few months ago I fired up my old Drake TR-7, getting on the air with some friends on 40 meters after not having used the radio for a while. It seemed to work fine - until I switched the audio...
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