KX4OMHere at KX4OM the main interests are restoring and operating vintage equipment, building stuff, Raspberry Pi computing, microcontrollers (PIC, AVR and Arduino), digital modes, QRP and straight key CW. You can contact me by email at: https://[email protected]
Site updated November 7, 2019. See under Technical Solutions: Updated 12-th Wave Transformers and added Tempo AC One and Galaxy AC-400 power supply restorations.
Here are some projects that I have completed. The link to the project page is in Green.
A Scalar Network Analyzer.
Always wanted a spectrum analyzer or VNA but the price of admission to those clubs is too steep? Consider a scalar network analyzer. You can sweep filters, antennas and characterize crystals. This is my build.
If you build or restore SSB transmitting equipment, you need to be able to check the modulation waveforms. Here is my TTG.
The 8640jr is a variable oscillator RF signal source designed by Wes Hayward, W7ZOI. Like its namesake, the Hewlett-Packard HP-8640 signal generator, it uses a high frequency oscillator range and divides it down for lower ranges. In my case, the 13 - 33 MHz range is digitally divided by 2 to get the iddle frequency range, and then divided by 2 again for the low range. Here is my 8640jr build.
Log Power Meter
This version of the Log Power Meter was designed by Wes Hayward, W7ZOI and Bob Larkin, W7PUA (June 2001 QST; article available as a Members Only download). See my detailed description and step-by-step photos of the construction here.
A Step Attenuator is one of the most useful test units you can have in
the shack. Combined with a signal generator and a Log Power Meter or oscilloscope,
you can make very accurate readings of things like stage gain in a receiver or
transmitter. I built mine just a bit different than some others that I've seen,
focusing on shielding.
Check it out.
A 40 Meter Superhet with Digital Readout I built this receiver
for my grandson,who has an interest in all things electronic. It is based on Dave Benson,
K1SWL's SW-XX transceivers.
Here's the link to the project.
A Step Attenuator is one of the most useful test units you can have in the shack. Combined with a signal generator and a Log Power Meter or oscilloscope, you can make very accurate readings of things like stage gain in a receiver or transmitter. I built mine just a bit different than some others that I've seen, focusing on shielding. Check it out.
A 40 Meter Superhet with Digital Readout I built this receiver for my grandson,who has an interest in all things electronic. It is based on Dave Benson, K1SWL's SW-XX transceivers. Here's the link to the project.
ELSIE L-C Meter. The ELSIE LC meter is an accurate, simple device for measuring inductance and capacitance. The ELSIE was designed by Joe Everhart, N2CX and Steve Weber, KD1JV. At one time it was kitted by the American QRP Club, but it's no longer in production. I made a board using EAGLE Cad, although it is simple enough for other methods. Although I now have an LCD-readout tester from eBay, the ELSIE is very handy when checking out capacitors, especially variable caps at hamfests. Here's the finished ELSIE.
The NoGa PiG (Power Indicator and Guard) ...don't hook up your DC supply to your QRP rig without it. It's invaluable during testing of those new designs and kits. It can save your circuit and $ worth of power supply fuses).
A 30 meter transceiver for Straight Key Night.
I built this rig for operation on Straight Key Night a few years ago. Click on the link and see the work as it progressed through the building period. This rig uses a modified Vectronics VXO transmitter unit, and the receiver section from the SW-40+ transceiver (with components for 30m) designed by K1SWL and described in the Elmer 101 web project. Here is the link to the build.
An enhanced Guppy-WaTTa-PiG Multifunction QRP Accessory. This project is a culmination of a lot of work between Russ, AE4NY and some other members of the NoGa QRP Club and me over a couple of years. It combines several NoGa QRP club kits, commercial board units and some homebrew units. The result is a very useful box that simplifies QRP operation of various transceivers, transceivers and receivers. Click here for details.
A -20dBm 20 meter test source, designed by Jim Kortge, K8IQY. I'm not providing any build photos, etc., on this one, because it did it just like Jim did, down to the 1/4" copper shielding tape. This is my primary reference source of RF for adjustment and calibration work in a 50-ohm environment. It does indeed read -20dBm on my log power meters. Check it out on the k8iqy.com web site.
"The Challenger 40", a homebrew 40 meter transmitter based on the Wes Hayward, W7ZOI-designed transmitter in Chapter 1 of "Experimental Methods in RF Design".
A Sealed Lead Acid Battery Charger of a rather unique design, by Bob, AA4PB. The article appeared in the May 2001 issue of QST. Check out my finished build photos.
The Plug PiG includes most of the basic functionality of the NoGa PiG in a small package. I decided to build it because the PiG is an accessory I literally use every day I'm at the workbench or operating in the field. I had the idea that I could sure use one in the car. I took apart one of those odd-shaped cell phone charger-adapters, and re-engineered a PiG to fit. I added an LED to the circuit to indicate that voltage is available at the socket.
A home-brewed circuit board version of the Precision VXO and Crystal Test Fixture designed by Jim Kortge, K8IQY. If you homebrew superhets or SSB transmitters with crystal filters, you really need one of these test sets, or one of the other designs out there, for obtaining crystal parameters. Here's my version of the PVXO.
Making Twelfth-wave Matching Sections for Coaxial Feed Lines Updated November 7, 2019
Making Printed Circuit Boards
Restoration work on the Tempo 2020 transceiver - Updated - New source for sprockets!
Tempo AC One Power Supply Restoration
Galaxy AC-400 Power Supply Restoration
Here are some must-visit links to very fine technical information, used with permission:
This web site was sparsely created using NoteTab Light on
Windows XP and is now maintained on a couple of Linux Mint 18