2M Cardioid Pattern Directional Antenna

This highly directional 2M antenna is ideal for fox hunting or pin point location of an interfering source. The two phased verticals are a long known method to null signals in one direction. A broad frontal pattern makes locating a signal easy, then the null is very sharp to hone in on a signal source's location.



Bp-Br Repeater Duplexers

This is a more complete treatment of VHF duplexers than the previous work below. This is the most helpful information that I have seen for new repeater installations.  It also is a good source of information for troubleshooting or reviewing repeater performance. 

NOV 16, 2022 Another gem from WA5OKO, this one a highly directional 2-M Cardioidal pair of verticals.    


Feb 12, 2020 Two more WA5OKO articles interesting for RF measurement methods.  "VHF and UHF Antnna Testing" and "NanoVNA User Guide".
Nov 21, 2019  "Installing Amateur Radio Duplexers" by Jerry Ritcie, WA5OKO.  See below for a must read for anyone who owns, survices or installs Amateur Radio Repeater.




Dec 12, 2010 Power Supply Restoration Rev A is now available. Extra pictures and details for reworking an Astron RS-35M included. 
Aug 6, 2011 "Amateur Radio Station Grounding and Lightning Protection"is now available. WP30A190 in pdf format or see description below.


Oct 1, 2011 "Panel and Chassis Construction" describes the techniques used to create the projects on this website. 


NanoVNA Users Guide

These inexpensive VNA are gaining popularity in the Amateur Radio market.  Selling for around $45 they are an excellent value for those needing to better understand the RF performance of their Amateur Radio station feed lines and antennas.

VHF and UHF Antenna Testing

VHF and UHF Mobile Antenna Testing has some pitfalls you may want to understand. Jerry’s article is a good read -see VHF UHF Ant Testing.

by: Jerry Ritiche WA5OKO


Installing Amateur Radio Duplexers

Understand the expensive duplexers only work properly when all ports are terminated into 50 Ohm loads.  The advertised specds only apply when such is the case. Read more....

by: Jerry Ritiche WA5OKO


Rectifier Design and Analysis.

Free Spreadsheet Calculator download.

Rectifier Design and Analysis. FW center tapped and FW Bridge Rectifiers designed accurately. Have you ever needed to calculate the voltage and currents in these circuits without using complex and tedious differential equations and integral calculus?  If you have, you will want to try this!  

Theory and practical design tools allows you to select optimum capacitor, rectifier diodes and transformer for your specific application - not just another chart.  Only requires an Excel® Spreadsheet.

Power Supply Restoration.


SP-10A-1 Single Driver Speaker


For those old dead linear power supplies new life is a fairly simple restoration project.  Shown here is an Astron RS-35M that was a victim of lightning but has now been restored to better than new condition with a simple 3 transistor regulator board.


Surpising performance from a simple to build, single driver, tuned port speaker.

Panel and Chassis Construction


Several request for information on how the panels and chassis were made prompted me to add this document. The processes, materials and software used are disclosed. Feel free to modify these to suit your needs and capabilities. 
Amateur Radio Station Grounding and Lightning Protection
See more pictures
Proper station grounding and lighting protection are important aspects of installing a radio station. "Amateur Radio Station Grounding and Lightning Protection" is an introduction to this complex subject. References are linked from the document for further study.


The image to the left is of the oak tree in the center of the image on the right. It is 65 feet from the tower and shared a lightning event with it July 5, 2011. The radio station and feed lines survived fine, would your's?

Amateur Radio Station Grounding and Lightning Protection

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