By Aubra E Til ley WMT

This is not an article about how to build an impedance bridge. Instead, it is aimed at developing a better understanding of what a specific bridge design can do for you and to serve as a guide in selecting what to build. While considerable effort has been extended on the hardware side, the material presented has been derived primarily from mathematical models. A mathematical evaluation of bridge characteristics for a variety of bridge configurations with unique component parameters requires...

Zack Lau KHCP

A VHF Driver for Hybrid Power Modules While not ideal, hybrid power modules are often a good compromise for the homebrewer who needs watts of VHF power. Not only are they easy to use, but most are quite rugged with regard to output load a 20 1 SWR tolerance is not unusual. They are designed for 50-Q loads and already have the coupling capacitors built in, so the builder merely has to apply the power and bias voltages. The major disadvantage is the substantially higher cost of repair you...

Sweep Those Filters

Experimenter's Exchange American Radio Relay League 225 Main Street Newington, CT USA 06111 L.L. Grace introduces our latest product, the DSP-12 Multi-Mode Communications Controller. DSP-12 is a user programmable, digital signal processing DSP based communications controller. Multi-tasking operating system built in PC-compatible V40 architecture allows development of custom applications using normal PC development tools and languages Motorola DSP56001 DSP processor Serial interface speeds from...

The American Radio Relay League

The American Radio Relay League, Inc, is a noncommercial association of radio amateurs, organized for the promotion of interests in Amateur Radio communication and experimentation, for the establishment of networks to provide communications in the event of disasters or other emergencies, for the advancement of radio art and of the public welfare, for the representation of the radio amateur in legislative matters, and for the maintenance of fraternalism and a high standard of conduct. ARRL is an...

By Peter Traneus Anderson KCHR

This article describes a simple SSB receiver using the new Harris HSP50016GC-52 Digital Down Converter DDC .1 The DDC is a complete Weaver-method receiver implemented digitally in one CMOS chip,2-3 A simple SSB receiver using the DDC needs only an RF A D converter, an audio D A converter, and a source of configuration bits. When combined with a good A D and a DSP, the DDC can perform all functions of a modern high-performance HF communications receiver. The present version of the DDC is limited...

By Randy Henderson WIW

What motivated me to construct this test instrument Did the effort exceed the rewards Not when I build or otherwise deal with projects using crystal filters. Now that I have an easy and comprehensive way of viewing the results, the construction and alignment of crystal filters is easier and less intimidating. The system described here takes much of the guess work out of applying salvaged or new crystal filters. It adds to my success in quickly building filters from inexpensive microprocessor...