Introduction: The RVS-8 is a full featured repeater voting system designed to work with today’s amateur
and commercial repeaters. The voter features 8 channel capacity, menu driven display system, programmable
logic states, on screen “signal to noise meter”, site activity logging and more.
Once installed, the RVS-8 provides signal to noise based, “real time” automatic audio switching for up
to eight sites. Multiple RVS-8s can be cascaded to provide up to 64 channels of voting.
Building the Kit: The RVS-8 is a medium to large sized project (not for beginners). It may take the average
builder several evenings to build, check out and align the voter (we averaged about 3 hours for assembling just
the PC board). Besides the normal building tools needed (small soldering iron or soldering pencil, wire
cutters, screw drivers, etc.), the only test equipment needed is a voltmeter or oscilloscope.
Kit Assembly: Before starting, you may want to get a copy of the QST article where the RVS-8 first
appeared. Although not needed for construction of the kit and written for an earlier version, it contains a little
more general information about the RVS-8 and how it works. If you don't have or can't find the article, a
reprint may be available from QST, 225 Main St., Newington CT 06111. We've included the updated charts,
tables and information from the article in this manual.
Changes from the Article: A few changes were made since the article. The PC board size was increased to 6
by 9 inches. After building several prototypes (including the one shown in the QST article), it became
apparent that component spacing was too tight and the PC board was expanded for ease of construction and use.
A larger LCD module is now provided. We were able to find a source of larger, back lit LCD modules
with connectors that fit in the same vertical space. The new module is more readable and easier to connect. The
78L05 was also upgraded to a 7805 with heatsink to handle the extra current required of the back lighting.
The control circuitry has also been changed slightly. A new schematic is provided in this manual. An
LM339 was added in place of the transistor for the COR and DIS Select line. This provides smoother selection of
the multiplexed input bus and a driver for the output selector. A current limiting resistor was also added to the
+12 line of J6 to prevent resets in case of shorting.
All of the LM324s were upgraded to TL084s. The new chips are a direct replacement and offer much
less crossover distortion than the 324s.
U7 was changed from a CD4051 to a MAX 4051. The change provides an extra 20 db of cross talk
isolation. The chip is a direct replacement.
J3 (Disable input) was upgraded from a header to a screw type connector. There was extra room on the
board.
Be sure to use the schematic, parts placement, and connector pinouts provided in this manual. It
matches the latest PC Board layout. Those items in the QST article are now outdated.
The software changed somewhat from what was described in the article. All references to db have been
eliminated. We found it was possible for users to properly calibrate their system, but still not get accurate db
measurements on the LCD module. All references made to signal strength, hysteresis, and S/N ratio are now
relative references (shown as numbers, instead of db).
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