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Radio Broadcast Technical Consulting and Sales
10032 Island Drive, Brainerd, MN  56401
Phone: 218.829.1326   

VSWR Calibrator
For FM Broadcast Transmitters

Built by M. W. Persons and Associates, Inc.
Made in Minnesota

This handy device is for setting calibrations on VSWR (Voltage Standing Wave Ratio) meters, otherwise known as forward and reflected power meters commonly used on FM broadcast transmitters.  The inspiration was an article written by Steven Rutherford in the Broadcasters' Desktop Resource and was built for radio broadcast engineer Jim Offerdahl at his urging.  Modified from the original concept, this instrument can help a radio broadcast engineer set reflected power meters and trip/fold back protections for transmitters.
Very simple and straightforward on the inside.  Easy to maintain. 
Just 6" x 2.5" x 2", it is run on three AA batteries.  A switch selects either a positive or a negative polarity metering sample to a transmitter's metering system.  A green light indicates the outgoing 0 to 4.5 volt DC sample is negative in relation to its shield on the BNC connector.  If the light is red, it means the sample is positive.  A switch, with a center off position, selects which will be employed.  It all depends on the brand and model of transmitter this box might be connected to.  There is a PVC protector to keep the switch safe from breakage and to prevent the switch from being accidentally turned on.

A 10-turn output level control is used to carefully set the outgoing DC sample level for setting reflected power metering and transmitter protection circuits.  This requires a jeweler's screwdriver.  In addition, there are two blue tip jacks for a voltmeter to read the exact voltage being put out by the instrument. 

The cost for a VSWR Calibrator is $199.00.  
BNC to 1/2" or 3/8" coaxial connectors are available too as are BNC to BNC cables.


Questions?  Email Mark Persons:  teki@mwpersons.com       

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page last edited 02/22/2016