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Coaxial Dynamics Model 81090 & 81091 Wattchman
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 Protects Your Transmitter From High
   Reflected or Low Forward Conditions

 Continuous Display of Forward
   and Reflected Power

 Audible and Visual Alarms

 Fast Fault Response (15ms)

 Remote Reset Provision

 110/220 VAC Input Switch

 Amplified DC Outputs

 Two Year Limited Warranty


The Coaxial Dynamics Wattchman Monitor/Alarm measures forward and reflected RF power simultaneously in 50-Ohm coaxial cables and transmission lines. It is compatible with our entire series of 7/8" through 6-1/8" Line Sections and will accept plug-in elements that range from 5 watts to 100 kW full scale from 0.45 MHz to 2300 MHz.

Similar in appearance to our 81070 & 81080 Series these units provide improved functionality at a reduced cost. Both models feature forward and reflected trip adjustments, a built in DC amplifier and 110/220 VAC input switch. Model 81090 has our standard 5/10/25 scales and Model 81091 has 15/30/60 scales.

A Station Monitor/Alarm system installation consists of a Wattchman, a dual socket Line Section and two plug-in elements for monitoring both forward and reflected power. The Wattchman is supplied with two 25-foot DC cable assemblies for connection to the line section, and a 6 foot AC power cord. Installation requires inserting the line section into the transmission line, connecting the terminals of the transmitter interlock systems to the proper terminals on the Wattchman and providing AC power.

Abnormal load conditions quickly cause transmitter shutdown within less than 15 milliseconds (including control relay). An audible single tone alarm will indicate system/transmitter malfunction. Relay contacts are provided for remote alarm and reset switching. Fail-Safe or Non-Fail-Safe mode is selected by a switch located on the rear of the instrument.

Your confidence in the quality and dependability of the Models 81090 and 81091 Wattchman is assured with the Coaxial Dynamics Two Year Limited Warranty.


Power Range

5 W to 100 kW

Frequency Range

0.45 MHz to 2300 MHz

Meter Specifications

30A full scale, 5%
1400 ohms terminal resistance
4-1/2 inch movement


5% when used with proper Coaxial Dynamics
line sections and elements

Response Time

Less than 15 milliseconds
(including control relay function)

Front Panel Controls

Push button reset
Trip set adjustments

Rear Panel Controls

Audible alarm switch
Fail-Safe mode switches
110/220 VAC input switch


Meter inputs
NO/NC control connections
Remote alarm connections
Remote reset connections
AC power receptacle
Amplified DC Outputs

Contact Ratings

5A at 110 VAC non-inductive

Power Requirements

110/220 VAC, 50/60 Hz, 10 Watts maximum

Dimensions (H x W x D)

5.25 in. (13.3 cm) x 19 in. (48.3 cm) x 8 in. (20.3 cm)


9.0 lbs. (4.08 kg)


Textured Blue Polyurethane Enamel Front Panel
Alodine (Yellow Iridite)

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