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Welcome

: Thank you for your purchase of the DWM-4 Digital Wattmeter. The DWM-4 represents

an advancement in technology that has never before been available in RF power measurement.
With the integration of a microprocessor to existing RF sensor technology, the DWM-4 offers the
flexibility of digital processing while keeping the interface to the user simple and straightforward.

Introduction:

 The DWM-4 is a four channel, microprocessor controlled RF wattmeter. It consists

of two main parts, the display unit and the remote sensor. The display unit has a 2 by 16 backlit
LCD module that provides the user with information about the RF that is being sampled by the
remote sensor. The user can simultaneously view forward power, reverse power and swr on the
same display for instant analysis of the antenna system.

There are two types of remote sensors. The HF/QRP sensor can sample RF from 1.8 to 54 MHz
and up to 150 watts. The VHF/UHF sensor can sample RF from 140 to 160 and 420 to 470 and up
to 150 watts. The modular design allows for the maximum flexibility with the minimum cost. The
remote sensor is supplied with a six-foot cable to connect to the display unit. A longer cable can be
used for truly remote sensing.

The display unit is controlled by a selection of menu screens on the display. The menu screens
and the data on them are selected by the two pushbuttons (Menu and Select) on the front panel.
Status information is also shown on the display.

Building the Kit:

 If you purchased the DWM-4 as a kit, the following instructions will give an

overview of how to assemble it. If the DWM-4 was purchased assembled, you may still want to
review the assembly instructions to become more familiar with the unit. If you want to get right to
operating the unit, skip the assembly instructions and go right to the operation section.

Before getting the soldering iron out, go through all of the parts in the kit and familiarize yourself
with each component and its placement. Most of the parts are common, but there may be a few of
them that may be new to some builders. There are just over 100 parts and 200 solder connections,
so take your time.

The instructions are written to assemble the unit using the height order of the parts form lowest to
highest. This will assist the builder in the installation of the components. There are various photos

Summary of Contents for Digital Wattmeter DWM-4

Page 1: ... minimum cost The remote sensor is supplied with a six foot cable to connect to the display unit A longer cable can be used for truly remote sensing The display unit is controlled by a selection of menu screens on the display The menu screens and the data on them are selected by the two pushbuttons Menu and Select on the front panel Status information is also shown on the display Building the Kit ...

Page 2: ...e the band polarity ___ Install the 10K 10 pin SIP resistor RP1 Be sure to note the orientation of the SIP resistor A small line or dot on the side with writing marks pin 1 ___ Install the 01uf monolithic capacitors C1 3 5 7 10 12 15 17 20 22 25 ___ Install the ceramic capacitors C6 100pf 1KV C26 27 10pf 500v ___ Install U2 the 7805 Align the 2 hole in the regulator with the 2 hole in the PC board...

Page 3: ...C board ___ Install the 14 pin header J8 Solder the shorter ends of the pins to the PC board ___ Install the relay K1 Be careful not to bend the pins over pushing them in You are finished with the assembly of the DWM 4 Main PC board Proceed with the assembly of the Front Panel PC board Assembly of the DWM FP PC board ___ Install the 10 pin header J7 with 0 1 inch spacing to the side of the front p...

Page 4: ...the hole and replace the washer and nut on the switch Be sure the solder terminals of the switches are aligned one on top of the other You may need to realign the switches later so don t tighten yet ___ Place the LEDs in the front panel board D1 Green D2 Yellow Be sure to place ground side down The ground leg of the LED is the one with the notched plastic next to it Do not solder them at this time...

Page 5: ...uld match the socket ___ Install U3 the LM339 by carefully pressing it into place in its socket Note that U3 has a notch that should match the socket ___ Install the ribbon cable with the red stripe connecting pin 1 of J7 to pin 1 of J7 2 x 7 header on the front panel ___ Install the ribbon cable with the red stripe connecting pin 1 of J8 to pin 1 of the LCD Module on the front panel VHF UHF Remot...

Page 6: ...t this time ___ Place the PC board onto the SO 239s Align the 1 8 jack with the hole in the enclosure Once this is in place you may tighten the nuts that are underneath the PC board You do this by pressing the board down on the nuts while turning the screw Repeat with the other three screws ___ Install the remaining four nuts on top of the PC board and tighten ___ Solder the SO 239s to the PC boar...

Page 7: ...te you must wind this in the direction shown in figure 2 ___ After scraping the insulation from the ends of all four wires connect the green 2 wire to the red 1 wire and twist together You will now have three leads the red wire on the left the twisted pair and the green wire on the right Do not install T1 yet ___ Install all of the resistors R1 2 3 and 4 ___ Install the 1N4148 diodes D1 and D2 Not...

Page 8: ...ncluded in the kit to the PC board in the hole to the left of T1 Place the other end through the center of T1 and solder to the bottom of the PC board ___ Install 1 8 stereo jack ___ Unwrap the enclosure Install the SO 239 connectors Put one 4 screw in hole and place two nuts on the screw Do not tighten them at this time ___ Place the PC board onto the SO 239s Align the 1 8 jack with the hole in t...

Page 9: ...mote sensor Connect the other end to input 1 on the DWM 4 display unit Other remote sensors for a total of four can be connected the same way to other inputs on the display unit Operation Turning the display unit on will show the model and software version of the DWM 4 The power LED is software controlled so it will only come on if the software is running properly You may have to adjust the contra...

Page 10: ... and holding the Select button turns on the alarm and counts from 1 1 to 30 0 for the alarm threshold Pressing the Select button again turns off the alarm The RELAY THRESHOLD menu is separate from the ALARM THRESHOLD The Select button works as it does with the ALARM THRESHOLD but only controls the operation of the relay K1 The RELAY RESET menu chooses between MANUAL and AUTO reset In MANUAL reset ...

Page 11: ...ed as table top or under shelf by using the mounting bracket The mounting bracket can also be used in a mobile installation The remote sensor is supplied with a six foot cable The sensor is usually mounted near the transmitter but it is possible to mount the remote sensor at the antenna for remote sensing Be sure to note that when mounting the sensor at the antenna the use of an antenna tuner will...

Page 12: ...ered with acid core We reserve the right to refuse repair due to excessive problems or damage due to construction Before any unit is sent to us you must first call or e mail to get return authorization All units sent back must be prepaid either by check money order or Credit Card unless other arrangements are made Package the unit carefully and keep in mind that we will use your packaging to retur...

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