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Reviews For: LDG DWM-4 Digital Watt Meter

Category: SWR & Wattmeters & Dummy Loads

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Review Summary For : LDG DWM-4 Digital Watt Meter
Reviews: 8MSRP: $129
Description:
This is a four channel microprocessor controlled RF wattmeter. Display unit and up to four remote sensors. LCD display shows forward,reverse power and swr. For HF,HF/QRP,VHF,UHF.
Product is in production
More Info: http://www.ldgelectronics.com
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0084.9
W9OY Rating: 2004-05-16
Accurate as a Bird and measures 4KW Time Owned: 0 to 3 months.
I bought one of these meters used, because I have 2 HF stations and the top shelf was starting to be taken over by wattmeters. Also I was annoyed by the need to switch between forward and reflected, or change slugs etc. so I wanted something that would give me all the readings at a glance, on either station without pusing any buttons, or flipping any slugs. The DWM-4 is out of production, so I was concerned about getting a second high power sensor but I thought I could reverse engineer a sensor so I took the plunge.

After looking over the schematic it looked like about any sensor would work with a little fiddling with the calibration, so I bought a sensor for a Palstar WM150M mobile wattmeter from Palstar. Palstar will sell you these sensors. I had to add 2 100K pots for calibration and a stereo 1/8" jack to the Palstar sensor. (Note: the tip of the plug is reflected and the stereo sleve is forward.) The pot was set up as a voltage divider and not just a variable resistor. One end goes to ground, the other going to the voltage from the diodes, and the variable leg goes to the DWM. Follow the calibration instructions in the DWM-4 literature. It works fine. The tracking between the LDG sensor and the Palstar sensor is within five to ten watts between 100w and 1500w output, and it is dead on with the Bird over this range as well. Under 100W the accuracy is a little worse because a few watts difference becomes an ever increasing percentage of innaccuracy.

In doing this experiment I noticed the output voltage from the DWM 2kw sensor was quite low compared to the output from the 150W sensor, so I used a 9v battery and a pot to explore the range of the DWM-4 on high power. Using this dummy sensor I found the DWM will read up to 4KW before it faults. I don't have an amp capable of 4KW but I can put out 2500W into my B.A.D. (big a** dummy) and it works fine, so over at least a 14 db range this thing seems to be as accurate as a Bird.

So here is the deal. 4 channels peak reading or average reading independantly selectable, with calculated SWR, SWR protection, probably up to 4KW on HF, and usable on VHF and UHF as well. The sensors can be remoted just about as far from the Meter as you want. It uses 1/8" stereo lines between the meter and the sensor so you can go to radio shack and buy a line for a couple bux if you want a different length. The meter can be set so that what ever sensor is active automatically is displayed, or you can manually choose a given sensor. I did not check the accuracy of the VHF and UHF sensors since I don't have that equipment hooked up anymore, but looking at the construction of the UHF and VHF sensors I see no reason that these bands would not be as accurate as the HF sensors. A commercial source for HF sensors is available. The Palstar likely can be calibrated as a low power HF sensor as well. I did not try this yet but the Palstar sensor has plenty of output so I expect it would work fine. In fact you could probably add a second set of pots and a seperate jack and you could use the Palstar as a low power sensor read off one jack and a high power sensor read off the other jack, or you could leave the pots out and use the calibration inside the DWM-4 on a given channel specifically for this low power palstar input. I have made sensors before, and it is not be that big a deal to make your own sensors, if you have the parts laying around, but by the time you procure the parts and a good box to put it in, and pay shipping charges, its just as easy to buy one. I expect the Ameritron WM30 mobile meter sensor would work as well.

Overall I am happy with the way this meter works, and it adds a lot of versitility while reducing button pushing and clutter to the station. Its a lot of fun to play with as well, and make it do what you want it to do.
K0PSK Rating: 2001-10-26
Nearly Excellent Time Owned: 0 to 3 months.
Make that a 4.5.

I found this item via the reviews, and bought it based on the reviews and the fact that the user/building manual was available to anyone who cares to peruse it.

This meter works very well (so far). I am impressed by my "perceived" accuracy. I would like to put it up against a "calibrated" meter to
get a real feel for its actual accuracy.

Why didn't I give it a 5?? A couple of minor but noteworthy "gripes".

A. The excellent feature (HiSWR) Relay only "closes" a relay in HiSWR condition (NormallyOpen). This reqires a minor (cut trace + jumper) modification to change it to Normally Closed operation. Making it "jumper selectable", would have been a "real nice faeture"(tm).


B. Sensors are essentially "married" (calibrated) to their respective input(s).
It seems like it could have been "module-ized". Possibly even "sensing" which sensor was plugged in where. (yes this last bit would have added additional complexity and cost).

C. The "enclosure" could/should have been made out of a moderately heavier gauge material. It is a little light for a meter IMHO. When flipping switches and pushing buttons, the meter has a tendancy to "slide back" on the surface it is placed on.
The supplied sheet metal screws stripped out 2 of the 4 holes that hold the cover to the chassis.

Overall This is an excellent product (especially for the price). I am very happy so far, and I would recommend to anyone. When I needed to change the normaly open alarm relay, to normally closed. The staff at LDG answered my email in under 24 hours with the modification included in their reply.

According to LDG theese meters are out of production, and they have stock on hand for only 2-3 more months of orders. If you want one, don't wait much longer to get it.



LDG seems like an excellent company to do business with. My only other experience was with their Z-11 Tuner I used on a friends rig. It worked great.

JNEWELL Rating: 2001-10-26
Agree with K6SBA Time Owned: 3 to 6 months.
I've been using this for about 5 months with two HF sensors and a VHF sensor. It works great, and LDG has been very helpful when I've had questions -- the hardware has been problem free, just the occasional user error!
K6SBA Rating: 2001-09-08
Buy One While You Can!! Time Owned: 0 to 3 months.
If you want a really fantastic, full featured digital SWR/power meter, you better buy one of these while you can. Due to lack of sales, LDG Electronics has decided to stop producing these gems. These meters come standard with your choice of TWO remote sensors (HF QRP, HF 150W, HF 2KW, or VHF/UHF). For a nominal cost, you can add to additional sensors to the meter.

Buy one while you can --- you have been warned!
W2VD Rating: 2001-08-07
Nice Product, Great Service Time Owned: 0 to 3 months.
I purchased my DWM-4 a couple of weeks ago. Much to my surprise, it did not work! I could not change from numeric to bargraph readings in position 1. In addition, the wattage readings were all over the place (I'm not talking about last digit jitter) and inaccurate. I called LDG, and spoke with a gentleman named Duane. Duane said that he thought that the CPU programming in the DWM-4 was bad. Much to LDG's credit, Duane sent out another unit with sensors immediately. I tested the new unit last night, and it works nicely. LDG stands behind its products. Even though the first DWM-4 that I received was defective, I would highly recommend this product to anyone (I also own an LDG AT-11MP which works great).
K8KHW Rating: 2001-06-06
Great Product Time Owned: 3 to 6 months.
Hello I have used the DWM-4 watt meter in my mobile for some time and it really does a great job. I use a screwdriver in the mobile and the swr alarm feature is really nice, just program where you want it to be and tune the ant intill no alarm and your ready to go. I also don't know how they do it for the price, And yes the High power remote is a great new product, it would be great in the shack, 73's guys Randy
W1WWJ Rating: 2001-06-06
Excellent Meter Time Owned: 0 to 3 months.
I just recieved the high power sensor for HF and compared it to my Bird 43. Right on!!!! This meter is high quality, allows 4 sensors (New High Power 2000 Watt). Great buy at $129. Can't go wrong, I do not know how they can do it for this price?
KG4EHV Rating: 2000-09-20
Very nice unit Time Owned: 0 to 3 months.
Great to have four radios on one meter. Super fit and finish. Sales staff was wonderful.