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Reviews For: Radio Shack MTA-20 Power/SWR Digital Meter

Category: SWR & Wattmeters & Dummy Loads

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Review Summary For : Radio Shack MTA-20 Power/SWR Digital Meter
Reviews: 12MSRP: $120.00
Description:
Radio Shack MTA-20 Power/SWR Digital Meter Maximum power rating is 2000 watts. Reads average and peak power.
Product is in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00124.4
WB0KWJ Rating: 2023-11-01
A good meter with poor ergonomics Time Owned: 3 to 6 months.
The Radio Shack MTA-20 SWR/Watt meter provides power and SWR readings into the amateur legal limit range, from 1.8 to 30 MHz. It can show peak and average power and SWR. The display and sensor units are separate, so that if you were to come across one without other, not an uncommon experience, either could be usefully adapted to other orphan sensing and display units. It requires 12 volts to operate, and uses a standard barrel connector. The display unit is a little more than an inch high and four inches wide, so doesn't take up much room.

It is no longer in production. They range in cost at hamfests from about $20-$80.

Accuracy is good across the HF range. If you have the service manual, which can now be found online, calibration is possible.

Some caveats. The display selection buttons are recessed and very small. Unless you've attached the display to something that doesn't move, pushing the buttons is a two-hand operation--one to hold the unit and the other to press a button.

The button markings are similarly too small to read, except up close.

The unit comes with a mounting bracket which can be positioned on the top or bottom, but will not allow mounting directly from behind.

Finally, the liquid crystal display is far too dim, and there seems to be no contrast adjustment. These are older units, and some dimming would be expected. However, I recall these never being very clear, even to much younger eyes. It is possible to disassemble the display unit and replace the four very dim orange LEDs with two bright white LEDs. Doing so seems to help display clarity a lot. This is an intermediate-level modification, as there is a lot to take apart, and it is not just a matter of soldering in new LEDs.

In sum, this is a good meter with poor ergonomics.
NQ4T Rating: 2016-07-21
Easy to read and use Time Owned: 0 to 3 months.
It was a hot summer afternoon as I ran around a hamfest trying to find an SWR meter that wouldn't break me after buying other goodies. My one SWR meter was a croas needle inside my MFJ tuner...the other was an antique Midland that was a pain to use.

I was surprised to find this thing at them hamfest for just 20 bucks...with everything still in the box. I plunked down my Jackson and took it with me.

Out of everything I bought that day...this little meter has been the handiest. I no longer have to guess my power output or SWR. Needles are nice...but the digital precision cant be beat.

Im sure its by no means the most accurate thing out there...but its more than what I need and with its 2000 watt handling,I wont have to buy another meter.

I do suspect the coupler can be used with other projects down the road...giving even more reason Im glad I bought this. But its quickly become my most used meter....even more than the one in my tuner.


NY2KW Rating: 2012-08-01
Outstanding - Best Price For Value Time Owned: 3 to 6 months.
I recentlly got a basket case MTA-20 and made huge efforts to find a complete Service Manual without success. Meter readings fluctuated wildly and totally inaccurate. I disassembled the Coupler - it is a very well constructed design with a sophisticated Bruene bidirectional coupler. I could not check component values without a Service manual but I checked for obvious shorts, etc and found none so I took apart the meter. That was a bit of a job but again very well constructed with SMD technology and microprocessor. I found several low value SMD resistors that read open and I even removed a few only to find they were fine. I figured bad solder joints so I reflowed all SMD components with a low power fine tip solder iron and reassembled. It works perfectly !! I got calibration instructions from one of the previous MTA-20 reviewers and I calibrated against a NIST HP 438A powermeter from 1W through 1000 W. This meter now reads within 2% of my Powermaster, Alpha and MeterBuilder powermeters. For SSB you have to keep the meter on Peak and only use Average for CW or Digital. I found an original owners manual and Radio Shack in later years added an addendum noting that for accurate SSB readings not to use Average which updates to quickly to be useful. For a fraction of the cost, this meters performs as well as any of the modern digital meters, with a small size and easily readable meter face. In fact, I fed it a 200mW signal from a NIST calibrated HP8920B service monitor and it read it as 0.18W while my expensive Powermaster did not even trigger a blip. It is quite linear across 1.8-30Mhz from 5W up to 1500 into a dummy load. Less than 5W it reads a bit low, ~ 5% off. I dont know about all couplers but mine also reads 50Mhz though consistently about 5 watts low but very useful for 6m as well. I am looking out for more of these and hope to find a full Service Manual. If you see one working well better buy it !!

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Earlier 5-star review posted by NY2KW on 2012-08-01

I recentlly got a basket case MTA-20 and made huge efforts to find a complete Service Manual without success. Meter readings fluctuated wildly and totally inaccurate. I disassembled the Coupler - it is a very well constructed design with a sophisticated Bruene bidirectional coupler. I could not check component values without a Service manual but I checked for obvious shorts, etc and found none so I took apart the meter. That was a bit of a job but again very well constructed with SMD technology and microprocessor. I found several low value SMD resistors that read open and I even removed a few only to find they were fine. I figured bad solder joints so I reflowed all SMD components with a low power fine tip solder iron and reassembled. It works perfectly !! I got calibration instructions from one of the previous MTA-20 reviewers and I calibrated against a NIST HP 438A powermeter from 1W through 1000 W. This meter now reads within 2% of my Powermaster, Alpha and MeterBuilder powermeters. For SSB you have to keep the meter on Peak and only use Average for CW or Digital. I found an original owners manual and Radio Shack in later years added an addendum noting that for accurate SSB readings not to use Average which updates to quickly to be useful. For a fraction of the cost, this meters performs as well as any of the modern digital meters, with a small size and easily readable meter face. In fact, I fed it a 200mW signal from a NIST calibrated HP8920B service monitor and it read it as 0.18W while my expensive Powermaster did not even trigger a blip. It is quite linear across 1.8-30Mhz from 5W up to 1500 into a dummy load. Less than 5W it reads a bit low, ~ 5% off. I dont know about all couplers but mine also reads 50Mhz though consistently about 5 watts low but very useful for 6m as well. I am looking out for more of these and hope to find a full Service Manual. If you see one working well better buy it !!
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Earlier 5-star review posted by NY2KW on 2012-02-02

Just picked one up in excellent shape. It tracks within 5% of my PowerMaster meter in both power and SWR from 1.8 - 30Mhz. Small, compact, accurate, easy to read - perfect for my workbench or if I go portable (comes with mounting bracket). Quality is far far better than MFJ products/
KG4FET Rating: 2012-02-22
accurate and easy to read Time Owned: 0 to 3 months.
Closer to a 5 then a 4 BUT...I had one of these years ago and kick myself for ever selling it. Found a used one for a heck of a price on QTH and bought it. It is everything I remember it is and more. Reads SWR or power in 4 settings (20/200/2000/Auto
Pros:
>Easy to read metering. The Digital read out is easy to read from every angle I can think of.
>Very good accuracy swr and power out.
>SWR is self calibrating. This is the reason more then any that it replaced the Welz SP-122 (Yaesu YS-60) on the primary station.
>Accurate power readings from QRP to QRO
>Remote mounting of the sensor. This has allowed me to put the display where I need it most and keep the remote at the amp.
Cons:(all minor)
>back light could be brighter
>reads SWR OR power not both like a cross needle meter. Switching back and forth is easy with a push of a button.
>Power takes a second to catch up when tuning the amp. To me this is actually a good thing. It has forced me to key for a few seconds less then I had with the Welz so the amp is not keyed as long during tune up
All in all this is an everyday user here and does a heck of a job for me. Nice for a portable operation as well. On peak it will hold the power reading long enough for a quick glace. If your a needle watcher this IS NOT the meter for you, if you need an accurate watt/SWR meter with a nice big display get one by all means. It is out of production but the manual is on line but it is self explanatory for the most part.
Bob Brown Rating: 2011-12-22
Old but very good Time Owned: more than 12 months.
I have owned this meter for over 10 years and it still works great. It seems to be quite accurate and I can rely on it for good readings. I was able to purchase a Service manual for it, so if it ever needs to be worked on or calibrated, it can be done.
NYTESKYY Rating: 2007-07-17
May be nice Time Owned: 0 to 3 months.
This may be a nice meter - I cannot tell, it jumps numbers so fast - never sits even close to one area. I installed in my car anyway because it looks so good.....and at least the swr meter is stable..
W9AC Rating: 2006-10-11
Excellent Accuracy Time Owned: 0 to 3 months.
I wanted to add one of these meters to my wattmeter collection and to test it against some of my best references. The MTA-20 almost perfectly tracks with my Alpha 4510 and LP-100 Vector wattmeters.

The MTA-20 is back-lighted with a soft orange color making it easy to read in the darkness. Display contrast is excellent.

What is most impressive is the build quality of the directional coupler. I was expecting a simple Bruene bridge but the sensor in this unit is much more sophisticated. I am really surprised to see that this is a R/S device. Whoever they contracted with designed one of the the most advanced wattmeters available for a ca. 1995 design.

The meter displays peak/average modes, can auto-select power ranges and can even be placed into a calibrate mode if the user wants to calibrate it against a known reference.

SWR accuracy is excellent across a wide power range, but requires several hundred ms in order for a reading to display. On CW, one must press and hold Tune in order to view SWR.

Overall, a very impressive product.

K0SSI Rating: 2006-03-12
Great SWR Meter Time Owned: more than 12 months.
I have 2 of these meters, one installed in my Jeep Grand Cherokee and one here in the shack. the remote mount sensors are great, and for mobile use, much more stable and reliable than an analog meter. I'll match either one to a Bird 43 wattmeter any day of the week!
73
Bill
KE9K Rating: 2005-07-14
GREAT METER ! Time Owned: more than 12 months.
I liked the first one I bought so well that when I ran across another one I bought it. Never a problem with these meters in 6 years. Joe ke9k
WB4M Rating: 2005-07-13
Mine didn't last long Time Owned: 0 to 3 months.
I bought one of these meters just as RS was closing them out; think I paid around $40.00 for it new. It was the first and only digital meter I've used, and I liked the small size with easy to read numerals. Sad part is, the power reading circuit failed after only a few months use. The auto-SWR circuit continued to function. I eventually bought another meter, not a RS model, but a SWR/Power meter that used the normal analog scale.
I see these meters being sold on eBay, and I am amazed to see people bidding up to $100.00 for this meter! I never had another meter such as a Bird to make comparisons, so I cannot say how accurate the meter is.