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Reviews Categories | Antenna Tuners | Dentron MT-3000 Help


Reviews Summary for Dentron MT-3000
Dentron MT-3000 Reviews: 32 Average rating: 4.7/5 MSRP: $279.95
Description: Dentron MT-3000
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K0OD Rating: 5/5 Oct 29, 2014 11:06 Send this review to a friend
Terrific tuner but metering is defective  Time owned: more than 12 months
Dentron's MT-3000A tuner has the honor of being the oldest piece of equipment on my operating desk. Acquired new for $350 around 1979, it served well for high power DXing and contesting on all HF bands. Nowadays I mostly use it to match to my 43' vertical for rag chewing. Performance degrades on 80 CW and especially on 160 where the occasional smell of melting Plexiglas warns that some watts are being lost to heat. Diehard 160 QRO ops should probably choose a heftier and much costlier tuner. Other hams will love the rugged and attractive MT-3000A.

My unit does suffer from a common and puzzling malady. The separate forward and reflected power meters have displayed erratic readings since Day One. K5LAD, WY3A and others blame this problem on improper bridge resistors R1 and R2. They argue that their resistance should be identical and probably around 50 ohms. Despite the MT-3000A manual listing values of 10 ohms and 43 ohms, my unit had resistors of 10 ohms and 47 ohms. The nearly identical Dentron W2 wattmeter also calls for resistors of 10 and 43 ohms. Is it possible that such an error went undetected until recently? I'm curious whether Dentron changed the bridge circuit during the tuner's years of production.

A rainy weekend provided time to tear into my tuner. First off I discovered that the internal dummy load was non-functional because the soldered-in fuse was blown. The wattmeter board with its questionable bridge resistors on the backside can be accessed by removing two screws and unsoldering a couple of wires. I decided to replace R1 and R2 with matched 50 ohms resistors. I examined the two cylindrical 1-8 pF trimmer caps C1 and C2 which are screwdriver adjustable through holes in the back panel. Those trimmers and three nearby pots are used for meter calibration. On my tuner C1 and C2 were difficult to turn with a jeweler's screwdriver which kept slipping from the slot. Dentron's skimpy manual says nothing about those adjustments.

Thanks to Bill Patton WY3A for composing calibration instructions: http://www.qsl.net/wy3a/Dentron_Mt-3000A.htm

The MT-3000A power meter, originally rated at +- 10% full scale accuracy, was never lab-quality. The meters are tiny by modern standards. Time and heat have surely taken a toll on components. But at least the power readings are now tolerably accurate and they rise and fall as expected when the matching controls are tuned. If you have ideas on further improving the metering accuracy please contact me at k0od@arrl.net
 
W8NVC Rating: 5/5 Oct 14, 2013 09:07 Send this review to a friend
Dentron #1  Time owned: 3 to 6 months
I own 3 Dentron tuners, the super tuner plus, the Dentron At 1-k and the mT 3000.
When i got a legal limit amp, i needed a big tuner.
I didnt want to break the bank with the Palstar.
So i found a good MT 3000. I was right. just like
the other Dentron Tuners i own, Just the Best.
No issues. you cant go wrong with a Dentron.
Made to last a lifetime. built like a tank.
 
WD5DJX Rating: 5/5 Aug 28, 2013 14:01 Send this review to a friend
Built like a Tank!  Time owned: more than 12 months
This tuner is one of the best tuners I have ever had the please of owning. I liked it so much, I bought 2 of them and use them every day. I have other tuners including a Palstar, but this thing will tune a barbwire fence if that is all you have for an antenna. The only thing that comes close is a Palstar or a Heathkit 2060. If you can find one and need a tuner, buy it! You will never regret it! WD5DJX - The Bull said that. BTW, mine are the MT-3000A model.
 
KC9YRX Rating: 5/5 Aug 26, 2013 22:27 Send this review to a friend
Someone has to pass away to get one.  Time owned: more than 12 months
The only way I could get one was from the estate of a silent key. No one in their right mind would sell theirs.
This thing can lay the reflected power meter flat on just about any part of the HF band. I run 200' of 450 ohm window line to an all band doublet @ 50'. All I had to do is tweak the window line length and the Dentron does the rest. Meter power buttons almost always pop off, but I just glued mine back on. I don't use the twin meters to tune it anyway, I have a big Swan WM-2000 at eye level.
If you have one, open it up. Man .. it's a work or art, clean lines, great solder joints.
The only way you'll get mine is over my dead body.
 
K5YZS Rating: 3/5 Mar 16, 2013 05:40 Send this review to a friend
Good on 40 Meters, But......  Time owned: more than 12 months
I bought my MT-3000A in 1980 and used it with Drake TR7 and Heath HA-14 (Kompact Kilowatt) on 80 meters thru 15 meters. So far so good. Then in 1985 I got interested in 160 m band after the noisy LORAN was shut down. I worked 160 meters with TR-7 barefoot as the HA-14 only went down to 80 m band. During years of use, the small flag push-button switch indicator flags quit working. In 1990 I added an Alpha amplifier to the mix and upgraded my antenna to work band end to band end on 160 meters with ladder line feeding the antenna, and the MT-3000A to make 160 meter QSY possible. In working at legal limit on the 160 meter band I used switch position "R" (most of the coil) and at times did arc the caoacitors. I got hold of the TL, and TLW modeling program by Dean Straw nd that inducated the C1 and C2 capacitors were to low in pF values (at 240 pF) to be efficient on 160 meter band. I removed top of case and did some high power transmitting and the the steel mounting plate at the ground end of the coil got too hot to touch (too much circulating current with the too small of pF capacitor values). Read the test article in QST history when natchers have too small of pF values. Very 1nefficient at around 0.8 dB metwork loss. What to do? Running the software indicated that doubling the pF;s for C1 and C2 would make the MT-3000A more efficient on 160 meters. OK !!! Read the latest
MFJ ads, where their high power matchers have now gone to 500 pF and 1000 pF on the output side
on the MFJ-9982. Wow. Its only taken manufactures over 30 years to wake up. Read Fredrick Terman's book chapters on network design and network dissipation. A 0.8 dB loss due to heating in a mis-designed network can heat up a network by almost 120 watts (enough to melt solder connections) when running 100% duty cycle 1500 watts. I added switches to select extra padding capacitors for 80 m and 160 m operating and my coil tap dropped from "R" to "L" tap and that is more efficient as was predicted by the model calculations. Proof ?
My steel mounting bracket no longer over heats on 80 m and 160 m. This unit uses heavy duty parts as noted by others, BUT it is not network efficient on 80 m and 160 m bands without modifications. Get the software OM's and learn like I did. 73 Jim, retired engineer, k5yzs
 
N7CPU Rating: 5/5 Jun 27, 2012 01:11 Send this review to a friend
Threw all my MFJs in the junkbox  Time owned: 6 to 12 months
What can I say that hasn't. I bought one off ebay that was corroded, rusted, dirty, etc...after about 20 hours of restoration (including photoshopping a new face) this has to be one of the best tuners ever built. Switches will handle more than 3kw pep without a problem, inductor is well spaced away from the caps and cabinet. The only weak link is as others have said that the balun leave some to be deisred. It does work and is within 15% of balanced, but I seriously doubt it would last long at 2kw let alone the 3 it is rated for. It will warm up with 300 watt carrier into a 300ohm load in a short time. Overall, it will match the proverbial coathanger and bedspring without breaking a sweat at the legal limit all day.

super great tuner IF you can find one. Even worth the restoration time if you fine a basket case
 
N0PL Rating: 5/5 Mar 11, 2012 17:05 Send this review to a friend
Gerat Tuner  Time owned: more than 12 months
I have had my tuner for a number of years (more than 10 but I just don't remember, probably closer to 20) and it has yet to cause one problem. Tunes anything I can hook up to it. I have some automatic tuners (LDG 1000) and there is no comparison between the construction. As said by others, if you get an opportunity to purchase one, GRAB IT. You will not be sorry.
 
K7NG Rating: 5/5 Feb 17, 2012 09:10 Send this review to a friend
Excellent & Reliable  Time owned: more than 12 months
I debated whether to give a 4 or a 5 on the rating, and decided to make it a 5 even though in my personal category that means 'no cons'.

The tuner has only one 'con' and that's that it really needs one ot two more 'bypass' positions in the antenna selector switch, and I mean 'full bypass'. There is one bypass position and it's Antenna 1 - you've a choice of bypass or tuned. Other positions are always tuned. I have a SGC 230 remote auto tuner at the base of a vertical and I would like to have a fully-bypassed-always switch position for it.

Now that I've spent lots of space griping about one minor issue: here's the 'pro's'.

* I haven't run into anything I couldn't tune on any frequency.
* I don't use a linear, so I doubt there's anything I could do to this tuner that could damage it.
* The metering IS accurate.
* Internal grounding is very well done.
* The internal dummy load is a nice touch. No problem with handling 150W for almost unlimited periods.

I've used it on field days and except for having to find space for it on a small table, it makes temporary antenna operations trouble-free.

I grew tired of grandiose claims about antenna tuners, so I went out and found one that looked like it might actually work, and I (for once) was right. The MT-3000 is it.
 
WC3O Rating: 5/5 Feb 9, 2011 11:12 Send this review to a friend
The best  Time owned: more than 12 months
A little rough on the no-coders there Ken, donít ya think? hihi

Yep, this is the best tuner I have ever seen. Ken left out a couple wonderful details. Silver connectors in the back. Silver switch contacts. That is the sign of a high quality RF product. I actually met Denny Hadd (The Den in Dentron) at AES in Cleveland a couple years ago. I felt like I met a rock star! hi

I told the folks at Palstar at Dayton that they should make a stepped inductor tuner and they looked at me like my hair was green. You can take your roller inductor tuners and run around the block with them. A stepped inductor is sooooo much faster and easier to tune. So Palstar, make a stepped inductor tuner, and no, my hair is not green.

So the MT-3000 has all the best stuff and it will tune a wet noodle to boot. If you see one and buy it, you will not be sorry. It is the best tuner ever made. And that is that.

Best 73 DE WC3O
Bob
 
AD6KA Rating: 5/5 Feb 8, 2011 01:46 Send this review to a friend
Can't Go Wrong With This One  Time owned: more than 12 months
The Dentron MT3000A is a TRUE high power, superbly built tuners. Just open one up and take a look. All steel chassis & enclosure construction, double bottom steel chassis. HUGE capacitors. Internal RF hookups are are 5/32" solid aluminum RODS, not cheesey stranded wires. Wafer switches are massive. You can tell THAT just by operating them. Now take the cover off and look inside! I suspect people who have had problems with theirs have gotten units that have been messed with, or they don't know how to properly operate a tuner. One poster said that the meters on his were not very accurate. Really? Did you try ADJUSTING the FWD & RFL power on the RF sense Board, Einstein? Two trimmer resistors too much for ya?

The only thing I would change on this tuner is to have ONE more "Coax Through" setting. There's only the one, on COAX 1. I might Mod that though, adding it to Coax 2 or 3. Hell, you could take out the 200w Dummy Load and run that line to an added SO-239 but it would **ONLY be a through setting***, no choice to Tune, but you'd have a 4th coax input for an already resonant antenna, though losing the dummy Load (which I don't use in the tuner anyway!

The damn things is indestructable. So in SOME units the meter bush buttons wore out. The units
are 30+ years old! Stop whining, look at the schematic, and replace them. (yeah you will have to find another brand and make of switch, BOO HOO. Be a HAM and not another NO CODE Appliance Operator!
 
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