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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | Dentron MLA 2500B Help

Reviews Summary for Dentron MLA 2500B
Dentron MLA 2500B Reviews: 31 Average rating: 4.6/5 MSRP: $1200.00
Description: 2 KW PEP Amp 160 80 40 20 15 10 m
Product is not in production.
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KG7FIU Rating: 2/5 Nov 11, 2017 03:51 Send this review to a friend
Not so hot  Time owned: 6 to 12 months
Well, I sold my Heath SB-200 to buy a MLA-2500B retrofitted with GI7B tubes. I thought this would be a wise investment since the 8875 tubes are now near unavailable. But find that I now prefer the old SB-200. First the SWR on the MLA-2500B is very high on a number of bands.

Had to buy an external antenna tuner that I use between radio and linear just to use the thing. Also the SB-200 had near instantaneous warm-up.
It now takes me an extra 4-5 minutes to tune up when changing bands. Sometimes when you're chasing a difficult DX station, that extra time is absolutely critical.

The fan is very loud--it sounds like an airplane. I have to turn the volume on the radio way up when the linear is on in order to hear anything. Even my wife complains "what the heck is all that noise?".

Also, I don't know if the original fan on the MLA-2500B has this issue -- but watch out for those sharp fan blades! Once when using the amp, things started vibrating a bit -- so I smacked
the back of the unit with my hand--hoping to stop the oscillations. I didn't realize the silly fan does not have a protective cage around the blades! Well, needless to say, it sliced up my finger pretty badly--and I was dripping blood on the floor.

The guy that sold me this amp told me it had 10 meters, but I can't seem to find out how to make it work on 10m.

In terms of power, I can get about 850 watts out on 20 meters, if I push it pretty hard. But that's not much better than my SB-200 was. I am guessing the GI7B retrofit may have reduced the power some. Oh, by the way--I am kind of afraid to hit it with too much power. I get blown fuses every now and then -- seemingly for no good reason.

I would eventually like to get rid of this amp, when I can afford to. Bought it for $550, but I'll be glad to sell it to anyone that wants it for $400 plus 50 shipping (That's another thing. It's a bloody heavy piece. With the limited space in my work area, I can wrench my neck and back trying to work on this unit).

Although this amp works, I don't feel that it's 100%.

So that's the reason for my low rating.
-john, KG7FIU
SV1AGK Rating: 4/5 Jan 29, 2017 10:12 Send this review to a friend
expensive tubes  Time owned: months
excellent amplifier without any problem for 25 years, problem only is very expensive final tubes 8875.
W5HEH Rating: 5/5 Jul 19, 2015 22:20 Send this review to a friend
GREAT Desktop AMP for the low Cost   Time owned: 0 to 3 months
THE TUBEs are RARE 8875 s , so be prepared to take very gud care of them and consider Grid protection. Mine is MLA 2500 not B,,,
got mine almost 10 out of 10 condition, so clean and nice condition, was surprised, all my signal reports are very good . Xcite with TS-930 Kenwood another oldie but goodie, using pin #7, 6, and 2 on DIN plug. i only run 500-600 watts SSB to extend Tube life, there are some mods for Russian tubes just in case . Also a Yahoo Dentron Group for help,i suggest an Inrush current protector . EAsy to tune , i use an oldie SA2060 Heathkit Tuner between AMp and Antenna, works great . Harbach's is offering Timming Relay and CAP/ PS board for these, For the low cost these AMPS are great if you find one in very good working order .Hope someday 8875 tubes will be produced , i want a back up pair lol.If you have more than 500. or save and buy a Twin 3-500z amp those tubes are available. 73s
K7FU Rating: 5/5 Jun 21, 2015 20:33 Send this review to a friend
Excellent Purchase  Time owned: 0 to 3 months
I picked up my MLA-2500 at the SeaPac hamfest a couple of weeks ago for $350.00. I was told it was working and that is about all they knew about it. I took it home and started inspecting the amp. What I found was a Like New amp with almost 0% dust inside the cabinet, including the fan blades. All of the bandswitch wafers looked almost unused and no flashovers. So after doing some research I decided to order the Harbaugh Cap and time delay kit before trying the amp on the air. Harbaugh shipped quickly and the install is fairly painless. (Take your time!) Ok time to test.... Turned it on to find out the HV was a healthy 2400V and the fan was running somewhat quietly. Ok lets see what 20 watts of drive will do.... about 500W out. (see a big smile forming on my face right about now) Hit is with 40 and about 700 W, now you can see my teeth as it was a big smile. Same on all bands. Things I would like to see different are the loud fan when running at full speed, and a loud relay. But for $350.00 I have a great amp and it looks good on my desk.
IZ0ANH Rating: 4/5 Dec 1, 2014 12:48 Send this review to a friend
Good  Time owned: 0 to 3 months
I used this amp from a friend for a short time, it seemed very satisfactory quality / price.

In Italy if they are not many, are indeed a few owners of this amplifier.
I would buy one but not found in europe.

Some selling is just a USA with high shipping costs
I wonder if one day I'll be able to have this amplifier?

Who can suggest me where to find a good Dentron MLA 2500B.
Thanks 73 de Camillo iz0anh
WB7ESV Rating: 5/5 Apr 21, 2013 20:36 Send this review to a friend
EXCELLENT AMP  Time owned: more than 12 months
I recieved my MLA 2500B 5 years ago from a SK estate. It had very low hours and looks like NIB.
It was off the air for about 1 year and after reforming the caps, it puts out it's rated power.
For the price, it can't be topped.
KI4FJS Rating: 5/5 Aug 18, 2012 12:17 Send this review to a friend
UNBEATABLE  Time owned: more than 12 months
Mine is not the B, but the 2500, which I have owned for 34 years, using the same pair of 8875's that came with it from the factory! What more could you ask for? It puts out a solid kw with 90 watts drive, and this rig has served me in Africa for 14 years under the calls TU2DP and EL8C, and since then for the last 10 years here in NC.
It had sat for 10 years unused in storage in Africa while I was on leave in the USA and I replaced all the caps in 1994 when I went back. The only way this rig will leave this house in its original box is when I leave this house in a box!
WA7KGX Rating: 4/5 May 5, 2012 09:44 Send this review to a friend
Check the connector mounting screws  Time owned: more than 12 months
I have a 2500 (not B) I bought many years ago just to get an amp with 10 meters before the FCC ban on 10 meter amps went into effect.

After many years of non use, I decided to put it back into service. So far I have removed the tubes, cleaned it, strapped the power connections to 120 volts, and powered up the amp with 40, 100, and now a 200 watt bulb in series.

I happened to notice that the two mounting screws for the RF OUT connector were loose. I have never touched these screws before. Indeed, this is the first time I've had the covers off since installing the original valves. One might wish to check these screws to make certain they are snug.
KD8JMQ Rating: 5/5 Jan 27, 2012 09:52 Send this review to a friend
I have two  Time owned: more than 12 months
Ok here are my thoughts;
If you find one in good shape with the original tubes(8875);and you see no less than 1kw and no more than 1300 watts; the amp is a buy.
Make sure the electrolytic caps are either new or replace them.
Never try to drive the amp past the alc.
Tune the amp and bring up the drive until you reach max output and set the radio for that wattage.
Use common sense

If you have ANY amp with original tubes and it still is putting out full power; It won't get any better.
Most 2500 amps that survived this long already have all the mods done!
I have two MLA 2500 amps. One I have ran for two years non stop with 1250 watt pep output,the other was just purchased with in new condition and not even a trace of dust inside on the fan.
Both amps put out Exactly the same output!
I paid 500 for the first amp
I paid 1200 for the "NIB" amp

My point; If it's working and you operate it with the Dentron protection mods in place; You won't have to worry about substituting some other tube.

Things I love about this amp

lots of power
smooth tuning
can run on 110v with good line current
clean output
CHEAP (A new amp doing the same will cost you big bucks and probably end up blowing something)

In my opinion; If the 8875 was put back into production; you would see everyone flooding the market to buy them and building amps around the MLA 2500!

Unless I "Kick the bucket" sometime soon or you kick my door down at gunpoint; YOU WONT GET MINE
K9MHZ Rating: 2/5 Jan 16, 2012 06:47 Send this review to a friend
It works, and it's OK  Time owned: more than 12 months
Sorry to veer away from the glowing reviews about this amplifier. I owned and operated one for 10 years and found it to be OK at best.

The swamping resistor input circuitry is an absolute joke. It was clearly cheap in design, allowing Dentron to avoid putting in a tuned input circuit into the small cabinet.

The cooling air was sufficient only until you operated with more than a small amount of duty cycle. I personally wouldn't ever use it on any mode other than SSB with lower, uncompressed drive.

The grid current was a mess.

It did "work", and the tube choice is a good and solid one, but Dentron definitely went on the cheap trying to cram it all into the small cabinet.
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