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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: 26 Average rating: 4.8/5 MSRP: $1200.00
Description: 2 KW PEP Amp 160 80 40 20 15 10 m
Product is not in production.
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ZL4TGH Rating: 5/5 Jan 5, 2009 00:52 Send this review to a friend
Bang for the bucks  Time owned: more than 12 months
15 years ago I swapped a TNC for the non-working amp. It came with 2 new valves and the originals also like new. A quick tweak on the voltage relay (about 5 minutes work) and in business. Put it in storage for 5 years and when I turned it on, bang! HT cap blew. Well tonight I replaced them all and with extra 0.01uF across them and 10 ohm on the HV B+ in case of arcing. Removed my GLA-1000B and put my sweetheart back in line. First contact with the repaired amp, over the south pole long path to Germany on 40! The guy was so excited it gave me a buzz also. Other ZL4's tried but he just could not hear them. My FT-2000D was only putting out 30w. What a great amp, before it's time.
KA9TZU Rating: 5/5 Nov 21, 2008 18:56 Send this review to a friend
Best amp I have owned  Time owned: more than 12 months
An extra class friend of mine bought this amp new in the mid 80's. I always thought is was great. When he moved he sold it to me for a song.

It sat on my shelf for over 5 years before I used it. Worked like a charm even though the caps arced now and then. The problem stopped on it's own, so I never replaced them. Put it away when I moved a year later and brought it back out 12 years later. Still worked great.

I have 2 sets of 8875 tubes I had bought back then in case I needed them. Not so far, originals are still at full power. I can easily get 1400 pep on 80 meters with a 40-50 watt drive. The swamping resistor is still in place. I have used this amp with numerous radios and it always has preformed for me. I am currently using it with an Yeasu 897D

I am converting a solid state medical research amp for amateur radio use. The amplifier uses 16 MRF150 MOS FETs in 8 push-pull output stages, which are driven by a push-pull stage using two additional MRF150s. Even when this amp is up and running, I will never part with my Dentron!!!!
W5VIN Rating: 5/5 Mar 11, 2008 10:48 Send this review to a friend
Retube  Time owned: more than 12 months
I just finished doing a retube on this great amplifier using the GI7B Russian triodes and W4ZT sockets. It will crank out well in excess of 1300 watts of power with less than 100 watts of drive power. To those that have this amplifier and it's tubes are going south this is a working modification that is not all that hard to do. It gives the MLA-2500 amplifier a new lease on life.
Charlie W5VIN
WA4RVB Rating: 4/5 Jan 28, 2008 07:50 Send this review to a friend
STILL GOING STRONG  Time owned: more than 12 months
AH6RR Rating: 5/5 Jun 9, 2007 20:02 Send this review to a friend
Rock Solid Amp  Time owned: more than 12 months
I bought my MLA-2500 at a local swapmeet for $85.00 it had 1 bad tube and the power supply had 2 bad filter caps and some blown diodes in the doubler. Well I could not find a 8875 that I could afford so I sold the good tube and bought 4 GI-7B tubes and all the parts I needed for the conversion plus a New Kenwood TM-271. So 2 months later and a little tweeking hear and there I now have an excellent amp with anywhere between 1300 and 1500 watts out with 2 of the GI-7B tubes. Great Amp.
W5VIN Rating: 5/5 May 19, 2007 18:42 Send this review to a friend
MLA-2500 Retube  Time owned: 0 to 3 months
I purchased a Dentron MLA-2500 with bad tubes. I replaced them with three 4CX-250B operating in modified grounded grid with screen and grid bias voltages. Both grids are at RF ground through coupling capacitors. I sort of followed the old QST article which used a Russian GU74-B. It was my initial choice but produced a less than stellar output. I redid the bias supplies using an LM431 and series zener for the negative bias. The screen bias uses an LR8N3-G high voltage regulator feeding a high voltage MOS transistor. For input matching I use an LDG 100Z Ultra externally between the antenna switching relay and the tube cathodes. It simplified impedance matching and is battery powered with memories. The amplifier will load to 1200 watts output and is quite comfortable at 1 KW out. There are several mistakes in the QST retube article article both in design and on the schematic.
Charlie W5VIN
AA8X Rating: 5/5 Feb 28, 2007 08:48 Send this review to a friend
30 years and still going strong!  Time owned: more than 12 months
Back in 1978, while living in Ohio, I purchased a new MLA-2500 from AES and for 30 years I have been very happy with this amplifier. This is an incredible amp and came with outstanding support from the staff of Denny Had, owner of the Dentron Company in Twinsburg, OH.

After having the original unit for a few months, Denton introduced the MLA-2500B that was an improved version. I called Dentron regarding the changes and they said to drop it off (I lived in the area) and they would update the unit to the full B version. This was a major undertaking, they replaced the power transformer to a new design that provided a tapped secondary winding for the high voltage, which would provide consistent efficiency at both the 1KW and 2KW power levels. They also replaced the 6 electrolytic capacitors to insure improved reliability as well as other minor upgrades. Although the front panel is original and still says MLA-2500, the factory added a labeled metal plate over the 5 push buttons to indicate the switches provide a different function on the B version.

Dentron completed the total upgrade and improvements at No Charge to me. Now that was a company that valued their customers. Too bad Icom wouldn’t do the same for the first 706 users. The American companies were still the best in providing support for their products.

My 30-year-old rig still has the original 8875 tubes and they still put out the legal limit. 3 years ago I replaced the 6 capacitors to insure continued reliability. I ordered replacement 100mf at 500-volt capacitors from Digi-Key and they are about the size of my thumb, very small compared to the original tall metal can ones that came with the amp. They were so small I had to mount them on a fiberglass pc board mounted to the chassis of the amp. I have never done any other modifications or other changes to the amp.

Too bad Dentron is no longer in business as they were a company that provided a first-class product with outstanding service and support.

This is a workhorse amplifier and should you have an opportunity to acquire one; I suggest you don’t hesitate to add one to your station.
IZ5DKJ Rating: 5/5 Dec 18, 2004 07:17 Send this review to a friend
Great Amp  Time owned: 6 to 12 months
My MLA-2500 work very well from 1976 with original
tubes (buy on ebay in 2004).
Small spaces and good performance, manuals and schematic are ready for download at

73 Simone IZ5DKJ
K9IUQ Rating: 5/5 Nov 10, 2004 17:29 Send this review to a friend
27 yrs and Still Going Strong  Time owned: more than 12 months
I bought my MLA 2500 in 1977 brand new for $800 which at the time was a lot of money. I have used this amp since then with no problems. It still puts out 1000 plus watts easily - still has original tubes and caps. I guess this amp was worth the money. Too bad Dentron went out of business, they made excellent quality products.
W7KID Rating: 5/5 Mar 9, 2004 01:39 Send this review to a friend
Awesome Amp, No Complaints  Time owned: 0 to 3 months
I had been looking for one of the 2500's because I have a Dentron MT3000A tuner and wanted an amp that matched, and the 2500 is the same case. I recently found one up in WA when I went up there to take my Extra exam. Turns out it was from a gentleman that belonged to our club down in Eugene. It had been sitting a little while in another members garage so I made sure to let it run for a while under no load. Then started running it under a load, bumping up the power a little at a time in continuous duty mode until I was at full power. I'm very impressed with the power this amp puts out. Although my 5BTV is not so impressed with the power it puts out, hihi. Actually no damage to the 5BTV, but you definately have to make sure your antenna will handle the power. Even on continuous duty, which I believe drops the plate voltage, I was still getting about 1200 watts out on CW. If I did have a complaint it would be the fan being loud. When you're not keyed it runs pretty slow, but then it goes full speed while keyed up and that is very noticeable. I may experiment with slowing it down a bit to cut the noise down. I really don't think slowing it down will hurt anything. It runs very very cool even after running it keyed for a minute at 1200 watts. Of course there's the tube issue, but if you take it easy on tune up, and don't run it full power all the time, I'm sure they'll last a long time. I generally don't run over 500 watts, so I'm sure I'll get lots of use out of it.

73, Ken
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