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| Reviews Summary for Dentron MLA 2500B |
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Reviews: 17
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Average rating: 4.9/5
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MSRP: $1200.00
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Description: 2 KW PEP Amp 160 80 40 20 15 10 m
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More info: http://
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W7KID
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Rating: 5/5
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Mar 9, 2004 01:39
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Awesome Amp, No Complaints
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Time owned: 0 to 3 months
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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
W7KID
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N4DEK
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Rating: 5/5
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Jan 4, 2004 16:25
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Excellent Amplifier
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Time owned: 0 to 3 months
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I was lucky enough to find one of these that was used less than 1 hour by the original owner so I grabbed it. Looked like it just came out of the box! This is my first MLA-2500 and so far I'm well pleased with it. As mentioned, it had not been used so I did have to replace all six HV caps in the power supply. First night I put it on the air it started blowing fuses and turns out it had three shorted caps. Since replacing the caps the amp has run flawless. Full legal limit with about 80 watts of drive. 100 watts will get you about 1800 out but that is pushing the tubes. Swamping resistor has not been removed from this one either. Seems to produce a very strong and clear signal on the air. Only complaint I have is with the relay, it is very loud! Aside from that I have nothing but good to say about this amp so far. Alot of bang for the buck in a nice small package. BTW: It does not have a tuned input but I use the tuner in my 756PROII and that works great. If you don't have an auto tuner in your rig you would probably want to run a small tuner between the radio and amp or either install a tuned input board.
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WD0FVV
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Rating: 5/5
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Apr 20, 2003 22:05
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Even after 25 years, still WOW!!!
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Time owned: more than 12 months
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I purchased my MLA-2500 (not the B model) in October of 1977. The MSRP was $899.50 and I paid $899.50 for the unit.
About 10 months later I had an issue with it blowing fuses when it was turned on. I spoke with Dentron and they informed me there were a bad lot of Sprague filter caps and they would replace them “no charge”. Darn right they would as I quickly filled out my warrantee card and sent it in!!!
Back it went and within 2 weeks back it came …repaired! The paperwork indicated they replaced 6 filter caps and 6 bleeder resisters.
Funny, I was then the Manufacturers Rep. for the, now defunct, Sprague Electric Company and no amount of searching could I come up with reference to defective caps from Sprague. Oh well, no one likes to admit mistakes.
From that point on I’ve driven the MLA-2500 with my FT-301 modified to prevent its output power lowered if it did not see a “perfect” load. Oh yes, I clipped the swamping resister on the input of the MLA-2500 also. Recently I began driving it with a new/old FT-902DM.
Wow, what a combination! 80 to 90 watts of drive always produced 1,000 to 1,100 watts “out” on 10 meters. Unbelievable! Now on 40 meters…holly poop, 1,300 watts OUT. And measured with my Bird 43.
This amplifier performed! No questions asked. It WAS run on 220 volts.
Ok, now more than 25 years later and still using the original two 8875 tubes, I’m worried. What the heck do I do if a tube goes out? I don’t know but here’s a secret. Tune for zero (that’s 0) milliamps on the grid circuit meter. I did not care what the power out would be until I tuned for ZERO milliamps (or so close to zero you just about can’t see the needle move) grid current. After I tune my amp for the “dip” in the grid..., hells bells (sorry) the power out was 1K, 1.2K, or even 1,300 watts OUTPUT!
So am I happy with the MLA-2500? Heck yes! It’s not good old Dentron’s fault Eimac decided to stop production on the 8875. It is only their fault they want out of business. Too bad! I’m sure the “good old boys” back in Twinsberg, Ohio could have gone on to make some mighty fine amplifiers.
Come to think of it, maybe it was *OUR* fault they went out of business. Are we Hams cheap or what?
Too bad I didn’t buy two of them when I could, or at least a spare set of 8875’s.
MIKE>>>>>>>>>>>
WD0FVV
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NZ4I
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Rating: 5/5
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Dec 28, 2002 23:20
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Great Amp
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Time owned: 6 to 12 months
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A very nice amplifier for the money. Easy to convert to other tubes, and still puts out a lot of power for its size. The soft start mod is needed. Due to the age of the amplifier, new capacitors is also good idea, especially if you add new tubes.
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KC4FWC
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Rating: 5/5
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Jan 3, 2002 00:15
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Great Amp!
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Time owned: more than 12 months
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Needs a soft start circuit. The filter caps can blow up if the amp is not used regularly. Other than that, big power. Nice of the fan to speed up and slow down when needed. Tubes are expensive but don't abuse them and they will probably last a long time. Take the swamping resistor out to drive it with less than 100 watts. Excellent amplifier. Run it off 220 V for best performance.
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WB8RLZ
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Rating: 4/5
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Sep 3, 2001 21:35
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SIMPLE MODS
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Time owned: 0 to 3 months
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JUST INHERITED A MLA 2500B, HAD ONE BAD TUBE,
SO I REMOVED IT!!. ALSO REMOVED (TEMP) ANODE LEAD. AMP STILL PUTS OUT A SOLID 500 WATTS +
I WATCH THE GRID DRIVE (LESS THAN 50 MILLS)
I ALSO REMOVED THE SO239 CHASSIS CONNECTORS. RESOLDERED ALL CONNECTIONS AND REMOUNTED WITH SCREWS AND STAR WASHERS. THIS CURES THE INTERMITTANT INPUT HIGH VSWR. BOTH CONNECTORS WERE LOOSE. ONE WAS RIVETED, DRILLED IT OUT AND REMOUNTED. THE AMP IS SUPER STABLE NOW. I WILL ADD 2 3CPX800A7'S IN THE FUTURE.
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SM4PEL
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Rating: 5/5
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Apr 4, 2001 17:50
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Good amp for less money
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Time owned: 6 to 12 months
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Just a great amp. If you can find one for a good price, bye it! The problems is if you blow the tubes, the 8875 is not on the market anymore, but you can make conversion to Svetlana tubes... See tech bullentin on http://www.svetlana.com/docs/TecBulletins/technoteNo44.html
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