| NJ6F |
Rating:      |
2020-11-25 | |
| Excellent Amp for 10-160 meters including WARC, Lowest Height |
Time Owned: more than 12 months. |
Excellent amp. Owned one since 1980. Had the 2500 non B version first which was great and traded it off for MLA2500B version in 2013, which I recapped with I believe 240Mfd caps. When you turn on amp if you hear a thud going on, it needs to be recapped, no big deal. Mine was whisper quiet when turning on after the recap. This is a untuned front end (big advantage) for WARC bands or any of them, so suggest you use a https://mfjenterprises.com/products/mfj-914 which allows SWR to really be minimum and is best for solid state transceivers compensating for freq and different coax lengths to the amp. Just use this MFJ-914, no tuner needed between rig and amp. Dentron had one like the MFJ that I came across a long time ago. Tubes last forever so don't be so paranoid about a second pair of 8875's. I also increased size of fuse resistor to I believe 2 watts, not sure, but cured the problem with the fuse resistor blowing mostly because of my furry pursian cat insisting on drying herself on the amp after getting wet hi... her fine hair would pop the fuse resistor on my older 2500. This amp is a keeper and no one makes one so LOW in height. I hate large, tall amps that get in the way. This one fits right under my metal bakers rack along with the MLA 3000 tuner. The ceramic 8875's are nice with 20-40 watts drive. Consider it a nice amp for AM operation and being that 25 watts is linear off a 100 watt amp in AM that is all you need for a decent 400+ output and a low foot print.
Amp turns on in about 45 seconds, ready for action and unlike those solid state amps, the power supply is self contained with hypercil transformer, in this compact amp, not a seperate unit. A very cost effective unit with low footprint, unlike the rest. |
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| KE4AMQ |
Rating:      |
2019-06-15 | |
| great oldie |
Time Owned: more than 12 months. |
| I have had this mla2500b for over 10 years. runs very good near mint with the original 8875 eimac finals. Still produces full power watch the grid current, and dont over drive it. I run very conservatively about 700 watts. I first 500 makes all the difference in the world. A GREAT AMP. |
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| SV1AGK |
Rating:      |
2018-11-18 | |
| excellent |
Time Owned: more than 12 months. |
no any problem ever. 1kw 35 years, same 8875 tubes.
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Earlier 4-star review posted by SV1AGK on 2017-01-29
excellent amplifier without any problem for 25 years, problem only is very expensive final tubes 8875. |
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| KG7FIU |
Rating:   |
2017-11-11 | |
| 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 |
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| W5HEH |
Rating:      |
2015-07-19 | |
| 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 |
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| former_K7FU |
Rating:      |
2015-06-21 | |
| 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:     |
2014-12-01 | |
| 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 |
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| WB7ESV |
Rating:      |
2013-04-21 | |
| 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.
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| KI4FJS |
Rating:      |
2012-08-18 | |
| 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! |
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| WA7KGX |
Rating:     |
2012-05-05 | |
| 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.
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