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Author Topic: MLA-2500 With 3CX800A7's  (Read 1721 times)
K6ZZ
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Posts: 2




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« on: January 14, 2006, 11:36:50 PM »

Hello Folks,

At the risk of bringing up a potentially redundant topic, I have a question regarding re-tubing an MLA-2500.  I have an opportunity to re-tube a Dentron MLA-2500 with a pair of 8874's or a pair of 3CX800A7's.  I have a pair of each and a tubeless MLA-2500 and I'm trying to decide which tubes to use.

I've been doing some research and have come across numerous references to re-tubing this model amplifier with 8874's, 3CX800A7's and a variety of russian made tubes.  My preference would be to use the 3CX800A7's however I saw a comment by K6GT indicating that the "MLA-2500 power supply wasn't up to the task".  Is that the case and what, if anything, can be done to beef the PS up?  Is it a matter of using better rectifiers and filter caps or is the transformer the problem (or all of the above)?

If you have or know someone else who has a pair of 3CX800A7's in an MLA-2500 I would like to hear your suggestions and experiences.  At the very least I know I need to build a plenum for cooling the tubes and replace the filament transformer.  I may also need a better/different fan as well.

Thanks for the help!

73, Bob K6ZZ
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K6AER
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Posts: 5743




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« Reply #1 on: February 04, 2006, 07:37:32 PM »

MLA-2500’s power supply is capable of about 1100-1200 watt PEP. Why not use a single 3CX800A7. Same dissipation as the two tubes. You will not get double the output with two tubes for the power supply is no capable of more wattage out of the amp.
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