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d&a 250 maverick

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d&a 250 maverick

Post by drunk monkey » Tuesday, 24 November 2009, 14:55 PM

i have a 250 maverick when you first tune it .it will do 500watts but when it sits for a few a key it up it drops down to 300watts but then you can key up and talk 5 or 6 times really fast it will slowly climb back up to 500watts
thats


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Re: d&a 250 maverick

Post by tubehead » Saturday, 16 October 2010, 22:57 PM

sounds like bad filter caps in the power supply reforming. you may need to get a tech to replace the filter caps.
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Re: d&a 250 maverick

Post by Nagant » Saturday, 16 October 2010, 23:25 PM

Sounds more like weak tubes. I'd have them tested on a calibrated mutual conductance tester. If the filters in the power supply were going bad there would likely be an AC hum on transmit. If they were bad one or more would be either open or dead shorted.
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Re: d&a 250 maverick

Post by Flattop » Sunday, 17 October 2010, 8:54 AM

When my da 250 acted like that it was the glass

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Re: d&a 250 maverick

Post by tubehead » Tuesday, 19 October 2010, 7:25 AM

i picked one of these up at a hamfest two weeks ago for $20. it got a smoked relay, some overheated resistors, and probably flat tubes. luckily i think i have everything i need to revive it in my junk piles. i was reading up on them and did see some stuff about weak caps causing low output.

i just sanded down the cabinet last night and started giving it coats of enamel. the chassis had been rained on so its drying out in the carport for now. i'll keep you guys posted on how this comes along. as long as the transformers arent smoked, i can revive it.
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Re: d&a 250 maverick

Post by 420Snowman » Thursday, 10 March 2011, 21:56 PM

Im trying to upgrade a DA Maverick Dual Power, it works great now but I would like to upgrade tubes, etc. to get some more output. I have read a few guys that have done "things" to these and are getting around 1000w out of them, any ideas?

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Re: d&a 250 maverick

Post by Night Crawler » Friday, 11 March 2011, 7:57 AM

420Snowman wrote: I would like to upgrade tubes, etc. to get some more output.

If the power transformer in that amp can't supply more voltage or current then it's capable of now even if you upgrade the tubes it will still show the same amount of wattage.

Wattage is calculated V x I = P where V = voltage I = current and P = wattage
As an example if the transformer can only supply 700 volts at 200ma maximum, the wattage would be 140 watts.

But if it were able to provide 700 volts at 300ma and the tubes that are in there now are only drawing 200ma at maximum output if you upgrade them to tubes that can draw 300ma then the wattage would be 210 watts.

Maybe you can get more output with different tubes maybe not it all depends if the power transformer is capable of providing the voltage and current demand of the tubes used for the upgrade.

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Re: d&a 250 maverick

Post by preacherman » Friday, 11 March 2011, 20:50 PM

I've got a maverick 250 dual power with tubes that have quite a few hours on them
and it falls off a little on a long key down. Still will do about 700 pep with a Cobra 29
w/a mosfet driving it. Great amp...great audio and just keeps on tickin'. I've had a couple
of very clean Palomar 300a's and they are gone but the old Mav is still here.
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Re: d&a 250 maverick

Post by dime196604 » Friday, 11 March 2011, 21:18 PM

Are tube amps cleaner on the output? Do they cause a lot of interference in home stuff like computer speakers or TV's like pills do?
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Re: d&a 250 maverick

Post by preacherman » Saturday, 12 March 2011, 15:58 PM

It depends on the unit. Tubes overload more gracefully than transistors and
tend to put out even order harmonics when they do as opposed to transistors that
do odd order harmonics that are harder to listen to. If you have a decent amp and
don't overdrive it...plus put a relatively clean signal into it, you should be fine.
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Re: d&a 250 maverick

Post by 420Snowman » Sunday, 20 March 2011, 21:13 PM

Preacherman, If you getting 700pep out of yours than something is not right with mine I guess. I am getting right at 350 on a bird meter, have you changed the caps on yours?

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Re: d&a 250 maverick

Post by 51 » Sunday, 20 March 2011, 23:58 PM

new caps, new tubes, TLC, re test!

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Re: d&a 250 maverick

Post by 420Snowman » Tuesday, 22 March 2011, 12:54 PM

Yea, gonna start with re capping and test, then see if I want to put tubes in it or sell it and get something better.

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Re: d&a 250 maverick

Post by crazy_cooter » Wednesday, 15 June 2011, 10:30 AM

preacherman wrote:I've got a maverick 250 dual power with tubes that have quite a few hours on them
and it falls off a little on a long key down. Still will do about 700 pep with a Cobra 29
w/a mosfet driving it. Great amp...great audio and just keeps on tickin'. I've had a couple
of very clean Palomar 300a's and they are gone but the old Mav is still here.
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What kind of meter are you seeing 700 watts with a maverick 250?
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Re: Re: d&a 250 maverick

Post by 420Snowman » Wednesday, 15 June 2011, 15:11 PM

crazy_cooter wrote:
preacherman wrote:I've got a maverick 250 dual power with tubes that have quite a few hours on them
and it falls off a little on a long key down. Still will do about 700 pep with a Cobra 29
w/a mosfet driving it. Great amp...great audio and just keeps on tickin'. I've had a couple
of very clean Palomar 300a's and they are gone but the old Mav is still here.
Preacherman
What kind of meter are you seeing 700 watts with a maverick 250?
Agree, I thought mine was weak....

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Re: d&a 250 maverick

Post by Nagant » Wednesday, 15 June 2011, 15:34 PM

I just recently sold an older grey case Maverick 250 that would only do 500 to 550 on my Palstar meter. All the tubes tested excellent on my B&K 707 tester as well. No twp are exactly the same. Some will do a bit more than others and then there is meter differences to take into account as well as peak input drive. On my old Welz meter, same as the Yaesu YS-60, I would see more PEP output from larger amps then on my Palstar meter. We aren't dealing with what I would consider precision meters or equipment in general.
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Re: d&a 250 maverick

Post by crazy_cooter » Wednesday, 15 June 2011, 20:42 PM

Your absolutely right, I have a great example to back this theory up! I had a Paradynamics 3 window wattmeter...you know the ones you buy for 99.00 out of the C----r Catalog? Well anyways, it showed my D&A Phantom was doing a whopping 1,500 watts of swing! I thought, WOW! I got a monster here! Then I got curious and borrowed a friends Dosy that was 6 months old and barely used. We compared the two, and found out that the dosy claimed my amp was putting out like 1,250-1,300 watts swinging. Then I got severely ticked off and went 4 counties west of me to a ham operator friends house and borrowed his Bird Wattmeter. There's no arguing Bird watts, what a bird says...is what it is, PERIOD! My amplifier is only swinging 850 BIRD watts, not a watt more. So I hope my experience goes to show you just how inaccurate one meter is from the next! If you have a friend with a Bird meter, let me know what your Maverick 250 is REALLY doing for wattage, you'll be in disbelief but it is what it is.
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