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6MJ6 vs 6LQ6/6JE6 in Phantom

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6MJ6 vs 6LQ6/6JE6 in Phantom

Post by hifiman » Monday, 21 March 2011, 12:29 PM

I just replaced my four 6JE6 driver tubes with 6MJ6 tubes in my Phantom Triple Stage. Now running 4 x 6 all 6MJ6. I see an increase of about 100 watts pep vs the 6JE6 tubes. My question is will running 6MJ6s as driver tubes hurt or overwork anything. Im driving it with a radio that is a 2 watt DK and swings to 17 watts and am seeing a 200 watts DK and a PEP of 1100 watts.

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by PA629 » Monday, 21 March 2011, 13:37 PM

The 6MJ6 is supposedly a heavier duty version of the 6JE6C/6LQ6. That said, RF Parts recommends no more than 50W AM from those old sweep tubes, 70W SSB. At the price of those things these days, I wouldn't go any higher than you are now and would probably go a bit lower in interest of tube life. Both my Firebird's use the same tubes and I rarely go over a 160W deadkey. My $.02, FWIW.
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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by Night Crawler » Monday, 21 March 2011, 13:58 PM

hifiman wrote:I just replaced my four 6JE6 driver tubes with 6MJ6 tubes in my Phantom Triple Stage. I see an increase of about 100 watts pep vs the 6JE6 tubes. My question is will running 6MJ6s as driver tubes hurt or overwork anything.
No, like was mentioned it's just a heavier duty tube and is a direct replacement for the 6JE6/6LQ6
Here's some information on it http://www.thermionic.org/sw6mj6.jpg
The reason your getting more output is probably because the 6MJ6's are in better shape then the 6JE6's were.

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by hifiman » Monday, 21 March 2011, 14:02 PM

Thanks. I probably can open up and turn down the dk in my DX2527 from 2 watts to 1.5 watts however on both my Sonars (dk 3.5 watts) if there is a way Im not sure how. If the tubes life are shortened by too high a dead key will it only shorten the life of the driver tubes or all 10 6MJ6s? Thanks and if the 6MJ6 tubes are heavier duty can they take more punishment not that I want to overdrive it. Luckily I have 6 spare 6MJ6s on hand and if needed.

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by hifiman » Monday, 21 March 2011, 14:09 PM

Night Crawler wrote:
hifiman wrote:I just replaced my four 6JE6 driver tubes with 6MJ6 tubes in my Phantom Triple Stage. I see an increase of about 100 watts pep vs the 6JE6 tubes. My question is will running 6MJ6s as driver tubes hurt or overwork anything.
No, like was mentioned it's just a heavier duty tube and is a direct replacement for the 6JE6/6LQ6
Here's some information on it http://www.thermionic.org/sw6mj6.jpg
The reason your getting more output is probably because the 6MJ6's are in better shape then the 6JE6's were.
Thanks for that link. Very informative.


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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by hifiman » Monday, 21 March 2011, 15:16 PM

Here is another couple of questions. I have heard once peeking the tune to turn the bottom load a hair to just where the wattage starts to drop. Coupling I think its called. Is that correct or does it matter. Also I rarely run on hi power. Will running on low power or med. power make the tubes last longer? Thanks

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by Sheriff Bart » Monday, 21 March 2011, 15:23 PM

My question is where did you find the 6MJ6's ?


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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by Night Crawler » Monday, 21 March 2011, 15:45 PM

hifiman wrote:Here is another couple of questions. I have heard once peeking the tune to turn the bottom load a hair to just where the wattage starts to drop. Coupling I think its called. Is that correct or does it matter. Also I rarely run on hi power. Will running on low power or med. power make the tubes last longer? Thanks
It's called over-coupling after tuning for maximum output turn the load control 1/4 inch clockwise that only has to be done when using AM to prevent the audio from sounding fuzzy or distorted and yes the tubes will last longer on low or medium since the plate voltage is reduced in that position.

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by hifiman » Monday, 21 March 2011, 15:55 PM

Sheriff Bart wrote:My question is where did you find the 6MJ6's ?


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There were already 6 in the amp on the final side that tested 100 to 105. I bought 10 more off ebay. 4 for drivers and 6 as spares. Ebay always has them including 6JE6s. Darn things are not cheap and I may one day do a tube conversion.

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by hifiman » Monday, 21 March 2011, 15:59 PM

Night Crawler wrote:
hifiman wrote:Here is another couple of questions. I have heard once peeking the tune to turn the bottom load a hair to just where the wattage starts to drop. Coupling I think its called. Is that correct or does it matter. Also I rarely run on hi power. Will running on low power or med. power make the tubes last longer? Thanks
It's called over-coupling after tuning for maximum output turn the load control 1/4 inch clockwise that only has to be done when using AM to prevent the audio from sounding fuzzy or distorted and yes the tubes will last longer on low or medium since the plate voltage is reduced in that position.
Thanks very much. Love these tube amps. I tried a 2x6 pill amp and it just isnt me. So I want to keep this Phantom running a while. It was in minty condition when I got it and only had a bad choke. So I replaced that and recapped it and now she is ready to talk. Thanks again.

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by Chester » Monday, 21 March 2011, 21:00 PM

Hifiman I have a Maverick 250 (D&A), 4 x4, and it works very well, I always tune the amp on High, and watch my top meter on the amp , after you peak everything out take your "Load" knob, (upper left on my amp) and continue clockwise until you drop about 4 increments on that upper meter, this will do the "over coupling" and you will see some swing. I typically go with the 1 to 4 ratio DK and Swing, I then back my driver off a little to put my DK where I want it. The DK on my radio is 3 watts , I have variable power on the radio and have experimented around and like the 3 watt value the best. Haven't burnt any tubes up yet , so go for it, D&A in my opinion made some nice little boxes.
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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by hifiman » Tuesday, 22 March 2011, 4:37 AM

Chester wrote:Hifiman I have a Maverick 250 (D&A), 4 x4, and it works very well, I always tune the amp on High, and watch my top meter on the amp , after you peak everything out take your "Load" knob, (upper left on my amp) and continue clockwise until you drop about 4 increments on that upper meter, this will do the "over coupling" and you will see some swing. I typically go with the 1 to 4 ratio DK and Swing, I then back my driver off a little to put my DK where I want it. The DK on my radio is 3 watts , I have variable power on the radio and have experimented around and like the 3 watt value the best. Haven't burnt any tubes up yet , so go for it, D&A in my opinion made some nice little boxes.
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Thanks. That was a big help. I was wondering which load knob to turn (upper or lower) for a slight drop and you cleared that up. I will using low or medium power most the time and I am not a long winded talker and even have a small 2 pill box that I use to talk locally most the time so I hope all those things will give a long life to the tubes.

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by Chester » Tuesday, 22 March 2011, 15:48 PM

Hifiman, if you go to "cbtricks.com" you will see an index listing for amps and schematics. Go to the "D" for D&A and you will see the owners manual on your particular amp, read thru that and it should accurately guide you as far as adjustment and settings. You can print it out.I had a fella send me a manual on my Maverick and it sure helped me operate it. Hope that helps.
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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by hifiman » Tuesday, 22 March 2011, 16:25 PM

Chester wrote:Hifiman, if you go to "cbtricks.com" you will see an index listing for amps and schematics. Go to the "D" for D&A and you will see the owners manual on your particular amp, read thru that and it should accurately guide you as far as adjustment and settings. You can print it out.I had a fella send me a manual on my Maverick and it sure helped me operate it. Hope that helps.
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Thanks I do appreciate that. It certainly looks as if back in those days they were more concerned about peaking a dead key vs swing. Of course back then radios were a 4 watt DK and maybe a 8-10 watt swing.

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by 420Snowman » Sunday, 27 March 2011, 18:52 PM

sorry to hijack, but I have a DA Maverick 4x4 and would like to recap it, what caps should I order?


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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by Night Crawler » Monday, 28 March 2011, 7:13 AM

In the schematic it's using three 100uf at 350 volts if it were me I would use 100uf at 450 volts to give it a little more working voltage on the caps.

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by 420Snowman » Monday, 28 March 2011, 7:44 AM

Perfect Nightcrawler!! I am going to go get those today!
Thanks as always sir!!

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Re: 6MJ6 vs 6LQ6/6JE6 in Phantom

Post by Nagant » Monday, 28 March 2011, 18:41 PM

hifiman wrote:
Chester wrote:Hifiman, if you go to "cbtricks.com" you will see an index listing for amps and schematics. Go to the "D" for D&A and you will see the owners manual on your particular amp, read thru that and it should accurately guide you as far as adjustment and settings. You can print it out.I had a fella send me a manual on my Maverick and it sure helped me operate it. Hope that helps.
Chester 221
Thanks I do appreciate that. It certainly looks as if back in those days they were more concerned about peaking a dead key vs swing. Of course back then radios were a 4 watt DK and maybe a 8-10 watt swing.

Yes and back then those sweep tubes were cheap and plentiful. As you well know those tubes are neither anymore. I'd definitely stick with max peak power tune keeping the carrier somewhat low on a sweep tube amp these days. Run conservatively those sweep tubes can, and often do, last quite a long time. Numerous tune ups, over driven, and high carriers shorten their lives greatly.

Have fun with the Phantom. They are a nice classic CB tube amp. I've run a number of them in my life as well.
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