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A Very Rare Find...

Lik2race

Lik2race

Member
Apr 9, 2009
28
0
11
I had been looking on the Internet, and came across this >>
JB 700 'Super Modulator, Made by MACO
The Seller says :
I have only seen 1 of these RARE ! Has 3- M2057 tubes. I drove this with 4 watts dead key and modulated to 15 watts and this bad boy produced 100 watts dead key and swung to 800 watts loud clean audio ;has 2 -new and
1 -95% M2057's, also comes with 2 used M2057's but condition is marginal.

I'll have it up and talking soon. Just for Information..
Stan
JB700a.jpg

JB700b.jpg

JB700c.jpg

JB700f.jpg
 
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Dirty Diaper said:
WOW!! What a driver! Looks like you have found the Holy Grail of amps LOL. Hope to hear you ! D.D. said that!!
Click to expand...

Thank you my Brudder..you're the one that told me about it..lol
I just got lucky enough to talk the guy into selling it at a price I could
afford..LOL...:thumbup1:
Stan
 
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359 said:
$300 don't sound too bad, whats tube availability like?
Click to expand...

? Don't know where that $300 came from..
But , there are PLENTY of those Tubes available..IF you don't mind spending
a bit to get 'em.. A bit costly. :blink:
 
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mackmobile43 said:
That's an incredible output for those 3 tubes and one very small transformer.
Click to expand...

I concur. Sounds like that may be the DC input power. Then again maybe that's what incredible about it. It does something no other amp in the entire world can do,defy the basic laws of electricity/physics. Oh wait, all CB amps do that anyway. :wink: I wonder what color the tubes are at 800 watts output. Probably the same color as the filaments on a long key. All in all it looks really good, like new in fact. :thumbup1:
 
The amp was made by Wawasee, not Maco. Those are nice amps as long as they are working. There were a lot of problems with the way they were wired, grid, filament, hv, wireing ran all over one another. HV seeping out of the wires getting into the bias was the main problem. I've worked on serveral and it took a little while to get them settled down. A few ferrite beads on the wiring in several different places normally settled everything down.
They would do pretty good wattage when everything was right. Make sure the fan is adequate enough to keep the heat off the tubes. The best I have seen you would tune it to max and then back off about 20% and they normally were very stable and would last a long time. Just don't hit them with a dual final radio, they weren't designed for that.
Good luck and congratulations on the find!!!
 
M2057 are a slightly tougher built 8950, and the 8950 is the same as a 6LF6, the heater voltage on the 2057 is 13 volt were as the 6lf6 has 6 volt heaters.

A m2057 plate can dissipate 40 watts and you can safely see up to about 70 watts output. Of the 70 watts, some power is lost due to the output circuit, the coils and capacitors. Figure about 10% loss from that 70 watts. So a 2057 can, as a general rule, safely do 60 watts.
In AM service, the carrier level in watts should be limited to about half the plate dissipation rating if you do not want to abuse the tubes. (i.e. the 8950 should be run at about 18 watts carrier level on AM) as the 2057 is a little heaver tube you can get a little bit more, but they are getting hard to find, and avg anywhere from 50 to 100 bucks each.
You have to remember that a lot of the old Amps were rated "input power" not output.
It is a nice clean looking Amp, I would not exceed the 100 watt dead key that the seller stated and no more that (peak) 15 watts drive.
Do not shove a big dead key into it.
If you drive the snot out of it it will make some big numbers.....but soon you will see the output drop and you will be looking for tubes.
Be very nice to it and it should live a long time.
It is a nice find, I had seen it on E bay when it was listed.
Enjoy.

73
Jeff
 
Lik2race said:
You might want to read up on them, as I did..amazing amplifier,
Stan:thumbup1:
Click to expand...

I did and it appears you've copied and pasted the sale ad verbatim and really have no idea what that amp will really do for output in reality.

If memory serves those tube dissipate about 40 to 50 watts each safely so a 300 watt output would be pushing it very hard.

But cb is alive and well I see and all you have to do is 100 to the name of the amp for sale and that's the output of that device.:pop:

I had an old pal350 which had a 1x3 configuration of 8950's and I flattened them by driving to to an output of 150 carrier and 450 watts pep.
 


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