6MJ6 Tubes

[W8RID]

Looking to replace all the tubes in my Econo-Amp 6meter. (4 total)

I'm not getting the power that I should be and I think it is the tubes.

I would like to test the ones I take out. Does anyone know of a local company that I could go to, to have them checked out. (Twinsburg, OH)

This amp is old and has not been used for 15-20 years. It is clean.

I'm thinking I have a bad tube or tubes. It should be putting out 1000W on CW and 700W on SSB.
I'm not getting anything near that. The max power I'm getting is 70W.

I would like to have them all 100% or more and all the same brand.

Been looking on the internet and not finding 4 that meet that criteria.

Any other places I should be looking??

Thanks

Bob
W8RID

 

[W8JX]

Even with good tubes if you could get 1000 watts CW out it would only be a few seconds. Maybe 500 but on 6 meters that is pushing it as tube efficiency drops. 400 is more realistic. SSB 500 watts or a bit more should be possible. Amps of that era were rated input power not output so 1KW input on CW is within realm of possibility.

[KA5N]

70 watts is probably what you're putting into the "Econo Six" and a grounded grid
amp just passes the driving power out the output.  So the amp isn't amplifing
at all.  Whatever the advertisement for the amp says, 1000 watts CW and
700 watts SSB on six meters with sweep tubes is just wishful thinking.  
You don't mention whether you have ever had this amp working and if it has been setting for a long time, who knows what might be going on.  Testing sweep tubes
on a tube tester is specious at best.  Best bet is to improve your antenna system
or get a real amplifier and forget messing around with sweep tube amps.
You can buy NOS (new old stock) tubes which will cost a pretty penny and may
not be in good condition.

Whatever good luck
Allen

[K8AXW]

The 6MJ6 tube is an old sweep tube and the numbers W8JX quotes is pretty much on the money.  I'm thinking 600W out maximum on HF.  6M, less.

[W8RID]

This amp was given to me.

It sat for probably 10-15yrs without running.

As for what I am putting into the amp that is around 14-15w.
I'm using a FT-726R.

I would be happy getting 400-500W out of it at this point.

I am relatively new to amplifiers. My Drake L-4B is up and running now and I'm getting more and more comfortable using it, setting it up and dialing it in.

The Econo Amp is even easier to set up and dial in.

Don't really need this amp. Just playing around with it and was finding these unusual output readings.
I'm not on 6m much. That is the only band that I have not made a contact on.

The pricing on the tubes is on the high side. So I don't know how much I really want to put into this unit.
Just trying to get some more info and guidance on how to proceed with this project.

Bob
W8RID

[W8JI]

I built a bunch of amps using that tube, including one of the first six meter amps on a "bet you can't do it" dare when I was doing consulting work at an amp manufacturer.

Despite my reservations, they made it into a commercial product. W8JX and WIK'ka pretty well nailed it.

On six meters, you would be lucky and the tubes would be hot just to get 400 watts. That's 400 watts PEP SSB, or 300 watts low duty cycle CW. We did a lot of testing, the design was very good, and 6MJ6's were about $2-3 each back then. 6LQ6's would not work well at all, so you are pretty much stuck with MJ6's.

I wouldn't even put tubes in an amp like that today.

[W8JX]

As for what I am putting into the amp that is around 14-15w.
I'm using a FT-726R.

I would be happy getting 400-500W out of it at this point.

Tubes may be still serviceable. With 15 watts of drive and good tubes you are not going to get remotely close to 400 watts. Tubes may be a bit soft but you need more drive here. Figure on a 8 to 10db gain here on 6 meters. This means with good tubes you need 40 to 50 watts of drive here for 400 out.  

[W8RID]

OK!!

That kind of gives me the answers that I was hoping not to get,but needed.

I will probably take it out of the loop and make a lamp out of it.

Thanks

Bob
W8RID

[AD4U]

The 6MJ6 tube is an old sweep tube and the numbers W8JX quotes is pretty much on the money.  I'm thinking 600W out maximum on HF.  6M, less.

I have a Swan 350A in my boat anchor collection.  This IS NOT the Swan 350 that runs a pair of 6KD6 tubes.  The 350A runs one 6MJ6 tube in the final.  With a NOS Sylvania 6MJ6 tube power out is 135 on 80 meters and around 80-90 on 10 meters.  Even with 4 tubes I doubt if you can get more than 350-400 watts out on 6 meters.

NOS 6MJ6 tubes are very pricey.  I paid around $70 for one from a reputable source.

Dick  AD4U

[WB2WIK]

For 6m, if the amp is well built and the tubes are the only problem, I'd be very tempted to replace all four of them with a single 4X150A or something.

Even at only 900-1000V on the plate, the tube will produce 200W output on VHF.  Quite a lot more with 2000V.

6MJ6s were a great deal 40 years ago, but those days are long gone.