how much drive into an old tube amp w/ straight 4 x 6LQ6

[mr_fx]

how much drive into an old tube amp w/ straight 4 x 6LQ6

Further more what kind of power out should a 4 tube 6LQ6 be putting out?

I have heard 100, 150, 200, 400, 500, 600, and even 800. so I really just don;t know

My buddy swears up and down any more than 3-4 watts on SSB will kill it. But most old sweep tune amps had a driver (i.e. 1x2, 1x3, 1x4) I know my buddy has an old Palomar Skipper 300 (1x3 6LQ6) and he claims 450 on SSB with only 4 watts of drive... I tried to explain that a straight 4 is a totally different animal and that the driver is most likely pumping 20+ watts into the 3 final tubes... but he does not seem to get it

 

[unit_399]

mr_fx -

I have an old boat anchor tube amp, an SBE SB2-LA. It uses six 6JE6 tubes operating Class AB1. SBE rated this amp at 1000W SSB, 300W AM, or 400W FM/CW, with 65 watts drive (maximum). To get the advertised output, I had to change the input impedance of the amp from 75 to 50 ohms. A little math shows that (maxed out) it's doing 166W per tube in SSB, and 50W per tube in AM, with roughly 10W drive per tube. I never drive it that hard. Usually 30W drive for 500W out in SSB.
If your amp is Class C grounded grid, then the input and output figures will vary slightly. However, since the 6JE6 and 6LQ6 tubes are interchangeable, the numbers for the SBE amp should be in the ballpark. 73s

- 399

 

[mr_fx]

it's AB, so 300 on the safe side and maybe 600 hitting it hard?
maybe 400-500 out for a nice middle ground

 

[GnG8d]

AB 1 or 2 will make a lot of difference.


Sent from my iPhone using Tapatalk

 

[AudioShockwav]

For me, a good rule of thumb is 5 watts input per tube with 6LQ6`s, so I would limit it to about total 20 watts (pep) drive for SSB use.
AM is real tough on old sweep tubes, even 6LQ6`s....and they are a very robust tube.
I would limit AM dead key to 100 watts and no more than 400 watts total output.
They "can" handle almost 200 watts of plate dissipation for a short period of time, I think GE said not to exceed 30 seconds.
The thing is, they are really getting hard to find in good shape, and expensive.
Anyone running sweep tubes now should limit the drive just to keep them alive as long as they can.
You used to be able to get these tubes for around 8 dollars each at the local store, so it was not a big deal to lose one, but now.....


73
Jeff

 

[RatsoW8]

With 6LQ6's in it I'd drive it to the radio museum and buy an amp with transistors.

 

[Robb]

Are the Russians and the Chinese making these sweep tubes still?

 

[unit_399]

Who needs Russian or Chinese tubes?? NOS Sylvania 6JE6/6LQ6 tubes are available here from several sources @ 10Mil pesos ($5.00) each.

-399

 

[SmackDown]

I have a Nitro 300 with 5 6LQ6 tubes. It does 300w avg. power. With 4 6LQ6's I'd guess its good for 250w avg.


3's


Oh, unit 399 are those tubes coming from here or are they stocked down there???

 

[unit_399]

Oh, unit 399 are those tubes coming from here or are they stocked down there???

In stock locally.

 

[RatsoW8]

In stock locally.

NOS 6LQ6 tubes would sell in the US for $35 -$75 USD each. It's way cheaper to run an amp with 811A's in it. Besides the 6LQ6 being an old TV sweep tube and not designed to be used in an amplifier. That's why they don't last long.

 

[tecnicoloco]

In stock locally.

The local electronic tv supply did not run out stock in sa

 

[Captain Kilowatt]

The local electronic tv supply did not run out stock in sa

Not likely they did run out as they do not have a million CB'ers pounding them to death in amplifiers.

 

[unit_399]

Not likely they did run out as they do not have a million CB'ers pounding them to death in amplifiers.

Exactamente !!

 

[AudioShockwav]

That is really cool and I never thought about stock somewhere outside of the US.
I got rid of my 300A ( i considered it a very good amp) because sweep tubes became too expensive, and I have passed on many good deals on sweep tube amps because of the same reason.
The only tube Amp i run now has 811`s in it because the are very reasonable in cost and easy to get.
I even sold off all of the spare tubes I had, String-bean here on the forum got the last few that I had.
Kudos, If I were you, i would stock up on a few spares.


73
Jeff