Take a look at the spec. sheet (http://www.pmillett.addr.com/tubedata/HB-3/Receiving Tubes Part 1/6CL6.PDF). It's a video O/P tube for TVs and O'scopes.
The 6CL6 has a high 150 KOhm Ra that argues against it being used as a "final" in an audio amp. It would make a DANDY current sink for a cathode follower or a differential amp.
BTW, a transmitter broadcasts radio and TV.
The 6CL6 has a high 150 KOhm Ra that argues against it being used as a "final" in an audio amp. It would make a DANDY current sink for a cathode follower or a differential amp.
BTW, a transmitter broadcasts radio and TV.
Please tell me what pentode plate resistance has to do with output power. Extra credit, tell me the plate resistance of a 12AX7, 6V6 and 31LQ6 at standard audio-use operating points (class A/AB).
6CL6s should work great for drivers of big tubes or output itself. Kinda like a 6BQ5 but a bit less current. I once drew up a design using a sextet in triode mode class AB PP, 20 or 30W output.
Tim
6CL6s should work great for drivers of big tubes or output itself. Kinda like a 6BQ5 but a bit less current. I once drew up a design using a sextet in triode mode class AB PP, 20 or 30W output.
Tim
Nothing, BUT O/P "iron" for the 6CL6 will be problematic. Ra for the EL84 is about 38 KOhms. The Dyna A-410 trafo, suitable for use with the EL84, has a CT 8 KOhm primary. Custom trafos with CT 32 KOhm primaries are indicated for the 6CL6.
I suppose a quad of 6CL6s substituting for each KT88 with KT88 O/P "iron" would work. 8 bias adjustment pots. per PP channel will be tedious. Obtaining the TIGHTLY matched octets needed for cathode bias seems to be impractical.
Announcer speaks into a microphone.
- > Microphone converts the air vibrating into an electronic signal by means of a piece of metal moving a magnet over a coil, The magnet pushes the electricity in the wire because electrons are moved in/through metal by magnetisim.
-> The weak magnet and coil inside the microphone is far too weak to excite an antenna so we need to amplify it.
This is where your tube comes in.
-> This slightly amplified signal is now able to excite a larger tube typically called an RF Amplifier tube.
-> The RF tube is most times indirectly connected (coupled) to a large antenna which "Transmitts" this "RF electricity" into the space surrounding the antenna. Then if powerful enough your town and country. (Roughly put).
Theres no way 2.8watts is useful for RF applications of large nature unless you're quite an experienced HAM which is far off in this case. (sorry)
So this tube cannot be used here.
Your radio antenna is excited by the electricity surrounding it.
-> Your Radio Amplifies the signal from the airwaves and then /converts/ it to an AF signal or "Audio signal" for you to hear.
- > Microphone converts the air vibrating into an electronic signal by means of a piece of metal moving a magnet over a coil, The magnet pushes the electricity in the wire because electrons are moved in/through metal by magnetisim.
-> The weak magnet and coil inside the microphone is far too weak to excite an antenna so we need to amplify it.
This is where your tube comes in.
-> This slightly amplified signal is now able to excite a larger tube typically called an RF Amplifier tube.
-> The RF tube is most times indirectly connected (coupled) to a large antenna which "Transmitts" this "RF electricity" into the space surrounding the antenna. Then if powerful enough your town and country. (Roughly put).
Theres no way 2.8watts is useful for RF applications of large nature unless you're quite an experienced HAM which is far off in this case. (sorry)
So this tube cannot be used here.
Your radio antenna is excited by the electricity surrounding it.
-> Your Radio Amplifies the signal from the airwaves and then /converts/ it to an AF signal or "Audio signal" for you to hear.
Eli Duttman said:
Ok, power, impedance, whatever, just tell me what it has to do with pentode Rp.
Calculate some operating points on the tubes I listed above. Find plate resistance. I think you'll see the 31LQ6 has Rp higher than a 6V6 yet runs 80W into a 2ka-a load, while 6V6 runs 10W into 10ka-a. These aren't triodes.
Tim
AB2 maybe
Looking at the GE datasheet for the 6CL6, the plus Grid 1 (AB2) operation region is quite linear. Need to bring the screen G2 voltage down to maybe +90V to get average plate dissipation watts down and use maybe +125V B+. The higher current/ lower voltage operation of AB2 mode will allow a low primary impedance transformer to be used then (maybe 4K plate to plate for two tubes in P-P). Would require a set of cathode followers to drive the grids then.
Paralleling more tubes in AB2 mode would allow even lower primary impedance so that eventually, with enough tubes (about 10 and 10 !!), one could use a dual 120V to 35V line transformer for the output xfmr. Can use G1 grid stopper resistors to help equalize plate currents in AB2 mode too (if always in +G1 region). Some small cathode current sharing resistors would be helpful too.
Sure will look impressive with all those tubes and 75W output.
Don
Looking at the GE datasheet for the 6CL6, the plus Grid 1 (AB2) operation region is quite linear. Need to bring the screen G2 voltage down to maybe +90V to get average plate dissipation watts down and use maybe +125V B+. The higher current/ lower voltage operation of AB2 mode will allow a low primary impedance transformer to be used then (maybe 4K plate to plate for two tubes in P-P). Would require a set of cathode followers to drive the grids then.
Paralleling more tubes in AB2 mode would allow even lower primary impedance so that eventually, with enough tubes (about 10 and 10 !!), one could use a dual 120V to 35V line transformer for the output xfmr. Can use G1 grid stopper resistors to help equalize plate currents in AB2 mode too (if always in +G1 region). Some small cathode current sharing resistors would be helpful too.
Sure will look impressive with all those tubes and 75W output.
Don
6CL6's were used as cathode followers is at least one Fisher amp I can think of,
and IIRC, they were allso used as modulators & outputs on some tube
CB gear.
Any rate, the GE book says with
Va 250V, Vg2 150V, Vg1 -3V
6CL6 will put out about 2.8 W into 7.5K ohms.
7.5K wouldn't be impossible to come up with, actually if
one just wanted to experiment a little the standard issue
5K output used with 6V6's & 6BQ5's would be close
enough for some rock n' roll...
and IIRC, they were allso used as modulators & outputs on some tube
CB gear.
Any rate, the GE book says with
Va 250V, Vg2 150V, Vg1 -3V
6CL6 will put out about 2.8 W into 7.5K ohms.
7.5K wouldn't be impossible to come up with, actually if
one just wanted to experiment a little the standard issue
5K output used with 6V6's & 6BQ5's would be close
enough for some rock n' roll...
6cl6 plate resistance/transformer
This is in reply to Uncle Ned's comment about the load resistance of the 6cl6. I have seen that it says 7.5kOhm load res in the datasheet but does that mean that you can simply put a 7.5kOhm resistor between the plate and B+? If so that would be great for me at least, but somehow I get the impression that you need a transformer that has a 100kOhm primary, and that is hard to find, right?
I have been contemplating the idea of nuilding a push-pull 6cl6 amplifier cause I have a couple lying around. Any help?
BTW I'm not going to drive a speaker here.
Thank you
This is in reply to Uncle Ned's comment about the load resistance of the 6cl6. I have seen that it says 7.5kOhm load res in the datasheet but does that mean that you can simply put a 7.5kOhm resistor between the plate and B+? If so that would be great for me at least, but somehow I get the impression that you need a transformer that has a 100kOhm primary, and that is hard to find, right?
I have been contemplating the idea of nuilding a push-pull 6cl6 amplifier cause I have a couple lying around. Any help?
BTW I'm not going to drive a speaker here.
Thank you
What I want to do is drive a line load, say around 5kohm, or as the datasheet says, 7.5kohm. Doesn't really matter to me. What I am looking for is the exact type of transformer I would need to interface the pair of 6cl6 tubes to this load.
If it is possible to drive speakers with these tubes, then all the better. But I get the impression that they are not good to do that.
If I were to find a transformer that had a immense ratio (1:50) could I then plug a 8 ohm speaker?
Thank you
ps: I searched but I did not find the "spud amplifier".
If it is possible to drive speakers with these tubes, then all the better. But I get the impression that they are not good to do that.
If I were to find a transformer that had a immense ratio (1:50) could I then plug a 8 ohm speaker?
Thank you
ps: I searched but I did not find the "spud amplifier".
I remember seeing the 6CL6 used in a "spud" amp (one tuber...) - maybe it wasn't here.
If you have a bunch of them, you could use push-pull parallel to get maybe 10-15W into a 4K-6K output transformer. No reason you couldn't use two more as a gain stage and triode wired as a phase inverter. Feedback will be required to get a reasonable output impedance. Six 6CL6s per channel...
Pete Millett has data on triode and pentode mode gain stages, including 6CL6. http://www.pmillett.com/pentodes.htm
But... the transformers are the REALLY expensive part - if you're spending that much, why not spend a little more on the best tubes for the job?
If you have a bunch of them, you could use push-pull parallel to get maybe 10-15W into a 4K-6K output transformer. No reason you couldn't use two more as a gain stage and triode wired as a phase inverter. Feedback will be required to get a reasonable output impedance. Six 6CL6s per channel...
Pete Millett has data on triode and pentode mode gain stages, including 6CL6. http://www.pmillett.com/pentodes.htm
But... the transformers are the REALLY expensive part - if you're spending that much, why not spend a little more on the best tubes for the job?
I just got around to looking up the specs on this one, since I have a few hundred of them. On page 2 of the GE data sheet they list a single ended class A amplifier configuration with a power output of 2.8 watts with a 7500 ohm load. This could be achieved with any of the low cost Hammond universal SE transformers. I believe the best cost / performance unit in this series is the 125CSE at about $32 USD.
They also provide curves for triode operation of this tube which look reasonably linear even into positive grid bias. I will have to explore this. I am guessing that you will get 1 to 1.5 watts.
I believe two of these in push - pull should provide about 5 to 7 watts with a 5 to 7 k load, although I haven't yet had time to try them out. It is on my list of tubes to investigate.
They also provide curves for triode operation of this tube which look reasonably linear even into positive grid bias. I will have to explore this. I am guessing that you will get 1 to 1.5 watts.
I believe two of these in push - pull should provide about 5 to 7 watts with a 5 to 7 k load, although I haven't yet had time to try them out. It is on my list of tubes to investigate.
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