Interesting - the specs of the 6BQ5 and 7867 do look pretty close. I had my eye on the 6BQ5 for screen driven duty, but I may try it elsewhere. On a similar note, one of our members has coaxed decent push-pull performance out of the 6BQ6, an unabashed sweep tube. Georce (Tubelab) has also thrahsed some amazing amounts of power out of a pair of 6BQ6 as well, though that was a "test to extinction" situation.
6DQ5 is a big brother of 6BQ6, about 2-3 times bigger and stronger! But yes, the same principle can use to drive 6DQ5, 7867 and other big similar tubes. 4 tubes 6DQ5 can give 200W in normal Push-Pull class AB1 with less than 4% distortion, and same output tubes work last 3 years every day 4-5 hours. (drive at g1: Ua=600V, Ug2=150Vstab.,Ug1=-45V, Ra-a=3800ohms, Ia-min=2x30mA, Ug1eff.~2x40Veff.)
Here is some interesting info:
I was hanging out at Stans (ESRC) swap tables during a rain shower at the Dayton hamfest. I spent that time looking at tubes. If I spot a big box with a number that I don't know, or vaguely remember from my past, I will open the box and check out the tube. I have "discovered" a few winners that way.
I remember the 6DQ5 from the dawn of the color TV era as being a big sweep tube that was never very popular. I found several in Stans collection, looked at them, and then put them back when I found that they were $10 each. I prefer cheap tubes for obvious reasons.
Maybe 5 minutes later a guy walked up and asked for 6DQ5's. He said that he was using them in an OTL audio amplifier. He wanted a particular RCA to match the ones that he already had.
I added that number to my shopping list and managed to find a few used $1 6DQ5's that didn't look too bad. I have collected about 6 since then.
Investigating the specs reveals a very high peak cathode current rating for a 1950's vintage tube, 1 AMP. This is why they work in OTL's and they will probably make a good P-P output tube. I'll hook mine up eventually.
I was hanging out at Stans (ESRC) swap tables during a rain shower at the Dayton hamfest. I spent that time looking at tubes. If I spot a big box with a number that I don't know, or vaguely remember from my past, I will open the box and check out the tube. I have "discovered" a few winners that way.
I remember the 6DQ5 from the dawn of the color TV era as being a big sweep tube that was never very popular. I found several in Stans collection, looked at them, and then put them back when I found that they were $10 each. I prefer cheap tubes for obvious reasons.
Maybe 5 minutes later a guy walked up and asked for 6DQ5's. He said that he was using them in an OTL audio amplifier. He wanted a particular RCA to match the ones that he already had.
I added that number to my shopping list and managed to find a few used $1 6DQ5's that didn't look too bad. I have collected about 6 since then.
Investigating the specs reveals a very high peak cathode current rating for a 1950's vintage tube, 1 AMP. This is why they work in OTL's and they will probably make a good P-P output tube. I'll hook mine up eventually.
I'd try that.... but with a less wimpy 250V reg screen and 400-500V anode
I've used this tube in some kick butt power supplies before I got my Lambda ... pretty unperturbable tube
Cheers!
Where could i get a larger version of this image? i can't read it? Some one can help me please?
hey-Hey!!!,
And now for a Class A option: B+ of 250, g2 of 100V and a-a load of 5k. Idle at ~90 mA per tube. I am building right now with 6CB5A; B+ around 270V, g2 reg'd around 110V( adjustable in LMA329 steps ) with a 5k a-a load. Obviously not going for Max Power... Front end is an E-Linear LTP using EL84's( pentode-mode ). I'll post a schematic as soon as I can scan it.
cheers,
Douglas
And now for a Class A option: B+ of 250, g2 of 100V and a-a load of 5k. Idle at ~90 mA per tube. I am building right now with 6CB5A; B+ around 270V, g2 reg'd around 110V( adjustable in LMA329 steps ) with a 5k a-a load. Obviously not going for Max Power...
Front end is an E-Linear LTP using EL84's( pentode-mode ). I'll post a schematic as soon as I can scan it.cheers,
Douglas
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.