Tube_lab, thanks for such the patient refresher on how the CRT TV operates )) My electronics hobby started right by the time when the tube TVs were finishing their way out (in where I lived at that time). I actually made my first own color TV from like-modules parts, I did not solder the PCBs myself but rather combined the pre-manufactured ones into a working set. So I completely missed the tube part of consumers TV history.
I think this your post deserves to be the #1 in this topic, kind of a pre-requisite for further reading and understanding.
Smoking-amp, your awesome list then also could be on the first page (i.e. #2) for quick reference, and updateable. If moderators would do that.
I think this your post deserves to be the #1 in this topic, kind of a pre-requisite for further reading and understanding.
Smoking-amp, your awesome list then also could be on the first page (i.e. #2) for quick reference, and updateable. If moderators would do that.
@Shef, i agree, these two gents are the men......
with the crt technology dying, the young may soon forget....
crazy drive can be the last frontier of tube amp building....
with the crt technology dying, the young may soon forget....
crazy drive can be the last frontier of tube amp building....
I "made" my first guitar amp at about age 8 by cutting a guitar cord in half and twisting the wires to the wires in the tone arm of a Magnavox HiFi handed down from my parents when they got stereo. I didn't yet have a soldering iron.
Soon I wanted to make myself a real guitar amp and a friendly ham radio guy even drew me a schematic, parts list, and pictorial diagram of how to connect up the parts. Where does a 10 year old kid with no money get parts? He helps the kid around the corner's father clean up his woodshop. Why? because I would go with him to the trash dump where there was an immense graveyard of discarded radios, TV sets, and HiFi's. Tubes, caps, resistors, transformers, small speakers and most everything needed to make things all for free! It took about a year but I built a Fender Champ 5C1 from old radio parts. I even managed to drag home a few things and get them working. How many kids in the early 60's had their own TV set? Before high school I had made about a dozen guitar amps, most with TV sweep tubes because they were easier to find than 6V6GT's.
I went to a technical high school where they had a 3 year vocational electronics program that essentially taught TV repair, with a bit of theory thrown in. It was 1967 and all our coursework was old, so everything was tubes. I finally learned that load line / impedance matching stuff and even understood why the little sweep tube (6BQ6) was louder than the big one (6DQ6). That frustrated me so much as a kid......If I could only tap the POWER I could see in that big fat tube, it would SCREAM!
The tech high school got me a job in a TV shop at age 15. I was supposed to help install TV antennas, but I could fix TV's better than the owner, so that's what I did. I don't remember all the details about how a tube TV works, since the last time I fixed one was about 1970, but at least I knew it pretty well about 50 years ago.
How about the exotic P1/100's fitting for this application? the recommended for g2 is 250V, or even 150V in some modes: https://frank.pocnet.net/sheets/030/p/PE1-100.pdf
PL36 is common in Brazil, thanks to several European makers installing here
So is a country where one finds 6DQ6B and PL36 at same shop in those TV times 🙂
Then some local makers loved to mix American and European types in same chassis, in different positions (eg. PCL85 for VOT and 6DQ6 for HOT).
So is a country where one finds 6DQ6B and PL36 at same shop in those TV times 🙂
Then some local makers loved to mix American and European types in same chassis, in different positions (eg. PCL85 for VOT and 6DQ6 for HOT).
Well DIYBras, you have produced some marvellous measurements on this thread; would you be able to generate crazy-drive curves for PL36? I'm sure many on this side of the Atlantic would be thrilled if you could.
In my second tube amp I've made (in 1996) I used a vertical output trafo salvaged from a Brazilian Philips KL-1, a hybrid color TV with PL508 output. I lost the PL508, and I used a 6DQ6B for it. In this time I don't know impedance matching, primary inductance, correct GAP for SE and leakage inductance. Even so, resulted in a interesting amp, but for good HF response it needed feedback (at this time my ears are good to almost 20kHz). For curiosity, this trafo is complex, with inumerous coils for convergence and the most weird oscillator I saw in my life 😱 Of course, I ignored all of them and used the "power ones". 20 years forward to present times, I measured this output trafo***, and have 9H primary inductance, and >50mH leakage inductance. Primary DCR ~~360R, and 14:1 turns ratio. ***to be fair, this is other trafo similar, from other TV. I don't have the 1996 trafo anymore. I noted that I put a battery in this amp input, I are able to displace the speaker very slowly, against common sense, better than a cap-coupled amp with eg. 10000µF. So what is going here?
About vertical linearity, according with RCA manual: the equivalent low frequency response for a 10% deviation from linearity is ONE Hz!!! Talk about a compromise for a output trafo! Now I understand why these trafos have a low primary inductance, when common sense predicts otherwise... Probably need to focus on (big) gap, to sustain such low response without saturating the core. In fact, the output tube plays only a part from the linearity requirement. In practice, I proved this to be correct (of course 🙄😛 ): I played with a vertical output stage for making my old 29" CRT TV I've made in 2006 a hybrid TV 😱😱 (the audio stage are already a SET with 6EM7). I tested with a huge SET trafo with almost 100H for 300B, and compared the result with the poor inductance KL-1 trafo. To be honest, the KL-1 trafo showed better LF response, with beautiful sawtooth. Probably is GAP related...
About vertical linearity, according with RCA manual: the equivalent low frequency response for a 10% deviation from linearity is ONE Hz!!! Talk about a compromise for a output trafo! Now I understand why these trafos have a low primary inductance, when common sense predicts otherwise... Probably need to focus on (big) gap, to sustain such low response without saturating the core. In fact, the output tube plays only a part from the linearity requirement. In practice, I proved this to be correct (of course 🙄😛 ): I played with a vertical output stage for making my old 29" CRT TV I've made in 2006 a hybrid TV 😱😱 (the audio stage are already a SET with 6EM7). I tested with a huge SET trafo with almost 100H for 300B, and compared the result with the poor inductance KL-1 trafo. To be honest, the KL-1 trafo showed better LF response, with beautiful sawtooth. Probably is GAP related...
Will be a pleasure, but.... I need to buy some; at the moment I don't have any PL36 (I've invested on PL509 and forget about PL36 😉). Not sooo easy to find recently 🙁
I have some info on the EL36/6CM5
12 Watt max (10W design)/5 watt (g2), Max Vg2 250V, knee 460 mA @ 150Vg2, gm 14K and Ri 5K at 100 mA, Mu 6, 200 mA Max DC
https://frank.pocnet.net/sheets/201/6/6CM5.pdf
https://frank.pocnet.net/sheets/030/e/EL36.pdf
6FW5/6DQ6B/6JN6/6GE5/6GV5/6JM6 are a little different (some Twin/Crazy drive curves posted earlier for 12GE5, working well )
17.5 Watt design/ 3.5 W (g2), Max Vg2 220V, knee 350 mA @ 150Vg2, gm 7300 and Ri 18K @ 65 mA, Mu 4.4, 175 mA Max DC
https://frank.pocnet.net/sheets/123/6/6GE5.pdf
12 Watt max (10W design)/5 watt (g2), Max Vg2 250V, knee 460 mA @ 150Vg2, gm 14K and Ri 5K at 100 mA, Mu 6, 200 mA Max DC
https://frank.pocnet.net/sheets/201/6/6CM5.pdf
https://frank.pocnet.net/sheets/030/e/EL36.pdf
6FW5/6DQ6B/6JN6/6GE5/6GV5/6JM6 are a little different (some Twin/Crazy drive curves posted earlier for 12GE5, working well )
17.5 Watt design/ 3.5 W (g2), Max Vg2 220V, knee 350 mA @ 150Vg2, gm 7300 and Ri 18K @ 65 mA, Mu 4.4, 175 mA Max DC
https://frank.pocnet.net/sheets/123/6/6GE5.pdf
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Hi,
I've been following this fascinating thread and I was wondering if I could put in use a quad of 6P31S I have. They are claimed to be equivalent to EL36 but they are beam tetrodes with less power dissipation.
I've been following this fascinating thread and I was wondering if I could put in use a quad of 6P31S I have. They are claimed to be equivalent to EL36 but they are beam tetrodes with less power dissipation.
Yes, some sellers want insane money for EL509/519, as if they are 2A3 or something. Look for Svet 6P45S - beefed-up EL509, bargains can still be found for big lots.
BTW, some used EL509 look as if they have splashes of dirt on the inside of glass envelope. These tubes test OK. What is this dirt?
electrons hitting the glass, typically where there are holes or gaps in the anode, gradually turns the glass brown
