At least European UL84's, EL86's and PL84's are the same tubes, with the exception of the heater, of course. UL84 was the eldest member of the family. In 1953 it was developed in parallel with EL84, but intended for service in hot chassis radios that also needed to operate from 110 Vdc mains supply. Next one was EL86 that Philips intended for their OTL radios with high impedance speakers. They just put an EL84 heater into UL84 cathodes. Soon after it PL84 appeared in TV AF power sections, an EL86 with 15 V 300 mA heater.
Best regards!
Best regards!
I had several "Hohner-Orgaphon 45MH" amplifiers with me in the service workshop and had the opportunity to measure the actual power output. The voltage from the rectifier was somewhat unstable, which can be attributed to the relatively high internal resistance of the HV rectifier and the (too) small capacity of the electrolytic capacitors in the doubler. Because of this, the undistorted power was much lower than declared, i.e. the supply voltage would drop ~25-30V at maximum excitation compared to the state without excitation. With continuous sine wave excitation, the output power was between ~36-40W (depending on the frequency) before clipping occurred. I used new and paired output tubes PL84 (EI-Niš), and the optimally adjusted quiescent current was ~15-16mA for each output tube.
The "Hohner-Orgaphon 41MH" amplifier had a slightly higher output power, despite the fact that the factory name suggested that it was a weaker amplifier. I had the opportunity to service and measure only one example of this type of amplifier, but it mostly gave ~40-44W before the appearance of clipping. Analysis of the rectifier connection of the MH41 model shows the difference compared to the MH45 model, where it can be seen that the MH41 G2 model has a slightly higher supply voltage (220V without excitation signal) compared to the G2 voltage of the MH45 (200V without excitation signal). I also adjusted the quiescent current to ~15-16mA per electron, but due to the higher supply voltage of G2, the negative value of the bias voltage of G1 had to be higher. Despite the fact that these output power data are significantly different from the PL84 electronics manufacturer's data, they worked stably and for a long time in these amplifiers and without any traces of overheating even at the amplifier's maximum power.
The "Hohner-Orgaphon 41MH" amplifier had a slightly higher output power, despite the fact that the factory name suggested that it was a weaker amplifier. I had the opportunity to service and measure only one example of this type of amplifier, but it mostly gave ~40-44W before the appearance of clipping. Analysis of the rectifier connection of the MH41 model shows the difference compared to the MH45 model, where it can be seen that the MH41 G2 model has a slightly higher supply voltage (220V without excitation signal) compared to the G2 voltage of the MH45 (200V without excitation signal). I also adjusted the quiescent current to ~15-16mA per electron, but due to the higher supply voltage of G2, the negative value of the bias voltage of G1 had to be higher. Despite the fact that these output power data are significantly different from the PL84 electronics manufacturer's data, they worked stably and for a long time in these amplifiers and without any traces of overheating even at the amplifier's maximum power.
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Hi Davorin,
did you measure the OT's transformation ratio and the PT's secondary voltages, too?
I think it was a very clever idea of Hohner's to use these valves. In those days any TV repairman had TV tubes in his tube case, of course, hence could service Hohner amplifiers very easily.
Best regards!
did you measure the OT's transformation ratio and the PT's secondary voltages, too?
I think it was a very clever idea of Hohner's to use these valves. In those days any TV repairman had TV tubes in his tube case, of course, hence could service Hohner amplifiers very easily.
Best regards!
With both types of amplifiers (MH45 and MH41), the output transformer has a primary impedance of Raa=5.5kOhms, which I obtained mathematically from the transmission ratio of 1:43. More precisely, it is ~5550 Ohms, because I applied a sinusoidal voltage of 7Veff (100Hz) to the speaker output of 3 Ohms, and I got ~301Veff on the PL84 anodes. The speaker was disconnected at the same time. The HOHNER company also used the widespread (in Europe) and cheap PCL805 tube in its "Orgaphone MH24" amplifier, which was used in the vertical deflection of black-and-white TVs, and also in some series of color TVs.
Thank you, Davorin, for your extremely unseful informations 
!
As said above, the Hohner company was very clever with using common (in those days) TV tubes. Btw, they also sold a 130 watts Orgaphon amplifier with a pair of PL519's as finals. Custos!
Yes, the PCL805 originally was derivated from the PCL85 and intended for frame deflection service in B/W TV's. It was some surprise for me when I found it in an old Koerting 837/997 colour TV set. Anyway, this set featured a 90° deflection angle CRT. When 110° CRT's became common here, a more powerful tube was developed, the PL508. Even this tube found use in a Hohner amplifier, the Champion (no, not the accordions of the same name), with four PL508's as finals.
Do you also know the Orgaphon PT's exact secondary voltages? Otherwise I'd need to re-engineer them from the DC voltages after the rectifier/doubler.
Best regards!
!As said above, the Hohner company was very clever with using common (in those days) TV tubes. Btw, they also sold a 130 watts Orgaphon amplifier with a pair of PL519's as finals. Custos!
Yes, the PCL805 originally was derivated from the PCL85 and intended for frame deflection service in B/W TV's. It was some surprise for me when I found it in an old Koerting 837/997 colour TV set. Anyway, this set featured a 90° deflection angle CRT. When 110° CRT's became common here, a more powerful tube was developed, the PL508. Even this tube found use in a Hohner amplifier, the Champion (no, not the accordions of the same name), with four PL508's as finals.
Do you also know the Orgaphon PT's exact secondary voltages? Otherwise I'd need to re-engineer them from the DC voltages after the rectifier/doubler.
Best regards!
Davorin, thank you so much for your essential first-hand account of this very interesting amplifier! Looking at the math the output does in fact line up, and these are very much a baby sweep tube it looks like even more now. Now I'm getting curious as to if the 6P43P-E would survive at these operating points.
Very interesting to see that this amplifier is so similar to how I have my 6CW5 set up, the main differences for me are the 4100~ ohm equivalent output transformer I'm using, and about 50-60 volt lower screen and plate supply. I'm gettting 20-25 watts out of mine. Crazy how bumping it up that much can make such a large difference in output.
Playing with this calculator (thanks Koda!) confirms everything too. Gonna do some more comparisons on it and see what I get.
https://www.vtadiy.com/loadline-calculators/power-stage-calculator/
Very interesting to see that this amplifier is so similar to how I have my 6CW5 set up, the main differences for me are the 4100~ ohm equivalent output transformer I'm using, and about 50-60 volt lower screen and plate supply. I'm gettting 20-25 watts out of mine. Crazy how bumping it up that much can make such a large difference in output.
Playing with this calculator (thanks Koda!) confirms everything too. Gonna do some more comparisons on it and see what I get.
https://www.vtadiy.com/loadline-calculators/power-stage-calculator/
I had these data written down, but they were lost, and unfortunately I can't remember the values measured a long time ago (mid ~80s of the last century!).
I better answer about OPT selection - Although I have a few OPTs not in use, from 2-50W, I already have what I need in good-quality and relatively powertful tube amps. After years and military, my hearing is not perfect at all. So, no need to find OPTs. I have only space for one 'large' listening system, so I'm not worried abput OPTs.
My goal for many of the TV tubes is mainly about antique radio hobbyists who like to build in the 'old style' - those who like to make small regen receivers and audio amps/preamps, and are not too stuck on highest fidelity or a great deal of power output, but more for short wave listening quality. If they have or buy good OPTs that's fine, or it's fine to just take one from a junk/non-restorable equipment.
Beside the two loads items I posted there are hundreds, maybe thousands, other mixed tubes in my storage building, from a closing of a surplus store, that have never been sorted. Those are in two big shipping pallet-sized boxes, I think those boxes are called 'gaylords' these days.
Other tubes , many non-6-Volt octal based sweep tubes of 15-25W anode power as well as tubes like the 6W6 and 6Y6 (which works very nicely as the wide band low power RF amplifier after a crystal oscillator to drive an 837, 807, or the like) have come from ham radio estates where those gentlemen saved them up for use as RF drivers, buffer amps, etc. The ham estates also yield many tubes used in all kinds of receivers well up into the 100 MHz - so for 1-30MHz, are prfect.
All the above tubes - odd types etc. - the radio-oriented people don't worry about creating snowflakes because they can just modify to whatever and arenot critical on OPTs.
So, the previous joke about sausages is appropriate. At least I save good tubes from the landfill. If they end up there some day, it is not I who have sinned.
The main thing, is when the tubes are free I will take them and try to see what gems may be present. A lack of 12AX7s, EL34s, 6L6s, European favorites, etc., does not discourage me, The 'audiophile' tubes are always picked-over and absent from these free tubes.
A personal project is an analog audio processor speech amplifier) for ham radio. If I use an odd tube, it will be one where several spares exist.
My goal for many of the TV tubes is mainly about antique radio hobbyists who like to build in the 'old style' - those who like to make small regen receivers and audio amps/preamps, and are not too stuck on highest fidelity or a great deal of power output, but more for short wave listening quality. If they have or buy good OPTs that's fine, or it's fine to just take one from a junk/non-restorable equipment.
Beside the two loads items I posted there are hundreds, maybe thousands, other mixed tubes in my storage building, from a closing of a surplus store, that have never been sorted. Those are in two big shipping pallet-sized boxes, I think those boxes are called 'gaylords' these days.
Other tubes , many non-6-Volt octal based sweep tubes of 15-25W anode power as well as tubes like the 6W6 and 6Y6 (which works very nicely as the wide band low power RF amplifier after a crystal oscillator to drive an 837, 807, or the like) have come from ham radio estates where those gentlemen saved them up for use as RF drivers, buffer amps, etc. The ham estates also yield many tubes used in all kinds of receivers well up into the 100 MHz - so for 1-30MHz, are prfect.
All the above tubes - odd types etc. - the radio-oriented people don't worry about creating snowflakes because they can just modify to whatever and arenot critical on OPTs.
So, the previous joke about sausages is appropriate. At least I save good tubes from the landfill. If they end up there some day, it is not I who have sinned.
The main thing, is when the tubes are free I will take them and try to see what gems may be present. A lack of 12AX7s, EL34s, 6L6s, European favorites, etc., does not discourage me, The 'audiophile' tubes are always picked-over and absent from these free tubes.
A personal project is an analog audio processor speech amplifier) for ham radio. If I use an odd tube, it will be one where several spares exist.
The 'BQ6 and other old sweep tubes are favorites for me because they need only low screen voltage, will take high plate voltages, and handle much cathode current vs plate dissipation. I agree on the 'CW5, very nice tubes.
Eh, I'm not a huge fan of UL anyway, personally 
Some stuff like the 6AV5GA or EL86 actually does pretty nice in UL, though. Just gotta watch the overall voltage sot hat they don't run away.
If anything they make UL less appealing as it's so trivial to implement them well in pentode mode. even a simple VR tube shunt works well for G2 regulation at like 150 volts.
Some stuff like the 6AV5GA or EL86 actually does pretty nice in UL, though. Just gotta watch the overall voltage sot hat they don't run away.
If anything they make UL less appealing as it's so trivial to implement them well in pentode mode. even a simple VR tube shunt works well for G2 regulation at like 150 volts.
Pentaphobia - the fear of amplifiers which use global negative feedback. Lots of people have it (not me). Every home brew tube amp that I’ve ever turned into a finished product and use has just had regular pentode output stages - and more than 20 dB of feedback.
Played with triode-connected a few times, but in the end never wanted to commit expensive output iron to it when it doesn’t make as many watts and I get sound l like out of pentodes. Got a few really high perveance vertical sweep triodes, that can get the plates down to 50 or so volts without positive grid drive, and under 1k Ra. Those might be worth a look, even w/o feedback. The downside of that little project is requiring 250 or so volts for the outputs and 350 just to run the driver stage (albeit just at a few mA).
Most of my amps follow a theme-
-Push pull
-affordable output transformers
-Concertina splitter
-Pentode connection
-Regulated screen voltage that's lower than the plate by some margin
-Global negative feedback from the transformer secondary to the volt amp stage cathode
I avoid anything that needs more than ~30 volts or so peak drive per output grid so I can stick to ~300 volt supply voltage and easy phase splitter and minimal total amplifier stages. This makes it easy to get 15-25 watts from plenty of common sweep tubes. Also, the concertina can handle this just fine with most reasonable common twin triodes, much more than this and a LTP or an extra stage makes more sense- along with added complexity of a negative supply for a decent tail resistor or a CCS.
It limits what I build but it fits my needs just fine without costing too much, so I'm happy.
If someone would like to make a relatively simple anti-phase amplifier with EL86/6CW5, or PL84/15CW5, maybe the description of the amplifier I made and which works to this day without failure and without signs of aging of the tubes, although the output power is much higher than that declared by the factory data, can help him.
https://www.diyaudio.com/community/threads/el86-push-pull-for-home.291614/
https://www.diyaudio.com/community/threads/el86-push-pull-for-home.291614/
Pentaphobia sounds more like a fear of pentodes...
I make my triode amps with lots of gNFB. (I think it's 8:1 ot 10:1).