While I was in Solid State Land, I stumbled into dead Heathkit aa-32 and revive to a canary. I grew to love my Heathkit AA-32 8w/ch amp. But I am worrying about its o/p tubes. 6GW8 are the original tubes on my unit and they are hard to get and expensive. I learned 14GW8(PCL86) uses same construction except 14v heater voltage. Anyone tried 14GW8 to replace 6GW8's? How was result? How was sound? Is it worth trying? Should I Ebay my AA-32 and move in to deeper tube land ?
Thanks in advance.
Thanks in advance.
that will be hard as pcl86 is fully identical to the ecl 86 BUT . it has a series heater . so it takes like three times the voltage to light it up .
to be more exact . ecl86 = 6.3v .55A PCL86 = 14.5v 0.3A
could work . but you will have to install a separate transformer . for your new series valves .
edit . if you would mod your existing amplifier to use the series heater variant of the ecl86. you would have VERY little worries about replacing its output valves . picked up a box of TV valves for €15 and 20% of them where pcl86
and its SO dirt cheap i bet you could get tonnes of them in europe of ebay .
to be more exact . ecl86 = 6.3v .55A PCL86 = 14.5v 0.3A
could work . but you will have to install a separate transformer . for your new series valves .
edit . if you would mod your existing amplifier to use the series heater variant of the ecl86. you would have VERY little worries about replacing its output valves . picked up a box of TV valves for €15 and 20% of them where pcl86
and its SO dirt cheap i bet you could get tonnes of them in europe of ebay .
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Yeah, only 3-4 years ago 6GW8's were easy to find and cheap, now they are $20-$50 each NOS, depending on the seller. PCL86's are probably your best bet as there are still a few available at more reasonable prices due to their uncommon heater voltage requirements.
See if you can find something close to a 14.5v transformer. I'm not sure what the tolerance is for the PCL86 heaters, so it's possible a more common 12.6v transformer might work, but I'm not qualified to answer that. Another option is a 10-11V transformer rectified to provide 14.x VDC.
I wonder if there's a Russian equivalent to 6GW8.
..Todd
See if you can find something close to a 14.5v transformer. I'm not sure what the tolerance is for the PCL86 heaters, so it's possible a more common 12.6v transformer might work, but I'm not qualified to answer that. Another option is a 10-11V transformer rectified to provide 14.x VDC.
I wonder if there's a Russian equivalent to 6GW8.
..Todd
I often see advertisements for 'boxes of TV tubes' you can get for next to nothing (I got 20 kilos for free) and they're FULL of PCL86..
ecl86 is little hifi tube.(originally for audio)...nice midrange(in all europ and us tubes brand ) no difeerent in sound bay heater voltage.so pcl...can use .... dc or ac 12 to 14.5 v.test this circuit in 6.3 line of your power transformer for new filimant voltage.
An externally hosted image should be here but it was not working when we last tested it.
Using a voltage doubler with this load (300mA per tube, so 600 for two of them in stereo single ended) will result in a voltage of only ca. 1.5x the input voltage. So at an input voltage of 6.3V, expect no more than about 10V output. That's a bit on the low side for a PCL.
You'd be Ok running them on 15 volts, lots of suitable transformers around. You could easily put in a series resistor to drop the odd half volt if you want to. 0.42 ohms is correct but 0.39 or 0.47 will be fine. ! watt rating would be adequate.
Thank you very much for all your replies
I will find some transformer to rectify to DC 14v or Ac 15v to reduce. This will take some time. I think I will keep my Heathkit aa-32 for now.
Thank you all
I will find some transformer to rectify to DC 14v or Ac 15v to reduce. This will take some time. I think I will keep my Heathkit aa-32 for now.
Thank you all
nice . keep your current gear . no need to buy anything hifi . that healthkit looks cool retro style . and is safe to . becouse its enclosed . i HATE to see valves being used as cristmas lights on top of a shabby looking wooden enclosure . not even talking about the D.I.Y wiring .
cheers .
cheers .
PCL86 and 14GW8 heater requirements
Be aware that the heater voltage requirements of the PCL86 vary from 13.3 to 14.5V 🙁 from different manufacturers (e.g. the Philips 1969 Databook has it at the lower voltage). The heater current is always 300mA. There is a way to configure 3-terminal regulators to be 300mA current regulators... that would be ideal for PCL86's or 14GW8's, or as 450mA or 600mA regulators for a YCL86 or XCL86 respectively (although be careful about heat limits in the regulator you you try to drive two tubes via one regulator from a wide-ranging voltage source). There is another circuit I have used with cheap PNP power transistors where the case of the transistor is bolted to the chassis without needing a mica washer. Let me know if you want me to post the circuits.
Be aware that the heater voltage requirements of the PCL86 vary from 13.3 to 14.5V 🙁 from different manufacturers (e.g. the Philips 1969 Databook has it at the lower voltage). The heater current is always 300mA. There is a way to configure 3-terminal regulators to be 300mA current regulators... that would be ideal for PCL86's or 14GW8's, or as 450mA or 600mA regulators for a YCL86 or XCL86 respectively (although be careful about heat limits in the regulator you you try to drive two tubes via one regulator from a wide-ranging voltage source). There is another circuit I have used with cheap PNP power transistors where the case of the transistor is bolted to the chassis without needing a mica washer. Let me know if you want me to post the circuits.
Are there two 6.3V windings on the PT? If so then they can just be series-connected and rectified to get the 13-14V required. Overall current draw will not change significantly.
BTW, see ebay item 370793847380 for a rather good deal on tubes (10 NOS PCL86 for some $40 shipped, no affiliation with the seller). AFAIK, Polam/Telam tubes were made on Philips equipment.
BTW, see ebay item 370793847380 for a rather good deal on tubes (10 NOS PCL86 for some $40 shipped, no affiliation with the seller). AFAIK, Polam/Telam tubes were made on Philips equipment.
Considering that the line voltage in the US is a good 5-10% higher than it was 40 years ago, you could use 12.6V ( simply add a second 6.3V transformer to series with your original supply to the output tubes).
12.6 * 1.05 = 13.23
12.6 * 1.10 = 13.86
12.6 * 1.05 = 13.23
12.6 * 1.10 = 13.86
Necro thread!
Seriously, did anyone else notice that this thread is 3 years old and was revived 2 days ago?
Seriously, did anyone else notice that this thread is 3 years old and was revived 2 days ago?
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