PCL86 amp?

[Cornelius]

Just bought an box 'unseen', with around 50-60 tubes from the net for about $30. Mostly tubes for old tv-sets; only 4 NOS ECC83/12AX7 there...

But there was lots of PCL86 there, which was used for the AF-stage in tv's. PCL86 contains one triode stage; apparently very similar to half 12AX7, and a pentode, similar to an EL84, but slightly lower max-voltage...

Anyone tried to make a small SE amp out of just one PCL86?
The only drawback i can see, would be the 13,3VAC requirement for the heater, (though, the ECL86 are similar, but with 6,3VAC heater... But those wasn't in the box... ) and maybe a bit low pre-amplification?

[Andy Le Blanc]

Another tube in series would get close to 24v.

TV tubes tend to pile up, some of the HV rectifiers have Xray ratings, real tube glow.

Have you found a characteristic sheet?

[Cornelius]

http://www.r-type.org/pdfs/pcl86.pdf

I think it could be run as an EL84, but with a lower anode voltage; say, 230-250V...

To quote from The National Valve Museum:

The PCL86 as a single ended audio amplifier would have a cathode resistor of 125 Ohms and an anode load of 5,100 Ohms and under these conditions would produce an output power of 4.1 Watts at a distortion of 10%.

[Andy Le Blanc]

That looks like a fun tube. That 4w 10% distortion figure might be max power.

It looks like it would like a low Plate volt. You might be able to use them like
a 6bm8/ecl82 in a push pull circuit too. One 12 ax7 as a pre or a couple pre
stages and a couple pcl86 might provide the inverter and power side.

[Cornelius]

I have most of what it takes to make a small SE amp, except for a suitable PT... I have some small 12-14VAC transformers here for the heaters.

Anyone seen a PT with around 170-200VAC ( @50mA) on the secondary? (planning on using SS rectifier.) Target voltage would be 230VDC.

I think the PCL86/ECL86 would be a fun bedroom amp. It should perform rather good, since the PCL86 was one of the last 'newly developed' audio tubes in the '60; at the time when those new thingys - the 'transistor', was all the rage...

[stiltamp]

Have a look to:

http://www.albertkreuzer.com/pics/el/ec ... ecycle.gif

[Andy Le Blanc]

Two back to back low volt transformers will work if the I rating is substantial.

after a bridge youll get peak VDC around 1.4 x ac applied and IDC .62 x sec.
rating

you'll have to budget your current but it works. Whats the AC voltage where your at?

[Cornelius]

The voltage here is 230V.

I'll se what time permits; i'm in the middle of restoring parts of my house and it's freezing outside...

Somewhat related:
I just got hold of 2 old radios; same model, but different build/year: Radionette Duett Hi-Fi, from '61 (top) and '62 (bottom). The '61 model uses an EL84 at the output stage, while the '62 model uses an ECL86...
Both radios are in near mint condition, and works perfectly.

A duet of Duetts
[img:600:800]http://mwlmf.net/albums/Duett/100_2850.sized.jpg[/img]
Backsides; tube placements are on the back cover. [img:600:800]http://mwlmf.net/albums/Duett/100_2851.sized.jpg[/img]
Schematic for the later model.[img:800:600]http://mwlmf.net/albums/Duett/100_2852.sized.jpg[/img]
For full size images, se my gallery: http://mwlmf.net/gallery/Duett

I know i shouldn't be, but i always get amazed over the sound quality these radios have, everytime i turn them on... The '62 model has a better bass/treble control, so that one are my favourite.

[Andy Le Blanc]

I had a similar style and age set like that given to me a long while back.
They are very nice..... the one I had, was a stereo with EL84, I think I still
have the pair SE OPT. They don't look like much. But the quality was very high.

I appreciate the schematic, its always good to see a working example.
There's a conjunctive filter in the plate circuit. That tone control is interesting.

With that voltage you could almost go transformerless, A 1:1 would work.
Is that 241 ac. I see on the bridge rectifier?

Maine gets the cold too. Had a month long stretch five years back of -20 F
Very happy with a wood stove, not bad this year, only one week of -F temperatures, so far.

[Cornelius]

242VAC at the bridge; take a closer look at the full size image at my galley, http://mwlmf.net/albums/Duett/100_2852.jpg to see all the different voltages; they're using all the grids separately with different voltages in the pentode part...
I'll take a snapshot of the schematic for the other radio later; both the OP stage and the tonecontrol are different there... (the schematics are neatly folded and fastened to the inside of the bottom plate on the radio... Decently done of them... )

Edit:
Do you see that 'loop' drawn between the two resistors right after the bridge rectifier? They have actually replicated that loop exactly in the radio with a piece of wire... (Edit2: yes, i know it's an air-coil; it's just fun to see a one-turn coil done in the radio very similar to the one in the schematic. )

[Cornelius]

The schematic for the earlier '61 model with EL84 at the output.[img:800:600]http://mwlmf.net/albums/Duett/100_2853.sized.jpg[/img]

[breakfastbuddy]

and i am working on a duett also , but its the smaler one with a ecl 82 or a 6bm8 tube . i want to make it as a octal one amp .
but i was to quick to take it apart and i dont have any schem .
jeg kommer fra Skien i Norge

[Cornelius]

Looking at the schematics, i'm thinking that these PT (and OT) would be perfect donors for the PCL86 tubes i have (just add a 13VAC PT for the filament.)...

But do i have the heart to slaughter these lambs?!

NOT the '62 model.... I'm listening to it right now, and i wouldn't for the world consider turning on my surround instead...

[Cornelius]

Ah, another Norwegian. We're starting to take over this board...

The smaller one? I'm guessing it's the Duett 2 from '57...

There was no schematic on the bottom plate? or on the inside of the cabinet?

Oh well, as long as you noted the wires on the PT and OT you shouldn't have any trouble making a nice SE amp...

[malt]

Hi, my Vingtor has a 12xa7 and a ECL86 nice little amp haven't seen any schematic for this amp. here is a pic of the inside.
[IMG:800:600]http://i141.photobucket.com/albums/r63/ ... ure048.jpg[/img]