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Old 15th Jan 2020, 7:37 pm   #1
crackle
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Default PL519 or PL509 valve

Hi
Has anyone got a PL519 valve in very good condition (NOS) going spare.
Or a PL509 might do as well.

All costs paid.

Thanks
Mike
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Old 15th Jan 2020, 10:09 pm   #2
westcliff
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Default Re: PL519 or PL509 valve

EL519s any good Mike?

Gus.
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Old 15th Jan 2020, 10:38 pm   #3
slidertogrid
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Default Re: PL519 or PL509 valve

EL519s must be a rare valve these days .
The only set I can remember that used them was a 'Colour boon special' 22" EMO . Made in France with a funny scam converted to PAL decoder. They weighed a ton thanks mainly to a huge mains transformer!
Maybe some other continental sets used them?

I can't help with a NOS PL519 / 509 but I am fairly sure I have a few set tested used ones somewhere .
If you don't find any new ones let me know you are welcome to one of my used ones.
Rich.
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Old 16th Jan 2020, 12:57 am   #4
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Default Re: PL519 or PL509 valve

I have a NOS Rediffusion branded PL509, PM Sent
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Old 16th Jan 2020, 1:15 am   #5
Techman
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Default Re: PL519 or PL509 valve

I've said this before, the EL509 is not a rare valve. There's thousands out there for sale if you look, and it's actually the PL509 that's getting rare and expensive.

I freely admit that I get a bit grumpy when people use up a dwindling resource which is the PL519 to feed RF linear amplifiers which thrash them to within an inch of their very short life in such devices. Those that are into preserving vintage colour TVs now have to search and pay over the odds for a valve that I remember costing no more than a fiver when I was repairing TVs back in the 70s. Homebrew audio amplifiers and ham linear amplifiers have now caused these valves to rocket in price compared to the 'EL' version, that's why I would always prefer people to use the 'EL' version in such homebrews.

However, there is another angle on this in that the 'PL' version is in many ways better in that it needs a lot less heater current than the 'EL' version. This high heater current of at least 2 amps can cause all sorts of problems in that the pin to base socket contact has to be perfect to stop a hot connection that can burn the base and crack the glass of the valve around the heater pins. To be honest, that particular base type is really not suitable for currents of that level and is the same as the 6KD6 which uses even thinner pins on an American 12 pin base type that has a heater current even higher at nearly 3 amps. The 6KD6 is a really good valve, but a disaster in 6.3 volt form with that pathetic base form. So although the 'PL' valve needs 40 volts, the current required is minimal and doesn't cause the same problems that the lower voltage, but higher current 'EL' version does. There's also often a voltage drop problem with the 'EL' heater supply, particularly if a printed circuit is used and, as already said, the actual valve base socket isn't up to the job, so the heater is often not fully powered as it should be.

I know what Mike wants this valve for, it's for the modified linear he's been working on and described in a recent thread on the forum. Using an EL509 type would mean finding a replacement heater transformer at 6.3 volts at a good 2 amps - 3 amps would be better, and it would have to fit roughly on the back of the unit where the 40 volt one is at the moment.

So to sum up, hopefully Mike can acquire a valve for his linear, as I fully understand why he needs it in this particular instance, the only problem being that it won't last very long in that grounded grid mode being put to a use which it was never originally intended, so I would recommend that he really needs several more as spare replacements. These valves lasted years with continuous use in the old colour TVs, whereas they can last just a few days when thrashed to the limit in RF linear amplifiers unless the 'talk time' is kept to a nominal level. It's normal for these valves when used in RF linear amplifiers to give an initial high RF output on first key up, but they seem to run out of puff as they get hotter and hotter and the poor old anode plate starts to glow bright red. The original twin 6JB6 valves that were in Mike's linear seem to always work in a different way in that they start off on the slightly low side, but improve over time as they get hotter, also I don't seem to remember the anode plates glowing red quite so readily in these amps as the 509 type seem to do, although they're all ex TV line output valves designed for pulse operation only.

Last edited by Techman; 16th Jan 2020 at 1:23 am.
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Old 16th Jan 2020, 1:18 am   #6
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Default Re: PL519 or PL509 valve

Quote:
Originally Posted by whiskas View Post
I have a NOS Rediffusion branded PL509, PM Sent
Pleased to see that you can help Mike out on this one, regardless of what I've just said in my above post
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Old 16th Jan 2020, 9:50 am   #7
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Default Re: PL519 or PL509 valve

Thanks for the replies and offers, I have contacted Whiskars to ask for confirmation of the height of his valve.
Yes you are correct it is to go in a linear amp to replace the PL519 which keeps getting a G2 to anode short. Its happened about 4 times now and a hard wack on the bench, with the valve the opposite way to how it normally sits, seems to clear it for a while. I dont understand why it is G2 that shorts to anode, I would think G3 would be more likely.
I suspect the PL519 I have may not like operating in a horizontal position. I am hoping the PL509 may be different.

Mike
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Old 16th Jan 2020, 11:03 am   #8
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Default Re: PL519 or PL509 valve

Hi Mike, see if you can find the full data sheet for the valve. It should show the preferred orientation for a horizontally mounted valve to prevent electrode shorts .

If you look at some threads on tetrodes and pentodes you will see that some pentodes are actually beam tetrodes, i.e. beam plates and not a G3

Ed
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Old 16th Jan 2020, 11:48 am   #9
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Default Re: PL519 or PL509 valve

The PL519 replaced the PL509 fairly early on in service. I can't remember why, possibly flashing over (some still did)
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Old 16th Jan 2020, 12:10 pm   #10
Peter.N.
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Default Re: PL519 or PL509 valve

They are a pretty tough valve, I have seen them working quite happily with the glass collapsed onto the anode because they have been running red hot.

I have a box of them complete with bases and top caps if anyone wants to build a linear.

Peter
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Old 16th Jan 2020, 1:37 pm   #11
Maarten
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Default Re: PL519 or PL509 valve

I seem to remember almost all line output valves are actually beam tetrodes.
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Old 16th Jan 2020, 3:29 pm   #12
MALC SCOTT
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Default Re: PL519 or PL509 valve

The PL509 worked quite happy in the horizontal position in the Rediffusion Mk1.
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Old 16th Jan 2020, 10:06 pm   #13
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Default Re: PL519 or PL509 valve

There is not much scope for changing the orientation as the valve holder is soldered into the PCB. All I can do is hope, and buy some more fuses. To be honest the G3 does look like a plate surrounding G2. But there is still another plate (anode) surrounding G3.
Mike
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Old 17th Jan 2020, 12:07 am   #14
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Default Re: PL519 or PL509 valve

Hi
Whiskas is sending me a nice NOS PL509.

Thanks to all for advice.

Mike
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