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Alastair E 5th March 2004 10:28 PM

EL519/KT90 The old debate
While in discussion with Edicron, on whether they could get Octal based '519 valves made, they suggested a Ei KT90, and I was told they share many of the same internal parts with the '519 I requested a data sheet on them which arrived today, but its tested under totally different conditions than the'519, so comparisons are difficult, although, the anode rating is 50W as opposed to 40 of the '519
Guess the only way is to get hold of a genuine Philips '519 and set it up as per the spec for a '519, give it a thourogh testing, and maybe plot a few curves, particularly the Ia at the higher end, and do the same with the KT90
I have a hunch that maybe there could be a similarity---Unless of course, you know different!!

I have a genuine Philips 519, coming from Germany Now I need a KT90 for comparison......

fdegrove 6th March 2004 12:46 AM



I have a genuine Philips 519, coming from Germany Now I need a KT90 for comparison......
You don't want to get me started on that one again, do you?

The KT90 is bl**dy expensive though...

Anode dissipation for the philips EL519 is 45W tops, BTW.


Alastair E 6th March 2004 12:34 PM

Price of KT90
Ive been quoted 12 sterling for a Ei KT90, as opposed to 7 for the PL519 Its a bit more...but would make a neater looking amp--IF they would work out as effective!

fdegrove 6th March 2004 01:29 PM



IF they would work out as effective!
Effectively doing what, exactly?


AV8R 7th March 2004 03:45 PM

KT90 vs EL509/519
I have been some 3 years ago to the Yugoslav factory in Nic and the parts used are all the same except grid 2 which is wound with a different pitch so as to operate G2 att 400 volt instead of 150 volt. i.e. the u is less between G1 and G2. Therefore has different curves.

The plate disipation ratings(35 w) are the same as the envelope glass is the same with the base change and no top cap lead out. It still is evacuated through the top as the could not modify their machines to evacuate through the bottom as is normal octal style.

If you don't mind running a little hotter before the plate glows dull red the 42 watts is acheivable.

The old GEC KT88 had a smaller plate surface area and they rated
their wattage with dull red as the norm but the glass envelope was a bigger diameter in the plate region so was less likely to melt by radiation disipation. The glass on EL519 tubes melts when the plate run plainly visible red and implodes.

Alastair E 7th March 2004 09:44 PM


Originally posted by fdegrove

Effectively doing what, exactly?


Well, Im looking at OTL work, where you need a high current. The PL519 is rated at 1.4A under pulse conditions, The russian 6P45s/El509 II is rated at 800mA under the same conditions

What would be great would be a PL/EL509/19 with an octal base, with the same high current capabilities! (and low G2 volts)

A certain Russian company marketed the 6p45s as a direct equivalent of the Philips EL509/19, but it falls short of total current capabilities, They then made an Octal version out of the same valve, and called it a EL509 II, which still fell short on current!

Maybe the Ei KT90 (with suitable adjustment of G2 volts) could do the trick--Only testing an example or two will really tell!--Bit of a pain, that high G2 though.... I was hoping to drive G2 with signal via a Mosfet for extra efficiency

Then again, Ill probably just stick to Top Caps!!--At least my NOS PL509/19 are "real" ones!! :angel:

fdegrove 7th March 2004 10:23 PM


It seems you're also dreaming about the same valve as Runeight is...

Actually, OTL or not, this should be a great asset to anyone building amps and pretty straightforward for EI to do.

They already resocket the EL519 with a different grid, all they need to do is nothing else but fit an octal socket...O.K. I'm oversimplifying but you get the picture.

There have been several threads here by Runeight on this as well as on AA and the Transcensent Forum.
Let's hope he can pull it off.

Hmmm...An octal version of the 6C33-C would be out of the question, I reckon...:D

Cheers, ;)

P.S. You'll also find the story behind the 6P45s in the same threads.

AV8R 8th March 2004 08:24 AM

EL519 vs KT90
Re basing the EL519 on an octal, yes, why? What is wrong with the Magnoval/ B9D base anyway?

The factory in Yugoslavia cannot be bothered as the quantities are not there.

As to the Russian 6P45/EL509, it will pull the same current or peak pulse in the same circuit with the same G2 volts. Just that they measured a different parameter. Both are good for OTL amps.

I made a 3 KW amp 30 years ago with 30 pairs of PL519. Needed 3 phase main power!

My chalenge to you guys. Is make a 70 Watt into 8 Ohm DC to 1/2 Mhz at full power OTL.

fdegrove 8th March 2004 08:46 AM



What is wrong with the Magnoval/ B9D base anyway?
It's not the magnoval base but the topcap that bother most people it seems.

If the EL519 was using the basing diagram of the KT88 we would have yet another pin compatible alternative in that power range.


The factory in Yugoslavia cannot be bothered as the quantities are not there.
I can only speak from pre-war experience here, in those days it was 10k units, mostly backed up by LOC etc.


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