Tube of the Month : The PL519

Hi!

Smart amplifier builders always looked beyond the mainstream tubes and searched especially among tubes developed for TV applications. In the last post I showed an amplifier with such a tube, the 6CB5A. Today I'd like to present a european TV tube, the PL519.

The PL519 is a European type which was developed as output tube for the line deflection circuit in TV sets.

It is a pentode on a 9 pin Magnoval base and the plate is connected to a top cap. The pinout is shown on the left. The first letter 'P' indicates a 300mA series heated tube. This means that it was intended to be heated in series with other 300mA heater tubes. If heated in this way 40V will be present across the heater. There is also a 6.3V version for parallel heating, called the EL519. It has the same electrical specifications as the PL519 except for the heater requirement. The cathode of this tube can deliver insane peak currents like other deflection output tubes. In this case 1.5A. It has a maximum plate dissipation rating of 45W. Connected in triode such beast can easily deliver more than 10W in single ended mode. Such TV tubes are extremely rugged and don't mind to be run at their limit. I recently visited a customer who has a 6CB5A amp built by me and which is in use since 2010. I checked the output tubes and they showed no signs of wear. I'm confident a PL519 would hold up just as long. As always lets have a look at the triode connected curves of this beauty:

A great alternative to 300B and the like if on a budget. And it leaves more funds to be spend on the output transformer and other parts of the amp. 

Lets have a look at some PL519 samples from different manufacturers starting with Philips.

The top cap:

The Magnoval base:

Some close ups:

The next one is labelled 'Karo'. Never heard of them probably rebranded from one of the main manufacturers.

Industria labelled PL519:

The box:

A whopping 6 months warranty. Back in those times 90 days warranty was the norm.

Valvo:

And lastly a Telefunken PL519:

Niclas from Sweden, again borrowed these to me, so no dissection. But some tube glow:

Best regards

Thomas