ECC99 Heater / Cathode Max Volt

[Peter Menting]

Does anyone have the heater / Cathode max Voltage for this tube, I am using it in an SRPP and will have 150 Volts on the plate of the lower tube.

Pete

 

[Eli Duttman]

Unfortunately, JJ's spec. sheet doesn't say anything about heater to cathode voltage. My seat of the pants reaction is to float the heater supply, regardless of whether it's AC or DC, and bias the heater off the B+ rail with a voltage divider at about +70 V.

 

[dshortt9]

For what it's worth this site claims U k/f to be 200v.

http://www.musicolar.ch/JJECC99.htm

 

[Peter Menting]

Thanks for the responses.
That 200 Volt figure is impressive if true, but I believe that I will take Eli"s advise and bias the heaters to 70Volts just to be safe.

Pete

 

[dshortt9]

Tubes of this type specify about 100v static c-f and 200 v ac. The E182CC may reach 200v static. The best I've seen is the 6H30 which is an impressive 400v. No need to bias the heater on this one.

 

[fdegrove]

Hi,

That 200 Volt figure is impressive if true, but I believe that I will take Eli"s advise and bias the heaters to 70Volts just to be safe.

It's only impressive if interpreted the wrong way: Vk/f 200V means with a heater 100VDC positive with respect to cathode, total DC and peak would be 200V.

With the heater negative with respect to the cathode total DC and peak is again 200V.

A lot of people misread this kind of data completely when the numbers are reversed, i.e. cathode more positive than heater and take the wrong measures.

Cheers, 😉