[Amps] Plate Bypass Capacitor

[Glen Zook]

I guess I missed the original message.  However, if you are talking about the maximum plate voltage on the 6146 tube then the maximum plate voltage is 400 volts ONLY when the tube is being used as a modulator in Class A. When used in Class AB-1 or AB-2 the maximum plate voltage for a 6146 tube is 750 volts.  When used as a Class C plate modulated stage then the maximum plate voltage is 600 volts.  When used as a Class C amplifier for FM or CW then then maximum plate voltage is 750 volts.  This per the RCA specifications sheets dated May 1, 1952.

For the 6146A/8298 tube there is no recommendation for use as a Class A modulator.  However, for all other applications the maximum plate voltage listed is the same as the original 6146.  This per the specifications sheets dated May of 1963.

Now the maximum input power to a single 6146 or 6146A/8298 is 90 watts for Class C telegraphy, 85 watts for Class AB-1 or AB-2, and 67.5 watts input when plate modulated.

For the article on the 6146 family of tubes that appeared in Electric Radio a while back (and has been republished in several other places since then) go to

http://k9sth.com/uploads/The_6146_Family_of_Tubes_1.pdf

Most of the commercially built amateur radio transmitters that used the 6146 family of tubes (from the 1950s through the 1980s) run at least 750 volts and in many cases well over 800 volts on the plates of the 6146 tubes.  There are a few examples that run closer to 600 volts but those are in the minority.

Glen, K9STH

Website:  http://k9sth.com


--- On Thu, 8/6/09, Bill, W6WRT <dezrat1242 at yahoo.com> wrote:

However, your example of 600 VRMS on the plate of a 6146 grossly exceeds the manufacturer's ratings. RCA rates the 6146 at 400 VDC absolute max, which corresponds to a RMS max of about 280 V when properly tuned. I realize your example was just for discussion but we might as well discuss real world. :-)