Hello gang! I have a Drake L7 and 2 power supplies. One shows 2700 plate volts, when driven with 65 watts, amp puts out 800 watts. The other one will do 3700 plate volts and will do 800 watts with 35 watts drive. Will the latter harm the amp in any way? Is 1750 watts at the plate too much for the two 3-500z tubes? Thank in advance.

Are both power supplies Drake? Normal voltage is around 2600 nominal. A 3-500 can handle 3700 volts no problem. Henry tan them as high has 4000 volts. The problem is the RF deck handling the voltage and not so much the tube.

I believe the 2700 volts is normal for the Drake L7 amp. The 3-500Z tubes will take up to 4000 volts, but the Drake PI network in the amplifier is designed for the lower voltage. I would use the 2700 volts. The 3-500Z pair of tubes can take about 2500 watts input at 60% amplifier efficiency.

With 1750 watts dc input ("watts at the plate") And 800 watts rf output Thst gives 950 watts of heat dissapated in the 2 tubes. The "500" in a 3-500z tube is the amout of heat it can dissapate (assuming adiquate cooling) Since 950 is less than 1000 you should be ok. Rege