The 77DX tube is likely getting soft (or will be) as 100 ma is
considered the absolute safe maximum and at that point you are also
likely well over the legal limit.
Reduce the drive and grid current and enjoy it.
Carl
KM1H
----- Original Message ----- From: "Larry P. Greenberg"
<wa9mag@ameritech.net>
To: <amps@contesting.com>
Sent: Tuesday, September 18, 2012 9:39 PM
Subject: [Amps] 8877 Grid Current
For a good number of years, I had a Henry 3K Classic export with a
single 8877. Peak power (fully tuned) occurred when the grid
current was low, around 10 to 20 MA. I recently picked up an Alpha
77DX with a single 8877. Peak power (fully tuned) occurs when grid
current is around 100 MA. Why is there a difference in operating
grid current between the two amplifiers? What is the maximum grid
current an 8877 can operate with out destroying the tube?
Larry, WA9MAG
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