[Amps] 8877 Grid Current

Carl km1h at jeremy.mv.com
Wed Sep 19 16:13:36 EDT 2012


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 at ameritech.net>
To: <amps at 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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