[Amps] 8877 Grid Current

donroden at hiwaay.net donroden at hiwaay.net
Wed Sep 19 22:29:13 EDT 2012


Metering errors ??
Don W4DNR


Quoting Carl <km1h at jeremy.mv.com>:

> 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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>
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