[Boatanchors] [AMRadio] 4-1000 question

[mac]

Ah-ha, a parasitic!  Plenty of literature on how to deal with that...

Dennis D.  W7QHO
Glendale, CA

*************
On Nov 6, 2012, at 5:41 PM, Paul Baldock wrote:

> I discovered the "no drive" currents vary with plate tuning control.
> It turns out that its oscillating up around 100MHz.
>
> This amp was designed for a 3-1000, so maybe I need a different APC
> for a 4-1000
>
> - Paul
>
>
> At 04:55 PM 11/6/2012, you wrote:
>> Based on the replies of been getting, I should have highlighted 30mA
>> grid current WITHOUT DRIVE APPLIED.
>>
>> Thanks
>>
>> - Paul
>>
>> At 03:50 PM 11/6/2012, Paul Baldock wrote:
>>> I have acquired a LK-2000 linear that uses a 4-1000 in grounded  
>>> grid,
>>> zero bias. B+ is around 3400V. Control Grid and Screen Grid are
>> both grounded.
>>>
>>> When I go to transmit (no rf applied) the standing plate current is
>>> about 140mA which is good. However the Grid Current (Ig1+Ig2) is
>>> about 30mA - I would have thought it should be zero but I am not  
>>> that
>>> familiar with using Tetrodes as Triodes.
>>>
>>> I tried a second tube (they are both pulls) with very similar  
>>> results.
>>>
>>> It does not appear to be a metering issue.
>>>
>>> Is this normal?
>>>
>>> Thanks
>>>
>>> - Paul   KW7Y
>>>
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