[Amps] Fwd: 8877 Grid Connection DC or Not

[gudguyham at aol.com]

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-----Original Message-----
From: gudguyham <gudguyham at aol.com>
To: dezrat <dezrat at outlook.com>
Sent: Tue, Nov 29, 2016 06:36 AM
Subject: Re: [Amps] 8877 Grid Connection DC or Not



<div id="AOLMsgPart_2_31e53d49-b8f3-4ab6-a1cf-7e9619dd0eba">
<div class="aolReplacedBody">Jim, I use the same scheme as the Ameritron AL-1500.  Easy and very effective.  Schematic is on their website for the AL-1500.  Don't forget a grid trip overload protection.

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-----Original Message-----
From: Bill Turner <<a href="mailto:dezrat at outlook.com">dezrat at outlook.com</a>>
To: Amps group <<a href="mailto:amps at contesting.com">amps at contesting.com</a>>
Sent: Tue, Nov 29, 2016 06:30 AM
Subject: Re: [Amps] 8877 Grid Connection DC or Not


------------ ORIGINAL MESSAGE ------------(may be snipped)

On Mon, 28 Nov 2016 21:00:21 -0600, you wrote:

>Has anyone run the grid of an 8877 not connected to ground as far as DC is concerned? 
>
>I really need to meter the grid current by bypassing the grid to ground with capacitors and several 10 ohm resistors in order to meter grid current. Metering grid current by the CT of the filament transformer, and the – of the power supply cant be done. Because the power supply – is directly grounded.
>
>Anyone had luck doing this?
>
>Thanks 73
>Jim W7RY

REPLY:

You might consider un-grounding the power supply if you can. It's not
a safety issue - the difference between true ground and B- is a volt
or two at most. That allows you to use the conventional grid meter
between ground and B-.  Trying to "ground" the grid with capacitors
can lead to unwanted resonances and instability as you probably know. 

73, Bill W6WRT
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