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Good to see some other working on adding Bias. I've been slowly collecting parts to redo the bias in a Palomar 900HD (4x2879). As such, the amp already had the Tip31c and 7805 Regulator circuit for bias. I began modding it to run at 28v with 4x MRF422's (I have HG's). My idea was replacing the 7805 and PCB trim-pot with a lower V regulator and using a panel-mounted 10T precision pot to adjust as needed. A calibrated 1v panel meter would fit nicely to aid in monitoring/setting bias v as needed. The variable bias idea I read long ago on R. Measures (Silent Key) SB220 website.

It was the ifw reference to G3SEK that got my attention. I built Ian's Tetrode boards where bias is 'steadied' by standing Screen current to help stabilize Screen voltage.
Anywho, we both got to the same place from opposite directions LOL.

<blockquote data-quote="Naysayer" data-source="post: 787928" data-attributes="member: 57429">Good to see some other working on adding Bias.&nbsp; I&#039;ve been slowly collecting parts to redo the bias in a Palomar 900HD (4x2879).&nbsp; As such, the amp already had the Tip31c and 7805 Regulator circuit for bias.&nbsp; I began modding it to run at 28v with 4x MRF422&#039;s (I have HG&#039;s).&nbsp; My idea was replacing the 7805 and PCB trim-pot with a lower V regulator and using a panel-mounted 10T precision pot to adjust as needed. A calibrated 1v panel meter would fit nicely to aid in monitoring/setting bias v as needed. The variable bias idea I read long ago on R. Measures (Silent Key) SB220 website.It was the ifw reference to G3SEK that got my attention.&nbsp; I built Ian&#039;s Tetrode boards where bias is &#039;steadied&#039; by standing Screen current to help stabilize Screen voltage.&nbsp; Anywho,&nbsp; we both got to the same place from opposite directions LOL.</blockquote>

[QUOTE="Naysayer, post: 787928, member: 57429"] Good to see some other working on adding Bias. I've been slowly collecting parts to redo the bias in a Palomar 900HD (4x2879). As such, the amp already had the Tip31c and 7805 Regulator circuit for bias. I began modding it to run at 28v with 4x MRF422's (I have HG's). My idea was replacing the 7805 and PCB trim-pot with a lower V regulator and using a panel-mounted 10T precision pot to adjust as needed. A calibrated 1v panel meter would fit nicely to aid in monitoring/setting bias v as needed. The variable bias idea I read long ago on R. Measures (Silent Key) SB220 website. It was the ifw reference to G3SEK that got my attention. I built Ian's Tetrode boards where bias is 'steadied' by standing Screen current to help stabilize Screen voltage. Anywho, we both got to the same place from opposite directions LOL. [/QUOTE]

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