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[Amps] Need for bias switch (CW/SSB)

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Subject: [Amps] Need for bias switch (CW/SSB)
From: "Jim Thomson" <>
Date: Tue, 12 Jan 2016 09:52:44 -0800
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Date: Mon, 11 Jan 2016 10:16:58 -0800
From: "Charlie" <>
To: <>
Subject: [Amps] Need for bias switch (CW/SSB)

I am putting a 8877 amp together. I was wondering why  some amps have a
"CW/SSB" switch.
Assuming the power supply can handle cw key down, other than higher
efficiency, what other reason could there be for this switch?


Charlie N6CFH

##  For  CW  use, there  is no need to use high amounts of idle current..on a 
gg triode amp. 
10-20 ma is ample for cw use.    which will require more  bias V... hence the 
switch.    Just use 
a string of  1N5408s  or  6A10s.... like  14-18 of em. 

## back in the old days the  cw  /ssb switch changed the B+.  This was for the  
1 kw  /2 kw pep
rules, when amps rated in input power.    for low power 600w  output  cw  /ssb, 
 eff is btter when using 
a lower  B+.   Then the plate load Z stays  the same. 

Jim    VE7Rf

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