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Re: [Amps] Weird tubes in an amplifier

To: <k7fm@teleport.com>, <amps@contesting.com>
Subject: Re: [Amps] Weird tubes in an amplifier
From: "Carl" <km1h@jeremy.mv.com>
Date: Wed, 29 Jan 2014 17:49:58 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
They were designed for Class B audio AND RF and have very low distortion. However the mu is only 12 so they take a bit of drive.
As a grid driven SSB linear run them as with any other tube that has a 100W 
plate dissipation.
Carl
KM1H


----- Original Message ----- From: "k7fm" <k7fm@teleport.com>
To: <amps@contesting.com>
Sent: Wednesday, January 29, 2014 12:15 AM
Subject: Re: [Amps] Weird tubes in an amplifier


On 01/28/14 7:24 PM, Mark wrote:
Just when I thought I had heard of almost every type of tube in an amplifier, I talked to a ham that has 2 VT4C's in an older home brew amplifier he has for sale.
The VT4C is aka the 211. They have 100 watts of plate dissipation each. Filament is 10 volts at 3.25 amps. Maximum frequency ratings of 15 MHz (whoops mc for that vintage). They were often obtained surplus from the BC-375.
My opinion is that they are a terrible tube for a linear amplifier. There 
are a number of triodes that can replace it, however these group of  tubes 
have been bought up by audiophools, who think these triodes put out better 
notes than other amplifier devices.
You can substitute a pair of 805 tubes, but they have also increased in 
price.  It might make a nice AM final amplifier, but may need some work 
for a linear.  You could trade out the tube sockets and filament 
transformer and use almost any triode.  Two 572B tubes would work
In short, you can make it work on the low bands - but why?

73,  Colin  K7FM
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