[Amps] Weird tubes in an amplifier

k7fm k7fm at teleport.com
Wed Jan 29 00:15:19 EST 2014


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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