[Amps] SB-220 Mod for GS-35b

[Gudguyham@aol.com]

In a message dated 2/5/2006 4:06:44 A.M. Eastern Standard Time,  
vk4ajs67 at optusnet.com.au writes:

I wonder  if anyone has refitted a Heathkit SB-220 with a GS-35B to
replace the  3-500z tubes?

I wonder how it went and any info would be of great  help.

Cheers John  VK4AJS

Vk4ajs67 at optusnet.com.au



I haven't done this with an Sb-220 but I did convert an Amertiron AL-82  
using this and it worked.  The Sb-220 does not have a pressurized cooling  system, 
but I suppose you can install the tube horizontally against the back  wall 
and have an external blower attached, that is what I would do.  I  would not 
expect any more power output than you would get from a pair of good  3-500's  
using the power supply specs of the Sb-220.  The GS-35B likes  ALOT of plate 
current.  I have found that in the AL-82 conversion using the  same power supply, 
the GS-35B made about the same power as the 3-500's for 100  watts input 
power, maybe a shade more, but not much.  However, with more  drive I am sure the 
GS-35 will outperform the 3-500's, but how much more drive  does one have?  I 
always base my homebrew amps or conversion amps with 100  watts drive, as that 
is what most of us have available.  The GS-35B can  probably easily take up to 
150 watts drive without surpassing the max grid  current, providing all else 
is right.  Good Luck 73 lou  W1QJ