In a message dated 2/5/2006 4:06:44 A.M. Eastern Standard Time,
vk4ajs67@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@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
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