<s>
A	O
Sutton	B-Algorithm
tube	I-Algorithm
,	O
or	O
reflex	O
klystron	O
,	O
is	O
a	O
type	O
of	O
vacuum	O
tube	O
used	O
to	O
generate	O
microwaves	O
.	O
</s>
<s>
The	O
second	O
use	O
,	O
sometimes	O
known	O
as	O
a	O
soft	O
Sutton	B-Algorithm
tube	I-Algorithm
or	O
rhumbatron	O
switch	O
,	O
was	O
a	O
key	O
component	O
in	O
the	O
development	O
of	O
microwave	B-Application
radar	I-Application
by	O
Britain	O
during	O
World	O
War	O
II	O
.	O
</s>
<s>
The	O
Sutton	B-Algorithm
tube	I-Algorithm
is	O
named	O
for	O
one	O
of	O
its	O
inventors	O
,	O
Robert	O
Sutton	O
,	O
an	O
expert	O
in	O
vacuum	O
tube	O
design	O
.	O
</s>
<s>
He	O
developed	O
the	O
first	O
models	O
in	O
late	O
1940	O
while	O
working	O
at	O
the	O
Admiralty	O
Signals	O
and	O
Radar	B-Application
Establishment	O
.	O
</s>
<s>
Sutton	B-Algorithm
tubes	I-Algorithm
were	O
widely	O
used	O
in	O
a	O
variety	O
of	O
forms	O
during	O
World	O
War	O
II	O
and	O
through	O
the	O
1960s	O
.	O
</s>
<s>
Their	O
role	O
has	O
since	O
been	O
taken	O
over	O
by	O
solid	O
state	O
devices	O
like	O
the	O
Gunn	B-Algorithm
diode	I-Algorithm
,	O
which	O
started	O
to	O
become	O
available	O
in	O
the	O
1970s	O
.	O
</s>
<s>
The	O
introduction	O
of	O
the	O
cavity	B-Architecture
magnetron	I-Architecture
caused	O
a	O
revolution	O
in	O
radar	B-Application
design	O
,	O
generating	O
large	O
amounts	O
of	O
power	O
from	O
a	O
compact	O
and	O
easy-to-build	O
device	O
.	O
</s>
<s>
The	O
problem	O
was	O
that	O
the	O
magnetron	B-Architecture
's	O
frequency	O
drifted	O
as	O
it	O
warmed	O
and	O
cooled	O
,	O
enough	O
that	O
some	O
sort	O
of	O
tuneable	O
microwave	O
source	O
was	O
needed	O
whose	O
frequency	O
could	O
be	O
adjusted	O
to	O
match	O
.	O
</s>
<s>
A	O
second	O
magnetron	B-Architecture
would	O
not	O
work	O
,	O
they	O
would	O
not	O
drift	O
in	O
sync	O
.	O
</s>
<s>
Sutton	O
,	O
a	O
well-known	O
expert	O
in	O
tube	O
design	O
,	O
was	O
asked	O
if	O
he	O
could	O
provide	O
a	O
version	O
that	O
could	O
be	O
tuned	O
across	O
the	O
same	O
range	O
as	O
the	O
magnetron	B-Architecture
's	O
drift	O
.	O
</s>
<s>
One	O
of	O
the	O
advantages	O
of	O
using	O
microwaves	O
for	O
radar	B-Application
is	O
that	O
the	O
size	O
of	O
an	O
antenna	O
is	O
based	O
on	O
the	O
wavelength	O
of	O
the	O
signal	O
,	O
and	O
shorter	O
wavelengths	O
thus	O
require	O
much	O
smaller	O
antennas	O
.	O
</s>
<s>
This	O
was	O
vitally	O
important	O
for	O
airborne	O
radar	B-Application
systems	I-Application
.	O
</s>
<s>
This	O
is	O
not	O
always	O
a	O
major	O
problem	O
;	O
the	O
Chain	O
Home	O
system	O
made	O
do	O
with	O
two	O
sets	O
of	O
antennas	O
,	O
as	O
did	O
early	O
airborne	O
radars	B-Application
like	O
the	O
Mk	O
.	O
</s>
<s>
In	O
1940	O
Bernard	O
Lovell	O
developed	O
a	O
solution	O
for	O
microwave	B-Application
radar	I-Application
by	O
placing	O
two	O
sets	O
of	O
dipoles	O
in	O
front	O
of	O
a	O
common	O
parabolic	O
dish	O
and	O
placing	O
a	O
disk	O
of	O
metal	O
foil	O
between	O
them	O
.	O
</s>
<s>
They	O
took	O
a	O
Sutton	B-Algorithm
tube	I-Algorithm
and	O
disconnected	O
the	O
electron	O
gun	O
and	O
reflector	O
,	O
leaving	O
just	O
the	O
cavity	O
.	O
</s>
<s>
The	O
usable	O
soft	O
Sutton	B-Algorithm
tube	I-Algorithm
arrived	O
in	O
March	O
1941	O
,	O
and	O
was	O
put	O
into	O
production	O
as	O
the	O
CV43	O
.	O
</s>
<s>
VII	O
radar	B-Application
,	O
the	O
first	O
production	O
microwave	B-Application
radar	I-Application
for	O
aircraft	O
.	O
</s>
<s>
The	O
system	O
was	O
widely	O
used	O
from	O
then	O
on	O
,	O
appearing	O
in	O
almost	O
all	O
airborne	O
microwave	B-Application
radars	I-Application
,	O
including	O
the	O
H2S	O
radar	B-Application
and	O
ASV	O
Mark	O
III	O
radar	B-Application
.	O
</s>
<s>
Post-war	O
intelligence	O
revealed	O
that	O
the	O
Germans	O
were	O
baffled	O
by	O
the	O
purpose	O
of	O
the	O
soft	O
Sutton	B-Algorithm
tube	I-Algorithm
.	O
</s>
<s>
Interviews	O
with	O
German	O
radar	B-Application
engineers	O
after	O
the	O
war	O
demonstrated	O
that	O
they	O
could	O
not	O
understand	O
the	O
purpose	O
of	O
the	O
unpowered	O
tube	O
.	O
</s>
<s>
The	O
soft	O
Sutton	B-Algorithm
tube	I-Algorithm
was	O
used	O
in	O
a	O
circuit	O
known	O
as	O
a	O
"	O
T/R	O
switch	O
"	O
(	O
or	O
many	O
variations	O
on	O
that	O
theme	O
)	O
.	O
</s>
<s>
Sutton	B-Algorithm
tubes	I-Algorithm
were	O
used	O
in	O
a	O
simpler	O
design	O
known	O
as	O
the	O
"	O
shunt	O
branching	O
circuit	O
"	O
,	O
which	O
was	O
T	O
shaped	O
with	O
the	O
transmitter	O
and	O
antenna	O
located	O
at	O
either	O
end	O
of	O
the	O
horizontal	O
portion	O
of	O
the	O
T	O
,	O
and	O
the	O
receiver	O
at	O
the	O
end	O
of	O
the	O
vertical	O
portion	O
.	O
</s>
<s>
By	O
locating	O
the	O
Sutton	B-Algorithm
tube	I-Algorithm
at	O
the	O
right	O
location	O
along	O
the	O
waveguide	O
to	O
the	O
receiver	O
,	O
the	O
same	O
effect	O
as	O
the	O
branch-duplexer	O
could	O
be	O
arranged	O
.	O
</s>
