During years of experience with the models 6150AD1/2 some users requested additional functions such
as:
Protection against unintentional switching off,
Non-volatile storage of the dose measured with the internal tube,
Dose alarm,
Programmable alarm thresholds for dose and dose rate,
Better resolution (more places after the decimal point) when indicating dose, alarm threshold, and so
on.
We met these requirements by introducing a new hardware release and extending the microprocessor’s
program. However, additional functions will inevitably make operating the instrument a little more
complex. Users who do not need the additional functions may prefer a simple model. For those users we
decided to continue the models 6150AD1/2, and to create »more intelligent« successors called 6150AD3
and 6150AD4. The 6150AD3/4 models are in the market since 1990. The 6150AD3 has the same
hardware and the same GM tube as the 6150AD1, which means it is the more intelligent successor of the
6150AD1. Internally the only difference between a 6150AD3 and a 6150AD1 is the contents of its
program memory (EPROM). In the same sense the 6150AD4 is the successor of the 6150AD2.
In 1994 the Scintillator Probe 6150AD-b came on the market. This probe required another modification
of the 6150AD for the following reason: as mentioned earlier, the 6150AD will automatically select
ranges and units when connecting an external probe. For this purpose the 6150AD needs certain
information about each probe type. The previous models 6150AD1-4 do not know the new probe type;
they indicate »Err ext« when connecting a 6150AD-b probe or some other unknown probe type.
Therefore we created the models 6150AD5 and 6150AD6, which will also identify the 6150AD-b probe.
We also used this occasion to add as a new function the indication of the relative standard deviation of
dose rate mean value. Again, the 6150AD5/6 models differ from their predecessors 6150AD3/4 only by
contents of the program memory.
Introducing the models 6150AD5/6 made the models 6150AD3/4 more or less unnecessary. Their
function is almost equal, and the additional ability of the 6150AD5/6 to identify the probe 6150AD-b is
surely no drawback. When buying a new instrument (without the need to recognize the 6150AD-b probe),
the only reason to prefer the 6150AD3/4 to the 6150AD5/6 would be that the user already has
6150AD3/4 models and wishes to keep his variety of models as small as possible. For this purpose the
6150AD3/4 is still available.
Next we have to discuss measuring quantity and unit. The 6150AD1/2 models are available in
R(Roentgen) units (measuring quantity is Exposure Dose J
S
) and in Sv(Sievert) units (measuring quantity
is Photon Dose Equivalent H
X
). Note that J
S
can be converted to H
X
according to
H
X
[Sv] = 0.01 Sv/R J
S
[R]
independent of photon energy. This means that J
S
and H
X
are very close related quantities, they just differ
by a factor of 100. Because this conversion is independent of energy, the 6150AD3/4/5/6 models allow
the user to select one of the two units R and Sv. H
X
is the legal quantity in Germany since 1986; however,
the quantity H
X
was hardly accepted internationally.
Page 2
Operating Manual 6150AD
03/2004
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