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It is important to remember that the greater the gradient, the poorer the uniformity across the block,
therefore fine-tuning may be required to establish the optimum temperature. While the gradient is
mainly linear there are small variations at the extremes of the gradient due to a loss of heat from the
hottest part of the block and a gain of heat from the adjacent column on the coldest. This is the
reason why the first column does not reach the lowest ideal temperature of the gradient and the last
column cannot reach the highest temperature.
A gradient calculator is included in the software which can be used to display more accurately the
temperatures of the block for any given gradient. The gradient calculator is located in the System User
main menu.
ADJUSTABLE HEATED LID
The heated lid of the TC-512 can be switched on or off depending on the user's requirements. Details
for editing the default lid parameters and those of an individual program can be found on pages 41
and 34 respectively.
The lid is unlocked by lifting the back of the handle as shown in the diagram below, this handle can
then be used to lift the lid. To close, simply lower the lid onto the block containing the samples and
press the handle shut.
The pressure of the heated lid must be adjusted for each consumable type used in the thermal cycler,
to ensure that sufficient pressure is present to prevent any evaporation of samples.
Prior to setting the lid pressure, obtain the lowest pressure by rotating the orange disc anticlockwise.
Then shut the lid and latch it. To obtain the correct pressure adjust with the lid in the down position by
gently rotating the orange disc clockwise until it is possible to just feel the pressure being applied.
Finally, rotate the orange disc a further quarter of a turn; the lid is now at the correct pressure for use
with the consumable. The pressure does not need to be adjusted again, unless a different thermal
block or consumable is used.
TC512 Techne Manual 19/12/08 3:30 PM Page 25
