MJ Research DNA Engine Dyad PTC-220, Operation Manual, Page: 31 / 157

4-11
Operation
Using the Optional Probe
The probe consists of a precision thermistor mounted in a thin-walled plastic tube. A thin
wire, encased in a small plastic tube, runs from the thermistor to the probe’s plug, which is
inserted into a slot at the back of the Alpha unit (see figure 4-3). A small amount of oil is
added to the probe tube to serve as the representative sample. The tube is loaded into the
block, where it can serve as the control reference for any programmed target temperature
between 0˚ and 100˚C.
When a probe-control protocol is run, the DNA Engine Dyad cycler controls block tempera-
ture to keep the probe vessel at the programmed temperature, using feedback information
from the thermistor. (See Chapter 5 for information on programming protocols for probe
control.)
Probe control cannot be used with heated-lid protocols .
Note: Because the thermal characteristics of a probe never precisely match those of an
actual sample, calculated control is often a better choice than probe control.
Customizing the Probe Vessel
For the most precise control of sample temperatures, install the probe’s thermistor in the same
type of tube that the samples will be placed in. This is particularly important when the sample
tubes have much thicker walls than the probe’s tube.
Follow these steps to customize the probe vessel:
1. Cut the hinge to the probe tube’s lid, if there is one. Remove the lid and the attached
amber-colored thermistor.
2. Remove the lid from the new probe tube. Add oil to the probe tube as described below
under “Adding the Oil.”
Probe
jack
Figure 4-3 A, Probe. B, Location of probe jack.
Probe plug
Probe tube
A B