Can a printer be used with my RF303RS?
Yes, test results can be printed by a serial printer (Such as the DPU-414, P/N 2248899) which is connected to the RF303RS serial port.
- Put your RF303RS into "simplex" mode. To do this:
- With the RF303RSturned off, hold down the "+" and "-" softkeys (used to select load resistance)
- With the "+" and "-" soft keys depressed, turn on the RF303RS. Wait a moment, then release the soft keys
- Your RF303RS is now in simplex mode. Using a straight-through serial cable, connect your printer to the RF303RS serial port. The RF303RS serial port is configured as follows: Baud rate is fixed at 2400. No parity, 1 stop bit. Configure your printer to the same settings the RF303RS uses, as shown above.
- Turn on your printer. Put it "on line".
- Take a power measurement reading. While the reading is being taken, push the "mode" button.
- Data will be sent to your printer showing power in watts and current, as well as load resistance. Carriage Return and Line-feed signals will be sent to your printer.
- Every time you push the "mode" button, one line of data will be sent to your printer.
Can data from the RF303RSbe exported to Microsoft Excel?
No. Microsoft Excel requires a comma-delimited file. Output from the RF303RS is formatted to be displayed properly by your printer, or on your computer monitor. RF303RS data is not comma-delimited.
The readings on my RF303RS are fluctuating. Is this normal?
- Interpreting RF303RS Fluctuating Readings
- The model RF303RS incorporates an accurate digital measuring system that has three modes. The first measurement mode (default mode) utilizes a relatively short sampling time and does not filter or average ESU output. The two selectable measurement modes utilize longer sampling times that tend to average ESU output. When using the default measurement mode, you may observe some electrosurgery units (ESU) output readings that fluctuate plus or minus 10% or more depending on the unit under test. This is normal operation and is not indicative of a problem with the RF303RS.
- Determining if the ESU is the Problem
- When fluctuating readings are observed with the RF303RS, the technician should take note and determine if this is normal behavior for the ESU under test, or if this behavior is a sign of a problem.
- It May be Normal
- If a fluctuating output is normal for a particular ESU (as determined by the manufacturer, see accuracy specifications for ESU), the user can calculate the average of the high and low reading observed on the RF303RS (fluctuating readings may be discernable on the RF303 display) or the user can utilize the RF303RS's Signal Averaging Mode (SAM).
- Older ESUs may have unstable output due to old technology or design. This is typical and is acceptable based on the manufacturer's limits.
- Many newer-generation ESUs utilize instantaneous feedback loops, which constantly adjust the output and can cause an oscillating effect. This is also satisfactory and is considered normal for these devices.
- It May be Broken
- In some cases, fluctuating ESU power output is evidence of a problem. Fluctuating output on some ESUs may indicate the weakening of output from power transistors or other ESU ailments and is not acceptable.
- Signal Averaging Measurement (SAM)
- If an ESU normally has fluctuating output, then operating the RF303RS in one of its Signal Averaging Measurement (SAM) modes makes sense. SAM significantly reduces fluctuating readings on the display of the RF303RS making it easy for the technician to read an average value.
- Upon power up the RF303RS defaults to the instantaneous algorithm for power output measurement which shows fluctuating ESU output. The user can select SAM by depressing the "mode select" and "- ohm select" keys simultaneously; each time the user initiates this key sequence the RF303RS will increment to the next mode, displaying "F X" momentarily. Starting at the default mode ("F 0"), the first mode entered is the one second sampling mode, ("F 1"); initiating the key sequence again will select the two second sampling mode ("F 2"), initiating the key sequence again brings the unit back to the default instantaneous mode and so on.
- Bottom Line
- If you observe fluctuating power readings on the RF303RS, it is likely that the ESU being tested has a fluctuating output signal. To obtain an average power reading, select the RF303RS's signal averaging mode.
When measuring power output of my Conmed ESU with my RF303RS, the bipolar power readings seem abnormally high. Can you explain why?
The load resistors typically used in ESU analyzers are not "ideal". They possess some reactive components that are frequency dependent. The RF303RS derives applied power by measuring the voltage across the set load and calculating the power (V2/R). Most other ESU analyzers on the market derive the applied power by measuring the current flowing through a set load and calculating the power (I2*R). At fundamental frequencies below 500 kHz and regardless of the load setting, the two methods of measurement are comparable. Above 500 kHz, and at the extremes of the loads, the readings displayed by the two methods will differ on opposite sides of the expected value.
As an example, when testing the Conmed Excalibur Electrosurgical Unit in the monopolar output with the RF303RS load set to 50 ?, the set value on the Conmed will correlate with the displayed value on the RF303. When in the Bipolar mode, the RF303RS will display higher than expected values - up to 35% higher. The same test performed on some current measuring analyzers will produce lower than expected values. This is due to the difference in fundamental frequencies between the monopolar and bipolar modes. In this case, the Conmed operates at 500 kHz in monopolar mode and 1 MHz in bipolar mode. When comparing readings measured with a V2/R device to readings measured with an I2*R device, total measurement difference will likely be larger than 35%, due to different methods of deriving power.
This does not mean that the RF303RS is malfunctioning or in error. Rather, it reflects the different results the two measurement techniques will produce when the load deviates from the nominal value used in the power calculations. It should be noted that most ESU manufacturers use the current measuring technique to calibrate production units.
This characteristic does not affect Electrosurgical Units that operate with a fundamental frequency less than 500 kHz, such as ValleyLab electrosurgical units.
