www.arrl.org QST March 2023 47
which is exactly what can be found in the Quick Guide.
As an example, if you want a 3.1 V half sine wave with a
2.5 V offset, a frequency of 18 MHz, and output on
channel 1, start with the turn-on screen, as shown in the
lead photo of this unit, and press the channel 1 and 2
buttons until the display shows channel 1 on and chan-
nel 2 off. The channel screen should also have a white
dot on the top left and no such dot on the screen next to
the channel 2 legend. Select the waveform by pressing
WAVE and the SINE selection on channel 1, and it
should go red.
To select the waveform, press
WAVE and then rotate the
round knob until the legend says
HALF WAVE. By press-
ing the frequency button, the value is selected by using
the left arrow key to move the leftmost digit to a 1. Next,
press the right arrow key so the second digit is selected,
and rotate the round knob until the second digit reads
18. Because you want a frequency of exactly 18 MHz,
use the arrow keys and round knob to set the rest of the
digits to 0.
Finally, press the
AMPL button followed by the arrow
keys and the knob to select an amplitude of 3.1 V. The
remaining item is the offset; press the
OFFS button
again followed by the arrow keys and knob so the
OFFS
legend on the screen reads the desired 2.5 V.
This sequence is typical for selecting a waveform from
the front panel. The vertical line of buttons selects the
item you want to adjust; the keys to the right have indi-
vidual results.
Compare a Couple of Numbers
As described earlier, the output waveform is a set of
programmed values coming out as a voltage whose
value over time is made up of these points generating
serially. According to the manufacturer, each waveform
(presumably of a repetitive waveform) can consist of
2,048 points. The waveform sampling rate is stated as
266 mega samples per second (MSa/S). These values
provide the limit for how accurate (or “smooth”) the
output waveform will be. Because a digital-to-analog
converter (and perhaps analog buffers) may be part of
the design, these numbers are limits, with the actual
speci ed values given by mode and setting, as appro-
priate, in the instruction manual.
Another number listed in Table 2 is the waveform verti-
cal resolution (14 bits, or 214, which is equal to 16384
counts). Again, the actual speci ed accuracies in ampli-
tude are given in the instruction le on the mini CD.
A Few More Keys
A few of the front panel keys are not discussed in the
previous example. In brief, they are:
MEAS (switches
between measurement mode and a count function),
MOD (controls modulation mode interface), SYS
(switches between system selections, such as sounds,
brightness, and save current settings), and
OK (controls
on/off for channels).
Several pages of instruction on the use of these buttons
are again found in the Quick Guide.
In Summary
When I received this unit, I was not very impressed. It
rattled — there was a screw loose and bouncing around
in the enclosure. Fortunately, it took only a few minutes
and four screws to open the enclosure and drop out the
loose hardware. Nothing else was loose, so after closing
it up, I proceeded with testing. The time it took to nd the
instruction le was also not impressive — it was located
several steps from the main le, and a RAR decompres-
sion was needed to traverse the le structure.
What was impressive was that once you turned it on
and tried to use it, you did not need many instructions.
Most functions are self-explanatory, and the response
to the labels was 100% for most direct functions. I ran a
number of quantitative checks. I did not list them here,
because the instrumentation I used, while typical of
many ham workbenches, was not demonstratively
accurate enough to prove the unit calibration. Certainly,
all were within 5 – 10%, but how much of each was due
to the unit and how much was due to the measuring
instruments cannot be determined.
Manufacturer: Hangzhou Junce Instruments Co.,
Ltd. (Juntek), No. 18, Xiyuan 1st Road, Xihu District,
Hangzhou City, Zhejiang Province, China, www.
junteks.com. Price: $99.98. Available at www.
amazon.com.
To Next Page
Loading...
Need help?
General
