Version: 13. September 2004
41
and controls and the NJQRP Club, contributing big ideas for the software
too.
Our kit contains the complete hardware including a programmed micropro-
cessor, naturally always with the up to date software version. In addition
we are offering an up to date service, with which processors with the actual
software are available, even if a kit was already build up earlier.
Description and Technical Data
The frequency counter distinguishes from other projects of this kind in two
points: first it is able to show the measured result on a LCD-Display and
second there can be given a shift by the user, which may be added or
subtracted. These adjustments are done using a four pole DIP-Switch and
two micro keys which influence the software of the microprocessor and
allow changes at any time. Therefore the application area covers a simple
counter for measuring and adjustments to frequency displays for RF-Oscilla-
tors until displaying the working frequency of transceivers whereby the IF
doesn’t matter.
All tests yet brought a maximum measuring frequency of > 40 MHz. For
higher frequencies in short will be available a preselektor group.
Technical Data
Working Voltage:
8 … 15 Volts
Current:
< 30 mA at U
B
= 12 V
Input Voltage:
min: 30 mV
max: 2 Volts
Frequency range:
> 35 MHz
Display:
2 x 16 characters LCD with backlight
Operation of the Counter
The counter allows two modes:
·
Counting
·
Programming a frequency shift
Counting mode
In counting mode is made a difference between direct counting and coun-
ting with frequency shift. Switching between these modes is possible
without a reset of the counter. By that it is possible to change the display
between direct frequency and frequency shift using an optional switch or
relay. An example for such an application would be a superhet receiver in
combination with a straight circuit receiver.
The frequency shift can be added or subtracted. The following table 1 shows
the possible adjustments of the DIL-Switch for counter mode.
DIP
ON
OFF
Function
1
Shift
Count
Mode switch
2
Frequency
Sum/Diff
+/- sel. when shift is active
3
Direct
Shift
Shift active or inactive
4
Shift
Count
Mode switch
Programming a Frequency Shift
To program a frequency shift DIP-Switches 1 – 3 are used to address and
program every of the 8 positions of the Display. DIP-Switch 4 is used to
enter the programming mode itself.
The following steps are necessary to program any shift:
1.
Switch off the counter
2.
All DIP-Switches to ON
3.
Press and hold both the Up- and Down keys
4.
Switch on the counter and release the Up-/Down keys
5.
After one second „Offset Prog“ on the display occurs
Now the counter is in programming mode and while pressing the Up-/Down
keys the last position of the Display can be programmed. All other positions
will be selected by switching the DIP-Switch first. For that the following
table 2 may be helpful:
DIP 10 MHz 1 MHz 100 kHz 10 kHz 1 kHz 100 Hz 10 Hz
1
OFF
OFF OFF ON ON ON ON
2
OFF
ON
ON OFF OFF ON ON
3
ON
OFF ON OFF ON OFF ON
4
ON
ON ON ON ON ON ON
