Vectronics VEC-821K - Manual (Page 20)

V E C-821K Instruction Manual Super CW Filter Kit
see which position works the best is to try it. This way you can really hear what the
filter is doing for the received signal, and which switch position works the best in
different band conditions.
OPERATING INSTRUCTIONS
You may use the VEC-821K with any communications receiver or scanner with a
BFO, (Beat Frequency Oscillator). You can also use the VEC-821K with and ham-
radio transceiver in either LSB or CW mode. The VEC-821K requires a 9-volt
battery power source, or any 9-18 volt DC source.
There are a few items that you will need to operate the VEC-821 K. We have
provided a list of these items below for your convenience.
•
Communications Receiver, scanner, or Ham Radio transceiver with proper
cables.
•
9-Volt transistor radio battery
• External speaker with clip leads
Receiver or Scanner Operation
As previously mentioned you can use the VEC-821 K with a communications
receiver or scanner. A BFO, or Beat Frequency Oscillator, or a Fine Tuning
control will assist you in fine tuning the received CW signal to the VEC-821K
center frequency. The center frequency of the filter being 750-800 hertz.
The filter requires audio from the external speaker or headphones output of the
receiver or scanner. Apply the positive side of the audio signal to the insulated
wire connected to the location on the circuit labeled INPUT. Apply the negative
side of the audio signal to the insulated wire connected' to the location o n t h e
circuit board labeled GND2. Please refer to the "Parts Placement" section,
Figure 1 for the location of both points on the circuit board.
Next, connect the POSITIVE l e a d o f t h e e x t e r n a l s p e a k e r t o t h e e n d o f t h e
insulated wire connected to the location on the circuit board labeled SPKR.
Connect the NEGATIVE lead of the external speaker to the point labeled GND
on the circuit board. Again please refer to the "Parts Placement" section Figure 1
for the location of the point labeled GND on the circuit board.
Next, turn the receiver volume all the way down, then clip the 9-volt battery to
battery snap. Set SW1 to the far left position. Now turn the receiver u p
slightly so you can hear the received signals on the external speaker. The
signal you are listening to is the "raw" or "unfiltered" signal. Using the tuning
knob on the radio, find a CW signal. A good place to find CW signals is in the