Vectronics VEC-830K - Manual (Page 15)

VEC-830K Instruction Manual Single Side-Band Filter
Probably the best method of seeing if the VEC-830K is working, or not, is to
listen to some "on the air" side-band signals. Then using SW1, select the filter
cutoff position that best cleans up the signal being received.
Carefully tune in a weak signal with the filter in the HI-PASS position. The HI-
PASS position is the left most switch position on SW1. Turn the filter on and
experiment with the selectivity switch to obtain the cleanest signal. The 2.5kHz
upper cutoff could be used when signals are not too cluttered with QRM and
more fidelity is required. The 2.0kHz upper cutoff position will give you the
best compromise between QRM reduction and fidelity. Where signals are really
bad, with a lot of QRM, try the 1.5kHz upper cutoff. The 1.5kHz upper cutoff
will slice off a large amount of the QRM at the expense of fidelity. The HI-
PASS position will not affect the high frequencies and removes low frequencies
below 375 hertz, including 60 and 120 hertz hum. The Hi-Pass filter is
automatically in effect when using the 2.5kHz, 2.0kHz, and 1.5kHz positions.
OPERATING INSTRUCTIONS
You may use the VEC-830K with any communications receiver or scanner. The
VEC-830K requires a 9-volt battery power source.
There are a few items that you will need to operate the VEC-830K. We
have provided a list of these items below for your convenience.
Communications Receiver or scanner with the proper cables.
9-Volt transistor radio battery
External speaker with clip leads
Receiver or Scanner Operation
As mentioned previously you can use the VEC-830K with a communications
receiver or scanner. The filter requires audio from the external speaker or
headphones output of the receiver or scanner. The positive side of this audio
signal is applied to the insulated wire connected to point on the circuit board
labeled INPUT. The negative side of the audio is applied to the point on the
circuit board labeled GND.
Use the open end piece of insulated wire
that is emerging from the junction point with the electrical tape. Please refer to
the "Parts Placement" section, Figure I for the location of signal INPUT point.
Next, connect the POSITIVE lead of the external speaker to the NEGATIVE
end of C9. Please refer to the "Parts Placement" section Figure 3 for the
location of C9. Connect the NEGATIVE lead of the external speaker to the
wire labeled GND on the circuit board. Again please refer to the "Parts
1