Vectronics VEC-820K - Manual (Page 18)

I E('-830/: Instruction _Manual Cll' Filter
communications receiver or scanner with a BFO control. use this control to
fine tune the received CW signal. If the receiver or scanner you are using does
not have a BFO control, it will be very difficult trying to tune the signal in
properly.
If the signal you are trying to receive is in a "pile up", then try the 80 hertz
filter cutoff. Then fine tune the receiver to "pull out" the desired signal.
Operation with an Amateur Radio transceiver is basically the same, but you
would use either LSB (Lower Side Band) or CW mode. All other connections
arc the same.
IN CASE OF DIFFICULTY
No Signal Filtering:
A neNyly constricted filter that fails to work upon initial power up. generally requires
a ver< close and careful inspection of all work. Please go back through all steps of
assembly and inspection. referring to the "Parts Placement" Figures
1. 2. and 3.
Most of the time there will be a part that is not installed or not installed
properly. a wrong value part in place of another. or a broken part. A close
inspection at this point will reveal some accidental mistake.
Intermittent Filter Operation
A filter that operates intermittently may have poor solder connections. a
problem Nyith broken wires, or low voltage power source. Self-oscillation.
may be caused b_v a defective U1 or U2. Also check for dirty or intermittent
switch operation.
Filter Stops Filtering:
A working filter that fails "in-service" generally indicates a failure of in one or
both U l or U2. If you suspect a bad U 1 or U2. then
do not touch
the part
with your fingers. If the part is bad, it could be HOT and could cause a serious
burn. Other things that should be checked is the supply voltage of the 9-volt
batten'. broken wires to and from the circuit board and switch.
No Speaker Audio:
No speaker audio can be a symptom of a bad SW 1, a broken Nvire or a bad C
11. Check the voltage from the 9-volt battery. A broken Nvire at the audio
input to the filter can also attribute to no speaker audio.
If technical assistance or factory repair is desired, please refer to the warranty
instructions on the inside front cover
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