VLF-3 Rev #1C Assembly Instructions
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7. Diagnostics Guide – First Steps
So you’ve read the information above about testing your receiver and you still aren’t
sure if it is working. If you have never used a Very Low Frequency (VLF) receiver, this
is quite understandable. Plug in headphones with the volume all the way down and turn
it on. Slowly increase the audio level volume control and listen for a 60 Hz hum. Touch
the ANT+ terminal with your finger, zero danger here, to see if the hum significantly
increases. If you hear hum, if the hum gets louder when you touch the antenna
terminal, then your VLF-3 receiver seems to work. Take it into the field well away from
power lines, connect the RTN to the metal of your car or to a solid ground stake,
connect the ANT+ to an antenna or connect a whip antenna to the BNC connector, and
listen again as you turn up the volume. This time you shouldn’t hear hum, but instead
crackles and pops, no matter what time of the say or night. If you hear these, then
you’re in business, your VLF-3 works.
If your receiver squeals when you raise the volume, find a better ground connection
and/or look for a source of feedback. If you are listening to an amplified speaker rather
than headphones, that easy to hear sound may be vibrating your antenna, which will be
picked up by the sensitive VLF-3 receiver and sent back to the amplified speaker.
You’ll have to separate the speaker more from the antenna or use headphones to
prevent this feedback.
If your receiver doesn’t even provide hum at the output, then something else is going
on. It could be a dead battery; it happens, even with new ones sometimes. Or there
could be a problem with the receiver. The following steps are the first suggested for
trying to find the problem. If after following these steps you still cannot resolve the
problem, then a component might be bad and more complicated testing may be
needed. Contact INSPIRE for help if needed.
1. Visually inspect the board looking for solder bridges between connections that should
not be there and look for connections that were not soldered. These two errors are far
and away the most common. Clean up anything that looks suspicious by removing
unnecessary solder. Solder things that need to be soldered. Sometimes a box cutter
or other small knife is needed to insure removal of unwanted shorts between printed
circuit board traces or solder pads. Of course be careful not to cut anything you didn’t
set out to cut, like yourself. Proceed to personal diagnostics, not covered here, if you
set out to hurt yourself; seriously, do not do that.
2. Double check the wiring to the “data” and “audio” jacks to make sure they are going
where they should go. Correct anything miss wired.
3. Connect the computer microphone input up to the “data” connector using a stereo
1/8” male to 1/8” male cable. Initially switch “mic/data” down on the VLF-3 to select
“data”, which should send the VLF signal to both the left and right outputs at the “data
connector”. Set the computer microphone level input to a modest level, perhaps 1/3
rd
maximum to start with. Set the receiver “data level” potentiometer fully counter
Содержание VLF-3
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