Vectronics VEC-1402K - Manual (Page 13)

VEC-1402K Instruction Manual 2 Meter Pre-Amp Kit
11
PC Board Inspection:
Before applying power to your kit, give it a thorough QC (quality control)
inspection. This will help you find inadvertent assembly errors that might
prevent the preamp from working or cause damage to sensitive parts. Follow
this procedure:
! Compare parts locations against the parts-placement diagram. Was each
part installed where it is supposed to be? Was the correct value used? Start
at one side of the board and work your way across in an organized pattern.
! Is transistor Q1 installed correctly?
! Inspect the solder side of the board for cold-solder joints and solder bridges
between tracks or pads. Use a magnifying glass to obtain a clear view of the
track area. If you suspect a solder bridge, hold the board in front of a bright
light for a better view. All joints should be smooth and shiny, indicating
good solder wetting and flow. Resolder any beaded or dull-appearing
connections.
Important Note: If you find a construction error and need to remove a part or
two, it will be easier if you have the right tools. One very convenient item for
freeing soldered-in parts is a "solder sucker". This consists of a suction bulb or
a spring loaded vacuum pump that draws molten solder away from the pad and
lead. Alternatively, you may use "solder wick". If you suspect you've damaged a
component during removal, it's better to replace the part than risk reusing it!
Your preamp may be installed inside a receiver, or mounted in a small external
"project" enclosure with RF-type connectors mounted on each end. The length
of bare-wire leads attaching connectors should be 1" or less. For longer
connections (up to a couple of feet), use small flexible 50-ohm coaxial cable
such as RG-174.
Finally, rosin flux can absorb moisture, which may cause a problem for VHF
preamplifiers --especially when they are mast-mounted in a damp environment.
To remove flux, use isopropyl alcohol (or 95% grain alcohol) and an old
toothbrush. Apply a generous amount of alcohol with the toothbrush and scrub
gently. Once the flux has fully dissolved, blot the bottom of the board dry with
an untreated tissue. Give it a final alcohol wash, and allow to dry thoroughly.
Caution: alcohol is highly flammable and must be used
with adequate ventilation! Use safety
goggles, and avoid prolonged skin contact.
It's also best to do this outdoors.