Install all low profile components first: usually resistors,
capacitors, diodes, then electrolytics and active
components.
Resistors should be mounted flush to the board.
Mount all capacitors, relays and connectors as flush to the
board as possible.
Bend the wires of the components at the bottom side
slightly outwards in order to hold the component in place for
soldering.
Solder as per techniques described above.
Flush cut excess wire leads and reflow the solder
connection for assurance and a better looking solder
joint.
Mark off each installation step in sequence as you complete it, in the
box provided (e.g.
).
Warnings and important points are posted with a
symbol.
Care of the IRF-510 MOSFET's
MOSFETs are susceptible to electrostatic discharge
damage (ESD). It is important to use proper grounding
techniques while handling the amp circuit board and the
MOSFETs in particular. While working with MOSFETs you
should wear a grounding strap and have an antistatic mat at
your feet. At the very least you should frequently ground your
hands to the nearest ground point. The IRF510 is a good
compromise MOSFET that will work up to 30 MHz but has
poor thermal characteristics of 3.5°C/Watt. When used in
intermittent SSB and CW service forced-air cooling is not
required. Tuning time with full power should be limited to less
than 30 seconds with 1-2 minutes between cycles to prevent
overheating. Operating at 29VDC does not press the MOSFET
to their limits. The Sil-Pad TO220 mounting kit has excellent
thermal performance and provides a greaseless thermal
interface between the MOSFET and the heat sink. Users
report that this amplifier can be safely used for contest CW
operation without further cooling. For PSK/RTTY forced air
cooling is necessary or a reduction of power by reducing the
input drive.
Other Construction Notes
1. Follow the sequence given to locate the next
component in a series to install.
2. The header parts are installed by matching the part to
the outline. Start by soldering one pin and then while
reheating, align the part flush and perpendicular to the
board. Solder the remaining pins.
3. The IPS511S, U5 component is pre-mounted since it is
a surface mount part.
4. The reference numbers used are not in sequence and
some references are skipped.
5. The circuit boards should be cleaned after soldering to
remove solder flux residue. I recommend “TechSpray
BLUE SHOWER” available in a can: 1630-16S. Use in
a ventilated area following instructions on the can.
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