HF PackerAmp V4, Construction Manual

Page: 23 / 76

Section 4 – Case and Chassis Assemblies
Case Preparation
•
Use a hobby knife to expose bare metal around the
inside and outside of the holes for the RF IN, RF OUT
and PTT so that when the panel part is inserted and
secured, you will have a good case connection to the
part body.
Heat Sink Assembly
•
Attach heat sink with four 4-40 x 5/16 screws to the
case. Install one 4-40 threaded standoff through the
case into the heat sink. Used to heat sink U4.
•
Attach the heat sink assembly to the case with four 4-
40 x ¼ inch screws, plastic wire clamps. Wires will be
placed under the clamps during assembly so only
loosely attach screws at this time.
RF Input Cable
The RF Input cable is best fabricated on the bench and then
installed in the amplifier.
•
The cable type is RG174. Length is 11 inches.
•
Thread four 23-43 cores over the coax sleeve. Adjust
to mid position. Shrink ½ inch length of black shrink
over cores.
•
Strip ¾ inch of the coax sleeve on each end. Comb out
the shield and tightly twist into a pig-tail. Trim to 3/8
inch.
•
Prepare two 1 3/8 inch lengths of black TEF 24AWG
wire by stripping 1/8 inch from each end. Tin one end.
•
The shields on both ends are connected to 1.4 inch
TEF #24 black hookup wire. Heat sink the shield when
soldering the wire to the shield so the inner conductor
is not melted.
•
Use 1/4 inch black heat shrink on the wire ends to
cover the bare shields.
•
Attach the cable to the BNC connector being careful to
keep the wire straight so the center conductor
insulation is not melted. Thread a short length of 1/8
inch red heat shrink over the center conductor. Form a
hook in the black #24 TEF hookup wire and attach to
the ground connection on the BNC. Solder this first.
Next, solder the center conductor in the slot of the
center pin of the BNC. Heat the 1/8 inch red heat
shrink with a heat gun to constrict around the wire.