-7-
C2
.001 uf
C2
.001 uf
C4
.001 uf
C4
.001 uf
C6
.001 uf
C6
.001 uf
RFC1
470 uh
RF choke
RFC1
470 uh
RF choke
RFC3-470 uh RF choke
RFC3-470 uh RF choke
RFC2
470 uh
RF choke
RFC2
470 uh
RF choke
RFC4
470 uh RF choke
RFC4
470 uh RF choke
C1
.001 uf
C1
.001 uf
C3
.001 uf
C3
.001 uf
C5
.001 uf
C5
.001 uf
600:600
600:600
+ Audio Out
+ Audio Out
+ Audio in
+ Audio in
- Audio in
- Audio in
- Audio Out
- Audio Out
Gnd
Gnd
Gnd
Gnd
R1-1K
R1-1K
R2
10K or 100K
fixed or variable
R2
10K or 100K
fixed or variable
R3
200
R3
200
R2
R2
R4
1K
R4
1K
T1
1:1
+
+
C7
100 uf
C7
100 uf
E1
E2
E3
E4
E5
E9
E8
E7
E6
i
Box SCHEMATIC AND WIRING PICTORIAL
C8
.1 uf
S
h
ie
ld
S
h
ie
ld
R
e
d
R
e
d
R
e
d
B
la
c
k
B
la
c
k
B
la
c
k
Sh
ie
ld
C9
.1 uf
47K ohm
J2
5 pin DIN connecto
r
J1
(TRS connector)
J3
(RCA connector)
Audio Out
Audio IN
Gnd tab
R2=
100K
factory
wired
4”
4”
3”
--------------------Parts List------------------
C1-C6 - .001 uf mylar
C7 - 100 uf radial electrolytic
C8,C9 - .1 uf monolithic ceramic capacitors
J1- 1/4” stereo jack
J2 - 5 Pin DIN
J3 RCA panel mounted jack
R3 - 200 ohm ¼ watt 5% resistor
R1,R4 - 1K ohm ¼ watt 5% resistor
R2 - fixed resistor or variable potentiometer
R5- 47K ¼ watt 5% resistor
RFC1 - RFC4 - 470 uh miniature r.f. Choke
T1 - 1:1 600 ohm Audio Transformer
Figure 1C
Figure 1B
Figure 1A
-6-
QUICK START TUTORIAL
1. Turn the
Output Level Control
fully counter clockwise. (See page 4)
2. Connect the audio source into the
Audio Input
jack (see page 4)
using a 1/4” stereo plug. Page 9 shows some possible cable config-
urations. Make sure the sleeve of the 1/4” stereo plug is connected
to the ground of the audio source.
3. Connect the
Audio Output
(see page 5) to what you would
like to drive. See pages 10-12 for possible cabling configurations.
Make sure that the ground pin on the DIN connector is
connected to the ground of what is being driven.
4. If you will be using a foot switch to key a transmitter or other
device connect it to the
PTT
RCA connector (see page 5).
5. Prior to applying an audio signal to the input of the
i
Box turn the
Output Level Contr
ol fully counter clockwise. (See page 4).
6. Apply an audio signal to the input of the
i
Box, Turn the
Output
Level Control
clockwise until proper audio level for the device
being driven is obtained.
Minimizing the effects of RF
A very common problem many amateur radio operators experience
with professional audio equipment while transmitting is audio distortion
caused by RF. Techniques have been developed to minimize the effects
of RF. In a perfect world one should use a star grounding configuration,
using heavy gauge braided wire from grounded equipment to the
central ground point and a short run of a heavy gauge wire to a
ground rod. In a perfect world all audio equipment should be
connected to a high quality power conditioner. In a perfect world
all audio cabling should use quality shielded wire (double shielded
is best). In a perfect world all audio signals cascading through the
audio rack network should be isolated with high quality audio
transformers. Few of us live in a perfect world so when we have
problems we have to make the RF environment we live in as good
as possible.
A
U
D
IO
IN
PT
T
A
U
D
IO
O
U
T
A
u
d
io
S
o
u
rc
e
R
a
d
io
o
r
A
u
d
io
C
o
m
p
o
n
e
n
t
Foot
Switch
i
Box
J
1
J
2
J3
V
V
V
