Watkins-Johnson Company WJ-8718A Owner's manual

1
This document and the subject matter
disclosed herein are proprietary items to
which Watkins-Johnson Company retains the
exclusive right of dissemination, reproduction,
manufacture and sale.
This document is provided to the individual or
using organization for their use alone in the
direct support of the associated equipment
unless permission for further disclosure is
expressly granted in writing.
WATKINS-JOHNSON COMPANY
700 QUINCE ORCHARD ROAD
GAITHERSBURG MARYLAND 20878
INSTRUCTION SUPPLEMENT
FOR
WJ-8718A AND WJ-8718A/MFP
1-Hz READOUT OPTION
(TENTATIVE MANUAL)

2
WARNING
This equipment employs dangerous voltages
which may be fatal if contacted. Exercise
extreme caution in working with this
equipment with any of the protective covers
removed.
NOTICE
This is not the original Instruction Manual for the 1-
Hz Option for the WJ-8718A Receiver Series, it is only
an attempt to write one from scratch.
It is based upon visual inspection and visual circuit
tracing on existing and unmodified WJ-8718A and
WJ-8718A/MFP receivers including this rare option.
The author is Paolo Viappiani of La Spezia, Italy
([email protected]), a radio collector whose only
purpose is to share technical information. It is a no-
profit work and consequently in no way this manual
may be sold and/or made object of commercial
transactions.
The work is still in progress, so any contribution and
suggestion is very welcome. The author also
apologizes for eventual ad unwanted mistakes,
misprints or omissions of which he cannot be held as
responsible.
La Spezia, Italy, June 2017
Revisions:
- Version 1.0 –June 2017

3
FIELD MODIFICATIONS INSTRUCTIONS
FOR INSTALLING THE 1-Hz OPTION IN
THE WJ-8718A OR IN THE WJ-8718A/MFP HF RECEIVER
The following tools are necessary to perform the modification steps:
Phillips screwdriver;
Soldering gun and solder.
Perform the following steps to install the 1-Hz Option in the WJ-8718A or in the
WJ-8718A/MFP receiver:
1. Remove power from the unit.
2. Remove top and bottom covers from the unit.
3. For the WJ-8718A:
Remove the six screws mounting the manual front panel to the unit.
Disconnect all cable assemblies from the old manual front panel except
A10P1. Disconnect A10P1 from the Front Panel Interconnect board A6A2.
Remove the manual front panel from the unit.
For the WJ-8718A/MFP:
Remove the six screws mounting the stock MFP front panel to the unit.
Disconnect all cable assemblies from the old MFP front panel (MFP-P12
from MFP-P14, MFP-P13 from MFP-P15, MFP-P1 [16-pin] from J2, MFP-
P2 [14-pin] from J1). Disconnect also the MFP-P6 plug from the J1 socket
on the Front Panel Encoder card A1- 796056-X, unplug that board from the
Front Panel Interconnect small motherboard (MFP-A1, 794310-X) and set it
apart temporarily.
Remove the old MFP front panel from the unit.
4. Place the unit with the bottom side facing up.
4
.
P
l
a
c
e
t
h
e
u
n
i
t
w
i
t
h
t
h
e
b
o
t
NOTES
- The 1-Hz Option is normally Factory-installed together with the 10-Hz
BFO Option, although this is not mandatory. It is recommended to have at
hand and to read carefully also the 10-Hz Option Manual anyway.
- For the WJ-8718A/MFP: before starting the 1-Hz Option installation,
please check and ascertain that all the Field Modifications considered in the
“WJ-8718A/MFP INSTRUCTION MANUAL REVISION A CHANGE 1”-
February 1991 have been already performed as described.
- This manual can also be used for installing the 1-Hz Option on WJ-8716
and WJ-8716/MFP receivers.
5. Find A6 I/O MB (Type number 791580) location by referring to Figure
5-8 of the WJ-8718A HF Receiver Instruction Manual.

4
For receivers with Manual Tuning Module only (WJ-8718A etc.):
a. Install A6JW5 by wire wrapping one end of a wire to A6X9, pin 42
and the other end to A6X8, pin 42.
W
J
-
8
7
1
8
A
/
M
F
P
1
-
H
z
O
P
T
I
O
N
M
A
N
U
A
L
G
.
7
8
.
9
b. Install A6JW6 by wire wrapping one end of a wire to A6X9, pin 44
and the other end to A6X8, pin 44.
c. Install A6JW7 by wire wrapping one end of a wire to A6X9, pin 46
and the other end to A6X8, pin 46.
d. Install A6JW8 by wire wrapping one end of a wire to A6X9, pin 48
and the other end to A6X8, pin 48.
For receivers already having a MFP front panel (WJ-8718A/MFP, etc.):
a. Install A6JW5 by wire wrapping one end of a wire to A6X9, pin 42
and the other end to A6X8, pin 7.
b. Install A6JW6 by wire wrapping one end of a wire to A6X9, pin 44
and the other end to A6X8, pin 12.
c. Install A6JW7 by wire wrapping one end of a wire to A6X9, pin 46
and the other end to A6X8, pin 14.
d. Install A6JW8 by wire wrapping one end of a wire to A6X9, pin 48
and the other end to A6X8, pin 54.
For all receivers:
e. Carefully remove the coaxial bridge (W6) that connects J7 to J9
(both placed on the aluminium chassis sides) unscrewing its P10
and P9 connectors. Set the bridge apart for possible future use.
f. Install the following coaxial leads:
1Hz-W1 (from J7 to A6X9, pins 5 [signal] and 6 [ground shield]);
1Hz-W2 (from J9 to A6X9, pins 3 [signal] and 4 [ground shield]).
6. Place the unit with the top side facing up..
7. Carefully insert the 796022 (1-Hz Option) card into the X9 socket of the A6
I/O mainboard (with the card rear facing the A6 I/O MB right edge).
NOTES
- Figures 1a, 1b and 2 (on this Manual) show the bottom side of the A6 I/O
mainboard (on a WJ-8718A and on a WJ-8718A/MFP respectively) with all
the above-mentioned modifications already performed, while in Figure 3 is
shown the bottom side of a NOS A6 I/O mainboard that had been already
Factory set up for installation of the 1-Hz Option.
- Instead of using wire-wrapping technique, all the required wire connections
can be installed by using PTFE-insulated stranded wires and standard strip-line
female connectors that have to be inserted into the proper socket pins. In this
case, two four-pole female connectors are required for the WJ-8718A, a four-
pole and three two-pole female connectors are required for the WJ-
8718A/MFP (as shown in Figure 4).

5
Figure 1a: A6 I/O mainboard of a WJ-8718A 1-Hz resolution receiver (bottom side).
Figure 1b: Further details of the same WJ-8718A receiver (A6 I/O MB, bottom side).