W4RT Electronics OBF-718, OBF-718-DIY, OBF-718-CW-DIY, OBF-718-SSB-DIY, OBF-ICOM, OBF-ICOM-500, OBF-ICOM-300, OPF-ICOM-CW-500, OPF-ICOM-CW-300, OPF-ICOM-SSB filter User manual

W4RT Electronics
A Division of
PanTechne Corporation
www.w4rt.com 16 September 2008
For the ICOM IC-718
The ONE BOARD FILTER (OBF-718) is an accessory for the ICOM IC-718. W4RT Electronics provides the OBF718 as a high-performance, lower-cost alternative to the ICOM optional filters for the IC-718, and the OBF-718
allows the inclusion of two filters rather than the single one by ICOM. The filters used in the OBF-718 are the famous
Collins Mechanical filters. The CW filter has a 500 Hz bandwidth and the SSB filter has a 2300 Hz bandwidth. Proper
termination is included on the PCB.
The OBF-718 is available in three forms, viz., OBF-718-DIY (CW and SSB filters), OBF-718-CW-DIY (CW filter
only), and OBF-718-SSB-DIY (SSB filter only). The following installation instructions can be used to install all three;
however, depending upon which OBF-718 you are installing, you may omit certain steps. For example, if you are
installing the OBF-718-CW-DIY, you do not remove the stock MuRata filter. The OBF-718 can not be utilized if any
Option filter is already installed unless that filter is removed (which can be done by W4RT Electronics if the
installation is being performed by W4RT Electronics).
Please READ the following BEFORE INSTALLING your OBF-718.
Installation is not trivial, so you should be confident that you have the skills and experience
needed to do the job correctly. You can damage your IC-718, so be very careful. W4RT
Electronics assumes NO responsibility for any damage that may be caused by your installation.
Further, W4RT Electronics doesn't provide technical assistance during your installation. If
you need help, then have W4RT Electronics perform the installation for the stated fee on
www.w4rt.com BEFORE you attempt the install. W4RT Electronics is not a radio repair
facility. If you damage your radio, you will have to send it to ICOM or another repair shop.
Figure 1 Page 1 of 4
1.
2.
3.
4.
5.
6.
7.
8.
Remove the bottom cover from the IC-718. Retain these screws to replace the bottom cover.
Refer to Fig. 1 and also page 50 in the IC-718 manual for reference.
Carefully unplug the four (4) ribbon cables (red arrows) from the PCB referred to as the MAIN unit.
Carefully unplug the two (2) coax connectors and five (5) plugs (yellow arrows) from the PCB.
Carefully remove the two (2) Tr-clampers (green arrows) from IC3401 and IC2901.
Remove the seven (7) screws holding the PCB in place (blue arrows). Retain these screws to replace the PCB.
Remove the PCB from the IC-718 with care and note that the DSP UT-106 remains attached to the MAIN unit
PCB.
Note the location of the MuRata filter (white arrow just above the location on the PCB marked OPTION FILTER)
to be removed ONLY IF the OBF-718-DIY or OBF-718-SSB-DIY is being installed. In this case, the SSB filter
is replacing the MuRata filter. It is NOT removed if you are installing the OBF-718-CW-DIY or if you are
installing the OBF-718-SSB-DIY as the Option filter.
Figure 2
9.
If you are to remove the MuRata filter from the PCB, then first CAREFULLY remove the solder from the five (5)
points shown in Fig. 2 by the red arrows.
10. Now, CAREFULLY remove the MuRata filter and place it aside.
11. Locate the OBF-718 to be installed and remove the film from the double-sided tape on the bottom side of the
OBF-718. If you are installing the OBF-718-S SB as the Option filter, cut off the two wires coming from the top of
the OBF-718-S SB PCB (these two wires are used only if you remove the MuRata filter).
12. Notice the four holes denoted by the blue arrows in Fig. 2. These are discussed in Step 13.
Page 2 of 4
Figure 3
13. CAREFULLY place the four (4) wires from the bottom of the OBF-718 into the four (4) holes (blue arrows)
shown in Fig. 2. Also, route the two (2) wires from the top side of the OBF-718 through the holes indicated by the
white arrows shown in Fig. 3. It is best to attempt to route all six (6) wires at the same time you place the OBF-718
onto the IC-718 PCB. Do not put wires in the holes denoted by the red arrows in Fig. 3 (same as the yellow arrows
in Fig. 4 when viewed from the other side of the PCB). WARNING: Be sure that the wire from the OBF-718
denoted by the blue arrow in Fig. 4 does NOT touch the inductor shown by the red arrow.
14. CAREFULLY solder the six (6) locations denoted by blue and white arrows in Fig. 3. Cut off excess wire length
from the OBF-718.
Figure 4
Page 3 of 4
15. Reinstall the IC-718 PCB. Replace screws first, then the plugs, cables and Tr-clampers, and finally the bottom
cover.
16. After you have the radio ready to operate, then perform the Initial Set Mode Operation (see page 41 in the IC-718
Manual).
 If you have installed the OBF-ICOM (both filters), then set OPTION Filter menu selection to FL-52A
if OBF-ICOM-500 or FL-53A if OBF-ICOM-300. The Option Filter is now the CW-NARROW
selection. The stock MuRata filter has been replaced by the Collins SSB filter and no additional selection
is required for the Collins SSB filter when Filter Selection Switch is set to NORMAL.
 If you installed the OPF-ICOM-CW-500, then set OPTION Filter menu selection to FL-52A. If you
installed the OPF-ICOM-CW-300, then set OPTION Filter menu selection to FL-53A. The Option
filter is now the CW-NARROW selection. When in NORMAL, the stock MuRata filter is activated.
 If you installed the OPF-ICOM-SSB, then set OPTION Filter Menu selection to FL-96. The Option
Filter is now selected when Filter Selection Switch is set to WIDE. If you replaced the MuRata filter
with the OPF-ICOM-SSB, then set the Filter Menu selection to NO.
NOTE: If you are interested in understanding more about the performance of these filters, then see the QRP Quarterly
article by K9QI (http://www.w4rt.com/obf/QQ-Oct-01-Filter-Review.pdf). Although the radio under discussion is the
Yaesu FT-817, both the FT-817 and the IC-718 use the MuRata CFJ455K ceramic filter as the stock filter. The
performance of the filters in both radios is essentially the same.
WARRANTY: ONE BOARD FILTER is warranted for a period of one (1) year from the date of purchase to be free of electrical defects in materials and workmanship.
If the ONE BOARD FILTER is determined to be defective, the defective item(s) will be repaired or replaced, at the sole option of W4RT Electronics, provided that the
purchaser returns said item(s), postage prepaid, with proof of purchase to W4RT Electronics, ATTN: Technical Support, 3077-L Leeman Ferry Rd, Huntsville, AL
35801. Include a description of the problem, daytime phone number, email address, and return mailing information. Any modification to the ONE BOARD FILTER by
purchaser voids the warranty. The warranty applies only to the original purchaser and is not transferable. Any damage to the ONE BOARD FILTER due to the
installation method or technique used by purchaser is the sole responsibility of purchaser and W4RT Electronics has no liability whatsoever.
16 September 2008
Copyright © 2008 by PanTechne Corp. All rights reserved.
W4RT Electronics, W4RT, and ONE BOARD FILTER are trademarks of PanTechne Corp.
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