Icom IC-746, Часто задаваемые вопросы

Страница: 83 / 113

IC-746 FAQ
Safe 2m TX/RX Sequencing
AH6LE has modified his IC-746 to provide safe sequencing for EME work.
http://www.ah6le.net/radiomods.html
Simple CAT interface
OK2WY has a "Simple CAT / programming interface for ICOM RIGs". Rumor has it that
he has also designed an in-board step attenuator.
http://www.qsl.net/ok2wy/projects.htm
Separate 2m TX/RX Antenna Lines
K7YVZ has proposed a mod to the VHF section to provide separate transmitting and
receiving antenna ports. The details can be found at his WWW site:
http://www.qsl.net/k7yvz/746mod/
G4YTL describes the same thing at:
http://www.mods.dk/mods.php3?radio=icom&model=ic-746&selectid=1919 - 1919
WA2TTP (Steve) reports:
"I did that mod recently and it seems to be working OK. I found a coax jumper in an old
Kenwood commercial radio that had the right connector on one end and I installed a
BNC flange mount on the other end. I mounted the BNC connector to a bracket on the
back of the radio; the bracket is attached with one 8-32 screw and nut through one of the
slots on the rear of the radio. The cable passes through the same slot. I put some shrink
tubing over the original plug and tucked it out of the way inside the 746. Seems to work
fine with my tower top pre-amp and 432 tower top transverter. As with all my antennas I
ran the 746 receive line through my patch panel, which makes it easy to disconnect it
when not in use. I also measured a 1.5 db improvement in sensitivity by going directly
into the receiver board."
Finally, W8FN (Randy) says:
To do this modification, you first need to obtain some of the Icom PC connectors used to
make internal RF connections. The female (PC board mount) connector is P/N
93602690 and the male connector is P/N 93602689. About 18 months ago the Icom
price was $1.07 per connector. I ordered six of each, figuring I'd screw up at least one
pair figuring out how to attach the coax to them. Icom parts (425-454-7619 option #3)
took a phone order and shipped them to me via USPS in just a few days.
The internal connection that needs to be broken in the radio is the HRX line from CTRL
unit J2 to RF unit J1. The source (i.e., the RX line from the T/R switch) is on the CTRL
unit and the RX input is J1 on the RF unit. With the radio upside down with the cover off,
remove the shield covering the left rear compartment on the RF unit. J1 is located near
the rear panel right next to the Key jack and just behind a small relay on the board.
Using the Icom PC connector pair and two short lengths of miniature coax, construct two
pigtail cable assemblies with a RCA female jack on one end and a male and female PC
connector, respectively, on the other. If you are really careful, you can use RG-174
miniature coax, but if possible try to find some RG-188 or similar coax with Teflon
Page 83 of 113
2003-02-08