![background image](http://html.mh-extra.com/html/icom/ic-746/ic-746_faq_612277034.webp)
IC-746 FAQ
Connecting and operating an LDG tuner is exactly the same; they even make a cable
specifically for the task.
Connecting and operating an SGC tuner is almost the same; you'll have to make your own
interface cable. Instructions for that are at:
http://www.sgcworld.com/products/Couplers/icom706.html
Sure, the page says its for the IC-706, but the external ATU interface is identical to that of
the IC-746. Once wired up, operation will be just like for the AH-4.
Finally, you could just fake the IC-746 into thinking that there is an ATU out there with a
dummy plug like that available from W2ENY at:
http://members.fortunecity.com/w2eny/tenatuner/
Operation is similar to that for the other tuners, but transmission stops after an 8 second
timeout instead of by tuner acknowledgement. You can even build this yourself based on the
information at:
http://www.mods.dk/mods.php3?radio=icom&model=ic-706&selectid=1864
or
http://www.qsl.net/wb8rcr/706Tune.html
http://www.qsl.net/g4fzn/706cct.gif
Don't mind that the info says its for the IC-706, all Icom rigs from this era use the same
circuitry/connector.
3.2.15 Why doesn't the rig SWR meter match my external SWR meter?
Its normal for different points along the RF "feed" to register different SWR readings. The
SWR meter in the 746 reads the SWR between the final amplifier stage and the tuner. Your
external SWR meter reads the SWR between the tuner and the antenna. The external meter
should always read greater than or equal to the meter in the 746.
It's actually possible to "match" your rig to your antenna by simply changing the length of
your feed line. For an extreme (but very workable) example, check out:
http://www.qsl.net/w5dxp/notuner.htm
This is not to say that the internal SWR meter is accurate. Posts that suggest that the internal
SWR meter reads lower at lower output power than at full output power. The effect is
noticeable, but not pronounced.
3.2.16 Which SWR meter should I trust: internal or external?
Both can be trusted, but tune by the internal meter.
You probably care because you are using an external ATU. Tune to bring the internal meter
to a minimum reading. Its the meter that tells you how happy your RF power transistors are
and whether or not you're suffering SWR power foldback.
Page 34 of 113
2003-02-08