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IC-746 FAQ
8.15
How do I adjust the 746 for best AM performance?
The 746 performs well on AM for general communications. However, many operators
choose (and fall in love with) AM for the sound. For this, the 746 can fall a little short of
expectations.
Start by improving your audio fidelity as described elsewhere in the FAQ. Then, WU1T
(Damon) suggests that the trick is to back off the carrier level. You don't want to run full
carrier or full mic gain. He also suggests turning compression off when using AM.
For general guidelines on setting up modern transceivers for AM use, check out:
http://www.thebizlink.com/am/tech/htm/plastic.htm
8.16
Is the IC-746 suitable for CAP and MARS operation?
For CAP (Civil Air Patrol) use, the IC-746 is compliant only for HF, and then only if it has
the CR-282 TXCO option installed. It's not compliant on VHF at all. See the following for
more details:
http://www.ntc.cap.gov/comm/equipment/hf_equipment.cfm
http://www.ntc.cap.gov/comm/equipment/Lists.cfm
There's more information on this general topic at:
http://www.ntia.doc.gov/osmhome/redbook/redbook.html
While I don't have a link for it at the moment, I've been told that MARS (Military Affiliated
Radio Service) must adhere to the same standards.
For both CAP and MARS, some grandfathering did occur, however, that should have expired
by now.
8.17
How do I adjust the Noise Reduction (NR)?
The level of NR you want varies by mode and personal preference. CW can generally
tolerate more NR than SSB. Most AM operators prefer little to none.
Fortunately, setting the correct level is very intuitive.
Start with the minimum, full counterclockwise setting (7-8 o'clock). Increase the level by
turning clockwise; the signal should sound better as you go. After a while, the signal will
start to sound worse; when that happens, simply back off a bit.
So, essentially, you adjust back and forth until you "home in" onto the best setting. Most
people end up between 9-12 o'clock for SSB and a little higher for CW.
As you eliminate noise, you alter the signal. In phone modes, that's often interpreted as
distortion. At some point, the perceived distortion becomes greater than the removed noise.
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2003-02-08