Icom IC-746, Часто задаваемые вопросы

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IC-746 FAQ
Try setting option 10 “Meter Peak Hold” to give you a better idea of your peak power output.
Or better yet, monitor your output on a scope with a standard two-tone test. There are
excellent instructions on using an oscilloscope to make PEP measurements at:
http://www.qsl.net/ab4oj/peptest.html
If you conclude that you have an audio feed level problem, then try increasing the
microphone gain or turning on some compression.
CW Break-In Turned off
When the rig is receiving, and Break-In operation is turned off; the rig will generate a
sidetone even though it is not transmitting. While this is good for tuning and CW practice, it
can fool you into thinking that there is no RF output. Check your settings and make sure you
really are transmitting (perhaps switch to RTTY mode and see if you get any output).
Internal adjustments set a little low
Apparently, many IC-746 rigs were factory adjusted with lower RF outputs of about 80-90
watts. If the fractional db of power is important, check out the power adjustment instructions
in the “mod” section of this document.
The service manual specifies setting R989 for 100W on 14100khz, R991 for 100W on
51000khz and R993 for 100w on 145000khz, mode set to RTTY, rf power pot set fully
c/wise.(pots on "main unit" board - the board with the filters on.) That’s three specific
adjustments to cover all 11 bands. Check the power output on 20m first. Contrary to what
the instruction manual implies, the alignment does not specify 100w on all bands.
Expect higher power on lower HF bands and lower power on higher HF bands.
6.6 How low can the IC-746 supply voltage be?
Well, page 69 of the Instruction manual says the supply voltage can range from 12 - 15 Vdc.
Whereas, page 84 says 13.8 Vdc +/- 15%, which is about 11.7 - 15.8 Vdc.
Despite what the manual says, some IC-746's run at voltages as low as 11.0 V dc. The
highest "drop-out" voltage reported so far has been 11.4 V dc.
Be aware, that while the IC-746 will operate at lower voltages, it does so at reduced power.
The power roll off starts at about 13.4 V dc, as evidenced from the measurements shown at:
Page 69 of 113
2003-02-08