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IC-746 FAQ
If you introduce additional devices or alternative interfaces (such as the DX4WIN logging
software using the "$10 Radio Shack" interface, talking to the IC-746 in CI-V address 56H)
then the PW-1 can become confused and stop talking to the IC-746.
One solution to the problem is to set both the IC-746 and DX4WIN for CI-V address 54H -
the same as the PW-1.
(But, shouldn't each device have a distinct address??)
3.5.3
How do I hook up a non-Icom RF power amplifier?
Start by examining the diagram at the bottom of page 79 in your instruction manual, but be
careful, it can mislead you into some expensive mistakes.
The ground and antenna connections are just as straightforward as they appear, no problems
there.
Do not hook the SEND output directly to your amplifier as shown. You will need an external
switching relay or circuit to avoid overloading the internal SEND relay. Burning out the
internal SEND relay is a common failure.
Not all amplifiers will have compatible ALC control signals. The IC-746 ALC input runs
from 0 to -4 Vdc. W7DS designed a circuit to aid in automatic amplifier band switching that
may be useful to you. Check out the "mods" section of this FAQ for more details.
3.5.4
Do I really need an external amplifier switching relay?
Most likely, yes. If you hook up a non-Icom amplifier that does not have a solid-state keying
interface, then you'll probably want an external switching interface.
This is often a hotly debated topic that has left quite a few blown out rigs in its wake. It is
possible to run an amplifier without a switching interface. The article at:
http://www.qsl.net/icom/keynotes.html
tries to describe the necessary conditions.
3.5.5
Why do I need an external amplifier switching relay?
Short Answer
It's far too easy to overload and damage the internal switching relay, resulting in expensive
and/or annoying repairs. The external isolation relays are cheap insurance for our rigs. Even
Icom technical support recommends them.
Long Answer
Given that the relay is prone to overload, the natural question that arises is; just how much
can it handle? Things get both lengthy and muddy from this point on, but since you're still
reading, we'll press on. Remember, you were warned.
Page 43 of 113
2003-02-08