[ICOM] ICOM 746 PRO

[Gary Fiber]

John,

I would not be afraid to try that. A number of years ago Icom came 
out with the IC-725 and was advertised at 100% duty cycle, 1 hour key 
down at full power.in QST into a good 50 ohm load.
Well as we all know QST has a policy to not advertise things that are 
not truthful and Yaesu took great exception to that advertisement. 
The ARRL called us at Icom and asked if they could try our 
advertisement on a new IC-725 Icom had sent, it was before it was 
introduced I think. The engineering department said yes do the 100 
watt 1 hour keydown test. So the ARRL did just that, found the IC-725 
stood up to the test. Then they told Yaesu the advertisement was 
truthful and if they could build a product that stood up to the same 
test they too could advertise it in QST.

Icom has always been stingy on the SWR they will accept. I know other 
manufacturers seem to allow you to operate into up to 3:1. I was 
always told by engineering Icom wanted to protect the finals as best 
as they could so it was better to limit the SWR it worked into.
Who knows but I never had any final trouble with my Icoms starting 
from 1982 when I purchased an IC-730 and now my IC-706MKII and IC-718.

I too am like most amateurs. Put up an antenna, connect the feedline. 
Maybe try to get some sort of respectable SWR, if I can't get there 
on all frequencies add a tuner in line and call it good. I am not 
expert in antennas but so much enters into a properly operational 
antenna beyond SWR. I tried one time cutting the feedline in 
multiples of 1/2 wave length. It worked out but you have to be exact. 
I am sure I messed that measurement up when I installed the connecter 
not allowing for it in the overall measurement. Even the Bird 43 says 
in its manual to include the directional coupler length when making 
your test cables to use with it.

I was there too when some people were blowing out the 2 meter front 
ends in the original 706. Many were running a tuned 5/8 wave antenna 
on the 2 meter side and forgot or didn't know that antenna worked 
very well on 6 meters. They were subjecting about 100 watts to the 2 
meter front end as the 2 meter 5/8 wave antenna was doing nothing to 
help attenuate that 100 watt 6 meter signal presented to it.  Seems 
good separation or using something different than that 2 meter 5/8 
wave solved that issue.

Antennas and radios its a wonder we can talk across the street sometimes.

Now I am messing with directional antennas in the microwave region 
for work and 802.11 Its amazing how far one can transmit a signal at 
2.4 GHz with a decent antenna.

Anyway I thought the QST story was interesting and its true I was 
working at Icom when that came about. All interesting stuff.


Gary Fiber K8IZ

>Remember the Icom is rated for full power, 100% duty cycle, brick on the
>key operation. (although I wouldn't try it for very long) I think the
>only way they can do that is by making sure that the radio sees a very
>low swr when there is full power.
>
>John
>N7JL

Gary Fiber K8IZ
GROL PG-19-6691
Washington State Resident