I'm listening to my latest purchase for the shack, an Icom IC-746PRO. I'm pretty happy with it, though admittedly its not a PRO3, it does very well.
I'm concerned still about the failure rate of the early 746PROs. This rig is one of that early group that had the biggest problems. It was sent back for repairs a couple of years ago and the mod was completed by Icom.
There are some changes that some other hams are doing to cut down the amount of heat on a couple of the components that are prone to failure. Apparently one part is biased “on” all the time in the 746, and this requires it to dissipate a great deal of heat even when in receive mode. The 756 line biased the part “off” so it wasn't conducting.
The real fix is a two-part deal. First, you add a heat sink to a driver IC, a very tiny one. Then you add a Zener diode so that the driver conducts only in transmit, reducing the heat it is subject to.
Since these are surface mount parts, I'm not going to be making these mods. If and when the rig fails, I'll have it fixed for certain, but I would like to find someone to make these changes. Simply installing the zener would bias the driver off saving it from much of the overheating problem.
With all that said, how about the rig?
Well, having used one periodically for the last couple of years, it's very user friendly. I used it first on 2 meter FM, then tried out HF. It works well on both.
I really miss the bandscope on the PRO3. I'm still hunting for some controls due to different placement, but by and large the rigs operate in a very similar manner.
Of course, this is just my first full 24 hours of having the rig, so I'm still playing with it.
I don't particularly care for the S-meter on the 746. When it comes to meters, I want a meter (or at least a graphical representation of one). The receiver on the 746 seems very, very good. The filtering works well, and all-in-all, the rig wouldn't be a bad choice for my main rig. I love my PRO3 and won't replace it with the 746, but I'll certainly put this new rig through its paces.
It would make an interesting mobile rig too …. hi hi!
I'm going to go spin the dial before we have to leave. More impressions later.
73 es CUL …. de KY4Z ….. sk…… dit dit …..