He suggests that perhaps you donвЂ™t need the heatsink with the VCC fix, as this modified circuit is similar to the circuit in the IC-756PRO, which does not seem to have an IC151 problem. What he did was find an 8 VDC line that was switched on only during transmit and used that to power IC151.

In addition to adding a heatsink to IC151, he also found a way to switch the VCC to the chip. K5LXP also experimented with heatsinks, but he took his fix a step further. OZ2M also shows on this page various heatsinks that some hams have designed and installed in attempts to keep the chip cooler. This will, of course, keep the part much cooler. OZ2M, an electrical engineer by training with five years of experience with Motorola as a Senior RF Design Engineer, points out on his IC-746PRO web page that in the IC-756PRO, the VCC line is switched on and off, with the IC only being powered when the rig is transmitting. Many hams point to the difference in the two circuits. WhatвЂ™s even more confusing, or dismaying, is that the IC-756PRO uses this same IC in the same application, but IC-756PRO owners donвЂ™t report anywhere near the number of failures that owners of the IC-746PRO do. If you read the IC-746PRO reviews on eHam, it looks as though quite a high percentage of the units fail, and many fail more than once.

Some IC-746PRO owners say that IC151 gets hot, causing it to fail prematurely. The first problem seems to be a thermal problem. There actually seems to be two problems with IC151. AES recently dropped the price of this radio to $1300, and for that price, I think itвЂ™s the best deal on the market.ДЄt least it would be if not for that nagging IC151 problem.

Icom 756 pro 3 serial numbers