Dan Graves wrote in message . ..
Were can I find out about these mods and what they do?

Dan
Hi Dan: you can find the Icom R75 mod's information he
http://groups.yahoo.com/group/icomr75/files/R75%20mods/
About your 2nd question:The sync upgrades provides enhanced
performance where the PLL stays "locked" under the most difficult
signal conditions.For example the KIWA sync upgrade is best described
as a "dual speed control voltage". The control voltage for the PLL
filter is tuned within an optimum window that is determined by signal
conditions.The response is slow to maintain a "centered" condition. A
second circuit provides the control accuracy to react to fast flutter
fading and noisey conditions. These two circuits provide a dual speed
control for the PLL.
The second major upgrade is to the Synchronous AM AGC. The dual speed
technique is used again to first center the AGC but still allow for
quick short changes in AGC characteristics as required by signal
conditions.In the files you can find others nice mods and tips for
enhancing the performance of your Icom. Ken