All, for anyone interested, we figured out how to increase the FM deviation
of the Icom 910H. It takes a fairly simple single resistor change to the
rig. A brief overview is online. Thanks to all those who offered comments.
On Fri, Dec 23, 2011 at 11:21 PM, James Cutler <jwcutler(a)gmail.com> wrote:
Has anyone successfully increased the maximum FM deviation of the 910H
when using the 9600 setting on the radio? We have not been able to. We
have two units, and one is maxed at 2.5 KHz and the other at 3.2 KHz
We've used the service manual to adjust the deviation to max higher values
(>7KHz). But, this doesn't affect the 9600 input path. Looking through
the service manual, on page 10-1 lower left corner, it shows that the gain
control we just set doesn't affect the 9600 path.
So, I'm thinking of modifying the over modulation detection circuitry to
allow for a larger peak to peak voltage signal to be input. The components
that see that voltage appear to be able to handle it.
Has anyone tried this, or know of another way to increase the deviation?