[Test-Equipment] FS: Heath IM4180 FM deviation meter

[Steve Harrisonusa]

>Nope it was the radio cuz I listened on the scanner first
>before setting it.

In that case, the deviation adjustment potentiometer was probably open
where you had it set all the way "open". Too much deviation means simply
that: the signal is deviating "too much": that is, spreading out from the
center (carrier) frequency too far. As someone else pointed out, as you
increased the deviation, the deviation increased far beyond the bandwidth
of the receiver's IF filter and so very little RF energy was detected as
the carrier swung through, then beyond the limits of, the IF filter. Your
transmitted signal became "wideband" FM. That would cause your voice to
become weaker and weaker the further you increased the deviation but that
does NOT mean your modulation was decreasing: you're still modulating just
like with the pot turned down, except now you're carrier is spreading out
way beyond the limits of everybody else's narrowband FM receiver IF
filters. And so they hear less and less of your modulation, so your voice
gets weaker and weaker.

Steve, K0XP