Topband: Transceiver Key Clicks

[Tom Rauch]

> The stock Omni VI+ has a very sharp and discontinuous leading edge.  The
> trailing edge is fine.

You can hear recordings of some radios at:
http://www.w8ji.com/keyclicks.htm

> It can be very difficult to design a transmitter with a symmetrical key
> shape while controlling power spikes with an ALC circuit.   The behavior
of
> ALC tends to react to the onset of power by using feedback.  Only, if the
> feedback loop is not fast enough to react to the initial power spike
before
> the time the ALC has settled, the damage is done.  Alternatively, by
making
> the ALC respond faster, it tends destroys the integrity of the keyed
> envelope.

Actually a design that would correct this is very simple.

The technology that would allow a near-perfect solution is the recent
invention of a cutting-edge device called an op-amp (like an LM-358). It's
just so new they may be waiting for cost to come down so they are
affordable.

Seriously, it is only pennies and a few hours of design time to fix these
problems before the radio is built. The real problem has to be no one in the
design process cares.

73 Tom