Something else that I should have mentioned, as it seems to be
overlooked too often...

"Willey" wrote...

using compression does not increase deviation on
FM an modulation limiter limits the
Audio MAX.

A compressor does NOT limit output to a set level.
What it does is attempt to keep the output at a preset amplitude,
by noticing when it is above or below that level and then starting
to compensate.

Do you see the implications of the above?
The output DOES exceed the preset level, until the system has
realized and compensated for it.

The *peak* deviation is that due to the maximum output
before the level is reduced again, not that of the preset level.

As standard, an FM CB is set so that it peaks at 2KHz absolute
maximum.
If you fit a processor, and adjust for 2KHz deviation, that will
be set for 2KHz when the AGC has corrected the level. Every time
your audio level increases (it is continually changing), the deviation
can hit several times that 2KHz requirement until the AGC has
corrected for the increase.
Totally illegal, and a serious cause of distortion and adjacent
channel interference.


Again a compressor does not change the deviation,


Incorrect.
See above and the other reply. There would be no point to
the circuit if it did not change the deviation in any way.


the limiter or clipper in
the radio prevents the over deviation.

Incorrect.
A manufacturer is free to fit a clipping circuit, if they
wish to - but it is by no means certain that they have.
Even radios from the same manufacturer, or with the
same model number, may use different circuits.
The list below is not a complete list of UK and EU FM CBs,
just a few where I quickly looked at the circuits...

Some use absolutely no clipping or AGC:
Amstrad 900 & 901, Binatone Breaker-phone,
Mustang 1000 & 2000, Spinneytronic.

Some use basic diode clipping, parallel diodes to
ground:
Fidelity 3000, Lowe TX-40.

Some use clipping with two diodes in series (Like
in Lou Franklin's clipping processor):
DNT B40,
Midland 77-104D, 77-104 (CEPT),
Team Lancaster,
Uniden UK CBs.

Some use an op-amp setup similar to the
K-40 processor circuit:
Colt 295, Maxcom 20E,
Magpie Autoscan,
Maxon MX-1000 & MX-2000,
Midland 4001, 77-104 (UK), 77-805.

Some use AGC systems:
Alpha 4000, Binatone Route 66,
Jesan KT 4004 / 5005 / 7007,
Midland 77-099, 77-250K,
Pama GX19 / 25 / 29 / 1000 / 2000.
Shogun (UK CB, not Emperor).


Now for the big question... if the radio does have some form
of processor (clipping or AGC), why the hell would you wish
to spend money putting another one in?


If the radio has no level control, the VoiceMax will be allowed
to take peaks well over the 2KHz deviation - distorting the
received audio and knocking out channels.
If the radio has clipping, then this comes into play and causes
distortion - the exact type of distortion that Griffter claims
will not happen with his product.
If the radio has AGC, then the excessive peaks from The SplatterMax
will still pass straight through... and why fit another AGC circuit
when it already has one?

Oh, and don't forget that the VoiceMax instructions* say that, if a
limiter is fighting your attempts and keep the radio within the
required limits, just disable the limiter.



Regards,
Peter.

* VoiceMax instructions:
Revision B dated 7/8/2007 7:23pm