Hi Merle:
It is interesting that this early criticism of the O2, that is lower average
power output for any given PEP, has not been more fully discussed here. Many
operators have noted that the O2 does not drive their amplifier as hard as
other RF Clipper based rigs, but no solutions have been offered, up to now.
I at first went about changing the timing constant for the hardware ALC in the
O2. I found out that by the time the average power increased, I was already
into distortion with the audio.
In my opinion, after much testing and effort, that the Ten Tec manual for the
O2 does not properly discuss the settings critical to the RF Compressor
adjustments. I have already made my comments regarding the failure of the ALC
lamp to provide the necessary guidance in setting the microphone gain levels.
Stated simply, to obtain the expected increase in average power, thru the use
of the on board RF Compressor, it is necessary to set the compressor level to
AT LEAST 7, and advance the combination of the microphone gain and the hardware
microphone gain to produce the expected increase in the RMS output.
In my O2, I drive the compressor to increase the average by least 3 db, which
is not inconsiderable. This increase was not possible with the ALC lamp just
flickering on and off.
With a little experimentation, you will find the gain settings which work well
for your set up, depending on the microphone and/or outboard audio gear being
used.
The ALC lamp basically remains on in my set up, using audio compression from a
W2IHY EQ Plus. I am now fully satisfied with the O2 transmitter, now that the
RF Compressor is adequately driven.
With average power gains of 3 to 5 db, I have seen no reduction in quality to
the audio, or splatter.
By the way, my comments apply to the current firmware release, not the new BETA
firmware.
It really can work! I think lack of metering was a real stumbling block here,
but as far as I can see, the issue is resolved.
73 and Happy DXing,
Mike
W2AJI
> From: merlebone@charter.net
> To: tentec@contesting.com
> Date: Sun, 1 Mar 2009 19:16:44 -0600
> Subject: [TenTec] Orion/Orion II Speech Processing
>
> Mike said:
> ----------------------------------------------------------------------------------------------------------
> "The ALC lamp is simply not an acceptable substitute for microphone preamp
> metering. Checking the signal quality at levels where the lamp is on
> considerably more than just on voice peaks indicates no increase in IMD at
> these higher microphone gain levels and much higher RMS output."
> ---------------------------------------------------------------------------------------------------------
> Mike, your observation on the ALC light, when using Speech Processing, is
> identical to my experience. I didn't mention that when I did the Speech
> Processing
> testing, but while the ALC light may be useful for initial setting the
> microphone gain,
> it is not useful when the speech processing is engaged. Lots of remote testing
> has confirmed that the signal and speech quality is very good with the
> speech processing at 7, 8 and 9. Their is no speech distortion or signal
> splatter even though the ALC light is on significantly with the Speech
> Processing on.
> http://lists.contesting.com/archives//html/TenTec/2009-02/msg00075.html
> 73, Merle - W0EWM
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