Hi Bill-- interesting problem. Not an expert here, but have used the VAC
input a fair amount. When using the VAC input instead of the microphone,
I've been told that many of the audio chain components are bypassed.
VAC is intended primarily for digital modes or use by those expensive
external audio processors. The digital modes don't do well with
equalizers, companders and all that. I was told that the audio chain
with VAC was pretty much limited to the TX Gain you mentioned and ALC to
limit over modulation, nothing more-- don't know the accuracy of what I
was told but it makes sense. So most of those steps in the referenced
article have no effect.
A normal microphone audio chain for broadcast or ham gear will almost
always have a compression (leveling) stage, because no one talks at the
same level all the time, and mic distance follows the inverse square law
as to volume and who can be that precise. VAC drops that I think, and
counts on your external processing to handle whatever leveling,
compression, equalization, etc that is needed.
This was real obvious when using VAC for remote audio that I do frequently.
Hope this helps-- I may be something else ....
Steve WA7DUH
On 10/5/2011 2:05 PM, Bill Ackerman wrote:
I have carefully followed the directions for Audio Gain Distribution
contained in this item:
http://www.mail-archive.com/flexradio%40flex-radio.biz/msg42531.html
I adjusted everything to the suggested readings with my face about 12"
away from the microphone (Heil PR-40 through external A/D converter
into USB port of the PC, PowerSDR 2.2.3, VAC enabled, Windows 7 Direct
Sound driver).
Over the past few days, I have been told multiple times that my signal
is strong but my voice is very soft (????). When I move my face to
within an inch or two of the microphone, I am told the readability is
now great, even though the "Mic" TX meter is bouncing up to +60 dBm.
So I have been operating that way and it seems to be working. It
appears that the TX meter is not giving an accurate reading for my
particular configuration.
The only difference between what I am doing and the instructions in
the above link is that I am adjusting the TX Gain in the Audio/VAC
panel of the PowerSDR Setup rather than Mic level control. It is
possible that going through the Windows audible drivers rather than
directly into the Flex3000 could be making a such difference in the TX
meter?
Thanks for helping me understand what I am doing wrong.
73,
Bill Ackerman
KF5MTW
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