To correctly set these radios for AM one should have some type of waveform
monitor such as the old Heath SB-610 or HO-10.
One thing that I noticed with my Omni VII and the 708A mike. The Positive
modulation peaks were not 100% when the negative peaks were hitting 100%.
The solution, reverse the Red and White wires in the XLR-4 connector that
plugs into the back of the mike. Once this was done, the positive
modulation is equal to the negative modulation. Without a waveform monitor
being a Heath SB-610, I'd never seen the issue. And yes, it takes more mike
gain for AM than for SSB.
Even with the Heath Apache and the RCA BC transmitter I have found that mike
phase does make a difference in modulation symmetry. A monitor scope will
tell the true story.
73
Bob, K4TAX
----- Original Message -----
From: <ac9s@mchsi.com>
To: <tentec@contesting.com>
Sent: Tuesday, October 02, 2007 2:52 PM
Subject: [TenTec] Orion II AM Mic Adjustment
>I have begun to play with AM on the O2 and it appears the microphone
>settings
> are significantly different than with SSB. I am running a Heil Goldline
> through an NCS multiswitcher. With the current gain setting on the NCS
> box I
> have the red led on the O2 flickering with the O2 software mic setting at
> 18.
> Today I checked in with an AM group on 3875khz and was informed that my
> audio
> was light. Sure enough, there was no flicker on the led. I turned the
> mic
> gain almost up to 100 - I could see increased gid current on my amplifier,
> but
> never a sign of the led lighting. The group informed me the audio level
> had
> increased, but that it was still a little on the light side.
>
> Does the LED work on AM? Should the mic gain be radically different
> between
> SSB and AM? I didn't see anything specific in the manual.
>
> Thanks for any input on the proper way to set the mic gain on AM.
>
> Keith
> AC9S
> _______________________________________________
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> TenTec@contesting.com
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>
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