Grant and group:
I ran a frequency response test on the O2 on AM and found the following (all
controls set flat, modulation at 50%, no compression or ALC):
20 -1 dB
30 +1
50 +1
200 +2
400 +1
600 0
1000 0
1200 -1
1600 -1
1800 -2
2000 -2
2400 -2
2800 -2
3200 -2
3400 -4
3600 -4
3800 -4
4000 -5
4200 -6
4400 -7
4600 -9
4800 -10
5000 -12
If you roll the low end down by 2 dB, you see a variation of +1 -2 dB (+-1.5
db) from 30 Hz to 3.8 KHz. The roll-off on the high end is fairly gentle,
and with a small be of external EQ, can be reasonably flat to 4.5 kHz.
Looking at the spectrum analyzer while doing the test showed the THD to be
less than 1/2% That's a damn good test result!
Ron Castro N6AHA
Chief Technical Officer
Results Radio, LLC
----- Original Message -----
From: "Grant Youngman" <nq5t@comcast.net>
To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Sent: Thursday, February 16, 2006 4:33 PM
Subject: Re: [TenTec] Request for check of Orion 1.3xx Behavior - AM
I change the TX bandwidth. The audio highs are lost, in the
Monitor audio, as the TX bandwidth is reduced from 3900 down to 900.
Thank you (all of you who responded) very much.
I'm not sure if this is no news or bad news. My presumption on the
original is that the response could be opened up to about 3.9 KHz on each
sideband, for a little better fidelity when the band was clear (and yes,
closed down to 3 Khz or so when things got crowded, but at least at the
ops
discretion). I never did sweep the Orion on AM, so maybe that wasn't the
case.
In the Orion II, the AM transmit bandwidth appears to be fixed at 6 Khz
(per
the new manual update). I'm presuming that means 3 Khz + Carrier + 3 Khz,
and if that's the case this new version of AM TX is certainly not an
improvement. Guess I'm going to have to drag out the audio oscillator and
sweep the II, to really verify what's going on, before crabbing to
ditnsbits
about ruining a good thing by (1) just messing it up or (2) making a
political statement in DSP code :-)
Thanks again ... Grant/NQ5T
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