Karl Heimbach wrote:
> Hello gang,
>
> I got my long awaited Omni VI Plus eight days ago, and am puzzled by
> what appear as self-generated birdies. I find them on all bands.
> With
> the antenna disconnected from the radio, DSP and notch filters off, no
>
> auxilliary filters engaged, in CW mode, I hear a moderate to strong
> tone
> at each of the following frequencies:
>
> 160 Meters: 1.8001, 1.8385, 1.8777, 1.8816, 1.8878, 1.9010, 1.9348,
> 1.9521, 1.9796, 1.9878, 1.9989
>
> 80 Meters: 3.5547, 3.5995, 3.6289, 3.6514, 3.6648, 3.7137, 3.8329,
> 3.8891, 3.9252, 3.9534, 3.9996
>
> 40 Meters: 7.0144, 7.0449, 7.0763, 7.1399, 7.1648, 7.1922, 7.2350,
> 7.2603
>
> 30 Meters: 10.1328
>
> 20 Meters: 14.0209, 14.0968, 14.1309, 14.1357, 14.2590, 14.3574
>
> 17 Meters: 18.0701, 18.0993, 18.1382, 18.1657
>
> 15 Meters: 21.0901, 21.1613, 21.1938, 21.2327, 21.2910, 21.3324,
> 21.3931, 21.4326
>
> 12 Meters: 24.9623, 24.9000, 25.0000
>
> 10 Meters: 28.1084, 28.1216, 28.1488, 28.1623, 28.1973, 28.2832,
> 28.2969, 28.3320, 28.4423, 28.4881, etc. to 29.7000.
>
> I do not hear these signals with my Icom 735, Ten-Tec Argo 556,
> Ten-Tec
> Delta 580, or Index Labs QRP plus; all of which sit on the same desk
> as
> the Omni VI. I've disconnected just about every suspect electrical
> device in my home without improvement.
>
> Has anyone had a similar experience with the Omni VI Plus or have a
> suggestion as to what to investigate next?
>
> Thanks in advance.
>
> Karl - W5QJ
>
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Hi Karl,
Although I did not confirm your frequencies, it is likely that many are
a result of the crystal mixing scheme. I was initially concerned about
this as I use my VI+ as an IF for 1296 EME- I could not tolerate a
birdie within that window (28.000-28.100). Although there were some, the
gain of the downconverter/ LNA completely masked them.
With my antenna connected on HF all but a very few are also masked by
natural noise. To me, this is a small price to pay for the excellent
phase noise characteristics of the radio.
Dale
W4OP
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