filtering problems?

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  • Problem
  • Updated 3 months ago
  • Not a Problem
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Using a 6600m 2.331and just getting on 6m I noticed some strange behavior.  While trying to run 17m FT8/CW on Slice A and listing on 6m for FT8 on Slice B, using both the front panel and smart SDR I get strange mix that appears to be AM signals.  I also can see this behavior when running 20m and 17m and running 6m and 80m again both front panel and smartSDR.  when I switch to 40m it disappears as well as 15.  I have not conducted a matrix test of all combinations of bands, however I did notice that if the behavior is present 6m & 18m and I open a third slice in smart SDR on 15m it disappears and I get good AM free reception. (second pic) Also there are some occasional CW signals it is like the front end is wide open or something.  I have tried bypassing the ATU, no difference am running v2.1.33, on Ant1 for all of the band slices.  While I am very close to WSB-AM 750Khz 50kw perhaps 10miles the AM signal is not WSB-AM.  Even my old IC-735 does not have issues with AM mixing like this situation.
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Lin N4YCI

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Posted 3 months ago

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3 months ago
Photo of Tim - W4TME

Tim - W4TME, Customer Experience Manager

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Official Response
So the first thing is that if slice A and B are on the same antenna, you are not using separate antennas and as such, you have entirely too much RF preamp gain on 20m and you are not using the preselectors (noted by the wide indicator)

You need to use a separate antenna for 6m

If you are close to an AM broadcast station, you need to turn off the RF preamp (or use attenuation) for all bands 10m and below and configure the panadapters to use the preselectors.  I suspect you are causing rectification internal to the radio and that is causing the AM radio station images.
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