artifact on TX

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Kb2uka80
Posts: 1
Joined: Wed Mar 15, 2023 3:12 pm

artifact on TX

Postby Kb2uka80 » Wed Mar 15, 2023 3:30 pm

Hello everyone,

I have 7000 dle mkii that was delivered last July (i guess we are calling these the mkiii but mine is still branded mkii and has the first newest chipset, not the most recent).

I run all sorts of audio equipment with the anan and I'm fanatical about clean audio. I've always noticed a small artifact when you key down, on the pan adapter but it has never been audible or visible in the transmitted signal.

About a week ago, i noticed what looked to be a 60hz hum on my TX. It was audible and visible. I've never had this issue before and decided to rearrange the shack and made certain all electronics were on one dedicated circuit. That didn't help. Here's what i have found:

not a 60hz hum, artifact is present from 0-95hz.
artifact is there with 1 watt drive, 100 watt drive and while using an amplifier.
artifact is present in dummy load and antenna system
artifact is present with microphone and/or audio interface, rack, xair, connected.
artifact is present with vac and line in
artifact peaks at about -72db on the pan adapter
when i key down with the amp engaged and no audio source connected to the rig, the artifact drives my amp to over 1kw and then the output power dissipates from there.

If I change my low cut freq to 100hz in the tx bandwidth, it goes away completely. If I change it to 95hz or lower, it's present.

If i disengage the "mic" button next to the gain slider, it goes away (remember there is no audio source, this is not noise from the mic). If i engage the mic button with 1db of gain, it's present.

I'm sending the radio off for diagnostic and possible repair. Would love to know the communities' thoughts?

Doug
kb2uka
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w-u-2-o
Posts: 5540
Joined: Fri Mar 10, 2017 1:47 pm

Re: artifact on TX

Postby w-u-2-o » Wed Mar 15, 2023 4:32 pm

Kb2uka80 wrote:not a 60hz hum, artifact is present from 0-95hz.

Can you provide a screen shot of this on the panadapter, with the unit in TX and DUP on, please? DUP on shows the RX1 input during TX, and it's assumed you have an appropriate coupler on the amp? Please show the entire window with all the controls visible, not just the spectral display.

What version of Thetis are you running? What version of firmware are you running?

artifact is present with microphone and/or audio interface, rack, xair, connected.

What about disconnected?

artifact is present with vac

That is difficult to believe. Would you mind demonstrating that with a screenshot as requested above? When I select VAC, and VAC is properly connected to a source of audio, and that source is not generating any audio (fully muted), when I key up I see absolutely zero movement of the transmit panadapter (in DUP) off of a -135'ish noise floor.

When you select VAC it doesn't matter if the MIC button is on or off. VAC is the source of audio. If you are getting this problem with VAC selected then the problem is either firmware or hardware.

artifact peaks at about -72db on the pan adapter
when i key down with the amp engaged and no audio source connected to the rig, the artifact drives my amp to over 1kw and then the output power dissipates from there.
That also makes no sense. If the artifact is down -72dB that is a mouse fart. No way that should drive an amp to 1KW. This is measured with DUP on, right?

Can you put an external power meter on the output of the 7000 and see what it says under these conditions?

When I use TUN to put out 1W I see -40dBm on the pandapter (DUP on). All things being relative and equal that means that a -72dBm is 32dB less than 1W, or approx. 1 milliwatt. No way 1mW is driving your amp to 1KW.

If i disengage the "mic" button next to the gain slider, it goes away (remember there is no audio source, this is not noise from the mic). If i engage the mic button with 1db of gain, it's present.

Is this true even with VAC selected and properly attached to a source of audio?

I'm sending the radio off for diagnostic and possible repair. Would love to know the communities' thoughts?

I'd be interested in a few more tests and measurements as discussed above, first.
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WM4CH
Posts: 59
Joined: Wed Nov 09, 2022 1:20 pm
Location: Cape Cod, MA

Re: artifact on TX

Postby WM4CH » Mon Oct 09, 2023 3:01 pm

I think I had the same thing.

I had to change the filter size RX and TX on SSB/AM at DSP.Options to 4096 to get rid of that out of pass band spikes. I had 2 spikes above and below the band pass, Setting 100 hz as the bottom got rid of both. But to have a 50 hz bottom, I had to change the filter size.

Others have mentioned that here too, which is where I got it from.

Here is my thread with pics:

https://community.apache-labs.com/viewtopic.php?f=46&t=4670

I am interested to hear if anything is found wrong with the radio, since I am going to send mine to Doug for other issues.

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