8000DLE internal noise - (switcher?)

N7CXI
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8000DLE internal noise - (switcher?)

Postby N7CXI » Sun Jan 27, 2019 3:09 am

Greetings, all.

I was tuning around 2.068 mHz earlier today, and saw a big, nasty noise spike that I decided to pursue.
Once I switched the rig into a dummy load it looked like the noise was being generated by the rig itself...?
I then fired up a small portable I keep for such things and verified that the noise is indeed coming from the 8000.
(only the radio and analog PSU powered and the noise is present. Kill power to the radio and the noise goes away)

I've since found there are quite a number of strong noise spikes coming from the 8000 up and down the HF spectrum.
Has anyone else noticed this and if so, is there a fix?

Thanks,
Jim N7CXI
N7CXI
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Re: 8000DLE internal noise - (switcher?)

Postby N7CXI » Sun Jan 27, 2019 3:42 am

Now that Scott was kind enough to move my post into the correct section, I can see that my 8000 is not alone in having this
issue.

In my case, at least the spikes are outside the amateur bands with the exception of a minor one at 14.031 . (thereabouts, it slides around)
However:- the whopper at ~2068 kHz averages -84dBm! that isn't by definition a "little" spike.

My .02 of course.

Jim N7CXI
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w9ac
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Re: 8000DLE internal noise - (switcher?)

Postby w9ac » Mon Apr 22, 2019 7:18 pm

N7CXI wrote:Now that Scott was kind enough to move my post into the correct section, I can see that my 8000 is not alone in having this
issue.

In my case, at least the spikes are outside the amateur bands with the exception of a minor one at 14.031 . (thereabouts, it slides around)
However:- the whopper at ~2068 kHz averages -84dBm! that isn't by definition a "little" spike.

My .02 of course.

Jim N7CXI

Jim,

Tune to 413 kHz in the LW band. There you will likely find the strong fundamental. 2068 kHz is the fifth harmonic of 413 kHz.

Paul, W9AC
N7CXI
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Re: 8000DLE internal noise - (switcher?)

Postby N7CXI » Fri Oct 11, 2019 3:48 pm

Thanks for the response, Paul.

In my case at least, I sold the problem and replaced it with a 7000DLE MKII. (no internal PC)
No switcher, no issue. :-)

73,
Jim N7CXI
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w-u-2-o
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Re: 8000DLE internal noise - (switcher?)

Postby w-u-2-o » Fri Oct 11, 2019 5:25 pm

There is a switching power supply in the 7000 MKII. It's built onto the Orion MKII card, same as it is in the 8000. That's how you get 5 and 3.3 from 12V on the card. But there is not the 12 to 50V DC to DC upconverter that the 8000 has.
N7CXI
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Re: 8000DLE internal noise - (switcher?)

Postby N7CXI » Fri Oct 11, 2019 5:41 pm

w-u-2-o wrote:There is a switching power supply in the 7000 MKII. It's built onto the Orion MKII card, same as it is in the 8000. That's how you get 5 and 3.3 from 12V on the card. But there is not the 12 to 50V DC to DC upconverter that the 8000 has.


Well, yikes.
Looks like I need to 'cruise for spikes' with the 7000 MKII then. Hopefully there won't be anything more than a couple of dB off the noise floor. 30 dB off the noise floor falls into "significant design flaw" territory, not that anyone asked. :-)

Thanks and 73,
Jim N7CXI
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w9ac
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Re: 8000DLE internal noise - (switcher?)

Postby w9ac » Tue Oct 15, 2019 2:59 pm

N7CXI wrote:
w-u-2-o wrote:There is a switching power supply in the 7000 MKII. It's built onto the Orion MKII card, same as it is in the 8000. That's how you get 5 and 3.3 from 12V on the card. But there is not the 12 to 50V DC to DC upconverter that the 8000 has.


Well, yikes.
Looks like I need to 'cruise for spikes' with the 7000 MKII then. Hopefully there won't be anything more than a couple of dB off the noise floor. 30 dB off the noise floor falls into "significant design flaw" territory, not that anyone asked. :-)

Thanks and 73,
Jim N7CXI


Scott is correct. Orion MKII uses a high-current DC-DC switching converter at U36. Any Apache product that uses Orion MKII -- and likely its progeny, will have switching spurs. Most spurs are masked by band noise when an antenna is connected. So, it's mostly an issue when looking at spectrum with a disconnected antenna. Still, it's annoying to see.

The Orion MKII receiver is so sensitive that it would likely require off-boarding U36 in a Faraday shield to knock the spurs down into the noise floor. This is what Flex did in the 6500/6700 -- and the result of their effort was marginal.

Here's a related thread that may be of interest:

viewtopic.php?f=17&t=2922

Paul, W9AC
N7CXI
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Re: 8000DLE internal noise - (switcher?)

Postby N7CXI » Tue Oct 15, 2019 9:48 pm

Thanks, Paul.
I haven't had time to do it yet, but I will poke around and what spurs turn up.

73,
Jim N7CXI

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