WIdeband spurs

[w9mdb]

Decided to play with the wideband display...
Apache 7000MKII DLE and Thetis 2.9.0.6

Does this look normal? 14.074 transmitting.....spurs are very inconsistent....biggest appears to be just above 42MHz and then around 53MHz on the 2nd biggest spur.

Screenshot 2022-05-09 153548.png (18.79 KiB) Viewed 5005 times

[w-u-2-o]

This is what mine looks like when transmitting on 14.074MHz: Conditions are an ANAN-8000DLE, KPA1500 amp at 1500W, PureSignal activated, feedback is from the KPA1500 internal coupler.

Capture.JPG (187.23 KiB) Viewed 4986 times

Yours looks like there is a serious problem somewhere. Under what conditions was it captured?

[w9mdb]

That was full power 100W out of the rig -- no amplifier -- into a dummy load.
If I drop the output power to 4W I get this

Screenshot 2022-05-09 173731.png (20.93 KiB) Viewed 4979 times

And at 6W the spurs suddenly jump up and look more like yours.

Screenshot 2022-05-09 173843.png (19.26 KiB) Viewed 4979 times

The difference I see now is that at 6W Thetis is claiming ADC1 overload and at 4W the ADC1 overload goes away. And this is controlling power by using the volume slider in JTDX and not the drive in Thetis -- drive is at 100.

[w-u-2-o]

Something is badly wrong. None of those little spurs should be there. You should be seeing even numbered harmonics only.

The ADC overload indication is also a bad one.

What version of Thetis and what version of firmware are you running? I'm suspicious that the firmware is not closing timing properly on your hardware. If you are running 2.1.18 you might try 2.0b.

[w9mdb]

Running 2.1.18. I'll go back to 2.0b and see how it behaves.

[SA3ATF]

As for the overload problem, check that none of the bandpass filters are in the off position.
For me, BPF-1 is always @ ByPass when I start the wideband display.

[K1LSB]

As for the overload problem, check that none of the bandpass filters are in the off position.
For me, BPF-1 is always @ ByPass when I start the wideband display.

I've always observed the same thing, the BPF-1 is always disabled when WB is selected. I've often thought of reporting that as a bug, because if someone wasn't aware of that behavior and suddenly starts observing ADC overload (from BCAM signals for example) on 80 meters then they wouldn't know what had changed.

But I didn't want to come across as a whiner so I never reported it.

Mark

[w-u-2-o]

I always run in bypass (preselector off) and I never see any ADC overload indications. The preselector is only third order, it doesn't offer a ton of rejection.

It's a moot point, anyway, since during TX the WB display is fed by the PureSignal feedback coupler if PS is turned on, and the PS feedback path does not go through the preselector.

Actually, that's a good question for the OP, @w9mdb -- is PS turned on when you are making these tests? It is when I did my screen shot. Although when I tried it without PS turned on it made no difference, but just in case the 7000 works differently than the 8000 (I don't think it does).

[K1LSB]

I always run in bypass (preselector off) and I never see any ADC overload indications. The preselector is only third order, it doesn't offer a ton of rejection.

I live 3-1/2 miles from a 50KW BCAM station. The prefilter makes a difference for me.

Mark

[K1LSB]

I always run in bypass (preselector off) and I never see any ADC overload indications. The preselector is only third order, it doesn't offer a ton of rejection.

I live 3-1/2 miles from a 50KW BCAM station. The prefilter makes a difference for me.

Mark

Edit: And that 50KW station employs a 7-element tower array that beams the strongest signal in my direction.

[w-u-2-o]

Edit: And that 50KW station employs a 7-element tower array that beams the strongest signal in my direction.

Daaaaamn

A little thread drift, so I am spanking myself : Since you can get to the cable that goes between the Orion MKII board RX1 input and the output of the PA/RF board, it would not be hard to insert a low cost, low power BCB high pass filter inline. Then you could safely disable the preselector if you wanted to use ADC0 on multiple bands simultaneously.

Example at this link.

[w9mdb]

2.0b only slightly better. I was using the Tune from JTDX earlier -- this is with Thetis Tune button on a dummy load. 14.074Mhz (seems the same on all bands).
Spurs jump up from drive level 5 (4.9W) to drive level 6 (5.9W measured by my LP700) and about 15dB it appears.
At 4.9W looks like this

Screenshot 2022-05-10 114408.png (22.08 KiB) Viewed 4801 times

At 5.9W looks like this -- where could the 24MHz spur be coming from? The 28MHz makes sense as the 2nd order harmonic.

Screenshot 2022-05-10 114457.png (22.82 KiB) Viewed 4801 times

[w-u-2-o]

Mike--are you running PureSignal while doing this or not? If not, please try it that way just to get a little more data. Also try two-tone so we can see what that looks like.

It would be great if other people with 7000's would post some results for comparison purposes.

[NC3Z]

It would be great if other people with 7000's would post some results for comparison purposes.

20M 7000DLE, 1500W from Acom 2000 using PS with couple built into Telepost LP700 sensors

Screenshot 2022-05-11 073921.jpg (91.33 KiB) Viewed 4688 times

[w9ac]

My 20m results connected to a dummy load. Blue face 7000DLE with late Orion MKII board. I had to disconnect my 10 MHz GPSDO as the receiver was picking up leakage from the GPSDO's fundamental and its harmonics. PS on or off, didn't matter.

The first photo is of the receiver, the second is while transmitting a carrier from WSJT-X to simulate W9MDB's test. I see some low-level harmonic content, but it would be filtered after the PA.

Notice the small 24 MHz spur reported by W9MDB. It's low-level and present whether in Rx or Tx. The two transmit spurs +/- the carrier measure -70 dBc when spread out for greater detail on the pan display. Not sure why there's a level disparity between WB and normal pan. Anyway, remaining transmit spurs are -80 dBc. Otherwise, I see no baseline spectra oddities when changing power from 1W to 10W, then 100W.

Paul, W9AC

[w-u-2-o]

I see some low-level harmonic content, but it would be filtered after the PA.

Why do you think that this spectra is coming from a path that is prior to the LPFs?

[w9ac]

I see some low-level harmonic content, but it would be filtered after the PA.

Why do you think that this spectra is coming from a path that is prior to the LPFs?

Within the transceiver case, there's high-level RF present before and after the PA LPF filter. To remove any guesswork, I can take a wideband spectrum analyzer measurement from a sample at the dummy load.

Paul, W9AC

[rbduck]

Here are my wideband plots. The top is transmitting with PS on. The bottom is receiving. I was transmitting the in top side of 75 meters.
On a black 7000DLE Mk II at 20 watts.

[w-u-2-o]

That's enough plots to know Mike's got a problem. The question is what problem?

Power supply? Firmware? I'm stumped right now.

[rbduck]

Would the type and/or location of the dummy load make a difference?

[alemrush]

Hi,

Are you using a switching power supply ?


Andre

VA2WR

[w9mdb]

Yes...a switching power supply. Doesn't everybody?
I'm also not using PS but doubt that makes that much of a difference.
I do have a new power supply I'm putting in...maybe I should accelerate trying that one.

[w9ac]

Just a measurement observation in response to Scott's earlier question and not relevant to W9MDB's issue...

Shown below is a 1-60 MHz transmit sweep measured with an Anritsu MS2721B analyzer. Test conditions:

ANAN 7000DLE with Orion MK II
5W WSJT-X carrier at 14090 kHz
RF sampled at dummy load with a Bird 4273 coupler
Analyzer set to 300 Hz RBW, 10 dB/div

The second harmonic is about 5-7 dB less than that shown in Thetis' BW sweep. I'm not sure if this difference is real or a level disparity between the BW and normal pan presentations in Thetis. So, it's inconclusive as to whether higher second harmonic content is truly measured in Thetis' WB display.

Any follow-up discussion should be started as a separate topic.

Paul, W9AC

[rbduck]

Yes...a switching power supply. Doesn't everybody?

I'm not using a switching supply. When I first got my ticket I was warned about the possibility for noise or RFI from switching supplies.
It was some advice from a friend. Also I purchased a three of the supplies that are used to power servers. They are switching PS's. Just out of curiosity. Grounded or ungrounded, two produced bad noise. One was quiet as a mouse.