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Poor quality CW and noise bursts start and end of xmits

Posted: Wed Jul 27, 2022 1:00 am
by rdwing
I am facing an issue with my new 7000 Mk3 running v2.7 Protocol1, that has very poor transmitted CW tone with a lot of distortion on the signal, and keying clicks on both key down and key up. This is observed on all bands. The antenna is a resonant fan dipole, there are common mode chokes and ferrites, and I don't believe there is any RF coming into the shack.

The following is from CW transmitted at 100W and received on a remote receiver, via the CWX built in keyer.
Screenshot 2022-07-26 021120.png
CWX Thetis
Screenshot 2022-07-26 021120.png (40.78 KiB) Viewed 2624 times
Screenshot 2022-07-26 021124.png
CWX RemoteSDR
Screenshot 2022-07-26 021124.png (64.58 KiB) Viewed 2624 times


This phenomenon somewhat occurs using the TUN button and 2TON buttons as well.
Screenshot 2022-07-26 020535.png
Tun+2TON Thetis
Screenshot 2022-07-26 020535.png (110.32 KiB) Viewed 2624 times
Screenshot 2022-07-26 020523.png
Tun+2TON RemoteSDR
Screenshot 2022-07-26 020523.png (1.25 MiB) Viewed 2624 times


Part of the problem seems to be incorrect timing of the relays when stopping a transmission.
A potential clue: I have a dummy load connected to ANT2. A power meter and antenna are connected to ANT1. When transmitting into the dummy load on ANT2 with a 100W carrier, when I stop the transmission by clicking the TUN button my power meter on ANT1 registers a blip of power, which I find very interesting.
Screenshot 2022-07-26 175238.png
Burst at end of xmit
Screenshot 2022-07-26 175238.png (193.24 KiB) Viewed 2624 times

Screenshot 2022-07-26 175803.png
XMIT Options
Screenshot 2022-07-26 175803.png (12.76 KiB) Viewed 2624 times

Re: Poor quality CW and noise bursts

Posted: Thu Jul 28, 2022 6:49 am
by PD3LK
Hi,

Resonant antenna on 3901 kHz ? What ham band is that?
Can you show us a example on a appropiated HAM band part?
What happens (next) if you reduce power in few steps?

Re: Poor quality CW and noise bursts

Posted: Thu Jul 28, 2022 7:31 am
by rdwing
PD3LK wrote:Resonant antenna on 3901 kHz ? What ham band is that?
Can you show us a example on a appropiated HAM band part?
What happens (next) if you reduce power in few steps?


Hi, it was the 80m/75m amateur band in the US. 3.901 MHz. It is a resonant antenna, a large multi band fan dipole.

Here it is on the 40m band. Antenna SWR is about 1.5 at this freq. There's nothing else in line, the tuner is bypassed for this. Seems pretty much the same.

I've discovered another issue as well. While sending CW into my dummy load, which is attached to ANT2, some blips can be seen coming out of ANT1, which are being transmitted over the air. I was pretty surprised to see that...see image at the bottom.

From 100W to 5W, the same behavior is seen.
100w.png
100w
100w.png (659.03 KiB) Viewed 2563 times

50w.png
50w
50w.png (433.08 KiB) Viewed 2563 times

25w.png
25w
25w.png (319.03 KiB) Viewed 2563 times

5w.png
5w
5w.png (291.32 KiB) Viewed 2563 times

nanovna-h4_2022-07-28_00-56-36.png
VNA-40m
nanovna-h4_2022-07-28_00-56-36.png (140.3 KiB) Viewed 2559 times

Screenshot 2022-07-28 012321.png
ANT2 transmissions leaking out on ANT1
Screenshot 2022-07-28 012321.png (2.05 MiB) Viewed 2551 times

Re: Poor quality CW and noise bursts

Posted: Thu Jul 28, 2022 9:23 pm
by dynamicfusion
Maybe shielding? Grounded?

Re: Poor quality CW and noise bursts start and end of xmits

Posted: Thu Aug 11, 2022 6:39 pm
by rdwing
It seems this is a firmware problem, and unlikely to get resolved at the moment.

Re: Poor quality CW and noise bursts start and end of xmits

Posted: Thu Aug 11, 2022 7:42 pm
by w-u-2-o
rdwing wrote:It seems this is a firmware problem, and unlikely to get resolved at the moment.

How did you come by that assessment? It could just as easily be a software problem. Or perhaps no problem at all, since it does not affect everyone.

Re: Poor quality CW and noise bursts start and end of xmits

Posted: Tue Aug 16, 2022 2:45 am
by w9ac
Can you capture the transmitted CW waveform in the time domain with an oscilloscope? That will tell us a lot about the root cause of any excessive keying bandwidth, hot-switching, etc. It may be easiest to sample at the input to your dummy load with a "T" coaxial adapter.

Paul, W9AC

Re: Poor quality CW and noise bursts start and end of xmits

Posted: Thu Aug 18, 2022 1:06 am
by JJ4SDR
To "rdwing,":

Curious about the time delays on the Options form. My PTT delay is 0 and the RF delay 30 ms. Not that this necessarily explains what you are experiencing. The difference between the PTT delay and RF delay in your case is very brief compared to mine.

Options 1.jpg
Options 1.jpg (29.74 KiB) Viewed 2147 times


I am not using the same Thetis version as you and also I am on Protocol 2 (radio is ANAN 7000 DLE MKII).
Thetis v2.9.06. x64 Protocol 2 v2.1.18

What W9AC suggests would be good to have.

73 de Juha
NI2M

Re: Poor quality CW and noise bursts start and end of xmits

Posted: Thu Aug 18, 2022 1:11 am
by JJ4SDR
Paul,

I am wondering what the numbers are on Options 1 form in your case? Mine may be off for all I know. I have only changed the PTT and RF delays, nothing else if my memory serves.

73 de Juha
NI2M

Re: Poor quality CW and noise bursts start and end of xmits

Posted: Thu Aug 18, 2022 1:34 am
by w9ac
JJ4SDR wrote:Paul,

I am wondering what the numbers are on Options 1 form in your case? Mine may be off for all I know. I have only changed the PTT and RF delays, nothing else if my memory serves.

73 de Juha
NI2M

Juha,

My CW settings won't apply to you for several reasons as I'm using a specialized Channelmaster.dll file, ASIO drivers, and some hardware modifications to optimize QSK. All delays are set very low, some to zero. As you requested, I have attached my Option 1 settings but please do not attempt to use these values.

Paul, W9AC

Options1.jpg
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