G90N FT8 communication link lost during CAT operation.

xyzyx

台式机使用wsjt-x和jtdx控制G90N进行FT8通联，经常出现软件找不到电台的问题。我试过把电台的接地端搭载机箱上，保证了电脑可以控制电台，但是当电台发射时电脑的有线网连接直接中断，同时CAT断开，软件停止发送并报错。

我还尝试了使用树莓派5来控制电台，这种情况下wsjtx是控制电台的，但是当连接ACC和CAT线时，电台上驻波显示非常奇怪，勉强用天调也是能调一下。但是同样的CAT断开的问题依旧会在发射的时候的出现，只能守听。

我怀疑是发射的时候干扰到了USB😞，暂时不知道怎么解决这问题，接地的话也不知道接在什么地方合适。

目前我只能使用手机上的FT8CN软件来进行通联，有些不太方便。有没有友台遇到过相似的问题？是怎么解决的？

BG5EQA

xyzyx I have experienced over 5,000 disconnections, and now I'm using a magnetic ring to keep it running continuously. However, the transmission power is fluctuating.

BA3QU

Please tell me about your antenna system.

xyzyx

BA3QU
Tianke said that the MA01 antenna was attached to the air conditioner's outdoor unit, and then he also installed four 5-meter ground wires, which were wrapped around both the outdoor unit of the air conditioner and the window sill inside.

xyzyx

BG5EQA Currently, I'm using a 10W transmitter directly, and I haven't paid close attention to the actual power output. When using the FT8CN app on my phone, the power output is around 9W.
When I connect this system to a Raspberry Pi, the resulting spectrum analysis shows a curve with three distinct peaks, and the resonant frequency is approximately 1.8.
When I unplugged the cable connected to the Raspberry Pi, the frequency dropped to 1.0, which is a perfectly normal single-band frequency display.
I am completely confused.

PPPPPAN

Add a choke coil.

xyzyx

PPPPPAN I tried installing the magnetic loop on the FT8 line using a USB cable this morning, and I still encountered the same problem.
Furthermore, when the radio was tuned, the computer's wired network connection also lost its signal.😂

BG5JKZ

Add a choke between the radio and antenna; for specific details, please refer to the Bilibili video.
[A few tips regarding using a high-power FT8 radio to transmit USB and an inductor loop antenna] https://www.bilibili.com/video/BV1dnsmz6EZQ

BG2EWI

The interference caused by common-mode current in RF systems is not effectively grounded; any electrical connection can cause interference. The solutions are: one, use a balanced antenna or add a choke coil; two, use an isolated data link box.

BH8AVW

BG2EWI
It can be said with certainty that a reliable ground connection is very effective against common-mode current!

The key requirement is a reliable ground connection!
As long as there is a reliable ground connection, common-mode current will be completely conducted to the earth, preventing common-mode interference at the device end!

I have been researching this for many years and have also helped numerous colleagues overcome common-mode interference issues!

xyzyx

BG2EWI

BG2EWI Is the isolation data transmission box a component specifically made by XieGu for the DE19?

PPPPPAN

xyzyx On the feed line

Liridice

Add a choke coil at the feed point of MA-01 antenna.

xyzyx

Liridice Currently, I'm using a magnetic base to attach it to an external unit, and the power output might not be able to pass through the choke. I'm not sure if connecting it directly to the radio end will work.

BH8AVW

Balanced feed, gP and other non-polar feed; susceptible to common-mode current interference.

In addition to reliable grounding, a common-mode chokes should also be included, which will help suppress common-mode currents.

In particular, it has a very good effect on protecting radio stations, especially those using Yaesu equipment.

BD3OZV

Does MA-01 require a time adjustment?
If the antenna doesn't require external tuning, natural resonance, and the radio station's internal tuner is off, it sometimes doesn't actually disconnect, leading to a very high standing wave. At that point, even pressing the transmit button on my handheld radio was ineffective.
For specific reference:https://forum.hamcq.cn/d/6237

xyzyx

BD3OZV The desired resonant frequency can be achieved by manually adjusting the antenna length.
I usually connect my computer or phone first, and then tune it to minimize the impact of other factors on the standing wave when transmitting.