FT-991 COM port issue

[VK7HH]

Hi All,
My FT-991 has recently developed a COM port issue. When plugging in the USB cable to a PC the COM ports no longer show (Standard and Enhanced).
The USB audio still shows up correctly.

I've uninstalled/reinstalled the relevant drivers, rebooted the PC, tried a 2nd PC and even did a full reset of the radio. So scratching my head why it's not working all of a sudden. Has anyone got any ideas on how to fix this peculiar issue. Up until today it had been working fine.

[ZL3RC]

Hi Hayden.
Ive been have a problem lately with the USB port on my FT-991 and I think Ive fixed the problem.
While its a little different to your problem maybe the same fix will work for you too.
What I was experiencing was the momentary dropping of the control "CAT" interface and the audio was doing the same. This looked to be independent as I would loose audio but not CAT control and other times loose CAT and not audio.
Mark ZL3TKI loaned me a USB isolator and problem solved. I would get about 10 to 20 mins then loose USB but today with the isolator inline the 991 has been sitting on 40m FT8 all afternoon with out a problem.

This is the isolator Im using and it may be worth a try.

https://www.aliexpress.com/item/USB-To- ... st=ae803_5

Not a nice URL so remove any spaces and line returns if you see any. All else fails search USB isolator on aliexpress, your find heaps of them.

Cheers
Roger

[VK7HH]

Hi Hayden.
Ive been have a problem lately with the USB port on my FT-991 and I think Ive fixed the problem.
While its a little different to your problem maybe the same fix will work for you too.

Thanks for the reply Roger.
I posted off the radio to get repaired under warranty as there was also an SWR meter fault. They will also check for the USB fault at the same time. Glad you got yours sorted.

Regards
Hayden

[IZ3TJC]

Hi Hayden, i have exactly the same issue on my ft 991 , usb audio working fine but no virtual com .
Plese may i know what was the exact issue ?
Many thanks in advance.

IZ3TJC Pietro