6600M: USB cable disables itself randomly

Holger Hannemann

I use the C232HM-EDHSL-0 cable without any USB  hub in the middle to control band switching devices for filters/antennas. The 6600M randomly disables the USB cable when transmitting resulting in undefined status of switches, no antenna connected etc. It happened on multiple bands and already caused relays to weld in one of the 2 x 6 switches since a 500 W amp was involved. Thanks god the amp survived. 

To correct it I need to disable and enable again the USB cable in the flex menu. The cable is still shown as enabled even so it doesn't work. The Flex-6600M and the mentioned USB cable are the only new components in the shack. All other switching hardware and amplifiers were in use before for a few years.

Anyone else with similar experience and any advice?

thanks in advance
Holger, ZL3IO

Steve K9ZW

Stations find the USB connection robust and steady. Sounds like signals are spanking some part of the USB connection. Perhaps try some additional TX RFI protection (toroids)? 73 Steve K9ZW Blog: http://k9zw.wordpress.com

DL4RCE

Hi Holger, experienced similar problems and it was because of RFI. There are several ways to counteract RFI in your shack, try searching the forum for it. It can be as simple to wind the USB cable around a ferrite core.

73, Volker, DL4RCE

Mike-VA3MW

Hi Holger

You have some good ideas above.  One other idea would be a new USB/RS232 FTDI cable.  It might have a hardware issue.

Mike

Mike NN9DD

Agreed not all usb connectors are created equal. FTDI chip for sure is a must Mike NN9DD

Mike-VA3MW

Flex only supports FTDI chipsets.  No other chipset will function for those devices connected directly to the back of the radio.

Warren-K6WKW

Holger, I use a 500W amp too and haven't had any such problem. I'd agree that either your chip in the USB cable has a H/W problem or RF is getting into it - or perhaps both. My shack is on the 2nd story so relatively un-grounded, but I use a remote antenna tuner so the SWR appears fairly low and I don't seem to have RF in the shack. You might check that you have an ED and not a DDHSL cable (3.3 vs. 5V cables).
Warren - K6WKW

Holger Hannemann

Thanks all for your feedback. As I wrote in my initial post the USB cable is the C232HM-EDHSL-0 with FTDI chip and came delivered together with the radio from FLEX.

All other hardware like BCD-decimal decoder, amplifier, cables etc. up to the antenna switching hardware is/was in use for over 5 years here now without any RF problems so far.

I will add some more ferrites to the USB cable. I'm not sure if the FDTI chip is the trouble maker or the Flex USB output but it needs a disable/enable action at the FLEX radio to get it working again. 

As a result 20 & 40 m relays plus the 50 Ohm antenna terminations in one of the 2 x 6 antenna switches are damaged now. It's not a fun job to replace those.

73 Holger

Holger Hannemann

Hi again,
I'd like to close off this topic. I found the bad guy in the equation. It was a short USB extension cable without proper shielding. After taking this out I wasn't able to reproduce the BCD signal loss while transmitting. Preventative some ferrites were added to the cable anyhow.

thanks for the input &
73 Holger, ZL3IO

DL4RCE

Hi Holger, very good! I now remember that I had similar problems. Hope that system stays stable.

Regards

Volker