Hum on transmitted signal

Al Matthews

I received my 6600 M today, and got right to familiarizing myself with it. I made a few quick contacts and I was told that there was hum on the signal. I looked at it on two other transceivers and on both panadapters you could see the hum superimposed on the signal the hum is there in CW, tune, and SSB. I tried a different power supply, all of them Astron linear supplies, and the issue persisted. I even put a scope on the output of the power supply to look for ripple and there was Virtually none. Could this be something about the SDR architecture and the 6600 that I’m not familiar with? Any help would be appreciated I also have a screen issue, and I wonder if this is something that others have observed. In the upper left hand corner of the screen there is a light area, what you might see if you put you finger on an lcd screen. It is there all the time. There is no such abberation on the Maestro I bought to go with the 6600m.

mikeatthebeach .

Not normal.... Have 6600M here and No Screen/No Hum issues 
Try a 50ohm dummy load --- Is it RF getting into DC Lines - etc
Might suspect RF getting into it on Transmit - Ferrite Cores can fix that ! 

Regarding the screen issue - attach a jpeg so we can see it to comment 

73 Mike

Burt Fisher

You have the same name as K1LTJ who I knew as a kid 58 years ago and look like him. I have a Flex 6400M. I think we are the only two still alive and active from that group from Norwalk area.

mikeatthebeach .

Al, 
 
Also if you have the Astron Linear Supply too close to the Flex
perhaps the AC Field of the transformer is causing issues with
the 6600M with an AC Field from the transformer induced Hum

If you have a DC Battery in lieu of the AC supply that would eliminate
that factor as an issue of the hum 

Mike

Bill -VA3WTB

Al, start by disconnecting things from the radio one at a time and use tune button to transmit. Something connect to the radio causing a ground issue.

Al Matthews

We're still alive?

Al Matthews

Hi Mike, I am using an Astron VS-50m linear supply. It is about 10 ft. from the 6600m. I tried the Astron 50 amp switcher that I also have. No difference.

Al Matthews

Good point Bill. I unplugged everything but the ethernet and power connector. (obviously). I then unplugged the ethernet cable, no change. I am running 1 watt into a dummy load.

Al Matthews

Here are the pix and a short video of the problems. I have also included a video so you can see and hear the problem. I do appreciate the help and suggestions. Any more ideas on what I might try? 

Al / K1LTJ

https://www.youtube.com/watch?v=efWKEKzp2Ak

Here is the picture of the light area that never goes away in the upper left corner of the screen. There seems to be some of this a the bottom center as well.

Burt Fisher

Great video, disconnect the ethernet the M can run without it. It shouldn't help but there is no logical reason for your problem so try illogical solutions. Mike said to try a  "DC battery" I think all batteries are DC but his suggestion is good.

mikeatthebeach .

Al,
 
Saw your video, if you get AC buzz with a Battery you should contact help desk

Also, the white Flare Up in the Upper Right of the screen most likely
will not show when SSDR is running. I suspect it is because of more
pressure in that corner due to mounting or shifting of the Touch Screen

Mine has a slight White Flare-Up in that area, but not seen when Display is active
or Booting Up. ( White Flare-Up in left upper Corner is on mine as well ).
Some may be more noticeable than others is my guess 

Possibly during shipping this can be aggravated, my guess this can be
fixed by a mechanical readjustment by Flex if you sent it back to fix the Hum
Issue

Maybe a ribbon Cable ground got loose during shipping to cause your Hum Issue
( Try with a DC Battery ). If your 6600 goes back, both Issues can be addressed
with a Help Ticket to Flex.

73 Mike

N4QM

Does the buzz change character or level if you raise or lower the touchscreen backlight illumination?

Wayne

Looks like at the factory either the touch screen or the backlight were mounted slightly off the correct position then missed during the qc process before it was shipped. You need to open a helpdesk ticket to get an rma and maybe while its there they will verify if the hum you are hearing is due to the rig or your shack environment. Be sure to describe to them exactly how to observe the white you are seeing or they may miss it when they try to make it repeat.

K3SF

a 10ft long DC power cable...seems like a perfect place to pickup RF and to have a very large voltage drop....

the flex input voltage is critical.

There are some s/w utilities to measure the input voltage...

see thread
https://community.flexradio.com/flexradio/topics/voltage-drops-chart

https://community.flexradio.com/flexradio/topics/flex-meter-v1-2

http://k5fr.com/DDUtilV3wiki/index.php?title=Main_Page

these s/w tools will measure the voltage inside the radio

Paul K3SF

Bill -VA3WTB

What is you DC power at the power connector on the Flex while in transmit at a 100w

Bill -VA3WTB

Al, I don't think you are going to get any further here, I would open a help ticket tonight.

Ken - NM9P

Try it by transmitting into the XVTR port to rule out any internal RF leakage as well.

Ken - NM9P

You may want to do a factory reset, as per the manual, and see if perhaps the processors glitched when booting up and something got set incorrectly.

Al Matthews

Bill, I removed everything one at a time, but the hum is still there

Al Matthews

Ken, I tried the xvtr port, but no change the hum is still there. I did a factory reset, but no change. The manual says to hold the power button from the off state until it blinks white. It turned white, but never blinked. I also tried downgrading the software without a change.

Al Matthews

I changed the touchscreen illumination Dennis, but it had no effect.

Bill -VA3WTB

Did you put in your help ticket yet,,time is wasting.

Al Matthews

Yes, I put one in Bill, so I hope to hear from them. I’m not sure if I’m ok with repairing a 5hr old $6000 (with gpsdo etc) Radio. This must be unusual, I have never bought a DOA transceiver in 59 yrs as a ham.

Al Matthews

And thanks for all the help everyone has offered. This is a great group.

Al Matthews

This is a great group of helpful people, with some great ideas on things to try. Thanks to all of you.

N8SDR

Al,  have you disconnected the Ethernet cable and tried as well ( didn't see that mentioned) , I'm curious as I have seen some routers and switches which are noisy and i wonder if that is getting into the radio via the cable. If it does away try another cable if its the newer style with the metal grounding around the connector try one without it a standard type 5 will suffice. If it also drops and reappears with another cable then start looking  down the line at the devices which are plugged into the router and or switches including other computers and such. Some of it comes into the network system via the cheap non filtered power adapters they use. Ground loops between the network devices can also cause issues.

Al Matthews

Thanks for the suggestion. Yes, I tested with only the power and dummy load connected. The problem was not affected by removing the Ethernet connection.

Burt Fisher

How about a battery?

Terry AB2UE

Try plugging astron power supply into a 3 to 2 prong adaptor as a test to see if hum goes away.

Burt Fisher

Did you ever fix it?

Al Matthews

Yes Burt, Tim has been a great help. It is an intermittent problem, and they will look into it for me. The support with Flex is great.