Constant Background Noise with FLEX-1500 and PowerSDR

Moose

I have a constant noise on all frequencies when using my FLEX-1500 with PowerSDR. The only way I can describe the noise is that it is like a jet engine at a constant speed in the distance. Not so much of a roar but a noise like steady high wind or water leaving a hose under high pressure. In the presence of strong signals I can get it to go away by reducing the AGC-T. With weak signals however I can't reduce the gain enough to make it go away. 
73,
Chris AK4SK

Jeffrey Gray

Had an issue similar to that. To get rid of it I had to put ferrite clips at end of the USB cable close to computer. Put ferrite clips on both ends of powerline, Noise is creeping in from unshielded line. Also put clips on monitor cable and power supply for it. A lot off the flat screen monitors use a switching supply. Switching supplies are notorious for generating noise.

Moose

Thanks for the reply. I'm using a laptop so I should be able to just unplug it and isolate it from any noise that could be coming from a power supply. I have some ferrites also so I'll try that as well.

John

My guess is the psu. But with a influx of undesirable goodies from china and elsewhere, it may be a good idea to get a good quality usb cable and a good non switching psu

Walt - KZ1F

Hey John, I have a question. When I ordered my 6000 I bought a 1500 and a PS large enough to run the 6000. FRS sold me an Astron SS-20, might be a 25, but I think it is a 20. I thought Astron made fantastic power supplies, right? When it comes to unswitched vs switched, is the Astron just 'another' switched ps?

K2CM

I had a similar problem this past week.  Traced the problem to a wallwart power supply that I was using in the shack.  Removed the supply, powered everything off the F6700's power supply, solved the problem.

Moose

I installed ferrites on the USB cable and completely unplugged the laptop, the noise is still there. I have one other power supply and that's the linear supply for the shack. I've had RFI issues before from power supplies and other devices but they've never been on all bands and that don't sound like this. I also use a USB sound card and I don't have this issue with it.
73,
Chris AK4SK

John

Best is to open it up and look for a big transformer. If it got one then its not switch mode, but having said that from the comments here http://www.eham.net/reviews/detail/1871
Place some clip on ferrite cores over the psu cables where it leaves the box and see if that cures it. It could be a rogue unit.

John

what other equipment have you got around it ? Try another laptop or connect it to a normal computer and see if that cures it ? Get a car battery and run it off that, to see if the noise is coming in via the mains or put some ferrite clip on cores on the psu mains cable. Its a matter of checking everything on your side first. You could even take it to a friends house and try it there. what happens when you disconnect the antenna ?

Richard McClelland, AA5S

I own a Flex 1500 and I experienced a similar issue; i.e., rather loud audio noise/hissing.  I thought that perhaps my particular 1500 had a manufacturing defect so I bought a second one but it also displayed similar noise.  I spoke with Graham at Flex Radio regarding this and it seems that this audio noise is endemic to the design.  I largely mitigated the noise by switching headphones from a very sensitive Ultrasonne set to a Bose headphone with the sensitivity setting switched from the default Hi setting to the Lo setting.  Also, for powered speakers, routing the audio through a headphone amplifier enables the ability to adjust gain levels lower to mitigate some of the noise.  Here is a link to the headphone amplifier that I use:  http://www.amazon.com/gp/product/B0002I9S12/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

Moose

I have only had the FLEX-1500 for less than a week. Since day 1 I've had this noise issue. The only stuff I have near it is the rest of my shack equipment. I have two transceivers (three counting the FLEX-1500), an LDG tuner, and a Timewave TNC/external sound card. It all runs off of the linear power supply and I have never had any noise issue related to anything in my shack. I have had noise issues around the house but they affected all equipment not just one and they don't sound anything like this. My main transceiver is whisper quiet. This noise is constant on all bands and all modes. It is there even with the antenna unplugged except I have to increase the AGC-T to hear it once the antenna is unplugged. I don't have a battery available nor do I have another computer or another place I can take it to try it. 

Moose

The noise I'm hearing isn't hissing so much, almost a low roar. A background hiss or static, as I'm used to with regular transceivers would be fine. If it is an issue with the design then so be it, but the FLEX-1500 is supposed to be one of the best receivers on the market. It may still pull out weaker signals, but my Yaesu FTDX-1200 is much more pleasant to listen to.

I turned in a help desk ticket, we'll see what happens. I was hoping it was some USB setting or issue with my computer but none of the replies have even suggested that so far.

Thanks for all of the replies.

73,
Chris AK4SK

John

It seems like it may be just how the transceiver is judging by your last comments, so it might be just the way it is or an adjustment in the menu. If you email me, I will send you my config file which you can load in and see if theat helps. Did you run the audio setup for transmit mode? The steps are listed on the flex 1500 pages somewhere.

Moose

I'm pretty sure I've followed all the set up steps in the manual but I'll review it to double check.

John

can you send me a message and I will reply to it with my config file and see if that helps you

George KF2T

For Walt, I have had both switched and unswitched Astrons. They are both pretty good. I did settle on the linear version because I was getting obsessed with cutting any noise sources out. I did find that BOTH could be improved by getting into the chassis with a Dremel and removing the paint at adjoining surfaces and where grounding lugs were installed. Crazy to have a painted surface where shielding and grounding is important! My RS-35 is as quiet as a battery. 

Moose

I appreciate the offer. I've been working with FlexRadio customer service. Let me see where that goes before I start changing things, I don't want to change too many things at once.

Moose

With the help of FlexRadio support the source of the noise I was hearing was identified as the NR feature. With it off the noise goes away.