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Re: Interference from PC?
Jim Sheldon
Art and all,
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You missed the point I was making - there are no birdies noted within the limited tuning range provided. This thing, as built will ONLY tune from 7.030 to 7.080. It was not designed as a complete receiver that covers the entire band. I'm absolutely certain there would be junk received outside of that range were it able to tune there. Plastic enclosure? What enclosure. Mine is operating on the desk as a bare, unshielded board. The only shielding involved is the coax to the antenna and the shielded audio cable from the I-Q output on the board to the Line input on the sound card. The enclosure is not supplied with this simple kit. If you want to put it in an altoids can or any other metallic enclosure, this is easily done, subject to whatever your imagination can devise. I'm merely stating that it OPERATES AS ADVERTISED by the designer. W0EB -----Original Message----- |
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Re: Interference from PC?
KY1K
OK, this person has experience, my views are different and contrary to this persons real life observations.
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Apparently there is no interference when operating the softrock-40 without shielding. Congrats to the designers of the softrock-40, they've managed to do something never before done in the history of receiver design. However, I've never seen a high quality receiver made available in a plastic enclosure.............. GL to all. Art At 12:47 PM 9/18/2005, you wrote:
I have my softrock 40 running. It's plugged into an external USB hub for --
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Re: Interference from PC?
Jim Sheldon
I have my softrock 40 running. It's plugged into an external USB hub for
power, and hooked up to my B & W broadband folded dipole. I can find no birdies within it's limited tuning range - 7.030 to 7.080 as specified in the AMQRP info. It is extremely sensitive, and copies signals within that range as well as my K2 does, and that's saying something. The K2 has by far the best receiver of any rig I've ever owned. All this talk about computer birdies and pc noise is pretty much unfounded. There is NO noise apparent with the scope on the DC voltage line coming from the USB port. The computer is a Dell Dimension 8100, Pentium IV @ 1.4GHz and even with the covers off, I still cannot find any birds attributable to the computer. I AM using just the bare-bones, unsupported SoundBlaster PCI sound card that's built into the Dell's motherboard. It performs adequately for the Soft Rock 40, but I would presume to say that if one had an SDR-1000, this card would definitely be struggling. My sampling rate is only 48 KHz, and it still does very well. Maybe this will allay some of the fears I see expressed here on the reflector. What the heck do you expect for $23 bucks a full blown SDR-1000? Jeez, lighten up and experiment with the thing! It works as advertised, and maybe even better considering the low end sound card I'm using. Jim - W0EB |
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Re: Interference from PC?
KY1K
I'm brand spankin' new to the group so didn't see the original thread.
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Expecting a sensitive receiver to operate just inches away from a wideband noise source is optimistic (IMHO). For best results, it needs shielding just like any other receiver and or transmitter does. Computer noise might not show up as clean carriers or be identifiable by tuning across the band. It appears as an elevated noise floor most of the time, which sounds like background noise. I'm sure many people have interference from their own computers and most don't even realize it's there because it sounds rather like normal atmospheric noise. For absolute best results, shield it. For casual listening on a crowded band, don't worry about it and run it as supplied. My softrock-40 is going on LF when I get it and it will be located away from the computer and shielded. Switching supplies, florescent lamps and computer interference is pretty severe at 190 kHz and I want to have good reception. I'm even considering magnetic shielding due to the nature of the interference at these frequencies. Regards, Art The supply from the USB connector is 5V. Are you using a separate power --
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Re: Interference from PC?
kb9yig
Hi Rein,
Actually I just plug my SoftRock into the USB socket on the front of my Dell 2400 machine. The little receiver plays quite nicely that way and others have had the same results with various computers. As I write this, I have a SoftRock playing on the same PC. Forty meters this morning at my QTH shows a flexuating base noise level of about -122 dBm and the peaks of the soundcard related spikes are visible to about -118 dBm. S5 signals are at about -110 dBm. Tuning around I find an S3 signal that is still good copy. I continue to be amazed at how well PowerSDR software and a simple receiver circuit work together to make a nice little receiver. 73, Tony KB9YIG --- In softrock40@..., "Rein A. Smit" <rein0zn@i...> wrote: Hi Tony,connector of thean USB cable connector?surprised to see an unshieldedetc just running off a TS 850 at leastIn fact it means that I will have toDelta44 sound card.the PC 135noise does not cause much of a problem. When the receiver is so.dBm with 10-15 dB spikes riding on the baseline every 1 kHz or soundcardAlso at the LO frequency, around 7.054-7.056 MHz there is a large builders ascontributes lots of noise near zero frequency. thethey finish their kits. If I can help with problems in getting wrote:little receive running, I would be happy to do so. -------Hi all, subject=Unsubscribe>YAHOO! GROUPS LINKS of -------Service <>. |
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Re: Interference from PC?
leon_heller
--- In softrock40@..., "Marsh Parker" <nc7v@e...> wrote:
--- In softrock40@..., "observer35" <rein0zn@i...> wrote:The supply from the USB connector is 5V. Are you using a separate powerHi all,Not me. Either with the SoftRock or my other rigs. supply? Leon |
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Re: Interference from PC?
Hi Tony,
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Thanks for your reply. From looking to the picture on one off the softrock pages I got the idea that the board was directly plugged into an USB connector of the computer. Looking more careful it seems the board is running from an USB cable connector? My question was more in general, not softrock specific. I was surprised to see an unshielded front-end that close to a PC I have been playing quite a bit with Linrad Spectran dspblaster etc just running off a TS 850 at least 30 ft from the PC and I get all kinds of stuff from the computer. In fact it means that I will have to put the computer in a second box with all inputs and outputs well decoupled I think. This is just monitoring basically antenna noise. I am expecting a board shortly and will let you know, using the Delta44 sound card. 73 Rein W6/PA0ZN kb9yig wrote: Hi Rein, |
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Re: Interference from PC?
kb9yig
Hi Rein,
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I have built about 25 of the v4.0 SoftRock40 receivers and find the PC noise does not cause much of a problem. When the receiver is calibrated to S9, (-73 dBM, 50 uV RMS), the baseline is around -135 dBm with 10-15 dB spikes riding on the baseline every 1 kHz or so. Also at the LO frequency, around 7.054-7.056 MHz there is a large broad spike associated with the LO and the fact that the soundcard contributes lots of noise near zero frequency. I will be quite interested in the experience of SoftRock40 builders as they finish their kits. If I can help with problems in getting the little receive running, I would be happy to do so. 73, Tony KB9YIG --- In softrock40@..., "observer35" <rein0zn@i...> wrote:
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Re: Interference from PC?
Marsh Parker
--- In softrock40@..., "observer35" <rein0zn@i...> wrote:
Hi all,Not me. Either with the SoftRock or my other rigs. I elected to put a 78L05 in place of Q1 so I can't comment on that. Marsh, NC7V
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Using a DDS card to Drive the SoftRock-40
Marsh Parker
I read Bill, KD5TFD'S comments in the AMQRP Future directions. I
wanted to do something similar. Be careful of the reference designators! They are from a previous version of the PCB/schematic and some have changed. His R18 (from version 3.1) is now R2 which is the LED current limiting resistor. I left it in. I put my 12v input header in place of R1. C2 is shorted to gnd. R1 is the same, but replaced by the input voltage header.. C8 is the same. His R2 is now R3, 5volts to Q2. I haven't finished my soft rock yet. Spent too much time on my L1 gnd short. Marsh, NC7V |
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Antenna input grounded
Marsh Parker
I just received my kit yesterday.
I found that the L1 lead, not the body which goes to gnd, was shorted to the gnd plane on the bottom side of the board. I used an xacto knife to cut the bridge. This was not a solder bridge. I did not use that pad for fear of a solder bridge to gnd. I used the antenna pad instead. Check with an ohm meter before installing L1, the larger pad (antenna input) just above the silk screen that says C21 for no continuity to gnd. I had several wrong installs of the thru hole parts because I was not careful to pay good attention to the silk screen and the small oriention line between the body of the resistor and it's other lead. Good luck, Marsh, NC7V |
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