Optiplex GX620 - Dedicated SDR + SAT

[Channel Hopper]

Interestingly ...I pulled the SDR play unit out of the pc and let it hang just outside the PC ..and the RFi was still present..
BUT bringing the USB cable out of the PC caused the RFi to reduce by about 90% ...so to me this is where the majority of noise is getting in ..
Hmm ...perhaps I can buy of make up a shorter screen usb A B cable ..
..as I think this would solve most of the issues..
Does such a thing already exist ?
If you spot one let me know..
rgds
VS

Try wrapping the PSU outgoing delivery cables in foil/clingfilm).

 

[Analoguesat]

Where does the two ends of the usb go? Ive lost track. One end is the ali tape shielded box isnt it?

 

[Vipersan]

Where does the two ends of the usb go? Ive lost track. One end is the ali tape shielded box isnt it?

The SDR play draws its power and transfers data via USB so apart from Antenna in this is the only connection..
USB (B ) at the SDR ..and USB (A) to the PC ...
..and it is on this cable that the RFi is being picked up radiated from the mobo ..
Thus if this cable was shorter and was screened with a braid that was earthed I suspect most of the RFi would vanish..
This cable would normally be outside the PC ..but is inside the case by neccessity now.
rgds
VS

..fully shielded USB cables are available but are rare for short A/B cables..
Manufacturers appear to think it unneccessary for short leads of about 0.5 m..
Long cable runs are easily available ..
The longer the run ..the better and more important the shielding it would seem.

 

[Vipersan]

S0 ..this is what I need but not at that price ..
Eeeek ..
It doesn't need to be silver..
lol
0.5m 8 Core Pure Silver USB A - B Interconnect Fully Shielded

 

[Vipersan]

guess I could make my own ..
took me a while to find these :-
5pcs Connector USB-B B type USB 2.0 male plug white Metal Shell solder for cable

Hot 10pcs Type A Male USB 4 Pin Plug Socket Connector With Black Plastic Cover

And for the cable ..
well not so easy to find ...so why not buy one of these and cut to length..
5M USB Active Repeater Cable Extension Lead for Computer Plug Socket Extender
one of the cable ends already made up for me ..
So would only have to fit the B end..
For every problem there IS a solution ..
you just got to find it..
lol

 

[Vipersan]

I can test the effectiveness of a screen A-B cable this evening having just got back my TL866 usb programmer ...as this came with just such a cable ..
Bit on long side at 2m ...but should allow me to test the theory..
It is fully braided and screened however..
My friend was loathe to return the programmer but he'd had it long enough anyway ..
lol

 

[Vipersan]

So what have I discovered ..
Well .. a ) in an ideal world a die cast box would be beneficial ..but since there are no commercial boxes even close to the physical size I need ..
2 layers of aluminium tape is a good compromise ..with a single earth wire which can be floated from those layers to various points including the hard drive case and taped down ..
b )Letting the aluminium tape 'boxed' SDRplay float and not taped to the outer metal shell of the PC is good ..
You'll see from the photo this is packed to float >> away from the PC casing..
c ) the shorter the usb cable the better ...a long cable can pick up stray RFi ...regardless of screening..
Ideal is about 50cm..
The cable has to be routed out of the case (sadly) to connect the SDRplay to a usb port..
I would have prefered an internal connection but this is not possible with this Dell.
d) ferrite clip around chokes are on order ..but have not yet arrived ..
These will clip onto and around the usb cable to hopefull further reduce RFi ...and I will be trying a homebrew screened A-B cable when the bits arrive.
In the meantime I have a non screened ...non ferrite 50cm standard cable in place ...
this you can also see on one of the photos..

Suffice to say they improvements on the FM radio band are substantial.
I have yet to try other bands...
Obviously using a localised stub antenna I _will_ pick up localised RFi ...but I'd say this is manageable..atm
Here are some photos ..
Showing the RFi bands at regular intervals before any of the above changes were made ...without antenna
...with antenna ..
Later photos of this same band with the RFi mostly managed ...again with Antenna and also without..
I think you'll agree this is not half bad ..
rgds
VS

 

[Analoguesat]

It wont help here as you have run out of expansion ports but many pci cards with usb connections on the back plane have an internal usb connection as well as the extra ones on the back.

 

[Vipersan]

Just gotta hope the CPU is fast enough ..
Not sure what the max is in the DELL ...but I shall no doubt want to max it out along with the memory ..
This is as far as I've got tonight and I'm ready to chill for a bit ..
I'm knackered ..
Progress was made though..
This PC/Radio/Satellite Combo has not and will not have internet access ..so all files are input by USB stick.
So far I have a working Crazyscan ...HDSDR..and VLC installed ..
Tomorrow I shall install SharpSDR.
Oh ...and a bigger monitor is needed I think.
My old eyes dont like that 17 inch 4:3
lol
rgds
VS

 

[Archive-8]

Just come across this jitter bug JitterBug

It's for filtering the emi & efi from the PC so you can send a cleaner signal to hi fi dac's

 

[smoggy07]

View attachment 91713
The cable has to be routed out of the case (sadly) to connect the SDRplay to a usb port..
I would have prefered an internal connection but this is not possible with this Dell.

Is there not 2 USB ports on the front? these should connect to the motherboard via a cable near to the where the power button cable goes, on the motherboard in the smallest of print it should say PWR RST USB or letters to that effect next to the pins

If you can live without USB on the front but don't want to damage the PC (and also don't mind loosing USB from the front) I have a spare USB unit and if it's any good to you it's yours

 

[Vipersan]

Thought about doing just that ...but sadly the Dellsff uses a propietory long ribbon style connector for everything at the front .
power button ...through leds ..headphone jack to usb ..all in one ..and nothing labelled ...so not easy ..at the mobo end ..and Id have to hack into the connections at the pc front ports from the rear ...so just not worth the risk imo.
rgds

 

[Vipersan]

Now for the first big disappointment ..
The Internal chipset ..although I belive capable is no able to produce widescreen video from the vga port..nor can it produce a high resolution ..
Simply not a selectable option ..thus I'm sort of stuck with 1360 x 768 4:3 ...
presumable WS monitors were not an option at the time this PC was created ..
Dell now do widescreen moinitors ..but never implemented a bios upgrade for the GX620 to allow their use..
Damned frustrating as the only way to get ws hi res is with an X16 pcie low profile graphics card ....but I'm using the slot for the TBS card..
doh!

 

[Analoguesat]

You can get usb - video adapters VS, not sure what the maximum resolutions on them are but one of the stations at work has one hanging off the back to give the staff member a third monitor. I think that one was about 30 quid a couple of years ago.

 

[Vipersan]

You can get usb - video adapters VS, not sure what the maximum resolutions on them are but one of the stations at work has one hanging off the back to give the staff member a third monitor. I think that one was about 30 quid a couple of years ago.

A very useful bit of info AS thanks ..

 

[Analoguesat]

One on ebay goes up to 1920*1080 if the monitor supports it

http://www.ebay.co.uk/itm/Super-Speed-USB-3-0-to-VGA-Video-Graphic-Multi-Display-Cable-Adapter-For-Win-7-8-/141754977428

assorted other ones are also available

 

[Vipersan]

Started the install of SDR# and all ascociated bits n bobs ..
So will get wxtoimg working fist as a test ...
You remember I said no internet connection for this PC ..well I just realised there has to be at least minimal connection to allow TLEs to update in Orbitron etc..
Dammit ..another problem to solve as there is no easily accessible CAT where the Optiplex is located..
doh!

 

[aceb]

USB WIFI dongle, all my PCs here use them primarily to keep the noise down. Might be an issue if you intend moving large files about for typical browsing levels of traffic. Ditto 2.4G keyboards and mice plus the USB3 socket cases have been soldered to the rear plate, that helped remove the final bits of EMI from my system. Oh, and getting 4 PSUs on appro from Maplin so I could chose the RF quietest one, everything else is ferrited and coiled.

Trying to find a quality shielded USB cable seems to be pot luck, I tried a few with varying results but have seen one that appeared to have a ferrite choke at one end that once cut apart turned out to be nothing but a lump of plastic! Too much cheap chinese shite about these days.

 

[Vipersan]

USB WIFI dongle, all my PCs here use them primarily to keep the noise down. Might be an issue if you intend moving large files about for typical browsing levels of traffic. Ditto 2.4G keyboards and mice plus the USB3 socket cases have been soldered to the rear plate, that helped remove the final bits of EMI from my system. Oh, and getting 4 PSUs on appro from Maplin so I could chose the RF quietest one, everything else is ferrited and coiled.

Trying to find a quality shielded USB cable seems to be pot luck, I tried a few with varying results but have seen one that appeared to have a ferrite choke at one end that once cut apart turned out to be nothing but a lump of plastic! Too much cheap chinese shite about these days.

Agreed aboute the shyte Paul...
As to the ferrite chokes ..like you I dont trust them to be fitted ...so prefer to fit my own ..which is why I ordered the cable clamp ones you fit yourself.

I just found a Digitazz 300mbs usb dongle in my junk box ..but can't seem to find drivers for it ...
anyone ?
Sows up as 802.11 n when plugged in ..
Sadly win7 doesn't recognise or install it automatically..
Has anyone got suitable drivers ?
I tried looking on the net but keep running into malware ..embeded crap ...and not the actual drivers ..
doh!

 

[Channel Hopper]

Agreed aboute the shyte Paul...
As to the ferrite chokes ..like you I dont trust them to be fitted ...so prefer to fit my own ..which is why I ordered the cable clamp ones you fit yourself.

My stock comes from dismantling old ATX power supplies.