Hi Stefan see my comments below appended

 

 

Hello Jim,

Thanks for the interesting read of your station :-)

Am 25.09.2016 09:11, schrieb James Cowburn:

PC is a Dell Studio 1749  running WSPR 2.12.

I can really recommend the use of the new WSJT-X v1.7.0 software which includes WSPR-2. At least for reception it improves things.     I'll give that a try! Thanks.  Also are you okay if I share the excellent spreadsheet you sent me some years ago?  It's really useful
 

It does have a tendency to fight with our cheap home broadband router supplied by British Telecom, resulting in the "Orange Light of Death" and subsequent grief from XYL and 2 teenagers as their Netflix/Music stream/Online gaming has just fallen over!    Ferrite toroids have been spectacularly unsuccessful in remedying this.  The best solution has been to try to run the CAT5 cables in my office as perpendicular to the coax feed and line of roof top wire as possible to minimise pick up and cross talk, but this hasn't really been that effective either.

What about WLAN / wifi?    The Wifi is okay, it's the cheaply built BT router that is poorly shielded and so picks up my 472khz signals through it's paper thin plastic casing (prob because it has internal antennae) and this plays havoc with the broadband signals which are in the MF band and superimposed onto the phone line.  I need a better shielded router with external wifi antennae

 

A bigger issue on Rx is the noise  pick up from both Dell (genuine kit and  not cheap copies either, which is annoying!) PSUs that feed the Studio and the XPS17 which is my main office PC. On batteries, I get about S1-3 of noise which is very good, but as soon as the PSU's are used and are under "load" then this rockets up to S7-9!  If they are powered on, but not driving the laptops i.e. disconnected, then they have no impact.    I'm wondering if it is the load that makes them noisier or whether the whole laptop acts as an augmented antenna when they are connected to it?

Does the QRM become lower when disconnecting the CAT5 / LAN cable? Some years ago i observed some common mode QRM just by a notebook, its supply and a connected LAN cable. If you take use WLAN instead, you may have lower QRM and also do not disturb the LAN traffic.   Interesting!!  J   I will give that a try later.  My XYL has demanded I go to a local charity event this afternoon so no radio until 5pm!!!

I've tried putting them in shielded earthed metal boxes (biscuit tins!) with no effect. (biscuits were nice though!).  Similarly, stacked ferrite toroids on the mains inputs and DC power out have had zero impact.  They both have a very bright blue LED on the power cable whereas older units for my Dell D610/20 series did not have this "bauble" and were much quieter, but also were lower rated at 60W or 90W as opposed to these beasts which are around 120W to 150W, and run alarmingly warm at times!

If it is no common mode problem with the LAN cable i would try to switch a pi-network in front of the power supply, on the 230V side. 2x 1 uF (e.g. WIMA MP3-X2 250VAC) and then a iron powder choke (e.g. T106-26) with many turns of 0.5mm cu wire, two windings, "anti-parallel".   I actusally have a very good quality old mains supply filter unit built like this, I'll dig that out and try it.   I'd assumed it was just the smpsu part radiating through the plastic casing and undoubtedly having no filtering applied at the 19.5 output so the power lead to the laptop acts as a great antenna!!   The PSUs are sealed and I don't want to open it if I can avoid it.

 

73s!!   Jim   G7NKS   IO92ub 

73, Stefan