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While the Testers are testing... 03 Nov 2021 19:57 #1

  • Tom_G0JSV
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OK, this is not a topic for any MB1 owners out there but for everybody else, where do you locate your ExpertSDR radio?

For me, the greatest source of noise was probably going to be the house and all the electronics within so I decided to locate the radio as far away as possible. But still within reach.

Luckily space was available so a waterproof cabinet was installed in the garden. The cabinet was supplied with 13.8v (in the end, 3 runs of 25A cable were needed to keep the voltage near to 13.8 when loaded. Approx. 40M run). 3 * Cat 5e runs were also supplied to the cab. (This was about 6 years ago when Cat 5e was all in vogue!!)

Initially I had an Anan 10e in the cab but about 4 years ago that radio was replaced with the SunPro2 SDR.

All Co-ax runs are relatively short (< 30 M) so RG-213 is used.

1 dedicated 2M vertical.

Then 3 HF aerials available. 1 * Full Windom Carolina. 1 * 13.5M Vert. 1 * 160/80M multiband di-pole. (Only 2 of the 3 can be used of course).

Pictures below.

Would love to hear your stories.


Tom G0JSV
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While the Testers are testing... 03 Nov 2021 20:09 #2

  • e72x
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Hi Tom,
What GPSDO unit are you using?

73,
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While the Testers are testing... 03 Nov 2021 20:41 #3

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???? I will have to remind myself by checking receipts from about 5-6 years ago. I don't think there are any markings on the unit itself but will check in the morning. But it works very well. (I did need to put a 6db attenuator in-line for best results)
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While the Testers are testing... 04 Nov 2021 22:06 #4

Appears the df9np, I have this for my IC-9700
www.df9np.de/page3.html
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While the Testers are testing... 05 Nov 2021 09:03 #5

  • Tom_G0JSV
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Finally tracked down the maker of the GPSDO that I showed in the original picture. This unit was supplied by Dieter Leupold DF9NP. A Google search will take you to his website. I bought the unit in 2015 and it has worked perfectly since then.

P1.jpg
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While the Testers are testing... 05 Nov 2021 11:21 #6

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Clear now...thanks!

73,
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While the Testers are testing... 05 Nov 2021 13:33 #7

  • VK6NX
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In my different AU QTHs for last years the main noise source are cheap solar converters in every second house (thanks to common only-green-energy-stupidity), outdoor pools motors / garden watering pump motors and absolutely zero noise protection on common 220VAC (when practically any cheap electric saw or drill plugged in 2 km away gives you fantastic time on RCV). The only way to make it work - filters, more filters, even more filters and magnetic loop on A2). This is also the main reason why I love IOTA activations :)

But there is something else. Power Supply of 13.8/15VDC (whatever needed for your device). In my experience half++ of the noise root causes are sourced from PS. I am bumping into EE doors already for some time :), trying to deliver a message that it would be very-very much appreciated if company-made power supply will appear in the store.
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While the Testers are testing... 05 Nov 2021 15:45 #8

  • F1DJY
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My experience concerning noise ... Switching power supplies are the first cause for me, those of the Shack !!, the others are insignificant. so I use a maximum of analog power supplies. I also have problems with the power supplies of the neighbors, mainly with the inverters of the photovoltaic collectors. I put ferrites on all the inputs of the SunSdr2. The PC is a fully shielded fanless Mini-PC; I had problems with vertical lines on the spectrum coming from screens (Dell) no problem with 4K Phillips screen, an Imac and an HD cinema screen shielded by nature. But what helped me the most was an earth connection made at the foot of the station with 15m of 50cm buried cable and 6 metal stakes of 1.5m inserted vertically connected to the cable. A large earth cable goes down from the beam in front of the schack window to the earth socket; all coaxial cables enter the station at this point and have their sheath connected to the earth cable. The electrical earth of the house arrives at the same place. This allowed me to eliminate the rest of the noise generated at the QRA, solved the problem of RFI in transmission and secure the installation against lightning.
73 Jean-Marie
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While the Testers are testing... 05 Nov 2021 17:52 #9

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The power supply feeding the SunPro2 is a linear PSU. QJ18030. I did originally have a switching PSU but changed mainly because I needed a variable voltage. The voltage drop is quite significant over the approx. 40M cable run. In the end, all three runs of the 25 amp 12v automotive cables where used in parallel to keep the voltage drop to a minimum when TXing. The PSU is set to 14.5v but I might need to increase that. I do have a spare car battery around here somewhere and will do a test over the weekend to see if this helps in reducing the background noise floor. I live in a rural area on the edge of a very small village. 25 or so houses. But there is a local pub/inn and one of the main sources of noise is a kitchen fan that comes on in the morning and goes off at 10pm. It wipes out 160 and 80M.
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While the Testers are testing... 07 Nov 2021 04:02 #10

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I have QJE (model QJ-1830SC, 30A) successfully dead a week later after using it with DX on full 100W CW. This was 5-6 years old PS, however I doubt there are any significant changes in its schematics for newer models.

Current replacement is QJE 30A PS30SWIV 4th gen - this one still working (6 month for now).

Main found problem with those "OJE" - you never know whats inside. Kind of gambling up until you open it after arrival and measure all parameters to see whether something need to be replaced. To be honest, my requirements for PS are a bit over "common", 'cause I target them for field operations (primary).
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