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by g1hbe
Fri Jun 30, 2017 10:56 pm
Forum: SDR Antennas
Topic: Bias T and active mini-whip
Replies: 15
Views: 6463

Re: Bias T and active mini-whip

I've noticed something odd about the bias T. If I have had it ON and then shut down the receiver, when I start up again it says the bias T is still powered but it is not. To make it work I have to turn the T off then on again.
by g1hbe
Fri Jun 30, 2017 8:14 am
Forum: SDRplay related
Topic: RSP2 LO 3rd harmonic spurious response only -20dBC
Replies: 17
Views: 7293

Re: RSP2 LO 3rd harmonic spurious response only -20dBC

Jukka - if you want to use off-the-shelf filters, you will need to transform to 50 ohms on the input side and then back up to 1k to feed the RSP. Not ideal. A better solution would be to download an RF package (something like RFSim99) and use it to design your own filter for a 1000 ohm system. All y...
by g1hbe
Thu Jun 29, 2017 9:20 pm
Forum: SDRplay related
Topic: RSP2 LO 3rd harmonic spurious response only -20dBC
Replies: 17
Views: 7293

Re: RSP2 LO 3rd harmonic spurious response only -20dBC

Yes but then the waterfall/spectrum display would not show up to 10 MHz wide! You can't have it both ways, this is the problem.
by g1hbe
Thu Jun 29, 2017 7:35 pm
Forum: General
Topic: Computer specification suggestions?
Replies: 3
Views: 2214

Re: Computer specification suggestions?

If you really need to see 10 MHz at a time, then you are certainly going to need a bit of horsepower. For general listening around, I find a couple of MHz (or less) of BW is enough, and my laptop i3 @ 2.4 GHz (with 4 Gigs of ram and onboard graphics) copes well. It actually works flawlessly up to ab...
by g1hbe
Thu Jun 29, 2017 7:13 pm
Forum: SDRplay related
Topic: RSP2 LO 3rd harmonic spurious response only -20dBC
Replies: 17
Views: 7293

Re: RSP2 LO 3rd harmonic spurious response only -20dBC

I think I've seen this documented somewhere. There are responses based on odd harmonics of the sampling frequency/LO. Just like the 'image' response on a conventional superhet receiver, there is no way to get rid of them without using front-end filtering. The RSP's have filters, but the lowest one c...
by g1hbe
Thu Jun 29, 2017 11:47 am
Forum: General
Topic: SDRConsole and SDRplay
Replies: 5
Views: 2583

Re: SDRConsole and SDRplay

Ah. The error at VHF seems to be about 50 KHz, but at low frequencies it is 5 KHz. This suggests an error in the reference oscillator, but it's a much bigger error than we normally see, and probably way beyond the calibration adjustment. I'm assuming you've tried a different program such as SDRUno o...
by g1hbe
Wed Jun 28, 2017 9:14 pm
Forum: General
Topic: SDRConsole and SDRplay
Replies: 5
Views: 2583

Re: SDRConsole and SDRplay

Is the frequency offset always the same, regardless of the frequency you enter (ie LF or VHF)? Or does the offset get worse the higher the frequency?
by g1hbe
Mon Jun 26, 2017 3:35 pm
Forum: SDR Antennas
Topic: Long Wire Antenna Performance Questions
Replies: 7
Views: 5339

Re: Long Wire Antenna Performance Questions

Ultravista - As Danube said, the two connections input connections on the balun form a 'differential' input. If you put the same signal on each end, they will cancel and there will be no output. Obviously a pair of wires twisted together are picking up the same signal so they should not be connected...
by g1hbe
Fri Jun 23, 2017 8:19 am
Forum: General
Topic: "Near Field" definition?
Replies: 1
Views: 1266

Re: "Near Field" definition?

Hi. My RSP2 is fed from a Wellbrook loop (or sometimes a random wire) only a few metres from my 160m vertical (it's for the 160m band, not 160m tall!) and I've not had any problems. I use fairly modest power levels though, never more than 35 watts PEP. One thing as amazed me - if I keep the power do...
by g1hbe
Sat Jun 17, 2017 11:59 pm
Forum: SDR Antennas
Topic: Longwire antenna question
Replies: 7
Views: 4096

Re: Longwire antenna question

Are you selecting the Hi-z input? You have to click on the Hi-z button. Other than that I can't think of much. The RSP is very sensitive on all bands.

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