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Some questions....

Posted: Sat Jul 11, 2020 10:47 am
by lagloose
Hello,

just bought an RTL_SDR device from ebay (the one in the blue metal case with the white dolphin). After first problems getting things to work (it should have been said, that the included USB cable ist an OTG type cable and does not work with the device connected to the computer...) it works now. Questions:

Any way to find out if this is a V3 version ?

I can listen to my local 70cm Amateur Radio Repeater. But i have to tune it 25kHz lower than expected. The official Downlink frequency is 438,650 Mhz. In SDSharp i have to tune to 438,625 Mhz. Why this ?

I still can't receive HF Signals. (Direct sampling is enabled). I had expected to get at least 'some' signals using a 5m long wire connected to the HF port. But nothing... Is a matched HF antenna so important for receivng HF signals ?

Thanx for ur answers.

Re: Some questions....

Posted: Sun Jul 12, 2020 7:16 am
by alanzfq
It is unlikely to be a V3 https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/

You need to calibrate the frequency.

Direct conversion often does not work well unless it really is a V3. Try a big antenna or amplifier.

Alan

Re: Some questions....

Posted: Tue Jul 14, 2020 9:52 am
by lagloose
alanzfq wrote:
Sun Jul 12, 2020 7:16 am
It is unlikely to be a V3 https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/

You need to calibrate the frequency.

Direct conversion often does not work well unless it really is a V3. Try a big antenna or amplifier.

Alan
Thanx for answer Alan.

Direct Sampling really is a mess with this device. Attached a 10m Endfed Antenna via 1:49 Balun. I could hear some signals on 20m but the direct sampling mode seems to be very very insensitive. Even the often very loud FT-8 signals were weak. Does it work better with a V3 ?

Re: Some questions....

Posted: Wed Jul 15, 2020 8:02 am
by alanzfq
You need to look up answers from those that have one.
My impression from what I've read is that most people are pleased with the way it works.

Alan