experience with mini dongles?

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wa5ngp

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Oct 20, 2013, 5:00:49 PM10/20/13
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does anyone have any pix or info on what these things look like inside?

Antenna MINI FM+DAB+DVB-T+SDR Dongle STICK RTL2832U R820T SDR Radio


or

I have an e4000 version but I was thinking of getting one of these and trying my hand at desoldering those caps and running it in direct mode without the tuner.  If these things are somehow double sided components that makes it impossible to get to those coupling caps I'd like to know.  Its going to be difficult enough already.  Fortunately, my neighbor has a nice microscope to help me do this.

tks
don

Siegfried Jackstien

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Oct 22, 2013, 11:00:20 AM10/22/13
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Hello don

No need for de-soldering caps if you use a stick with r820t tuner

The r820t tuner does not use a zero if like the e4k sticks

It uses a low if and only the I inputs on the rtl chip

So ... the q inputs are left free

Tacksolder 2 small wires on pin 4 and 5 (balanced q input)

Set direct sample q branch in the driver window of the rtl stick

Enjoy shortwave with direct sampling :-)

If you select i/q sampling (when used on vhf uhf) then the driver takes care
of just using the I inputs

If you select q branch direct sampling you can receive shortwave without any
upconverter needed (but upconverter should work maybe a bit better?!?)

... so .. with adding a 1:4 balun on the q inputs and another coax connector
you will not loose vhf uhf ... but additionally "gain" shortwave

Dg9bfc

Sigi


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David Jones

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Oct 22, 2013, 10:26:10 PM10/22/13
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this works?

and what if i attach Q-input to stock mcx antenna,
will it overlap with shortwave or add noise when using default mode I/Q?

wa5ngp

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Oct 23, 2013, 8:35:32 AM10/23/13
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tks for that info Sigi,  I need to go back and study those block diagrams again.  I should have raised my ebay bid yesterday.  :(

I am wanting to run in "direct mode" so that I can listen to the 3.395mhz IF in my old SB101.  At the moment with my e4000 and upconverter I'm getting a lot of FM radio bleed thru and what looks like other  false signals from intermod or something.

have you noticed how hot 10M is the last week or so?

73
don

Siegfried Jackstien

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Oct 23, 2013, 3:42:45 PM10/23/13
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You should use 2 different connectors (or a switch) between your 2 inputs

Vhf uhf goes to tuner chip

Hf goes via balun dir3ect to sampling chip

I would NOT MIX them together (you can never say what will happen)

Just use 2 coax connectors and youre set

Dg9bfc

Sigi


> -----Ursprüngliche Nachricht-----
> Von: ultra-c...@googlegroups.com [mailto:ultra-cheap-
> s...@googlegroups.com] Im Auftrag von David Jones
> Gesendet: Mittwoch, 23. Oktober 2013 02:26
> An: ultra-c...@googlegroups.com
> Betreff: Re: [ultra-cheap-sdr] experience with mini dongles?
> > Von: ultra-c...@googlegroups.com <javascript:> [mailto:ultra-
> cheap- <javascript:>
> > s...@googlegroups.com <javascript:> ] Im Auftrag von wa5ngp
> > Gesendet: Sonntag, 20. Oktober 2013 21:01
> > An: ultra-c...@googlegroups.com <javascript:>
> > Betreff: [ultra-cheap-sdr] experience with mini dongles?
> >
> > does anyone have any pix or info on what these things look like
> inside?
> >
> > Antenna MINI FM+DAB+DVB-T+SDR Dongle STICK RTL2832U R820T SDR
> Radio
> >
> > http://www.ebay.com/itm/MINI-FM-DAB-DVB-T-SDR-Dongle-STICK-
> RTL2832U-R820T- <http://www.ebay.com/itm/MINI-FM-DAB-DVB-T-SDR-Dongle-
> STICK-RTL2832U-R820T->
> > Antenna-SDR-Radio-New-
> >
> /111194600489?pt=US_Video_Capture_TV_Tuner_Cards&hash=item19e3b6f429
> >
> >
> >
> >
> > or
> > http://www.ebay.com/itm/New-DVB-T-RTL-SDR-Realtek-RTL2832U-R820T-
> USB-DVB- <http://www.ebay.com/itm/New-DVB-T-RTL-SDR-Realtek-RTL2832U-
> R820T-USB-DVB->
> > T-Tuner-Receiver-PAL-IEC-Input-
> >
> /261311162855?pt=US_Video_Capture_TV_Tuner_Cards&hash=item3cd75be9e7
> >
> >
> >
> > I have an e4000 version but I was thinking of getting one of these
> and
> > trying my hand at desoldering those caps and running it in direct
> mode
> > without the tuner. If these things are somehow double sided
> components
> > that makes it impossible to get to those coupling caps I'd like to
> know.
> > Its going to be difficult enough already. Fortunately, my
> neighbor has a
> > nice microscope to help me do this.
> >
> >
> > tks
> > don
> >
> > --
> > You received this message because you are subscribed to the Google
> Groups
> > "Ultra Cheap SDR" group.
> > To unsubscribe from this group and stop receiving emails from it,
> send an
> > email to ultra-cheap-s...@googlegroups.com <javascript:> .
> > To post to this group, send email to ultra-c...@googlegroups.com
> <javascript:> .
> > Visit this group at http://groups.google.com/group/ultra-cheap-sdr
> <http://groups.google.com/group/ultra-cheap-sdr> .
> > For more options, visit https://groups.google.com/groups/opt_out
> <https://groups.google.com/groups/opt_out> .

wa5ngp

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Oct 23, 2013, 10:09:16 PM10/23/13
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here are the pix I was looking for

after looking at the wiring  in these pix I see your point that the I signals are not used on the 820 version.  Furthermore, looking at the spec of the 820 only a differential IF is output, not differential  I Q signals like E4000.  So this must mean that the 2832 can create I and Q internally if needed.

furthermore, I can see that the mini version is no worse to unsolder.
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