RTL SDR dongle

[Kurt Theis]

If I could throw my .02c in here:

Not all rtl dongles are the same. I have 2 of the rtl-sdr dongles sitting
in front of me. The earliest ones received 27mhz thru appx 1700 mhz. There
is no front end to speak of, and they are prone to overload. To receive
below 27 mhz required a hardware mod that many times would destroy the
device unless you are skilled with soldering smt devices.

Also the software (rtl_fm) wasn't capable of using the bypass - it needed
to be modified. some of the newer software did work OK. As an HF receiver,
it was a horrible solution.

The folks at rtl-sdr.com realized this and a few years ago put out a new
version known as the V3 model. The marking on the device is "RTL2832U
R820T2 TCXO+BIAS T+ HF". It is the same size and comes in a shiny (sort of)
aluminum case is is today about $25 on Amazon etc.

The V3 model does receive on HF down to  a few 100 khz since the bypass
parts are already installed. Many of the newer sdr programs know to use the
Q mode receive and tuner bypass options to receive in the HF region. With
gqrx, as mentioned before, there is a no limits checkbox that needs to be
checked for the software to work below 27 mhz.

I've been using one of these for a couple of years and it works, but not
that well. Without an AM band notch filter the am broadcast stations wreck
hf band reception. A decent one is about $10. Next, there are image issues
across the hf band, greater when above about 14 mhz. The sensitivity is not
good and, again, they are prone to overload.

I tried it connected to the IF out of my K3 and would not do it again. As
was suggested, the sdr SdrPlay rsp1 receiver is about $100 (there are newer
and better sdrPlay units) works and doesn't require the am notch filter.

(Aside - you may not require the notch filter when coming out of the IF
port of the K3 - I didn't try).

There are newer dongles from other suppliers that do not cover HF by
default and may or may not work in HF. I think almost all require an
upconverter (another $45 to $75) to be useable. But now you have 3 devices
(am filter, converter, rtl dongle) on your desk.

The rtl-sdr dongles are a good solution for those just learning what radio
is and want to play without spending much more than dinner money, but if
you can afford a K3 you can do better than using an rtl dongle for a
panadapter display.

>
Using an sdrPlay rsp1 works (somewhat) when used with the right software,
and may be an option for you. I can't recommend the rtl-sdr option.

Kurt
--
Kurt Theis
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