[amsat-bb] RTL-SDR downlink

Eduardo PY2RN py2rn at arrl.net
Fri Jun 17 19:20:55 UTC 2016

   Hi Patrick.
Agreed, it will depend on the environment conditions for each one/station.   Usually devices connected to a computer are very subject to suffer with RFI /EMI all the ways,  USB cables makes great antennas, unfortunately.   So toroids and shielding are a must,  but may be not enough sometimes.   

Regarding  metal cases for these dongles (not only RTL, but FCD and others with plastic cases) 3M and similar have a thin copper tape which is auto-adhesive  (and yes, the adhesive side is conductive as well!)   I am using to mitigate RFI/EMI on these devices, and other plastic boxes I have here.
Ed   PY2RN

      From: Patrick STODDARD (WD9EWK/VA7EWK) <amsat-bb at wd9ewk.net>
 To: "amsat-bb at amsat.org" <amsat-bb at amsat.org> 
 Sent: Friday, June 17, 2016 1:16 PM
 Subject: Re: [amsat-bb] RTL-SDR downlink
Hello, Ed!

Thanks for your reply! If I had my satellite station in a proper ham
shack, where the radios are inside and antennas are outside (or
the antennas are not within a few feet or a couple of meters of
the radios), it is possible that the house or building may be enough
to keep the transmitter from affecting the RTL-SDR dongles.
I don't have that option for working satellites, even when I am at
home. My antenna is always within a few feet or a couple of meters
of my radios, both transmit and receive. Putting the dongle in
a case with some shielding, and maybe adding some filters in front
of the dongle, could make that work in my situation. Between the
time and money needed to do that, I think I'm doing fine when I use
a FUNcube Dongle Pro+ or SDRplay. In fact, whenever I move to a place
where I can install a proper satellite station in the house,
with antennas outside and the radios inside, I know my existing
SDR receivers (FUNcube Dongle Pro+ and SDRplay) should work fine
in that environment as they have when I've worked portable.


Twitter: @WD9EWK

On Thu, Jun 16, 2016 at 11:08 PM, Eduardo PY2RN <py2rn at arrl.net> wrote:

> The cheap RTL dongles are as much sensible (or more) than the others more
> expensive.Lack of filtering is the big issue although there are some
> practical and easy workarounds to improve it.For ham satellites downlink
> frequency stability should not be an big issue, there are some models
> already been sold  with 0.5PPM TCXO option which are still cheap.It is a
> great opportunity to operate full-duplex on amateur satellites with very
> low investment and improving operational capabilities.
> EME (Moon bounce) audible signal RX comparison between TS-2000 / RTL /
> FunCube Pro+ can be seen here:
> https://youtu.be/3OxyO5ylwfs
> 73
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