RTL dongle for 6m WSPR

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G6AIG's picture
Last seen: 1 year 4 months ago
Joined: 2010/11/17 - 11:28
RTL dongle for 6m WSPR

Dear Whisperers,
Just to share a positive experience using an "ezcap" style DVB-T RTL USB dongle and 6m:

I have a system running with a single dongle, with 3 separate "IFs".. one for WSPR,
one for the BRAMS 49.97MHz meteor beacon (into SpectumLab) and one for general 6m band surfing. This works really well!

The dongle is the standard R802T "ezcap" style clone, 6 euros on Ebay. black case, white writing, with
RTL 2832U and R820T tuner. It also has back-to-back protection diodes built in and miniature RF plug.

The key thing to get this working is to use a good filter, to get rid of Band II VHF radio!
I built a filter similar to the http://www.wb5rvz.com/sdr/hf_bpf/08_band1a.htm
6m Softrock design. This has only 2 coils and 3 capacitors, but it works really well.
My version used junk-box components, with dust-core coils mounted 90 degrees to each other.

I am using SDR-Radio V2.2 1676(beta) SDR software from http://v2.sdr-radio.com/
You can have multiple receivers with one dongle!! (need to DE-select current VFO only).
This is a little tricky to sort out, but it does work!

I am also using the free WsAudio Device software as a virtual cable. This works well, with
sample rates 125KHz (standard). Each audio output from the SDR software feeds a different virtual cable.

I am going to try this setup also for 2m, but I don't know if the phase stability is good enough?
My dongle required 44 ppm frequency correction to get it just right for WSPR. (has anyone tried 2m WSPR
using these dongles?)

Antenna is vertical Folded dipole with twisted wire balun (better than coax balun!)
http://myweb.tiscali.co.uk/g8hqp/radio/projects/2mVertical.html this works exceptionally well!
(I used 450 Ohm ladder line for the antenna, and PCV-covered mains wire for the balun).
It is an exceedingly quiet, wideband antenna, in my urban environment.

1140 -25 -0.5 50.294566 0 CT1GVN IM67 37 spotted straight away (not uploaded)
If anyone is interested in datails, I can upload some photos/screenshots, 73's