I have successfully built a 12kHz downconverter for Icom (T)RXes that
use a 2nd -and last- IF at 9MHz. The adapter can be used to receive DRM
HF broadcasts with commercial HAM rigs/RXs and plugs on the optional
filter socket (no soldering required).
Some devices that can mount optional 9MHz filters are:
IC-706/MKii/MKiiG, IC-725/726/728/729, IC-735, IC-R70/71/75 receivers.
A first test with a balcony homebrew antenna
(http://spazioinwind.libero.it/ik1zyw/temp/IMG_0030.JPG) and an
IC706MKiiG allowed me to receive bitXpress banner on 15.896 MHz and
listen to Deutsche Welle on 6MHz broadcast band. I used "dream" software
The same downconverter can also be used with SDRadio
(http://www.sdradio.org/, without sideband rejection) in order to
accomplish narrowband filtering, or SSB/CW/FM demodulation for some
receivers (such as IC-725/728 that require an optional unit for FM
I will soon carry on further reception tests as well as side-by-side
comparison with 455-12 DRM converters on other receivers.
If there is enough interest I will publish a complete description of
this downconverter, including the design involved. - unless I receive an
offer to buy the whole project :-) -
QRPp-I #707 + www.paolocravero.tk + I QRP #476
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