[Lowfer] Downconverter for Software Defined Radio

[Lyle Koehler]

An article from CQ VHF magazine called "The Soft Radio" is available
from the FlexRadio web site at http://www.flex-radio.com/ This
article mentions using a device called the DX Time Machine as a
downconverter for software defined radio experiments. Although
originally intended for recording and playing back a segment of the
HF spectrum, the "recording" half of the DX Time Machine looks like
it would do a good job as a SDRadio front end. Details of the Time
Machine are at http://www.expandedspectrumsystems.com A Time Machine
kit with a single band filter board costs $135. The web site also has
the detailed instruction manual (including a parts list) and the
schematic for the Time Machine. It looks as though the downconverter
could be built easily on a prototype circuit board, and most of the
parts are readily available from Digi-Key. For those of us who are
interested in receiving LF and MF signals, it would be better to use
TUF-3 double balanced mixers instead of the TUF-1 mixers supplied
with the Time Machine kit. Ocean State Electronics lists the TUF-3
mixers in their catalog at http://www.oselectronics.com/ose_p82.htm

Lyle, K0LR