ozQRP MDT, Construction Manual

Page: 4 / 42

MDT Construction Manual – Issue 2 Page 4
1 I
NTRODUCTION
The MDT (Minimalist Double Sideband Transceiver) is an inexpensive and easy to build kit for
the 40M band. It is ideal for the first time builder as all parts except the microphone socket are
mounted on a single PCB and all the components are through hole. There is a SMD tuning diode
but this comes pre-installed. The PCB is a high quality double sided type with ground plane,
solder mask and silk screen.
The plastic case is small and lightweight and can easily be held in one hand. The front and rear
panels, which are made of PCB material, come pre-cut and feature silkscreened labeling.
The low receive current of the MDT means it is ideal for battery operation. The transmitter
outputs between 1.5 and 2 watts DSB which is ample for short distance contacts through the
day and long distance contacts under good conditions. DSB transmissions are entirely
compatible with SSB transceivers, and in fact most operators won’t be aware unless you tell
them.
Building the MDT is quick and easy. The receiver doesn’t require any alignment and the only
setup required for the transmitter is setting the microphone gain and balancing the mixer to
null out the carrier.
A kit of parts for the MDT including everything you need, such as enclosure and front and rear
panels is available from
www.ozQRP.com .
MDT Specifications and features:
1. Size 130mm x 100mm x 50mm.
2. Direct Conversion receiver. Sensitivity 0.4uV for 10dB S+N/N.
3. Double Sideband transmitter. Nominal 1.5W output. Up to 2W depending on power
supply voltage.
4. Selectable frequency range. 7.090MHz - 7.130MHz or 7.050MHz - 7.110MHz.
5. Microphone amplifier accepts standard low impedance dynamic or Electret microphone
with selectable on-board bias resistor.
6. LED transmit power and modulation indicator.
7. 3.5mm stereo headphone connector. Can power external loudspeaker.
8. Carrier suppression up to 50dB.
9. All spurious transmit outputs better than -46dBC.
10. Receive current approximately 50mA.
11. Transmit current approximately 250mA at maximum power output.
12. Reverse polarity protection using a series-diode.