ozQRP MDT, Руководство по монтажу

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MDT Construction Manual – Issue 2 Page 36
11 T
ESTING AND ALIGNMENT
11.1 G
ENERAL
The minimum tools and accessories needed to get the MDT tested and aligned are listed below:

Digital multimeter.
 50 ohm dummy load capable of dissipating at least 2 Watts.

Power supply capable of 13.8V DC regulated at 1 Amp.

A second receiver.

Small adjustment screwdriver.
These additional instruments are recommended to fully test and align the MDT.

QRP wattmeter or oscilloscope

An audio signal generator.

An RF signal generator.

A frequency counter.
Figure 22 lists typical voltages at various points around the board and can be used
to verify operation.
11.2 P
OWER ON

Connect a 50 Ohm dummy load to the antenna socket.

Connect the power supply to the DC connector.

If your power supply does not include a current meter, connect a multimeter in series
with the power supply positive lead and set to measure current.

Turn on the power supply and note the supply current. It should be around 50mA. If it’s
far from this turn off immediately and look for problems.

The relay should be de-energized and the board in RX mode. To verify that there are no
obvious problems do a quick probe around the board with a multimeter and check the
DC receive voltages as shown in Figure 22.
11.3 R
ECEIVE

Set the Tune control to around the middle of the range.

Turn the AF gain control to halfway. You should hear some low level hiss come from the
headphones indicating that the audio stages are working.

Remove the dummy load and apply a RF signal of about 100uV to the antenna connector
and rotate the Tune control until a clear tone is heard in the headphones.

If no signal is heard check the receive circuit.

If you don’t have a signal generator simply plug in an antenna and listen. You will get a
good idea if the receiver is working correctly by comparing to another receiver.