Checking the Board

All the wires that need to go off the board are marked with an arrow for easy identification. These locations are the ANT (antenna), SPEAKER, 12 VOLTS, VAR RES (volume control), and VAR CAP or WIDE (to the tuning capacitor).

A 6" length of hook-up wire needs to be soldered at all these locations to be used for testing, and after the board is mounted in the box, to connect the off-board components. Also, one lead to a 5 volt pad and one to a ground pad is needed for the volume control. If you are using an internal speaker, another lead should be soldered at "SPEAKER GROUND".

If a metal box is used, and metal screws and spacers are used to mount the board, the board will be grounded to the box. The rotor of the tuning capacitor, coax connector, phono connector, and DC power jacks are automatically grounded to the box by the mounting screws.

If a plastic box is used, a ground wire will need to be connected to the following parts: antenna connector, speaker phono jack, DC power jack, and the tuning capacitor.

For a quick check of the board, do the following steps:

1. Using test leads with alligator clips, hook up the speaker.

2. Hook up the power supply.

3. Touch your finger to the top lead of R4, marked "AUDIO CONTROL", and you should hear a 60 cycle hum.

4. If you live near strong AM radio stations, touch your finger to the crystal filter side of the MMIC and you should hear AM stations out of the speaker.

5. Hook up an antenna wire to pin 3 of L2. You should hear WWV. At this time of the solar cycle, WWV is best heard during the day.

6. Adjust C16, "BFO ADJ", and a tone should vary in pitch. At the lowest tone, you should be able to understand the announcer and get the correct time! Set the tone between the high and low tone.

7. With a frequency counter, check for VFO operation at pin 7 of U1.

8. Without a frequency counter, attach the antenna to the antenna connection on the board. Adjust the "ANT ADJ" trimmer at L1 and listen for a "rushing noise" from the speaker or for signals. C32 can be adjusted to find signals.

If VFO oscillation is verified with Step 7 or 8, then the receiver is working and final alignment can be done after it is mounted in the receiver box.

When the receiver is being used in this "haywire" mode, be careful to keep any hook-up wires away from the VFO toroid or you will have unexplained frequency changes. When moving your hand over an unshielded VFO circuit, "hand capacitance" will cause minor frequency changes.

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Last Update: 05/06/97
Web Author: David White, WN5Y