Our preferred assembly procedure

Joachim Köppen DF3GJ Kiel/Strasbourg/Illkirch Summer 2003

Based on my own experiences with assembling the receiver, I suggest a somewhat different approach than described in the manual. I prefer to assemble each individual stage or unit of the circuit, starting from the output end, and test its proper functioning. Only then one proceeds with the next stage. This allows early detection and elimination of any faults.

1. First of all, check whether the holes in the printed circuit board provided for the coils L4 and L5 (the ones within a metal can) are large enough for the matel tags of the can to pass through. If not, use a small screwdriver to enlarge a bit the holes by pushing it through the holes, from the top as well as from the bottom.

2. Mount all components on the front and rear panels. Provisionally mount the circuit board on the bottom panel. Assemble the enclosure, except the top panel.

3. Solder the circuit board to the potentiometer lugs, and make all the connenctions between the board and the sockets J1, J2, J3, and J4.

4. When the board is well fixed, undo the screw connecting the board to the bottom panel, open the enclosure screws on one side, remove the bottom panel, and fix the enclosure screws again.

Now we have the circuit board well mounted (and protected) in the enclosure and the external connections can be made by the appropriate plugs. This makes it easier to handle and to test. We can begin with mounting of the components, proceeding in the sequence of the stages sketched in the accompanying circuit diagram and board layout.

The components of each stage may be mounted to the board in any sequence, but often it is wise to start with the larger ones, as they will restrict the space for the other parts. When any test results are not satisfactory, it is a good idea to check the voltages and compare them with Fig. 19 of the assembly manual.

• Step 1: The power line up to the LED Test 1: The LED should light up when you switch on.
• Step 2: The audio amplifier Test 2: Plug in the headphones at J3 or J4, apply power. Touching test point TP2 with a finger should cause a fairly loud humming to be heard. The action of the volume control can also be verified.
• Step 3: The audio pre-amplifier Test 3: Touching test point TP3 with your finger should produce a stronger hum noise than heard in Test 2.
• Step 4: The test oscillator Since this will not be operated in normal operations, we can make Jumper 6 right from the start as a temporary connection out of two pieces of bare wire - each about 1.5 cm long - so that they can be brought together to switch on the oscillator during tests. Test 4: If you wish and if you have the facility, you could check whether you can hear the signal of the oscillator in a short-wave receiver.
• Step 5: The mixer and the local oscillator Test 5: When L5 is correctly tuned - see the manual for more detailed instructions - it should be possible to hear a whistling tone from the test oscillator, especially by touching TP1 with a finger.
• Step 6: The R.F. amplifier Test 6: The whistle signal should be stronger now. Also, tuning L4, C6, and C2 would increase the loudness. When listening to a frequency away from that of the test oscillator, say 20.1 MHz, the tuning of L4, C6, and C2 will cause a noticeable increase of the hissing noise.

Here the components of these steps are indentified in the circuit schematic:

and here on the board layout: