This is a Board 1 replacement for the Electroluminescent Receiver. It has provisions for mounting a PIC 16F628 DDS VFO based on a simplified PIC-EL DDS VFO, developed by VK5TM (the VK5TM simplified PIC-EL). The PIC EL project will work with the same PIC. It can also accept the output of any DDS VFO without the need of an amplifier after the DDS chip (AD9850 or AD9851). The board can be used with the Vackar VFO, same as the ELR receiver, or a DDS VFO. A slide switch at the First VFO Amplifier allows switching between the Vackar VFO and an external DDS VFO.

The BandPass Filters have been modified to cover 40 to 10 Meters. With the Vackar VFO, the receiver will cover the original 40, 30, 20, and 17 Meters and has the original IR connections to the Crystal Filters for switching the VFO frequency and the Crystal Oscillator frequency.

Using a DDS VFO allows coverage of all the bands covered with the new BandPass Filters - 40 through 10 Meters. Since they are varicap tuned, the coverage is continuous from 7MHz to 30MHz, allowing SWL reception. An AM detector or a regen detector can be added for listening to SWL stations.

A transmitter function was added to the PIC-EL DDS VFO that removes the offset from the DDS frequency when a Key output is grounded.

This activates a relay at the end of the VFO amplifiers that sends the DDS output to a Transmit Out connection which to sent to the input of your choice of amplifier and lowpass filters. The output is about 200 mV.

See Transmitter to Interface with the SLR for connecting to a Novice tube type transmitter, QRP amplifiers and QRO amplifiers.

Holes marked with black arrows in the above picture should be drilled with a 9/64" drill bit. Look along the edges of the board. The spacers/screws supplied with the kit are larger than the mounting holes on the board (1/4").

Note the holes in the middle of the VFO in Section 1 (left side of board) which hold the back of the DDS VFO. The hole nearest the edge of the board is usually the only one used along with both of the holes at the bottom edge of the board.

In the bottom middle of the board, Section 2, below the left edge of the left relay, below the 1K resistor, is a hole that is too close to the the 1K resistor and 12V Pad (notice the arrow). A spacer placed there will short to the pad. If you use a spacer/screw there you need to trim the pad a little so there is no short to the spacer or screw.

Most of the components for this section come from Bag 5 and 6. Use a VOM (volt-ohm meter) or DVM (digital volt/ohm meter) to measure resistance values on the resistors (do not trust the color codes) and a small magnifying glass to read the numbers on the small capacitors.

____Wind the VFO coil. Use the large toroid, T68-6 (Bag 6, Yellow color, outside diameter 11/16"), and cut a length of wire 16" long. Start with 1" of wire on the end where you start. Wind 18 turns on the toroid and put a 30 degree gap between the ends of the winding. A turn is counted each time the wire passes through the center of the core.

____Wind one of the FT50A-75 ferrite cores (Black color, Bag 4) that is used at the 5V input to the VFO. Measure 8" of wire and put 7 Turns on the ferrite core. Wind evenly around the core with a 30 degree space between the ends of the winding. This is the VFO RF Choke.

____After winding the cores, trim the excess length, and scrape the enamel off the wire on the ends as close to the toroid/ferrite core as possible. Then flow solder onto the wires.

Please Note!: Pre-tinning the wires shows where you missed scraping the enamel and makes a good solder connection on the board.

____Mount spacers on each side of the board on the four corners to provide support for insertion of parts and easy soldering.

The roll of tape is holding up the board so all the spacers can be seen. Using the spacers
in this manner helps insert parts and provides a stable platform for soldering.

Begin each section by filling in the parts that have the value inside their footprint. They are the following:

____1 - Large RF Choke (Bag 3), Footprint on PCB is a rectangle with square edges, "Large RF" inside the rectangle. Choke is a wirewound choke about 1/2" long with black plastic ends.
____2 - .01 capacitor (Bag 3), Footprint on PCB is rectangle with rounded edges, ".01" inside the footprint. One is in the picture above and the other is next to the photodiode at the bottom of the board.

Resistors:

____1 - 1M (Bag 4), Next to photo diode in lower right hand corner.
____1 - 39K (Bag 6), below FET (2N5486) Remember, square edges for resistors, do not put the resistor in the 39pf NPO capacitor footprint.

____1 - 47pf NPO (Bag 5), Orange colored, small square, labeled "470, JCC". Placement of this capacitor depends on whether you are using the stabilizer. If using the stabilizer, capacitor goes inside the stabilizer parts box as shown in the picture above. If not using the stabilizer, capacitor is put in the bottom footprint outside the box.
____2 - 39pf NPO (Bag 4), small, blue colored, short leads, labeled "390J, 201". One is located next to the FET (2N5486).

The second 39pf is located at the tuning capacitor, leave one end unsoldered until the tuning capacitor has been mounted. Bend the capacitor toward the large hole so that most of the lead length is underneath the board. The short lead will barely reach the main tuning capacitor if mounted flush with the board. Push unsoldered lead against the PCB to keep out of the way. Some kits will have one with longer leads.

____2 - 3.3pf NPO (Bag 4), Orange colored, small square, leads flared out, labeled "3R3 D", or short leads, grey with black top, labeled "3R3" (R looks like a P). Both located next to the "Frequency Cntr" box. May be a ceramic 3.3pf in kit, note different ones in the picture.
____1 - 68pf NPO (Bag 6), orange colored, small square, long leads, labeled "680". NOTE! Silkcreen is labeled wrong, 47pf is incorrect and put this 68pf in its place.
____2 - 100pf POLY (Bag 5), Clear plastic, tubular part with long thin leads, labeled "100". One next to Relay, one next to FET (2N5486)
____2 - 120pf POLY (Bag 5), Labeled "120". Same as above, both located near the FET.
____1 - 10pf NPO (Bag 5), Orange colored, teardrop, labeled "100, A1J". One lead is unsoldered and goes through the large main tuning capacitor hole. The 10pf will reach 10MHz WWV as well as the amateur bands.
____1 - 82pf NPO (Bag 6), orange, small square, short leads, labeled "820K".

Note: Be careful not to splash solder on the Poly capacitors. Do not remove the solder if you get any on the poly caps. It will be very difficult to remove and could destroy the capacitor. Just check to make sure the solder is not touching one of the lead wires.

Solder

Other Parts:

____2 - Yellow Trim caps (Bag 1), Next to relays, note flat area on body and match to the flat on the footprint.
____2 - LEDs (Bag 3), Red color, next to relays. Match flat of the LED to the flat on the footprint. The short lead is on the same side as the flat. Note: If you ordered the Super Bright LEDs, one can be placed next to the 1N914 diode. See Modifying the LEDs.
____1 - 1N914 diode (Bag 4), black band, very small size. Note band on footprint and mount accordingly. Bend the leads about 1/8" away from the body of the diode for easy insertion into the PCB.

____1 - 2/8 Ceramic Trim cap (Bag 1), Note arrow over one leg, match the arrow on the trimmer to the arrow on the footprint. Clean and tin pins for a good connection when soldering on the board.

Note: Placement depends on whether you are using the stabilizer. If you are using the stabilizer, the trimmer goes inside the stabilizer parts box as shown above and in picture below. If you are not using the stabilizer, the trimmer goes next to the 14.068 text.

Be careful soldering the yellow trimmers, the tabs are difficult to solder. Check the following picture and make sure yours does not look like this:

Add more solder to fix.

Solder

Solder

Solder each one individually

Important Blue Relay mounting information!

1. Clean and tin the pins with solder before mounting to ensure a good solder joint. Wipe the excess solder to the top of the pin so the pins will fit in the holes. The pins can be difficult to solder without pre-tinning.

2. Be sure to mount the relays flush with the board. If mounted slightly off the board, the relay will flex back and forth while handling the board, and break the pins between the relay and PCB.

You can use a tie wrap, using the center hole and any hole around the core, or use a screw and nut with a 3/16" rubber grommet inside the toroid. (Parts not provided in kit)

A small 3/16" grommet can be cut to fit inside the core, and with a 3/4" long screw and nut (4-40's), use the hole in the middle of the footprint to hold the ferrite core onto the board. (Parts not provided in kit)

This picture shows the VFO and RF Choke held down with 4-40 nylon screws, 3/16" rubber grommet, and a metal 4-40 screw underneath the board.

Arrows point to the dual holes and tiny rectangles that indicate where the feet of the main tuning capacitor will be soldered. Note the outline of the capacitor. The main tuning capacitor is soldered underneath the board. Small U shaped wires are placed in the holes and held down with masking tape. Then the board is turned over and the legs are soldered to the U shaped wires and the ground plane.

____1 - 5 section tuning capacitor (Bag 1), Because of its weight and size, best to mount after all the other parts have been mounted on the PCB. Information for mounting the tuning capacitor is at the end of the instructions for Board 1: First Mixer, Post-mixer Amplifier, Crystal Filters.

If you are using both the Vackar VFO and the DDS VFO, either now or later on, the VFO section above should be finished with the instructions above.

____3 - 100 ohm resistors (Bag 3), (brown, black, brown)

____1 - 100K resistors (Bag 3), (brown, black, yellow)
____1 - 1K (Bag 3)
____1 - 470 ohm (Bag 4)
____1 - 2.2K (Bag 4)
____1 - 56 ohm (Bag 6)
____1 - 5.6 ohm (Bag 6)

____1 - T1-1T Minicircuits transformer (Bag 4), Note the dot on the T1-1T transformer and match the dot on the silkscreen. The dot on the outside of the footprint can be seen after the part is mounted so that you can double check proper mounting.
____1 - LED (Bag 3), Red color. Match flat of the LED to the flat on the footprint. Note: If you ordered the Bright Red LEDs, install them now. Do not use Super Bright LEDs here unless you change the bias resistors. See Modifying the LEDs.
____1 - Phototransistor (Bag 5), transistor looking part with three leads and a glass face, the "B" pin is not connected to any traces and can be soldered later to help hold the part after it has been aimed at the IR LED across the board. Best to bend the part at a 90 degree angle, to shoot across the board, before soldering on the PCB. Mount phototransistor as high as possible using all the lead length.
____1 - MOSFET (Bag 2), (Picture) static sensitive part, touch a ground wire before taking it out of the bag, notice the dot on MOSFET (may be difficult to see, hold at an angle to a light source and you can see the shadow of the dot), the dot is located to the left of the second line of the text on the MOSFET. A dot is placed outside the footprint so that you can double check your placement after it has been soldered to the PCB. The leads on each side of the part need to spread apart slightly to fit the footprint.
____1 - Zettler Relay (Bag 6)
____1 - Bifilar ferrite core
____1 - 2N5109 with heatsink (as just finished from above)

A mistake was made on labeling the relay pins. The 'C' pin and the 'VFO OUT' pins are reversed. The 'C' pin is the common of the relay and the 'VFO OUT' is the Normally Closed pin.

Use this text and the pictures to make this fix.

The .01 cap that takes the output of the 2N5109 from the center connection of the Bifilar coil is removed between the connection to the Bifilar coil and the labeled 'C' pin on the board.

The small coax cable will be connected after the board is populated. You can do the fix below now.

Take a new .01 from the cardboard strip, but do not cut it off, keep the full length of the leads and clean them. Solder the .01 between pad that goes to the center of the Bifilar coil (there will be a hole there from the removal of the old .01 cap) to the pad near the edge of the board that is labeled 'VFO OUT' on the top of the board. You can run one wire of the cap through that open hole to help mount the new .01 cap. Remember to clip the excess wire of the .01 on the top side of the board when finished soldering.

Solder the shield of the coax cable to the ground plane next to its new location right next to the other hole of the old .01 cap. (Labeled 'C' on top of the board) Next, solder the center conductor of the coax on that pad which has the hole for the old .01 cap.

____Check the dot on the MOSFET and the Minicircuits transformers.
____Put the bottom of the PCB in front of a bright light. If you see light shining through any of the soldering holes, you missed a solder connection.
____Did you remember to set the "Gain Adjust"(blue 500K trimmer)to about 450K? (1st VFO Amplifier)
____Make sure the 330mfd Electrolytic is mounted correctly.
____Look at all the 100 ohm (brown, black, brown) resistors and check that the size of the footprint underneath the resistor is shorter than the length of the resistor body.
____Look at all the 100K (brown, black, yellow) resistors and check that the size of the footprint is as long as the resistor body. Look for the bright yellow band to find these resistors.
____Check the tab on the BPX38 Phototransistor and the 2N5109 transistor and make sure it matches the footprint.