Using the Blue Lightning Transceiver

A 1-amp, 12 Volt, well filtered and regulated power supply should be used with the receiver. If the voltage drops below 10.5 volts, some of the IR switching may not work. If a 13.8 Volt power supply is used, use three 2 amp rectifier diodes in series to drop the voltage to ~11.5 Volts to the receiver. Cathode side (Black band) goes to the receiver, anode side to power supply. The receiver works best with a supply voltage of between 11.5 and 12 Volts.

Total current draw of the receiver with no signal is about 1 amp, but the audio amplifier (TDA2002) can draw instantaneous peaks of up to 700 mA.

The first indication of a weak power supply will be distortion in the audio amplifier. Wall warts (plug-in wall transformers/power supplies) are not filtered enough and will cause hum in the audio. A 1 amp wall wart will work, but be aware that most of them will cause hum in the audio and need additional filtering.

Several wall warts were tested with the receiver and we never found one that did not cause hum in the audio.

The receiver is designed for use with Hamstick antennas on the inside of a condo/townhouse window. The RF amplifier and lots of mixer gain helps the receiver work in areas with poor reception.

A 17 meter ham stick will bring in all the bands of the receiver with equal gain. Hamsticks for the other bands, when used as a general purpose antenna, will show marked differences between the bands. For example, a 20 meter Hamstick will bring in 20 meters with a bang, but be poor on 40 meters.

There is a 50 ohm pad at the output of the RF amplifier that can be changed to fit the receiver to your antenna farm. A 3dB 50 ohm pad comes stock with the receiver, but it can be increased to 6 dB, or even 12 dB, to reduce overloading the receiver when using very good outside antennas. See Circuit Details, RF Amplifier, "Adjusting Gain".

If you need more gain, the 50 ohm pad can be bypassed for more gain from the RF Amplifier. To remove the 50 ohm pad, remove the two .01 capacitors that go to and from the pad, and then insert one .01 capacitor in the two unmarked holes just to the right of the pad. That jumpers the output of the bifilar coil directly to the relays.

The bands are chosen with the DDS VFO by pushing Button 2 and turning the DDS VFO knob within one second. The DDS VFO will scroll through the bands until it reaches the one you want and and release Button 3.

The bands on the DDS VFO are 60, 49, 41, 31, 25, 22, 19, 16, 15. The next band is 200kHz, which does not have the offset programmed and is a signal generator that outputs the exact frequency it is showing. It is used to determine the center frequency of the crystal filters so it can be programmed into the offset frequency.

This procedure is not necessary as it has already been done, but is shown here in case you change crystal filter frequencies. To use this function, tune the 200kHz band near the frequency of the Crystal Filter frequency and peak the output at the S-Meter. Use the 100 Hz or 10 Hz tuning digit to find the peak. The peak frequency is then the offset frequency put into the programming for the bands.

The next band shows 0 and is a general coverage band that has the offset programmed (plus 3.546 MHz) and can be used to go to any frequency between the limits of the Bandpass Filters, below 60 to 10 Meters.

BFO Tuning

There is so much difference in hearing sensitivities between individuals that being able to set the audio gain to different levels was considered very important in the design of this receiver.

There is a black PC mount potentiometer labeled "Gain Adjust" at the BFO amplifier directly above the MOSFET. This pot varies the injection level to the product detector. The injection level is indicated by the LED brightness at the BFO amplifier.

For minimum noise from the audio amplifier, this pot is usually run with the LED barely on. Increasing the injection level will raise the audio level a noticeable amount. For quiet ham shack locations, this pot will give all the variation you will need in audio levels.

Some features on receivers that are not included are the following:

Noise Blanker

Notch Filter/Q-Multiplier

Audio Filter

Check out the article in the September/October 2002 QEX, "The DX Prowess of HF Receivers", and the design features of what he considers best for DX hunting. Most of those features are incorporated into this receiver.

Some of them are the following, taken from the article, page 38:

Check out the article and compare!

You are welcome to send an image of your completed project. Any comments you have, be sure to email.