Unfortunately many Long Wave radio stations have closed down over the past couple of years and very little remains to test our beloved radios.
This little module allows you to hear what AM radio really sounded like back in the 50's and 60's. The few remaining signals on AM are heavily compressed and limited in bandwidth.
The board runs from 12V dc at 80mA and takes a Bluetooth input from a Laptop computer or smartphone, The modulation frequency response is very flat and is only -3dB down at 20KHz. Thanks to the Class E transmitter design the modulation characteristics are very good indeed. The carrier frequency is crystal controlled.
The output is fed through a pi attenuator so that the modulator can feed into any load without affecting the modulation characteristics.
The
RF output impedance has been designed to be around 1000 Ohms and a
length of wire can be used as an 'Antenna' to couple the modulator to
your vintage set. Do not connect directly to any receiver without a
suitable attenuator as you may damage the receiver. It is generally
sufficient to 'loosely couple' the modulator to the receiver.
The
range of the modulator is only a few feet depending on what is used as
an antenna. This is not intended to be a long range radio transmitter.
It is a high quality modulator to allow you to use your vintage
equipment and feed whatever audio you desire to it.
The board has both Bluetooth and line level inputs. A 3.5mm stereo jack socket is provided. Plugging a 3.5mm jack into this input mutes the Bluetooth input and allows direct line level connectivity.
Left and right audio channels are summed together to give mono transmitted audio.
The listing is for the PCB only (built and tested).
These are hand made and tested using brand new components. The board measures 9 x 4 cm approx.
Please see my other listings for other frequencies available including Medium wave and Short Wave.
Thanks for looking!
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