Whole House FM Transmitter 3.0

The Whole House FM Transmitter 3.0 broadcasts a static free signal 150 feet in any direction. Compatible with most audio sources like TVs, Home Stereo Systems, iPods, Smartphones, MP3 players and computers. You will love the ability to broadcast your favorite music and audio sources to any FM radio. Integrates seamlessly with home and car stereos.

• Frequency Range: 88.0 ~ 108.0 in 0.1 MHz steps
• Pre-emphasis: US and EU Pre-emphasis Options
• Frequency Response: 20Hz ~ 15KHz
• Signal to Noise Ratio: >65dB
• Audio Performance: 0.2% distortion
• Stereo Separation: 40dB
• Large Screen Interface: 1.34″ x 1.10″
• Tuning Design: Stable PLL Technology

Per the instructions, the power supply is not standard even though it looks like the same one as my Droid smart phone. They warn you not to use this supply on other items or any other supply with the phone.

You need an RP-sma to BNC female adaptor to connect to coax cable or a better antenna.

improvements or modifications

You are going to have to turn your remote stereo up to double the usual volume level, because if you try to turn up the volume level on the source device or try to turn up the "line in" volume on the unit, you are going to have terrible distortion.

To sound its best, this unit requires a signal processor between the source and the transmitter. Either there is no AGC (Automatic Gain Control) circuit or it simply does not work well. A good AGC circuit would help address the common complaint of low audio volume or under deviation. A functional AGC would help to avoid over-modulation which is audio distortion. Instead, you have to turn the audio way down to about half way, thus making the unit transmit with much lower volume than broadcast stations.

According to an Amazon review, "there is no AGC in version 3.0. It was mentioned in the early instructions by mistake, and has been removed from the current instructions. "

audio processing / compression

Using computer software audio processing such as Thimeo Stereo Tool 10.10.

Using a hardware audio processing device between the audio source and the transmitter.

antenna

Use the long wire antenna for best range. Try to run it as straight as possible, either vertically or horizontally although vertical polarization is probably best. If you run the unit on full power you will definitely want to use the wire antenna as the short telescoping antenna does not radiate well enough to protect the transmitter from reflected power which could cause damage.

The wire antenna is 133½" long (the wire part) and including the screw base would be almost 134".

• 133½" = 11' 1½" which appears to be a 1/2 wave for an end fed (long wire) antenna.

increase power via secret switch

The 2.0 had a switch in the battery compartment under a small sticker that will bump the power up above regulation. You can get a paper clip and move the slide switch. However, on the 3.0 version to extend range from 150' to 600', you now just press the Cycle button then, at same time, press the Mute button, until the lightning bolt at the top of the screen appears.

• You can access the higher power by holding both the CYCLE button and MUTE simultaneously while the unit is operating (has power).

Pre-emphasis

The advertising claims =, "US/EU Pre-emphasis matches the emphasis to the FM radios in your region and reduces noise at higher frequencies."

Pre-emphasis amplifies the high-frequency components through a simple Pre-emphasis circuit. In North America 75μs is used, and in Europe, 50μs is used. In order to have a normal frequency response, a De-emphasis circuit should be added to the radio receiver. Just as the same as Pre-emphasis circuit, it has a time interval after receiving the radio waves, and it is the same as the one of Pre-emphasis circuit.

• Try switching to EU and see if it benefits. ???