Newbie FM tuner question

[Lapis]

The noise increases as the modulating frequency increases with FM, so broadcasters increase the high frequencies at the broadcast transmitter (pre-emphasis) and the receiver is expected to perform a mirror-image reduction of high frequencies (de-emphasis) which also reduces the noise. A switch is often provided to select between 50 microsecond (European) and 75 microsecond (North American) de-emphasis time constants.

The antenna you have goes across the 300 ohm terminals.

Not only that but there are defects in sound quality with recording FM.

 

[Lapis]

Although not technically required by the FCC, the use of pre-emphasis on FM radio has been a de-facto standard since at least the 1950s. Many AM stations have also been using pre-emphasis since the late 1970s, and in fact U.S. stations broadcasting in AM Stereo, and all AM stations (mono or stereo) in Canada, are required to use the NRSC "modified 75 uS" pre-emphasis curve.


The de-emphasis switch on the back of a tuner is designed for FM, however since many tuners run the AM audio through the FM Stereo decoder chip and de-emphasis (even though it's totally unnecessary and only degrades the sound), it may change the way AM sounds as well.



75 uS pre/de-emphasis is the standard for North & South America and a few Pacific Rim countries (Thailand comes to mind, but I know there's a few others).

50 uS is used everywhere else: Europe, Africa, Australia, most of Asia, etc.

25 uS was designed to accomodate the use of Dolby FM, and is long since obsolete.

This has been with all Frequency Modulation engineering already.

 

[john2]

I have to agree with WA2ise i spent months being trained in AE theory and TBH at the end of the day, its what works for where you are, sooo many variables, just keep experimenting and you will always find better soloutions.

On paper aerial science seems an exact but in reality a metal coat hanger can work best

 

[john2]

rx sensitivity is what really helps

 

[spxer]

Antenna balun

I have an old Pioneer receiver with an FM antenna connection labeled "75 ohm unbal". It is a friction type connection, not a coax connector.
I also have an old FM antenna on a tower that I assume is 300 ohm. I recently reconditioned the antenna with new stainless screws etc. I am using a 75 ohm coax feed. I installed a balun at the antenna connection. Is that correct?
I do not have a balum at the receiver. Is that correct?
The reception was not good with much noise. I installed a ground wire into a 110v plug-in to the ground connection on the back of the receiver. That has helped tremendously.
The biggest problem now is static when the plasma TV that sets just above the receiver is also turned on.
I am an electrician, but antennas are a black science to me. Am I doing anything properly here? Thanks

 

[mhardy6647]

The only way to stop the RFI (Radio Frequency Interference) you're experiencing with your plasma TV is to unplug the TV from the AC mains when you want to listen to the radio.