FM radio question

[RichD]

I use an armband FM radio when jogging. It has
a switch "local", obviously for nearby stations.

What does this do, at the circuit level, and why?
How would you measure its quality or performance?


--
Rich

 

In the old days of analog tuners, (with the big knob) some of the tuners' front ends saturated for lack of a better word, when in the middle of transmitting country. ?Le three fifty thousand watt stations withinh a half mile and on fairly flat terrain. tis would cause probems. ghost stations with audio from more than one of the ral ones, all that. But this was analog.

The doodad you have is probably digital and has a seek function. Putting it in local makes it only stop at the stronger stations. Ususallu it deos not change the gian of the RF preamp stage like in the old days becauase the technology has supposedly so improved over the years.

However, that does not explain why a forty year old Pioneer receiver gets more stations clearer than a newer and better rated digital tuner. you cannot overload htese new packaged front ends really, probably because their specs are bullshit. Just like many years ago when they went to Dbf instead of uV for sensitivity. The uV spec was supposed to be into 300 ohms. then a couple of people started quoting it into 75 ohms. so now, standards are needed. Then they went to Dbf. I don't like it but it did solve a problem. I would stil rather it be quoted in uV.

 

[Helmut Wabnig]

On Mon, 22 Dec 2014 21:31:46 -0800 (PST), RichD
<r_delaney2001@yahoo.com> wrote:

I use an armband FM radio when jogging. It has
a switch "local", obviously for nearby stations.

What does this do, at the circuit level, and why?
How would you measure its quality or performance?

Put an attenuator into the antenna line.
A simple resistor in a simple device with a simple switch across
to bridge it.

A test bench for radios is something like this:
http://www.rohde-schwarz.com/en/product/cmw500_overview-productstartpage_63493-10844.html


many many dollars.


w.