Americana "last gasp" AM only transistor radio

[ctc17]

FM is transmitted horizontally polarized like TV, so your antenna should be 'flat'. Generally with low power FM stations they use yagis so they can direct the signal exactly where they want it to go.

With am the big stations use 2 or 3 vertical antennas and can direct exactly where they want the main radiated lobe to go by phasing the antennas. Sense it skips all over the place, polarization doesnt matter. The general rule is bigger is better. All the ferrite rod does is makes the coil appear much larger than it really is.

Im not saying that that the front end and IF doesnt affect it, but antenna is the majority.

I have noticed some degradation with KNX, our local CA powerhouse that any radio, even you teeth could pick up at night through CA, NV, AZ on and on. I figured they just cut their power back trying to save money because of the economy.

[jr_tech]

Originally Posted by ctc17

FM is transmitted horizontally polarized like TV, so your antenna should be 'flat'. Generally with low power FM stations they use yagis so they can direct the signal exactly where they want it to go.
I have noticed some degradation with KNX, our local CA powerhouse that any radio, even you teeth could pick up at night through CA, NV, AZ on and on. I figured they just cut their power back trying to save money because of the economy.

Many full power FM stations now use circular polarization, in an attempt to provide a better signal to automobile radios and table radios that use "line cord" antennas, so orientation of the line cord or headphone cord in this case, may not be as critical as it once was.

According to the FCC website, KNX still transmits at 50KW.

http://www.fcc.gov/fcc-bin/amq?list=0&facid=9616

Perhaps their ground system has degraded over the years?

jr

[ctc17]

Originally Posted by jr_tech

Many full power FM stations now use circular polarization, in an attempt to provide a better signal to automobile radios and table radios that use "line cord" antennas, so orientation of the line cord or headphone cord in this case, may not be as critical as it once was.

According to the FCC website, KNX still transmits at 50KW.

http://www.fcc.gov/fcc-bin/amq?list=0&facid=9616

Perhaps their ground system has degraded over the years?

jr

Interesting, the antennas for KNX are located in a public park where all the local soccer teams meet. Its says the phase angle is 0 so I wonder if their just broadcasting omni.
Interesting stuff.

[jr_tech]

Originally Posted by ctc17

Interesting, the antennas for KNX are located in a public park where all the local soccer teams meet. Its says the phase angle is 0 so I wonder if their just broadcasting omni.

I appears that they are only using one tower, so it would be non directional (ND-1 is shown). If you check the "ASRNs within .5 km" list, it appears that there are 2 nearby towers that are owned by CBS, perhaps these were used at one time to provide a different pattern day- to -night.

jr

Update... Scott Fybush to the Rescue....He says that in the late 50s CBS experimented with a directional array...but it did not work out:

http://www.fybush.com/site-020313.html