Richard Harrison wrote:
Pete wrote:
"So now my logical question is why are the FM whip antennas even
extendible if they play better fully collapsed?"

Length is adjustable to tune the antenna to resonance so that excess
reactance does not block too much signal from the receiver. Resonance
depends on the station you want to receive.

Wavelength = 300 / MHz

At 100 MHz, wavelength = 3 meters

If the best antenna length were 1/4 wavelength, length would be about
0.75 meter = 75cm/2.54cm/in.= 29.53in. which may be shortened by 5%
for "end effects" which calculates to about 28 inches for a 100 MHz
station. Higher frequency stations may require shorter lengths and
lower frequency stations may require longer lengths. We don`t know
the design of the radio and what inherent reactance may reside
inside. So, we really don`t know how long the adjustable antenna
needs to be.
It is far better to experiment with the length of the antenna to get
the best results.

Some radios use the same antenna for several bands of a multiband
tadio. So adjust the antenna if necessary for best results.

Best regards, Richard Harrison, KB5WZI

Thank you Richard. I understand what you said. This was a lower to mid
frequency station (97.5 MHz), and it required a shorter length, but other
stations right next to it came in fine at a longer extension. This is weird
stuff, and its obviously dependent on the radio guts and what is going on
with that one station as far as location and power, etc. It is refreshing
to be in a newsgroup where people are helpful, and not condescending and
vulgar like so many others if you know what I mean. Thanks again to you
all.

Pete