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At 11:30 AM 7/28/97 +0000, you wrote:
>Does anyone care to tackle why my car AM radio seems to suffer from 'front 
>end overload' from WPZE in most of that area, or 1430 or 1090 (depending on 
>how close to those antennas I am)?  I know the phenomenon exists in FM 
>tuners, but I didn't think it happened on AM.  I can faintly yet clearly 
>hear 590 or 1090 under WBZ or any of the other AM stations when I'm within, 
>say, a quarter-mile of these. 
It absolutely does happen on AM, and different radios are susceptible to
different degrees. Moreover, the sensitivity of any individual radio
probably depends somewhat on the frequency to which the radio is tuned. I
live in Arlington, just north of Route 2 and just east of the Lexington
line. WNFT is less than one "airline" mile from my house; WNRB is 2.1
airline miles away. WRKO, which is between 5 and 6 miles away may actually
put the strongest signal over my property. In any event, as I drive west on
Route 2 past the WNFT site with the car radio tuned to WADN, WADN's signal
first seems to drop off in intensity (the place where that happens depends
on which car I'm using, and, of course, which pattern WNFT is running--the
radiation to the north and west is considerably less at night). Then, I
start to hear WNFT. Then the WNFT signal becomes louder and the distortion
becomes worse. Finally the radio conks out completely and, until I get to
the opposite side of the axis of the towers, I can't hear anything unless I
tune elsewhere on the dial. When the reception returns, I'm listening to
WADN again, with a little WNFT in the background, and obviously, a weaker
sounding signal than I ought to get. That problem clears up if I drive
another 0.1 mile or so along Route 2.

The points where these effects occur are quite different if I drive east
from 128 along Route 2. Obviously, there is a hysteresis effect. Once the
front end of the radio saturates, the signal strength has to drop
substantially below the level at which the effect first appeared before it

WNRB interferes to some degree with WXKS as I drive along School St in
Watertown, and Common St, which is the continuation of School St in Belmont.
these streets are about a mile east of the WNRB TX. Usually, it is
impossible to hear WQEW New York at night as I drive along School and Common
Streets from about Church St in Watertown to Pleasant St (Route 60) in
Belmont. And WQEW does not come in normally until I approach the top of
Belmont Hill. However, the effect is nonlinear. If the skip is particularly
good, WQEW can "break through" the stauration effect, and I hear it more or
less normally.

As to the situation around Wellington Circle, you aren't talking about
WPZE--that's the station on 1260 with TX on the Quincy-Milton line. You're
talking about WEZE (590). All three stations that you write about, WEZE,
WILD, and WXKS, are 5 kW. (WXKS is 1 kW at night--when they remember to cut
their power.) WEZE is directional. WILD is ND. So is WXKS by day. So, WEZE's
signal is stronger than WILD's or WXKS's signals in certain directions
(north and south of the TX). To the west, WEZE puts out the equivalent of
only about 400W. I'm not surprised that WEZE doesn't splatter as much as the
other two stations, but the way your radio behaves is probably also a
function of the station's frequency. Moreover, you need to learn to
distinguish between splatter (which is the station's fault) and lack of
selectivity and immunity to front-end overload (which are the radio's
fault). Splatter manifests itself as scratchy sounds that show up on the
adjacent channels in synchronism with modulation peaks on the interfering
station. Lack of selectivity causes you to hear the program of the
interfering station, more-or-less undistorted, on adjacent channels. I've
already described the effects of front-end overload in painful detail
earlier in this message.

- -------------------------------
Dan Strassberg (Note: Address is CASE SENSITIVE!)
ALL _LOWER_ CASE!!!--> dan.strassberg@worldnet.att.net
(617) 558-4205; Fax (617) 928-4205