What is the max power (dBm) a AM receiver can get in the real world?
 

What is the max power (dBm) a AM receiver can get in the real world?
Let us say the receiver is sitting very close to a station antenna,
the station has the max power FCC permits.

Thanks

In article , (Jianhong Wang) wrote:

What is the max power (dBm) a AM receiver can get in the real world?
Let us say the receiver is sitting very close to a station antenna,
the station has the max power FCC permits.


It would depend a lot on the efficiency of the receiving antenna the
receiver was connected to.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/

What is the max power (dBm) a AM receiver can get in the real world? Let us say
the receiver is sitting very close to a station antenna, the station has the
max power FCC permits.


The "blackout" zone is 1 volt/meter.

Any station, regardless of its power, has such a zone.

Good city service is 25 mV/m.

The area covered by the 25 mV/m signal is a function of frequency, power and
ground conductivity.

In article , Jianhong Wang wrote:
What is the max power (dBm) a AM receiver can get in the real world?

I've stood about a fourth of a block away from the tower array of a
50,000 watt station (WQEW-AM 1560 New York). With a satisfactory
quality pocket transistor radio.

The signal was extremely distorted. Overload.

Couldn't get any closer becasue of the damned fence around the
property.

--
Sven Weil
New York City, U.S.A.

That question is a non-starter. A poorly-designed reciever will probably freeze up
within a mile of a 50kW antenna, while a superb one could likely take several
volts-per-Meter and not even squeal, even when within the tuning house or at the base
of the tower..
--
For direct replies, take out the contents between the hyphens. -Really!-



"Jianhong Wang" wrote in message ...
What is the max power (dBm) a AM receiver can get in the real world?
Let us say the receiver is sitting very close to a station antenna,
the station has the max power FCC permits.

Thanks

"Jianhong Wang" wrote in message
...
What is the max power (dBm) a AM receiver can get in the real world?
Let us say the receiver is sitting very close to a station antenna,
the station has the max power FCC permits.

Thanks

Don't know offhand, but you can have fluorescent bulbs light up near a
transmitter, and you can have a crystal set drive a speaker.

The Raytheon manual on things to do with your CK-722 has a receiver
that uses a crystal set to develop enough DC to run a CK-722 receiver
tuned to the same station.

The obvious improvement is use a crystal set to listen to another
station entirely with the transistor radio.

It sucks a little of the energy out of the local broadcaster, reducing
his antenna pattern, so you can hear a more distant station.
--
Ron Hardin


On the internet, nobody knows you're a jerk.

Bob Haberkost wrote:
That question is a non-starter. A poorly-designed reciever will probably freeze up
within a mile of a 50kW antenna, while a superb one could likely take several
volts-per-Meter and not even squeal, even when within the tuning house or at the base
of the tower..

I think his question is how many dBm would be received at the front end
when sitting at the base of the tower. Not how many dBm can be received
and still use the radio.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

You see, though, it's not dBm for AM radio....it's V/m, since there's no "typical"
impedance associated with the receiving antenna.

And in the end it's still a question of receiver design, anyway. And, worth noting,
is that different antenna designs will have different close-range propagation
characteristics, so that it can't be specifically stated without knowing the antenna.
This is, after all, why the FCC specifies inverse km measurements, and those
measurements are done in far-field conditions.
--
For direct replies, take out the contents between the hyphens. -Really!-


"Scott Dorsey" wrote in message ...
Bob Haberkost wrote:
That question is a non-starter. A poorly-designed reciever will probably freeze
up
within a mile of a 50kW antenna, while a superb one could likely take several
volts-per-Meter and not even squeal, even when within the tuning house or at the
base
of the tower..

I think his question is how many dBm would be received at the front end
when sitting at the base of the tower. Not how many dBm can be received
and still use the radio.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Thank your guys for all your answers. As scott mentioned, I want to
the possible max power (dBm) a receiver can get no matter it works or
not. I know it depends on a lot of things, like receiver antenna
efficiency. But could you give me a empirical number assuming that
reciever's antenna is most efficience in the thoery.

Thanks
(Scott Dorsey) wrote in message ...
Bob Haberkost wrote:
That question is a non-starter. A poorly-designed reciever will probably freeze up
within a mile of a 50kW antenna, while a superb one could likely take several
volts-per-Meter and not even squeal, even when within the tuning house or at the base
of the tower..

I think his question is how many dBm would be received at the front end
when sitting at the base of the tower. Not how many dBm can be received
and still use the radio.
--scott

Why?

And then, as I said, each antenna system is different at close range. It could be
only a volt or two per meter, it could be several tens of volts...close enough, you
might even be able to draw an arc off of the metal pieces.

It's too undefined a question to give you a definitive answer.
--
For direct replies, take out the contents between the hyphens. -Really!-



"Jianhong Wang" wrote in message ...
Thank your guys for all your answers. As scott mentioned, I want to
the possible max power (dBm) a receiver can get no matter it works or
not. I know it depends on a lot of things, like receiver antenna
efficiency. But could you give me a empirical number assuming that
reciever's antenna is most efficience in the thoery.

Thanks
(Scott Dorsey) wrote in message
...
Bob Haberkost wrote:
That question is a non-starter. A poorly-designed reciever will probably freeze
up
within a mile of a 50kW antenna, while a superb one could likely take several
volts-per-Meter and not even squeal, even when within the tuning house or at the
base
of the tower..

I think his question is how many dBm would be received at the front end
when sitting at the base of the tower. Not how many dBm can be received
and still use the radio.
--scott

On Tue, 02 Mar 2004 15:58:39 +0000, Bob Haberkost wrote:

That question is a non-starter. A poorly-designed reciever will probably freeze up
within a mile of a 50kW antenna, while a superb one could likely take several
volts-per-Meter and not even squeal, even when within the tuning house or at the base
of the tower..

Seems like the old Mod Monitors would take 10v.
Usually from a tap in the final amplifer.

Ron

Well, exactly...sortof. I don't think the question is what was the maximum
that any "receiver" would take, as I also considered the various
off-the-transmitter modulation monitors as the top end of that range. What
he's clearly asking is how much RF any given receiver would be exposed to at
close range. But how close? And with what antenna (what wavelength)?
Series or parallel fed? Etc., etc.

The question needs many more parameters to get a hard answer, and that hard
answer is of no significance since the scenario isn't a real-world question.
And the final indication that this is a non-question is the reference to
dBm...for dB, one needs an impedance of the load. AM receiving antennas do
not conform to an impedance, unlike FM and other VHF and up sets that
usually use either 300 or 75-ohm feeds. With those one can take field
strengths and convert them to power....without a corresponding impedance,
the AM question is undefined. And in the interest of the truth (even for a
purposeless question) I wouldn't presume to assume to specify an answer
which has no basis in reality. -- For direct replies, take out the contents
between the hyphens. -Really!-



"Ron" wrote in message ...
On Tue, 02 Mar 2004 15:58:39 +0000, Bob Haberkost wrote:

That question is a non-starter. A poorly-designed reciever will probably
freeze up
within a mile of a 50kW antenna, while a superb one could likely take
several
volts-per-Meter and not even squeal, even when within the tuning house or
at the base
of the tower..

Seems like the old Mod Monitors would take 10v.
Usually from a tap in the final amplifer.

Ron