OT (?) -- AM radio reception - bad reception.

[Jim McLaughlin]

I have two pretty fancy receivers here in the house --- one a one year
old big honkin' Sony with FM and all sorts of home theater stuff, which is
in the family room in the daylight basement.

The other is an older (10 years or so) Onkyo,

Both work great on the FM side of the radio spectrum.

Neither works well ( actually, piss poor) on the AM side with lots of
pops, crackles and hisses. It actually grates on the ears. Both have
digital tuning mechanisms so that on the AM side I can hit the exact
frequency (e.g. 550) or 5 khz up or down from the frequency (e.g. 555, 560,
545, 540). Same thing with 860 or 109, etc.

Both have the "T" shaped antenna made out of twin lead 300 ohm wire
attached to the AM antenna screw on connectors.

I have a really cheap Rat Shack battery powered AM / FM combo that gets
great AM reception. It has one of those 6 inch or so telescoping rod
antennas on it. Nowhere as long as the antenna wires on the Sony or the
Onkyo.

With the power outage here in SW PDX yesterday I used the portable for
info on what was going on.

Using the portable brought up the questions ---

Why do the big honkin' receivers get great FM reception and crap AM
reception?

Why does the cheap battery portable get really good AM reception?

What if anything reasonable can be done inexpensively to improve the
AM reception on the big honkin' receivers?

Any ideas?

Thanks.

[N7RX]

Could be a bunch of things:

- The fancy receivers might be too fancy - there's lots of high power AM
radio waves floating around the metro area and your receiver front end
might be overloaded and "desensitized" where the dumber and deafer
portables are not overloaded; This is the most likely problem - I'd
disconnect the long wires from the AM antenna. The dipole is only needed
for FM.

- The little magna-bar antenna on the fancy recievers could be oriented
poorly with respect to stations you're trying to hear. Similarly, they
could be coupling with a local noise source.

- Could be a case of the fancy receiver doing a little bit of
everything, but nothing well. The portable is designed to only one thing;

- The fancy receivers just plain suck.

[Bryan McGivney]

It's all about the antenna! The T shaped antenna you describe is a dipole
antenna made for FM reception. The old receivers I have both have an AM
antenna on the back. I am talking about mid to late 70's Marantz and H/K.
Both get acceptable AM reception. The H/K has uncannily good FM reception
but only after I researched antenna design on the internet a bit and made my
own antenna. I made a simple dipole antenna out of a broken extension cord.
If you really want good AM reception I suggest you invest some time or money
(which ever you have more of) in an antenna designed for AM reception.

Good Luck,
Bryan
Durham, Oregon.