Lower AM Band Reception Questions

[Steve Green NEPA]

A week ago I bought an AM-FM-CD player to lug to work on various jobs. It seems I've collected a hundred or so discs of untelescoped air checks and songs in .wav form, and those are far better entertainment than that of the actual live radio.

I'll haul along the Grundig S450, too, at times, to try DX on a break or two. The job is seven big rooms that need painting, and I'm always all alone there overnights (except for this cat that wanders in the always-opened doors and wants some of my little fish steaks on crackers :- )

Thing is : The CD player is seemingly noise-free on the lower AM frequencies. And that's with wall current. I can listen to WFAN's overnight sports guy Steve Somers FAR more clearly than I can on the Grundig. The S450 is a swarm of static below ~ 900 kHz when plugged in.
So, in fact, is the GE Superadio II .
The cheaper Memorex AM-FM-CD is remarkably noise-and-static free.

(Note: this is all wall-current. I don't want to wear down batteries just to hear WFAN or WBT for hours. Batteries are for DX).

So what's with the noise and/or the lack of noise? Why is this so? The cheap AM-FM-CD player obviously didn't give much shrift to the radio portions ; the tuning is ridiculously imprecise and way too fast. Yet, it is so quiet at the low end.

Can the Grundig S450 and/or the GE Superadio II be tuned, or aligned, to eliminate or minimize that racket below 900 kHz ? Or are they simply too sensitive?

(Lol -- the Memorex, despite its name and legacy, doesn't have a casette player!)

 

[frankberry]

It's possible that the CD/radio has very low sensitivity on the low end of the dial an a very narrow IF response.

 

[KB1OKL]

The Super Radio has a directional ferrite antenna for AM, try turning the radio and see if you can eliminate the noise. That way you can tell if it is line noise or not.

 

[Steve Green NEPA]

@ frank and KB :

Not too long ago in a restaurant where I worked, there was an AM-FM radio on the back wall of the food prep room. I mean, it looked like a clock radio someone had nailed to the wall.

Despite flourescent lights all over, roaring electric ovens, microwaves, and the devil-knows-what-else, that radio ALSO was darned good for DX. No noise on AM.
The tuning on it, of course, was ridiculous. You'd just touch the tuning knob a tad and it would go from 1360 to 1520. Then you'd have to backtrack and front-track until you locked in, say, 1450.
The lower band was much the same as on the new CD/Radio. We were listening to a Yankees game when they were on WABC -- very nicely -- in the middle of this miniature Grand Central Station eatery in Pottsville PA.

The Grundig and the GE SR II both have the ferrite bar, but irrespective of the location in the house (seven big rooms) both those radios achieve only a marginally mimimized noise level for about 45 degrees out of the full 360 rotation when you spin them.
The house is also a corner house, which fiendishly is provided two sets of outside overhead power lines, one set of them along the front and the other along the lenghthy side.

As I mentioned, this is not the end of DX for me. I've dealt with power line noise before and I have my CDs. My question was based more on tweaking the 'good' portables somehow below ~ 900 kHz, so they'll behave more like the lousy $29 CD/Radio. I don't suppose that's possible, though, huh?

 

[Schroedingers Cat]

Some radios are never properly aligned. Many cheap AM radio are optimized at the top end to compensate for groundwave differences. The radio on the wall may be next to a metal vent pipe or vertical air duct

 

[boombox]

I'll venture a quick guess -- it may be the way the power supplies are designed.

I have a Superadio I that has a slight AC buzz from the power supply, and has since I got it. It's low level, but it's there. It will also pick up stray household AC noise (like dimmer switch noise, electric motor hash, etc.) through the AC cord and supply.

Unplug it and run off batteries -- noise is vastly reduced or completely gone.

I have a boombox that's much quieter on AC. The boombox obviously wasn't designed as a DX radio, although the radio in it is excellent, and I have used it for DXing.

Of course, it also has a cassette player (which I don't use, I use it for the radio).... It also has a higher audio power output (over one watt) than the Superadio's 600 or so milliwatts, and the power supply is also obviously designed to power a cassette deck as well as the radio section. I think that may be a factor in the noise level reduction.

I'd guess your CD / AM / FM also has higher power output than the Superadio (and probably the Grundig) also. So it's possible the power supply's design may be part of the reason your CD box is noise free.

But like I said, this is just a guess.