AM tuner - build or buy ?

[Freq Band]

I have an FM only tuner..........I want AM as well.
I am not going to replace my Luxman T110 FM only analog tuner...I am too fond of it.
I already have a portable palm-sized AM/FM radio, that I source through the headphone-out (into my preamp/amp), but that relies on the interconnect as the antenna, resulting in poor reception.

Is it possible to build a "higher quality" AM band receiver, than I can buy?

There are a lot of diy AM "first timer" projects out there, although I'd like to shoot for quality.

The info in this article is very interesting:

(see highlighted paragraph too !! )

Article

Any suggestions welcome.

=FB=

 

[mikka]

Fisher on eBay

 

[NewYorkDave]

The cheap GE "Super Radio" has a surprisingly good AM front end, and a headphone output which you can use to connect to your system. The "slide rule" tuning is kind of a bummer, but you really can't beat it at that price.

 

[PRR]

> I want AM

WHY???

I'm not just being wise-ass. In most civilized areas, AM radio means major compromises. What you want AM for determines what the radio must do.

As sad as they are, the general run of $2 AM radios do about as good a job as is possible. You need some special situation to do better.

If you are "close" to a strong station, a wide-band AM tuner can reveal a spectacularly faithful reproduction of what they put in the transmitter. Much more treble than you expect. Can't avoid the fact that most AM today is grossly over-compressed. That's the only way they can keep their business going.

If you are far out in the desert, and want to pull Denver or L.A., you want a decent antenna, ample gain, and lots of selectivity, to the point that you don't hear anything over 3KHz.

If you are near town, and "your" station is not very much stronger than others, about the best you can do is a little gain and a LOT of filtering to knock the crap down. Any non-junk $2 radio will do that. (Yes, there's some real junk on the market.)

I spent several years tweaking on a golden-age Stromberg-Carlson.

In my suburban area, antenna and gain were non-issues: a loopstick or 2 feet of wire pulls-up more noise than you know what to do with.

Wide-band opens up the treble, but also opens up monkey-chatter from every adjacent-channel station in the US and Canada (and Mexico too, if the Canadians weren't overwhelming Mexico in my area).

And you can't avoid the fact that AM does not lock to a signal(*), so you get every same-channel station underneath the one you want. (There are no "clear channel" allocations any more: one former clear-channel broadcaster in NYC now has 17 other western hemisphere stations on the same channel, from 25 watts to 25KW.)

(*)Actually, a synchronous detector can give some AM lock-in. My father the old-time radio geek didn't believe it at first, because sync-det was just way-difficult back when AM was king. It is still a very difficult problem. The only practical answer is a chip. Maybe someone has done that. I notice that none of the marketed radio chips do anything fancier than ceramic filters and a buffered detector.

> Is it possible to build a "higher quality" AM band receiver, than I can buy?

If you have a Strong Local Station, a crystal radio will give great results, and is certainly a DIY thing. Understand that most listeners don't want quality, so the broadcaster hammers-up the sound to stop them in their tracks. You'll mostly hear how modern broadcast limiters can slam everything into a 3dB dynamic range without getting fuzzy.

A TRF with a large (10 foot) loop can give sharp sound a bit further out, but parts for a TRF are hard to source. If there is ONE station you want, it is maybe doable. But tuning a 3:1 band is hard work even if you can find the gang-caps.

People DIYed superhets, but it seems to be a lost art. And certainly you can't get the parts without scavenging a radio, you can't get the good parts without scrapping a good radio, and it is surely easier to fix the radio than re-engineer it.

I've heard the GE and Tivoli are good. These and the Golden Oldies are surely better bets for all-round AM use than any DIY except a crystal set.

 

[Guest]

I use 2 receivers for AM: Collins R-392 in garage, and BC-348-R in bedroom. BC-348 has 915 KHz IF, so I use a transistor radio tuned to 915 KHz as a second IF and AM demodulator. I take 915 KHz from grid of the last IF tube through a capacitive attenuator. Collins is expencive on eBay because of collectors, BC-348 is much cheaper.

 

[Freq Band]

> Why???

(in Los Angeles) talk radio, morning traffic reports,
and this oldies jazz station, that actually sounds old :wink: ...on AM :
http://kkgo.am/music/Features.asp

...oh, and the Plil Hendrie show :
http://www.philhendrieshow.com/Radio/Guests.aspx

....so yes, many many stations in this metro area.

I grew-up about 1/4 mile from a 60k watt AM transmitter :idea: :idea:
.....if I remember correctly, we could walk over to it's surrounding chain-link fence, with a flourescent tube in hand, touch it to the fence, and it would glow.

=FB=

 

[bcarso]

[quote author="Freq Band"]> Why???

(in Los Angeles) talk radio, morning traffic reports,
and this oldies jazz station, that actually sounds old :wink: ...on AM :
http://kkgo.am/music/Features.asp

...oh, and the Plil Hendrie show :
http://www.philhendrieshow.com/Radio/Guests.aspx

....so yes, many many stations in this metro area.

I grew-up about 1/4 mile from a 60k watt AM transmitter :idea: :idea:
.....if I remember correctly, we could walk over to it's surrounding chain-link fence, with a flourescent tube in hand, touch it to the fence, and it would glow.

=FB=[/quote]

I built a crystal set and strung a fairly short backyard antenna when I was around 8 I believe. KMPC was a few miles away broadcasting with 50kW. I would listen with headphones and frequently fall asleep with them on.

They were loud enough that my father, down the hall, would hear this in the middle of the night and get up to find out where in blazes it was coming from.

 

[CJ]

Get yourself an old car radio, maybe even a tube set, and wire it up.
The push buttons are too cool!

 

[PRR]

> in Los Angeles

Then sensitivity and antenna are nearly non-issues. Aside from the univeral earth-made static, cities are full of man-made noise, and also chock-a-block with AM signals. And even in sprawling LA, you can't get very far from a transmitter, or at least you have a choice of nearly equvalent programs from near and very-near towers. A foot of wet macaroni will pull enough atmospheric noise (and signal) to overwhelm the worst input stage's self-noise.

> talk radio, morning traffic reports

Basic AM radio/tuner. You don't need great S/N, except you want enough treble-cut to keep the static down. Any non-junk radio will do.

> this oldies jazz station, that actually sounds old ...on AM

That IS a special case. Do they have Power? Are you within ~20 miles of the tower? Is there an electric train or welding shop nearby? If the signal overwhelms ambient electric noise, you may enjoy a 6KHz bandwidth instead of the 2KC or 3KC that ordinary radios give you.

Gary Owens is still working. Good for him.

KKGO is 20KW day, 7KW night, but uses a 4-tower array so we can't compare it to the old 50KW single-tower transmissions. It seems to be bi-di to favor Bakersfield and avoid Mexico.

> Radio Deluxe with John Pizzarelli

Maybe 15-20 years back, you could drive up and down Rt 22 in NJ and it seemed that either Bucky or John (or both) was playing in every roadside dive.

> grew-up about 1/4 mile from a 60k watt AM transmitter

I wonder what damage that did to us?

If you are in that situation, and like that station, you can get super-clear reception with very simple systems. If bcarso's father heard it, obviously there's enough output from a crystal to feed the Hi-Fi Aux input. At that range there isn't even much need for a tuner: I often used just a couple feet of wire, a crystal, and an earphone. Didn't really need an authentic crystal: we had to have every contact in the telephones cleaned yearly to keep the AM background down.

If you are in that situation, and DON'T want that station, it can be tough to find a tuner with enough front-end tankage and low IMD which will pull-up other stations without contamination from the local monster. Sensitivity is pointless and often bad. A loopstick may help reject the beast.