AM reception with crystal set...

[pianoplayer88key]

Ok, I decided to give myself a bit of a challenge, and built myself a crystal set using an old Radio Shack 200-in-one (and also did it on a 300-in-one) science fair kit I still have.

Basically, I built the crystal set, plus an audio amplifier. However, instead of sending the output to an earphone that came with the kit (which I DO have), I used clip leads to connect to one end of a stereo (I would have used mono if I had one) patch cable. I then plugged the other end into an iRiver IFP-899 mp3 player/recorder I have, set it to record monitor external mic mode, and plugged in my $30 Panasonic headphones to the mp3 player's output jack. For an antenna, I used a Select-A-Tenna, and also tried a longwire.
On both units, I think there's a flaky connection somewhere in the variable (tuning) capacitor, cause sometimes stations would cut in and out as I fiddled with it.
However, when I had it working properly, I was able to receive (from approx 32°46'N 116°57'W, all at night):
600 KOGO
690 XETRA
760 KFMB
800 XESPN
830 KMXE
860 XEMO
910 KECR
950 XEKAM
1040 KURS
1070 KNX
1090 XEPRS (? - heavy adjacent-channel interference from KSDO)
1130 KSDO
1170 KCBQ
1210 KPRZ
1240 KSON
1270 XEAZ
1360 KLSD
1470 XERCN
1530 KFBK (!)
1540 KMPC
1580 KMIK (!) (and KBLA)
1700 XEPE

I was quite surprised at how strong KFBK and KMIK came in, considering it was a crystal set. In the past when I built the same crystal set (although it could have been my antenna), I couldn't hardly hear ANYTHING with it!

Where can I find a digitally-tuned walkman < $25 that, compared to a crystal set with a tuned full-wave longwire antenna cut for the frequency you're trying to receive, is AT LEAST 120dB more sensitive and selective than the crystal set, and still has decent audio bandwidth (for example, if the selectivity is measured at +/-10kHz, it has 5kHz of +/-6dB audio bandwidth, and for selectivity +/-20, bandwidth is 10kHz)?

Also, using that crystal set, is there anyone that could suggest how I could get a good signal (preferably 24/7) on a non-IBOC Radio Disney station? Using my Shockwave, at night I have been able to hear 1110 KDIS (plagued by adjacent-channel interference from 1130 KSDO San Diego), 1240 Albuquerque (local 1240 WAS on the air, but with no modulation), 1290 KKDD (but often has co-channel interference), 1580 KMIK (often plagued by KBLA), 1680 KAVT (usually very weak, some adjacent interference from 1670 KHPY Moreno Valley), and 1690 Arvada/Denver (used to be a regular until Roseville (near Sacramento) signed on). What type of antenna should I set up, and what frequency should I cut it for? I noticed while listening to KMIK on the crystal set that it was VERY high fidelity - like a CD! I assume this was because of the ultra-broad selectivity of the crystal set.
Also I've noticed that KDIS seems to be using 5kHz (or something like it) audio in the daytime during IBOC operation.

 

[PhilJSmith67]

I recently played around with one of those things sold by Cracker Barrel for $9, which consists of a 10ft wire antenna, a high-Z earphone, and a crystal plus tunable coil in a cylinder.

With the "stock antenna" I only could get one station (890 WLS) which is 50k @ 10 miles distance. But, with the antenna connected to long curtain rod, I picked up about a dozen stations very well. The audio quality on some of the stations was FANTASTIC, except for 780 WBBM which was buried in its own HD Radio noise. Wow, that digital hash sure was crisp, though! Made me wish my ears could decode OFDM!

 

[pianoplayer88key]

> I recently played around with one of those things sold by
> Cracker Barrel for $9, which consists of a 10ft wire
> antenna, a high-Z earphone, and a crystal plus tunable coil
> in a cylinder.
>
> With the "stock antenna" I only could get one station (890
> WLS) which is 50k @ 10 miles distance. But, with the
> antenna connected to long curtain rod, I picked up about a
> dozen stations very well. The audio quality on some of the
> stations was FANTASTIC, except for 780 WBBM which was buried
> in its own HD Radio noise. Wow, that digital hash sure was
> crisp, though! Made me wish my ears could decode OFDM!
>

Huh... I couldn't hear KOGO's HD hash... maybe it's because I was checking it at night.

Also, I've noticed that I can tune up past 1700 AM with it, but I can't go much below 600. What do I need to change? Would sliding the antenna coil on the ferrite bar change anything?

Also, is there any way (assuming they're still broadcasting 10kHz analog (but unfortunately not C-Quam) audio, I could pull in KMIK 1580 from Phoenix, 300 miles to the east, in the daytime? There is a 50kW KBLA 1580 in Santa Monica to contend with, and a 1kW 1550 XEBG in Tijuana.
I could hear KMIK just fine a couple nights ago with it.

 

[westlife]

> Also, is there any way (assuming they're still broadcasting
> 10kHz analog (but unfortunately not C-Quam) audio, I could
> pull in KMIK 1580 from Phoenix, 300 miles to the east, in
> the daytime? There is a 50kW KBLA 1580 in Santa Monica to
> contend with, and a 1kW 1550 XEBG in Tijuana.

Of course! Just wave the magic wand you got from Harry Potter, and you can make any radio pick up any signal from anywhere in the galaxy with perfect quality, 24 hours a day!

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