Detector for a crystal radio

[kd8dey]

In the old FT 225 RD ( 2 meter all mode) i used them to replace the 1 diode AM rectifier by a 2 diode rectifier for Am.
Worked like a charm.
In the FT 847 i replaced the bandswitch diode ( universal switching diodes a la 4148 type, with the Schottky ones.
Less noise, lower distortion.
Need some? ;)

I wouldn't mind trying some.
Maybe try it out in a crystal radio or see what difference they make in a Cobra 29 I fixed and had been trying to sell. where else would they work good at besides band switching & detectors?

[kb2vxa]

OH POOH! How can you call it a crystal set without a crystal? Modern diodes are grown junctions, hardly authentic. You can go the way I did, tinker together a point contact crystal detector with anything you can use as a whisker, a small sewing needle will do. Dig a few lead weights out of your tackle box, an old bottle cap (probably lying in the bottom of the box) and find yourself a chunk of galena and you're all set. Smack the galena with a hammer to expose a fresh surface and pot it in lead using the sinkers and bottle cap, you'll end up with something that looks like this only cheesier but who cares as long as it works?

[KG4CGC]

OH POOH! How can you call it a crystal set without a crystal? Modern diodes are grown junctions, hardly authentic. You can go the way I did, tinker together a point contact crystal detector with anything you can use as a whisker, a small sewing needle will do. Dig a few lead weights out of your tackle box, an old bottle cap (probably lying in the bottom of the box) and find yourself a chunk of galena and you're all set. Smack the galena with a hammer to expose a fresh surface and pot it in lead using the sinkers and bottle cap, you'll end up with something that looks like this only cheesier but who cares as long as it works?

+ 100 internets.

[NQ6U]

Raw galena crystals large enough to supply detectors for a dozen radios can be had on eBay for around ten bucks. I might buy one myself--I'm trying to get the male grand-rodent interested in ham radio while he's still in the impressionable stage.

[PA5COR]

I'll pop some off to you this week.
You can make diode mixers with them, they will work up into the Ghz area depending on the specific diode.
Any place a germanium diode is used they have their place.
Due to their lower on voltage, i used them in audio limiters i made, where the diode acts as rectifier element to make the voltage to limit the audio.
A normal silicon diode has between 0.6–1.7 volt drops[1], while a Schottky diode voltage drop is between approximately 0.15–0.45 volts. This lower voltage drop can provide higher switching speed and better system efficiency.
A typical application of power Schottky diodes is discharge-protection for solar cells connected to lead-acid batteries.
And yes, when i was 12 i used a dirty razorblade and pointed wire for my first chrystal radio... for lack of money.
Been there, got the T shirt, and moved on ;)

The switching time is ~100 ps for the small signal diodes, and up to tens of nanoseconds for special high-capacity power diodes. With p-n junction switching, there is also a reverse recovery current, which in high-power semiconductors brings increased EMI noise. With Schottky diodes switching essentially instantly with only slight capacitive loading, this is much less of a concern
Schottky diodes are useful in switch-mode power converters; the high speed of the diode means that the circuit can operate at frequencies in the range 200 kHz to 2 MHz, allowing the use of small inductors and capacitors with greater efficiency than would be possible with other diode types. Small-area Schottky diodes are the heart of RF detectors and mixers, which often operate up to 50 GHz
http://en.wikipedia.org/wiki/Schottky_diode
Small signal Schottky diodes like the 1N5711, 1N6263, 1SS106, 1SS108 or the BAT41–43, 45–49 series are widely used in high frequency applications as detectors, mixers and nonlinear elements, and have replaced germanium diodes, rendering them obsolete. They are also suitable for ESD protection of ESD sensitive devices like III-V-semiconductor devices, laser diodes and, to a lesser extent, exposed lines of CMOS circuitry.
For the rest look there.
http://www.radio-electronics.com/inf...rier_diode.php
Good place if you are interested in the theory.

I wouldn't mind trying some.
Maybe try it out in a crystal radio or see what difference they make in a Cobra 29 I fixed and had been trying to sell. where else would they work good at besides band switching & detectors?

[kd8dey]

Thanks, I'll be looking for them to give them a try.

[N8YX]

At one time, HP offered hot-carrier diodes which are the functional equivalent of a BAT85. I have a bunch of 1N5711s and have used them for such things as ring mixers, filter switching and similar RF applications.

Next big project is to match up a bunch of quads then go after all of my 7-line stuff which uses 1N4148s in mixer duty. I did that to several of my FT-90x series rigs. Which, incidentally, used 1SS61, 1N60 and similar germanium components. Ergo, I have a few if you folks need them.

[KC2UGV]

At one time, HP offered hot-carrier diodes which are the functional equivalent of a BAT85. I have a bunch of 1N5711s and have used them for such things as ring mixers, filter switching and similar RF applications.

Next big project is to match up a bunch of quads then go after all of my 7-line stuff which uses 1N4148s in mixer duty. I did that to several of my FT-90x series rigs. Which, incidentally, used 1SS61, 1N60 and similar germanium components. Ergo, I have a few if you folks need them.

Let me know how many green backs to send your way, and I'd could use a couple :)

[N8YX]

Let me know how many green backs to send your way, and I'd could use a couple :)

I still have to test that PK-232 - if you want it.

Just cover the shipping of that unit and I'll throw a few diodes in the box.

[WØTKX]

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