Recent postings about Crystal Radios

on the AMFMTVDX Listserver 


Date: Sun, 16 Aug 1998 13:12:51 -0700
Subject: Re: [AmFmTvDx] Early Morning Loggings on the Xtal Set
From: (ragnar danneskjold)

On Sun, 16 Aug 1998 10:31:23 -0700 (MST) Rick Lewis writes:


>I may be being strange here, but I must say I don't see the value of 
>telling an international list that you're receiving local AM signals 
>available to anyone with a radio. 

Rick, 

I suppose that with your disability you have never seen a crystal set. I
assumed that everyone has and maybe I am wrong in assuming you don't know
after reading your reply.

Let me explain a crystal set. A crystal set has no resistors, no fixed
capacitors, no FET transistors, no amplifier section, no driven speaker,
no volume controls, no RF gain circuit. It uses no battery power or
electric power from the AC circuits in your house. It doesn't even use
sunlight for power. There is virtually nothing in a crystal radio set.

A crystal set consists of only a ground wire, an antenna wire, some high
Z 2000 ohm headphones, and a detector. The detector is either a rusty
razor blade and a graphite pencil lead, a piece of galena rock and a
safety pin, a piece of germanium or germanium diode and a filament wire,
a piece of carborundum from a broken grind disc or grind wheel, or maybe
a piece of iron pyrite stone you picked up from the ground. 

A crystal set is nothing more than a hand tuned coil sometimes with taps,
a 365pf tuning capacitor, the detector and the ground and antenna.
Receiving anything with a crystal set is a miracle in itself. Remember
you are doing this with no battery or AC power. It is real free radio. 

The power for the crystal set comes from the signals sent by the
transmitting station. The crystal set is very weak because it is
unpowered. Believe me, to make a radio out of nothing but wire, a couple
of magnets and a tuning capacitor taken from a broken radio and pick up a
station 44 miles away while the sun is up is a real accomplishment.

There are people who try very hard to do just that, pick up a station 44
miles away with a xtal set. If you can go to www.midnightscience.com or
write to xtalset@midnightscience.com you can see what I mean. Crystal
sets are the precursors to all radio we use today. They are fun to play
with and I actually get lots of replies about the crystal sets. 

I build crystal sets mainly to receive medium wave BCB because my coils I
wound are tuned for it, but I can just as easily wind coils for
shortwave, longwave or even F M believe it or not. 

>Maybe I'm missing something vital here, but I just don't see the point
of
>it. If I had  radio that *didn't* get those signals, I'd throw it away!

Werner Funkenhauser has put much about crystal sets on his A M DX web
site, not just my posts but LOTS of other posts from everywhere from
Canada to Europe. If you had a crystal set that received 44 miles away
during the day, you would be a real happy camper. 

Just remember it is made of rocks and wire, has no external source of
power and gets radio signals for free. Maybe I can let you try out a
crystal set and see for yourself that they work and cost nothing to use.
The other benefit is that they never wear out.

If you already know all this stuff, well, sorry for the waste of all the
bandwidth. Maybe I could build you one?

Ragnar


_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]

---

From: "Bill Harms" 
Date: Sun, 16 Aug 1998 17:07:49 +0000
Subject: Re: [AmFmTvDx] Early Morning Loggings on the Xtal Set
In-reply-to: <19980816.131314.4526.3.lwdxer>


My first real radio was crystal radio that I built with my Dad when I 
was in second grade.  It had a huge earphone that was similar to a 
phone receiver.  I remember that the earphone had a fairly good 
sized magnet wrapped in wire and a steel (tin) plate attached to 
the magnet. The antenna coil was wrapped on a toilet paper roll and 
the crystal was a germanium crystal mounted in a lead/solder disk 
about one half inch in diameter.  all of this was mounted on a 12 
inch by 12 inch - one inch thick piece of pine. With the set I could 
pick up all of my local stations in Spokane and some of them were 
actually in the clear.  On occasion, I heard KGO San Francisco and 
KSL in Utah as well as a station in Seattle KIRO.  The clincher was 
in order to pick up these distant stations, it had to be late at 
night when most of my local stations were off the air.  Remember the 
days when most stations signed off every day?

Bill Harms
http://www.erols.com/wharms/tis/

> Let me explain a crystal set. A crystal set has no resistors, no
> fixed capacitors, no FET transistors, no amplifier section, no
> driven speaker, no volume controls, no RF gain circuit. It uses no
> battery power or electric power from the AC circuits in your house.
> It doesn't even use sunlight for power. There is virtually nothing
> in a crystal radio set.
> 



---

Date: Sun, 16 Aug 1998 15:19:23 -0700
Subject: Re: [AmFmTvDx] Early Morning Loggings on the Xtal Set
From: (ragnar danneskjold)

On Sun, 16 Aug 1998 17:07:49 +0000 "Bill Harms" 
writes:


>My first real radio was crystal radio that I built with my Dad when I 
>was in second grade.  

Those memories are sure nice. Doing things like that are among the things
I like to remember most. I hope I can do the same for my kids.

>It had a huge earphone that was similar to a phone receiver. 

As a matter of fact, the older dial type phone receiving speaker [the
part you put to your ear] have a perfect match resistance wise for a xtal
set. I have used them for this before.

>I remember that the earphone had a fairly good 
>sized magnet wrapped in wire and a steel (tin) plate attached to 
>the magnet.

This is the exact same as my headset.

>The antenna coil was wrapped on a toilet paper roll and 
>the crystal was a germanium crystal mounted in a lead/solder disk 
>about one half inch in diameter. 

I cut off a piece of PVC pipe from the garage for the coil form. I
drilled holes at each end to put the ends of the wire through and put
taps at every 10th turn. I cheated and put a germanium 1N34 diode in
instead of a germanium xtal. I went high tech all the way! 

>all of this was mounted on a 12 
>inch by 12 inch - one inch thick piece of pine. With the set I could 
>pick up all of my local stations in Spokane and some of them were 
>actually in the clear.  On occasion, I heard KGO San Francisco and 
>KSL in Utah as well as a station in Seattle KIRO.  The clincher was 
>in order to pick up these distant stations, it had to be late at 
>night when most of my local stations were off the air. 

Were you in Maryland then? If you were that was some *AWESOME* DX on a
xtal set much less a powered rig.

>Remember the days when most stations signed off every day?

Well at least every week for maintenance on Sun. night or Mon. morning.I
do remember some stations shutting down at 10 or midnight. Those days are
gone. Everyone has two xmitters now.

Ragnar


_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]

---

From: "Jesus Humberto Molina" 
Subject: Re: [AmFmTvDx] Early Morning Loggings on the Xtal Set
Date: Sun, 16 Aug 1998 21:14:59 -0500


Hi All.

Nice coincidence ¡
One of my kids want to make a Xtal set for his school science fair ¡
[ well, i help a little bit in his descision ;-) ]

> >The antenna coil was wrapped on a toilet paper roll and 
> >the crystal was a germanium crystal mounted in a lead/solder disk 
> taps at every 10th turn. 
>I cheated and put a germanium 1N34 diode in

Just the number that we need (1N34), thanks.

A couple of MW antennas on the San Salvador's volcano are visible from 
his school, maybe this help us the day of the demostration.


"saludos" from San Salvador, El Salvador.

Humberto Molina

________________________________________

Salvadoran stations list at:

http://www.Geocities.com/CapeCanaveral/lab/7104
________________________________________


---
From: kjzuk
Date: Tue, 18 Aug 1998 09:48:53 -0400
Subject: [AmFmTvDx] Crystal Sets/Antenna


     A great way to supercharge a crystal set is to use a loading coil 
     between the set itself and the piece of wire you use for an antenna.
     For instance, take a 100 foot piece of wire and string it up to a 
     nearby tree. Put a loading coil between the antenna and your crystal 
     set. For a coil, I've used a 3 or 4 inch diameter piece of white PVC 
     pipe (always use white, black or colors conduct and will short out the 
     coil) and wrap some #12 or #14 contractor grade household wire around 
     it. Drill two holes at each end of the piece of PVC (total coil length 
     maybe about a foot or 18 inches) to thread the wire through so the 
     coil doesn't unspool. Connect one end of the coil to the antenna with 
     an alligator clip, then bare a few places in the coil as taps so you 
     can change the loading of the coil. Connect another alligator clip to 
     the antenna input of the crystal set and move up and down the coil 
     taps to find the best place of resonance. This trick not only acts as 
     a tuned circuit (sort of like the TRF stages of a Superadio) it also 
     maximizes the efficiency of the antenna. Also try your set without a 
     ground. Although the overall strength might decrease, the Q 
     (selectivity) might increase providing sharper tuning. Using a neat 
     Heathkit crystal set made for the bomb shelter years of the late 
     fifties I have logged many states via just a mighty diode and a high 
     impedance earpiece. If you want to cheat, parallel tune a real radio 
     to what you are hearing through the crystal set to verify the 
     station's identity. Above all....have fun. Karl Zuk


---

From: "Bill Harms" 
Date: Tue, 18 Aug 1998 12:40:35 +0000
Subject: Re: [AmFmTvDx] Crystal Sets/Antenna
In-reply-to: <5d986bb0@cbs.com>


I tried something like this with my wedge antenna (a three high - 18 
inch base triangular shaped air-core tuned loop).  It had sharp 
tuning and I could easily differentiate between my locals.

Bill Harms
Elkridge, Maryland
http://www.erols.com/wharms/tis/

>      Although the overall strength might decrease, the Q
>      (selectivity) might increase providing sharper tuning. Using a
>      neat Heathkit crystal set made for the bomb shelter years of
>      the late fifties I have logged many states via just a mighty
>      diode and a high impedance earpiece. If you want to cheat,
>      parallel tune a real radio to what you are hearing through the
>      crystal set to verify the station's identity. Above all....have
>      fun. Karl Zuk
> 
> ---



---

Date: Wed, 19 Aug 1998 20:27:57 -0700
Subject: Re: [AmFmTvDx] Crystal Sets/Antenna
From: lwdxer(ragnar danneskjold)



On Tue, 18 Aug 1998 09:48:53 -0400 kjzuk writes:
>     A great way to supercharge a crystal set is to use a loading coil
>     between the set itself and the piece of wire you use for an
antenna.

My rig already has tapped coils, are you saying that it needs a second
set of tapped coils?

>     coil) and wrap some #12 or #14 contractor grade household wire
around 
>     it.

I always use #14 enameled wire. Its insulated and easy to scrape off for
the taps.

>Drill two holes at each end of the piece of PVC (total coil length 
>maybe about a foot or 18 inches) to thread the wire through so the 
>coil doesn't unspool.

This is exactly the way I wound my coils. I plan also to experiment with
spider web coils.

>Also try your set without a 
>ground. Although the overall strength might decrease, the Q 
>selectivity) might increase providing sharper tuning.

NFG. [No Flippin' Good]

I have found the better the ground the better the signals 100% of the
time. The closer the ground rod is to the set, the better. If the ground
wire is short things always work very well.

>If you want to cheat, parallel tune a real radio 
>to what you are hearing through the crystal set to verify the 
>station's identity.

I have always found that having a xtal set near a powered radio almost
always detunes the powered set and decreases its sensitivity. I don't
know why I have found this to be so, bus strangely enough it happens.

Ragnar


_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]

---

Although we have made every effort to ensure the reliability of our
sources, we do not assume responsibility for their accuracy.
Standard disclaimer applies!


© 2000 Bob's Radio Web