Crystal Shortwave?
 

I apologise if this is not the proper group, and will greatly appreciate
direction to the proper one.

I have just gotten into crystal sets after years away from the electronics
feild (studied at Nuke ET "A" School and FC "A" School in the Navy in
1995-1996).

I would like to build the EconOceanic at
http://antiqueradio.org/econmain.htm but the plans call for a dual vari-cap
from an old superhet (using the RF section and Oscillator sections
seperately to tune through the five coil pairs.) But I cannot find this
vari-cap anywhere!

Here the designer shows the coverage of the various circuits in a graph. I
am quite rusty (I never really worked on Comm equipment, I am a gunfire
control technician by training) but if I understand this, I should be able
to tune all but the lowest frequencies (.50-.75 or so) without the RF
section cap (40-460pF). Again, IF I COMREHEND THIS PROPERLY, I should be
able to substitute a single 365pF vari-cap for the oscillator section,
ommitting the higher RF cap section, and tune all but the lowest BC
frequencies.

This is fine by me since I live five miles from WSB, the local blowtorch
transmitter siting at AM 750.

I just wanted to run my plans by the experts before I wind the two biggest
coil pairs for this radio.

If someone wants to take the time to answer, even via email, I'll be happy
to figure out how to ship a 6-pack of homemade apple cider in appreciation.

Alternatively, if someone can reccomend a different radio schematic that can
tune 5810, 5850, 9955, 9975, and 13615, that too would be appreciated.

(The above freqs are for EWTN broadcasts throughout the day and night.)

Thanks

Franklin Jennings
Atlanta,GA

Franklin Jennings wrote:
I apologise if this is not the proper group, and will greatly appreciate
direction to the proper one.

I would like to build the EconOceanic at
http://antiqueradio.org/econmain.htm but the plans call for a dual vari-cap
from an old superhet (using the RF section and Oscillator sections
seperately to tune through the five coil pairs.) But I cannot find this
vari-cap anywhere!



This is fine by me since I live five miles from WSB, the local blowtorch
transmitter siting at AM 750.


Alternatively, if someone can reccomend a different radio schematic that can
tune 5810, 5850, 9955, 9975, and 13615, that too would be appreciated.

(The above freqs are for EWTN broadcasts throughout the day and night.)

Hi,
I'm a crystal radio fanatic. First I'd recommend checking in with the
guys at http://www.midnightscience.com/rapntap/

I see two bigger problems than finding the cap. With WSB 5 miles away
you are going to literally be swamped with RF and may not be able to
hear much SW at all. Secondly, hearing ANY SW on a crystal set is kinda
hit and miss in the best of circumstances. The signal needs to be VERY
strong and remember that you'll have very little selectivity.

As for finding the cap...just find an old $2 plastic clock radio at a
yard sale or Goodwill store.

There's some guys on Rap-n-Tap who could probably get into more detail
about a xtal shortwave set. I built one once - with an audio amp - and
yes I heard some wispy traces of SW signals. Its anybody's guess what
frequency - or even what band - they were on.

I'd recommend building something like a 2-tube regen set - or even a one
tuber using something like a 6SN7 (dual triodes). On the same site
where you found the xtal plans I think he also has a 2-tube Doerle
receiver. Thats a good performer and if you're not into vintage tubes
thats where you can replace the two #30s with a 6SN7 or even 12AU7.
You'll find lots of these project on the web.

Good luck and see you over on R-n-T.

-Bill

Franklin Jennings wrote:

I apologise if this is not the proper group, and will greatly appreciate
direction to the proper one.

I have just gotten into crystal sets after years away from the electronics
feild (studied at Nuke ET "A" School and FC "A" School in the Navy in
1995-1996).

I would like to build the EconOceanic at
http://antiqueradio.org/econmain.htm but the plans call for a dual vari-cap
from an old superhet (using the RF section and Oscillator sections
seperately to tune through the five coil pairs.) But I cannot find this
vari-cap anywhere!

Here the designer shows the coverage of the various circuits in a graph. I
am quite rusty (I never really worked on Comm equipment, I am a gunfire
control technician by training) but if I understand this, I should be able
to tune all but the lowest frequencies (.50-.75 or so) without the RF
section cap (40-460pF). Again, IF I COMREHEND THIS PROPERLY, I should be
able to substitute a single 365pF vari-cap for the oscillator section,
ommitting the higher RF cap section, and tune all but the lowest BC
frequencies.

This is fine by me since I live five miles from WSB, the local blowtorch
transmitter siting at AM 750.

I just wanted to run my plans by the experts before I wind the two biggest
coil pairs for this radio.

If someone wants to take the time to answer, even via email, I'll be happy
to figure out how to ship a 6-pack of homemade apple cider in appreciation.

Alternatively, if someone can reccomend a different radio schematic that can
tune 5810, 5850, 9955, 9975, and 13615, that too would be appreciated.

(The above freqs are for EWTN broadcasts throughout the day and night.)

Thanks

Franklin Jennings
Atlanta,GA


http://www.tubesandmore.com

There are plenty others if you dig a bit.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Franklin Jennings wrote:
... I would like to build the EconOceanic at....

-ex- writes:
.... Secondly, hearing ANY SW on a crystal set is kinda
hit and miss in the best of circumstances. The signal needs to be VERY
strong and remember that you'll have very little selectivity.
....[snip]....

Unless something has really changed, you shouldn't be so negative about
hearing SW on a crystal set.

About 1958, on a simple xtal set (antenna, coil, capacitor, diode, phones)
although I don't remember the exact stations (Quito and Radio Moscow?), I
do remember hearing LOUD shortwave signals. At the time, my antenna was
the top strand of a barbed-wire fence on wooden posts (length UNknown,
but probably less that a couple-hundred feet) and the ground was the guy-
wire to our house's power pole.
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

I see two bigger problems than finding the cap. With WSB 5 miles away
you are going to literally be swamped with RF and may not be able to
hear much SW at all. Secondly, hearing ANY SW on a crystal set is kinda
hit and miss in the best of circumstances. The signal needs to be VERY
strong and remember that you'll have very little selectivity.store.

Build a tuned circuit for WSB and use the voltage generated as the power
supply for a transistor amplifier for your SW listening.
You will find info on the web.
Mike

Build a tuned circuit for WSB and use the voltage generated as the
power
supply for a transistor amplifier for your SW listening.
You will find info on the web.
Mike




That's a great concept.... I'd like more specific info on WEB sites.
Can't quite figure what to type in the Google search box for this.


Ed

"Ed" wrote in message
3.175...

Build a tuned circuit for WSB and use the voltage generated as the
power
supply for a transistor amplifier for your SW listening.
You will find info on the web.
Mike


That's a great concept.... I'd like more specific info on WEB sites.
Can't quite figure what to type in the Google search box for this.
Ed

I looked for a while and found many dead sites. I did find this one, this
guy has done some serious research on crystal radios.
You might recognize the name.
http://www.bentongue.com/
Look at #25

I looked for a while and found many dead sites. I did find this one,
this
guy has done some serious research on crystal radios.
You might recognize the name.
http://www.bentongue.com/
Look at #25



Great! That site I had missed in my searching. Probably my best
reference, now. Thanks.



Ed

Ed wrote:
Build a tuned circuit for WSB and use the voltage generated as the
power
supply for a transistor amplifier for your SW listening.
You will find info on the web.
Mike





That's a great concept.... I'd like more specific info on WEB sites.
Can't quite figure what to type in the Google search box for this.


Ed


Here's a couple...

http://www.scitoys.com/scitoys/scito...ade_radio.html

http://www.midnightscience.com/


Have fun!

John