Vacuum Tubes, Inc.: Vacuum Tubes, Electron Tubes, Radio Tubes, Audio Tubes, Industrial Tubes, Ballast Tubes, Guitar Tubes, Capacitors, Tube Sockets, Tube Testers
   
Last Update 01/31/12
Home_old
Search Results_old
Products_old
Product 1_old
Product 2_old
Product 3_old
Home
test
Search Help
Containers
About Us
About VTI
Tubes we are buying
Catalog
Antique Tube Equivalents
Catalog Download Page
Ordering
General Information
Secure Online Order Form
Order Form Search
Thank You for Your Order
Orders Search
Contact Us
Contact Information
Ask the Expert
Directions
Test
123
Terms of Use
Products
Vacuum Tubes
New Tubes (01A to 6AH7GT)
New1
tesing
New Tubes (6AH9 to 6MV8)
New Tubes (6N5 to 16A8)
New Tubes (16AK9 to 1630)
New Tubes (1631 to 8552)
Vacuum Tubes 1A
New Tubes (8556 to ZM1032)
New Tubes (396A to 5967)
New Tubes (5971 to 8228)
New Tubes (8233 to KU610)
New Tubes (LCF86 to ZM1032)
test
Used, Tested Tubes
Page Test
test
Audio Tubes
New Audio and Western Electric Tubes
Used Audio and Western Electric Tubes
Antique Tubes
Collectible Tubes
New Western Electric Tubes
Used Western Electric Tubes
Sockets, Adapters & Parts
New Manufacture Tube Sockets
New-Old-Stock Tube Sockets
Adapters and Parts
New-Old
Capacitors
Electrolytic Capacitors
500 Volt Silver Mica Capacitors
630 Volt Film Capacitors
1000 Volt Ceramic Disc Capacitors
Ballast Tubes & Delay Relays
Ballast Tubes
Delay Relays
Dial Lamps
Books & Pamphlets
Tube & Tester Literature
Audio Literature
Radio, TV, & Miscellaneous
The Jackson Model 648 Manual
TheCompleteWELibrary
Tube Testers
Our Guarantee
Tubes We Are Buying
Services and Schematics
Tube Tidbits
Substituting for the 7591
Wunderlich Tubes
Octal Tubes and Their Predecessors
RCA Receiving Tube Manuals
Antique Tube Equivalents
Two Digit Types From 1 to 100
The Amazing Crosley Autoexpressionator
An FM Crystal Set
Some Additional 1600 Series Tubes
A Note on Bernie Magers
The Founding of RCA
The Vacuum Tube Situation by Elmer Cunningham
Gold Seal Metal Glass Tubes
Vacuum Tubes Hall of Shame
Fake Single Plate 6B4G
Fake 6JK6
6L6GC False orgin of country
Fake 12AT7 number 1 remarked 5965
Fake 12AT7 number 2 remarked 6414
Fake 12AU7 remarked 5965
Fake 12J5GT remarked 1626
Fake 12SK7 remarked 12SJ7
Fake 45 remarked 2A3
Fake 80 remarked 5W4G
Fake 7581A remarked Russian 6L6GC
Fake 8417 remarked 6Y6GA
Fake 6AJ8/ECH81 remarked 6JX8/ECH84
Fake 6C5G remarked 6L5G
Fake 6SQ7 remarked 6SZ7
Fake 6Y5GT remarked 84/6Z4
1620 mis-marked as 1622
5693 mis-marked as 5963
test
New Tubes (7236 to ZM1032)
side menu test
Transmenu test
test
Fake 12AT7 number 2 remarked 6414
Fake 12AU7 (remarked 5965)
Search Results
Xmod
Site Map
Terms
Privacy
Login Page
testing
Junior Sales Force
Junior Sales Force
Site Map
Admin
Site Settings
Pages
Security Roles
User Accounts
Vendors
Site Log
Newsletters
File Manager
Recycle Bin
Event Viewer
Skins
Languages
Site Wizard
Authentication
Solutions Explorer
Host
Host Settings
Portals
Module Definitions
File Manager
Vendors
SQL
Schedule
Languages
Search Admin
Lists
Host Accounts
Skins
  
Vacuum Tubes, Inc.

Tubes We Are Buying

Vacuum Tubes, Inc.

 We Accept These Credit Cards
Vacuum Tubes, Inc. - Credit Cards We Accept!
Use module action menu to edit content
An FM Crystal Set

An FM Crystal Set

I was reading my favorite internet newsgroup the other day, and the discussion had turned to whether or not it was possible to make a crystal set capable of receiving FM stations. The opinions were varied. Some flatly stated that it was not possible. Others said it was possible, but the circuit was complex. Still others debated whether slope detection or ratio detection would or would not work, with proponents for each side. I do not have a lot of electronic experience, but it was all very interesting to me. It was especially interesting, given that I had seen a demonstration of a working FM crystal set made by my good friend Ed Garner. I have prevailed upon Ed to provide plans for building this crystal set, along with some limited explanation (limited mostly by my ability to understand it). Here is a list of required parts:

1 - Set of high impedence headphones (about 2000 ohms). Do not use crystal phones.

1 - Set of adjustable TV rabbit ears or a pair of metal tape measures.

1 - 1N34 diode

1 - 20 inch length of 3 inch diameter copper sewer pipe

1 - 20 inch length of 0.75 inch diameter copper water pipe

1 - 4 inch by 4 inch square of copper or brass

1 - Variable capacitor, 3 uuf to 20 uuf

2 - BNC coaxial connectors

1 - Coax T connector

1 - Small metal box for detector

1 - About a 6 inch length of solid bus wire

1 - Set of appropriate connectors for your phones

1 - 6 feet to 15 feet length of coaxial cable

* - Coaxial cable end piece connectors as required, or you could hardwire everything

* - Appropriate solder, soldering iron, and tools

MAIN ASSEMBLY:
The main body of the set is a resonant cavity designed to be resonant close to the FM band. Most of the dimensions are fairly critical, and good solder joints are required! During assembly, refer to the diagrams that follow. To assemble the main body, first solder the 0.75 inch diameter tube to the center of the 4 inch by 4 inch base. Prepare the 3 inch diameter tube by adding the tuning capacitor very close to the top. Then add the BNC connector on the opposite side of the tube, with the center conductor 4 inches from the bottom. Drill a hole 1.25 inches below the center of the BNC connector just large enough to pass the bus wire. Make a stiff, flattened "U" with the bus wire from the BNC connector to this hole on the inside of the tube. The bottom edge of this "U" should be 0.25 inches from the inner (0.75 inch diameter) tube, when the cavity is assembled. It is best to test the fit several times before soldering. Once the 3 inch tube is prepared, it is centered around the 0.75 inch tube and soldered in place. Now solder a connection from the variable capacitor to the top of the 0.75 inch tube. Note that the tops of these tubes are left open. The main assembly is now complete.



THE DETECTOR BOX:
Assembly is straightforward as in the diagram. Drill a hole, and add a coaxial connector to one side of the box. Drill the appropriate hole(s) and add the phone plug on the other side. The outer part of the coaxial connector and one side of the phones are connected to the box. A 1N34 diode is soldered to the center of the connector and to the other phone connection.



PUTTING THE SYSTEM TOGETHER:
Attach the "bottom leg" of the "T" connector to the BNC connector on the main tube. Connect the detector box to one side of the "T" using 13 +/- 1 inch of coaxial cable (This dimension is critical). Connect the TV rabbit ears to the other side of the "T" using 6 to 15 feet of coaxial cable (A 3 element yagi can be substituted for the rabbit ears). Plug in the phones on the other side of the detector box, and you are ready to try out the FM crystal set!

Note: the rabbit ears or tape meadures should point 180 dgrees from each other. It is advantageous to adjust them for the intended frequency (distances are from one end of the dipole to the other): 88 Mhz = 63 inches, 100 Mhz = 56 inches, 108 Mhz = 52 inches.
  

(877) 307-1414

jim@vacuumtubesinc.com

1080 Sligh Blvd.  Orlando, FL 32806  

Copyright (c) 2012 Vacuum Tubes, Inc.  | Terms Of Use | Privacy Statement | Site Map | Login
Website by WSI Internet Marketing