National Radio SW3 & SW5 Unwound
Coil Forms
I BROUGHT THEM BACK!!!!
I was making these coil forms in the past, but due to low demand I stopped
making them. After getting numerous requests, I have decided to see what kind
of demand there is and brought them back.
If demand is good I will keep them going. If not I will not make anymore.
Now you can
buy one of those National Radios even though it doesn’t come with the coil
forms.
These are exactly like the original, including the slot for the tickler
windings.
The National SW3 & SW5 all share a coil design identified by three independent windings (Primary, Secondary, and Tickler) and a unique 6 pin base. This 6 pin base is unlike that of a regular 6 pin tube socket.
There were six coils for the radio that allowed coverage
from 1.50-MHz to 33.3-Mhz.
Coil 1 (115 to 200 meters
(1.5-2.6MHz)
Coil 2 (65 to 115 meters
(2.6-4.6MHz)
Coil 3 (40 to 70 meters (4.3-7.5MHz)
Coil 4 (21 to 41 meters (7.3-14.3MHz)
Coil 5 (14.5 to 25 meters (12-20.7MHz)
Coil 6 (9 to 15 meters (20-33.3MHz)
A datasheet of the coil winding information will be included.
I have been building the classic 4, 5, and 6 pin coil forms for some time now with great success. Customers all over the world have been very satisfied with them. Many sold on Ebay with comments saying they are of high quality and work great.
You have to
wind your own coils with this plug in coil form. It is made from Grade XX
Garolite (Phenolic). Garolite is superior to Bakelite and it works flawlessly.
The forms are equipped with a rim as well, making it easy to insert and pull
out.
Coil measures 1-1/2" Diameter X 2-1/4"H (+/- some). Exclusive of the
pins.
This is a specialized coil form for the National Radios only. It does not fit
in any standard tube socket.
The coil form will plug into a National 6 pin socket as shown in the photos.
Socket is not included.
It is shown for identification purpose only.
I personally build these by
hand, one at a time in a regular home workshop!!
There is no fancy machine shop involved, no fancy CNC equipment used.
Each piece is handcrafted from
various pieces of Grade XX garolite (phenolic).
They are very time consuming to build, but still lots of fun to make anyway.
The pins are the exact same size pins used in the original National coil Forms.
By no means am I getting rich
on selling these. There is a lot of labor involved in building these. Each one
has to put on a lathe so the tickler slot can be cut out. The holes have to be
carefully drilled using a specialized custom template jig I designed and built.
Each pin and the rim is glued in place piece by piece. In addition to the
intense labor, there is the cost of the garolite, the pins, and the special
glue and of course, the Ebay fees.
To use it, just wind the wire
(usually magnet wire,) around the form following the chart for the number of
turns, drill a small hole where you leave off and feed it through the center
down to the pins. Then just solder the end of the hollow pins. To keep the wire
from unraveling, apply some clear polyurethane or clear nail polish. When
drilling the holes for the tickler coil, drill in the cutout or above. Do not
drill below the tickler cutout!!
Now you can finally buy of those old National radios you have seen on Ebay, Marketplace,
or one of the many radio shows but didn't because the seller didn't have the coil
forms for it.
4, 5, and 6 Pin Coil Form also available in my Ebay store. Look under coil
forms.
You will love these coil forms.
Listing is for one (1) piece.
I have compiled the information from personal experience, talking to owners of
the radios and from information I found on the internet. If any of the
information in this listing is incorrect or can be added to, I would appreciate
if you would share it so I can pass it on to others.
As in all my
listings, I combine items to save you on shipping costs.
Be sure to request an invoice if you are buying several coil forms so I can
adjust shipping costs.
Check out my other ebay listings.
Tube Socket is not
included. It is shown for identification purpose only.