[Boatanchors] National SW-3

[Al Klase]

Bill and Arlene Hooper wrote:
>.... However, this makes me
> wonder if there is anyone out there who can point me to a source of
> information about the differences in versions from the first production to
> the last.....

Hi Bill,

You're right there are articles out there, but I'm not sure
anyone really boiled down the differences, but I'll take a
stab at it:

The differences were the tubes.  As new families became
available, the circuit, primarily the COIL DESIGN was
changed to get better performance. Fundamentally, the series
60 & 70 coils have fewer turns on the tickler coil that the
earlies series 10 & 20.  This is consistent with the use of
higher gain tubes.  The early sets have some slight wiring
difference to account for the various power sources.

So the sets fall into 3 groups:

Early:  SW-3 AC (2.5V), tube lineup 35+35+27; 6DCSW-3 (6V)
36+36+27; 2DCSW-3 (2V) 32+32+30 all use series 10 and series
20 coils

Middle:  ACSW-3 (2.5V) 58+58+56 or (6V) 6D6+6D6+76,  uses
series 60 & 70 coils

Late: Universal SW-3  (6V) 6J7+6J7+6C5 or (1.5V)
1N5+1N5+1A5, uses series 30 & 40 coils

As far as I know, all coils work in all sets to some extent.

See Bill Fizette's article in the August 1993 Old Timers
Bulletin (Antique Wireless Association) 

73,
Al


-- 
Al Klase - N3FRQ
skywaves@bw.webex.net
Flemington, NJ 08822
Web Page:  http://www.webex.net/~skywaves/home.htm