please explain the history of AC and DC power use in postwar S scale ?

Not sure about the marketing, but the DC only locomotives had a DC stamped on the cab right after the number, as in "322DC." 

I think the DC locomotives was due to shortages during the Korean War. (Might be wrong on this.)

Rusty

That's great information, Thanks Very Much! 

It mentions a special rectifier tube that changed color from red to blue when under load. That sounds pretty cool for 1940's technology.

The reason for discontinuing DC was due to the shortage of Alnico 5

due to the Korean war. HO trains were all discontinued. Some small manufacturers

may have been allocated small amounts, but not Gilbert.

Herb Wasserman

There were also no really good/powerful/cheap rectifiers in the late 40's and early 50's. Flyer made some with gas tubes and some with selenium rectifiers. Good/cheap/reliable silicon diodes had not been introduced yet.

We had one DC Gilbert engine. In 1955 we (my dad) bought a selenium disc full wave bridge rectifier rated 4A. It is 2"x2"x4" and was not cheap at the time. The tubes in the Gilbert DC power supplies were also expensive to replace if needed.

Just for information, the 332 engines in 1947 were DC and not marked on the cab. In 1950 an uncatalogued 332DC engine was made. The cataloged 1950 engine was a 334DC which was also made. In 1948 and 1949 332 engines were made with either DC or AC motors.

342 engines made in 1947 and 1949 were DC. In 1948 a 332 could be either AC or DC. A 342DC was made in 1948, 49 and 50. No further DC engines were made by Gilbert after 1950.

I have a 332DC I haven't run in decades that I built a bridge rectifier for with a directional switch from Radio Shack parts. It ran really well. It was around 1981. I remember the dealer at the show asking me if my girlfriend was a model. We've been married 30 years and she still looks pretty good. And yes Ace it has the permanent magnet field coil.

Thank you all for the comments and info. We really take cheap solid-state rectifiers for granted in modern times.

I've wondered if others have converted these old series motors for DC track power? I'm really happy with the quiet operation of my AF#372 GP7 and the convenience of positive remote reversing with DC track power, like the smaller scales.