Silver-Marshall Model 730
Round-the-World
Four
Homebrew Regenerative Shortwave Receiver
This is my version of the Silver-Marshall
Model 730 receiver. It was also known as their "Round-the-World Four". It
is a shortwave regenerative receiver that was sold as a kit but also popular
with homebrewers of the late 1920s. John Dilks has a good write up and links to some of the original
documentation.
The radio was available with a metal cabinet for shielding but one of the
unusual features was that the chassis was mounted upside-down. This was
done to allow access to the plug-in coil on top of the set via short inconnecting
leads. I built mine this way originally but quickly realized that this was
a real pain to work with so I flipped my panel and did it the conventional
way.
The plug-in coil (seen as an old
tube base) is easily accessible via the hinged lid.
Here's a photo of the chassis layout.
This is a wonderful receiver. Very solid and consistent regeneration,
quite stable and more than ample audio power. Plenty capable of driving
a speaker and as an afterthought S-M should have included some means of volume
control and/or interstage phone jacks.
...
10 Oct 2007
