Silver-Marshall/Aluminum Square Case IFs

Silver Marshal Front View

     Silver-Marshall started into the superhet business in the fall of 1924 by supplying an IF module that contained three separate IF transformers.  They changed the design in the spring of 1925 and put the transformers into three separate aluminum cases. A few months later they changed the design again and put the transformers into three bakelite cases.  The separate aluminum cased transformers were only produced for a couple of months so you don’t see superhets using them very often. Here are a few particulars of my Silver superhet:

Silver Marshal Top View
Silver Marshal Inside Angle View
Silver Marshal at 2003 Estes Auction

This is how the set looked at a 2003 Estes auction.

Silver Marshal Oscillator Coupler

     Inside angle view of the set.

Silver Marshal IF Amplifier

Silver-Marshall oscillator coupler.

Silver Marshal Tuning Dials

     The above photo shows a close up view of the oscillator and antenna tuning controls. The small knob at bottom center controls regenerative amplification in the first detector. The knob adjusts a small capacitor that is connected between the plate of the first detector tube and one side of the tapped loop antenna. This is a common control on many mid-20s superhets.

     The photo at left shows a close up view of the engraved front panel. I don’t know if this was a standard panel offered with a kit or a one-time-only engraving.

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Scott Worlds Record Super 9<     HOME     >Silver kit

McMurdo Silver

McMurdo Silver

     Silver-Marshall advertisement from the spring, 1925, Citizens Radio Call Book.

Silver Marshal ad CRCB Spring 1925

Type

Peak Freq.

Lower 3 dB

Upper 3 dB

Bandwidth

Relative gain

Pri. ohms

Sec. ohms

#1, SM 210

63.6 KC

41.5 KC

81.6 KC

40.1 KC

10.0

110.1

293.4

#2, SM 210

64.1 KC

44.1 KC

80.3 KC

36.2 KC

10.5

108.5

297.7

#3, SM 211 .0094 cap

65.7 KC

63.4 KC

67.9 KC

4.5 KC

13.0

3.6

205.9

     The table below records the bandpass measurements of the IF transformers. The 211 filter transformer (transformer #3) was tuned with a .0094 mfd capacitor across the primary winding and it was measured with the grid leak capacitor and resistor intact. These transformers are supposed to peak at 60 KC.

Silver Marshal Front Panel Engraving

     Close up view of the aluminum square cased IF transformers.

     Top inside view of the set. This radio was in need of some restoration work when I purchased it (it was similar to my Scott). I usually don’t like to mess with any of my radios if they’re in halfway decent shape. I always prefer an original radio to one that has been restored. In the case of the Silver I felt like I had to do something to make it more presentable. I cleaned up the individual components and rewired the entire set but I left the cabinet alone. I think it turned out OK. However, if I did the restoration work over again I would probably do things just a little bit different.