Magnaformer 9-8

     The Magnaformer 9-8 shown here was probably built in the early to mid 1927 time frame. I base that view mainly by the engraving on the front panel, which I believe is early for a Magnaformer. The set was professionally wired and it was probably sold complete to a customer. Here are a few particulars of this set:

Magnaformer 9-8 Front View 2

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Madison-Moore<     HOME     >Master

     This is a schematic diagram of the Magnaformer 9-8, as copied from a construction article in the October, 1927, Popular Radio magazine. I have probably made an error in the time frame that my set was manufactured (as reported above). I now believe that my Magnaformer was probably built in late 1927.

Magnaformer 9-8 schematic PR October 1927

September 6, 2014 Update

     Radiart advertisement for the Magnaformer 9-8 from the November, 1927, Citizens Radio Call Book magazine.

Magnaformer ad CRCB November 1927

Type

Peak Freq.

Lower 3 dB

Upper 3 dB

Bandwidth

Relative gain

Pri. ohms

Sec. ohms

RF 61, #1

71.4 KC

66.1 KC

77.5 KC

11.4 KC

11.2

44.1

101.2

RF 61, #2

71.6 KC

66.2 KC

77.4 KC

11.2 KC

11.6

43.8

100.7

RF 61, #3

70.7 KC

65.6 KC

76.3 KC

10.7 KC

11.8

44.2

100.5

RF 61, #4

69.8 KC

64.5 KC

75.4 KC

10.9 KC

11.2

45.1

104.0

RF 61, #5

70.5 KC

65.8 KC

75.8 KC

10.0 KC

10.4

43.4

99.2

     The bandpass measurements of the IF transformers didn’t have any hidden surprises. The Magnaformer factory was trying to target an IF frequency of 69.73 KC. All five IF transformers are the same and they seem to be fairly well matched. The bandwidth of the IF transformers should produce good audio response. The last IF transformer (#5 feeding the second detector) was measured with the grid leak resistor and capacitor in the circuit and the secondary of the IF transformer referenced to A+. All other transformers were measured with the secondary of the transformer referenced to A-. Both methods produced about the same response.
     The Magnaformer 9-8 is a well designed and manufactured set. The schematic diagram of the Magnaformer 9-8 can be found on Nostalgia Air here.

     Close up of engraved panel.

Magnaformer Engraved Panel
Magnaformer Chassis Number Engraving

     Remler tuning capacitor and drum dial.

Remler Drum Tuning Dials
Ferranti Audio Transformers

     Radiart Laboratories R. F. 61 IF transformer.

RF 61 IF Transformer
CU 71 Oscillator Coupler

     Top inside view of the set. The IF amplifier is in the left rear, the oscillator is in the front center, and the audio amplifier is in the right rear.

Magnaformer Top View

     Unicoupler CU-71 oscillator coupler.

     Ferranti audio transformers.

The number 777260 is engraved on the bottom of the chassis.