National FB-7
Copyright 2003, Alan R. Klase. All rights reserved.

The National Company introduced their AGS receiver in late 1932, but they were acutely aware that it was too expensive for the average amateur operator.  Their clever solution was a stripped-down seven-tube version of the AGS dubbed the FB-7.  A ham could buy an FB-7, with one set of coils, for fifty-five dollars, and gin up his own power supply and speaker.

A NEW NATIONAL

H. F. RECEIVER

(Pictures and text from National AGS brochure R 20M 333)

Designed specifically for the amateur, but embodying professional design details, this exceptional receive offers a number of unusual refinements. Strictly single-control tuning and front-of-panel coil changing for swift and convenient operation - full vision dial and panel-mounted calibration curves for fast logging - efficient – compact and inexpensive.

From such a receiver, National built, one expects remarkable performance - and gets it. A seven-tube super-heterodyne circuit provides ample selectivity and high gain.  And quality in every detail from Litz-wound transformers to double shielding provides reliability and stability. We invite you to inspect the FB-7 and to compare it with any other H. F. Receiver on the market. We are confident of your approval, for by every nicety of design and mark of fine craftsmanship, the FB-7 reveals its heritage from the AGS.

  • Single Control Tuning (No trimmers).
  • Full Vision Dial with SLF 270º Condenser.
  • Front-of-panel coil change.
  • CW Beat Oscillator Switch on panel.
  • Front of Panel Switch for "cutting" B voltages during transmission.
  • Phone Jack, connecting ahead of final audio stage.
  • Calibrated Volume control located under tuning knob, for one hand operation.                                                            





 
Technical Features
  • Single-conversion superhet - 500 KHz IF
  • 0.8 - 33  MHz - plug-in coils
  • 2 IF stages
  • Crystal filter - on FB-X
  • Bandspread:  bandspread coils
  • External power supply

As time went on, improved versions of the basic set appeared.  The principal options were a crystal IF filter and air-tuned IF transformers.  The air-tuned IF cans are tall, about the same height as the top of the tube plate caps.  Receivers are unmarked and identification is possible by inspection only.  The table on the right should be helpful.  General coverage coils were available to cover 800KHz to 34 MHz, and band-spread coils were made for the 20, 40, 80, and 160 meter ham bands.  Coils were priced at $10 per pair, and blamk forms were available for $3.65 each.  However, it seems that, many FB-7 owner may have purchased only one set of coils.

There was even a version with an internal power supply.  Extra space was added to the back of the cabinet.

* National was inconsistent with punctuation of FB-X.  FBX, FBX, FB-XA, FBXA, ect. all appear in National ad's and publications.
Model
 Air-Tuned
IF's
 Crystal
Filter
FB-7

FB-X*
X
FB-7A
 X
FB-XA
 X
 X

Advertised FB-7 coils:

NUMBER
 RANGE
 OBSERVED LABLES
AB 20
 20 Meter Band Spread
 DET/OSC 14.0 - 14.4 MC
AB 40
 40 Meter Band Spread
AB 80
 80 Meter Band Spread DET/OSC 3.6 - 4.0 MC
AB 160
 160 Meter Band Spread
FB AA
 18 -34 MHz (?)
 DET/OSC 19-33 MC
FB A
 11.4 - 19.5 MHz
 DET/OSC A
FB B
 7 - 11.7 MHz
 DET/OSC B
FB C
 4 - 7.3 MHz
 DET/OSC C
FB D
 2.4 - 4.2 MHz
FB E
 1.5 - 2.5 MHz
FB F
 800-1500 KHz

Coils with lables such as D1/D2/D3 or 1-/2-/3 14.0 - 14.4 MC etc. are beleived to be AGS coils, but early FB-7 advertising photos show C1/C2 coils.  The detector and oscillator coils in the AGS and FB-7 may well be identical.

An FB-X with RF amplifier that appeared on E-Bay in June of 2003.  The spacers between the units allow access to the crystal-filter control on the right side of the receiver.  As is the case with almost every surviving FB-7, the original tuning knob has, long since, been swapped out for a larger diameter unit.

Power Supplies

5880 AB (as used with the SW-3)
5887 AB low cost supply for FB-7   $24.50
5897 AB High voltage for operation of  '59 tube at full rating.   $34.50