A worthy successor to the famous National 1-10, the new model HFS Receiver/Convertor is a unique and extremely versatile instrument. The unusual frequency range of 27 to 250 megacycles, selectivity characteristics particularly suited for the constantly increasing occupancy of these frequencies, and high useable sensitivity are but a few of the features which make model HFS the logical choice for amateurs, laboratories, news services, public utility and airline personal, or any occupation requiring compact, dependable VHF receiving equipment.

The circuit of this new Receiver/Convertor is basically superhetrodyne - superregenative with its i.f./ convertor output channel at 10.7 megacycles. Thus, it is equally adaptable for use as a complete VHF Receiver for AM, FM (by slope dection) and CW signals or as a convertor in conjunction with any superhet receiver capable of tuning 10.7 mc. When used in the latter manner the result is dual conversion type operation with excellent image rejection at all frequencies from 27 to 250 megacycles; all features of the receiver to which the HFS is connected become operative for VHF reception. The HFS will also serve as the front end of a high fidelity FM broadcast (wide band) instillation simply by connecting the convertor output to a 10.7 mc. FM i.f. channel and suitable amplifier-speaker system. For maximum stability and flexibility, power for the HFS by a separate unit and where 112/230 volt 50/60 cycle source is available, the National 5886 Power Supply is employed. The HFS may also be powered by the National 686S Vibrator Power Supply and a storage battery or a combination of "B" batteries and storage battery. The 686S operates from 6 volts D.C. and provides all voltage required. A storage rack for the complete compliment of coils is provided inside the Receiver cabinet.


Tuning System:

A two-ganged main TUNING capacitor, A panel-controlled TRIMMER capacitor and six sets of plug-in coils are used to tune the receiver in the six bands as follows:

Band Frequency Coverage
A 178 - 250 mc.
B 120 - 178 mc.
C 80 - 120 mc.
D 56 - 80 mc.
E 41 - 60 mc.
F 27 - 42 mc.


TUNING dial, TRIMMER control, REGEN control, AUDIO GAIN control, INT-EX (external position connects the i.f. output to the output receptacle and disconnects the second detector and audio stages) Switch, Convertor Output Control (on rear apron) and B+/OFF Switch.

1st Det. 6AK5
h.f. Osc. 9002
i.f. Amp. 6SG7
2nd Det. 6SK7
1st Audio 6J5
Audio Output 6V6GT/G
Convertor Output 6J5


The HFS measures 16 - 9/16" x 8 3/4" x 8 1/2", weighs 19 lbs. (25 lbs. packed for shipment) and the finish is smooth gray enamel.


Model HFS (including complete set of coils) net $125.00

Type 5886 Power Supply 115/230 v. 50/60 cycles a.c. Net $22.43

Type 686S Vibrator Power Supply 6 v. d.c. Net $34.16

TB-1 Tilt Base Net $3.95

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