1-10

1-10 on the left

1-10A on the right



With the progress of radio in the last few years, there has been a definite trend toward the general use of the ultrahigh frequencies for a variety of services. The National Type 1-10 Receiver, designed originally for experimental work, has proven to be well suited to general ultrahigh frequency use, as shown by the continued application of the receiver to amateur and commercial services. Its simplicity, compactness, sensitivity and ease of operation are outstanding in this type of equipment

TUBES AND POWER SUPPLY

The type "1-10" receiver employs a 4-tube circuit, consisting of one stage of tuned R.F., a self-quenching superregenerative detector, transformer coupled to a first stage of audio which in turn, is resistance coupled to a power output stage. The receiver is designed for operation from the National Type No. 5886 AB power unit, all voltage dividers, etc., being built in so that but one B-voltage lead is necessary. This power supply furnishes six volts at 1.6 amperes to the heater circuit and 180 volts at 35 milliamperes to the plate and screen circuits.

TUBE COMPLIMENT
R.F. 954
Detector 955
First Audio 6C5
Second Audio 6F6

ANTENNA

The importance of an efficient antenna cannot be over emphasized. The antenna lead, or leads should be brought directly to the antenna binding post at the top of the receiver. The transmission line must be efficient. As a rule, "twisted pair", or similar lines, are not satisfactory at frequencies much above 40 or 50 mc. The open wire or transposed line is much better.

OUTPUT CIRCUIT AND SPEAKER

The plate circuit of the output tube is brought to the output jack, located at the rear lefthand side. There is no output transformer in the receiver. The headphone jack is located on the front panel, just below and to the left of the main dial. This jack is wired into the output of the first audio stage in such a way that when the phones are plugged in, the signal input to the last tube is completely disconnected. If the speaker is to be disconnected, a jumper must be inserted in the tip-jacks to connect them together

CONTROLS

The main dial is the tuning control. The switch at the lower righthand corner breaks the positive B-supply lead and is useful for temporarily rendering the receiver inoperative during periods of transmission or when changing coils. When using B-battery plate supply, the switch should be thrown to the "Off" position at all times when the receiver is not in use, in order to avoid parasitic drain. No switch is provided for opening the heater circuit. There are three small dials in addition to the main tuning dial. These control detector regeneration , audio gain, and the alignment of the R.F. circuit, and are marked accordingly.

OPERATING CHARACTERISTICS

The "1-10" receiver is designed primarily for the experimenter and to this end has been made to have maximum sensitivity and a wide frequency range. The use of a self-quenching superregenerative detector with a stage of tuned R.F. provides excellent se sitivity and AVC action. The coils are used in pairs. The coil sockets of the R.F. and detector sages are marked "1" and "2", respectively, to correspond with the coil designations. With any pair of coils in the receiver, the audio gain control should be dvanced to 3 or 4 on the dial. Advancing the regeneration control will throw the detector circuits into superregeneration. The regeneration control has some tuning effect, increased plate voltage causing an increase in frequency. It is important that the egeneration control be advanced sufficiently so that the detector is oscillating strongly.

Shipping Weights: Receiver 16 lbs., Power Supply 17 lbs.

Type 110 Receiver and 6 sets of coils, without tubes, speaker or power supply. List Price, 85.00

Type 5886 Power Supply for above receiver, less tube. List Price 29.50

Source: National 1-10 Receiver Manual, dated 9-42

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