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Operating the Neutrodyne Receiver
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0 10 20, 30 40 50 GO 70 80 SO 100 CONDENSER SETTING DIVISIONS
FIG. I
Wavelength calibration curve showing approximately at what settings of dials 2 and 3 the various stations may
be expected
ing " beat notes" and the usual regenerative whistling. As the dials are rotated the programs of different stations will be heard, first softly then with greater intensity and clarity as all adjustments are properly made for that particular station.
THE WAVELENGTH RANGE
THE Neutroformer coils specified in these articles are designed to cover a wavelength range of from approximately 200 to 600 meters. The wavelength calibration curve is shown in Fig. 1 and has several broadcasting stations' wavelength calibration points indicated.
USING DIFFERENT TUBES WITH THE NEUTRODYNE
IN THE early stages of neutrodyne receiver development, receivers were constructed that allowed the neutralization of a given tube and circuit capacity and which did not operate efficiently when different vacuum tubes having different capacities were used. With the placing on the market of the UV-20 1 -A and the dry-cell tube, this matter of basic design was very carefully studied, and now they, and other tubes, can be used with comparatively good success. It has been found that C-30 1 -A tubes are the best for the radio and audiofrequency amplifier circuits. The C-300 or UV-200 is the best to use as detector tube. The UV-20 1 -A is very good as an amplifier tube and is a close second to the C-30 1 -A. I have been in intimate touch with many users of neutrodyne receivers and a great many of them have had good success with WD-11, WD1 2, VT-i, VT-2, 216-A, and UV-199 tubes. When using any of these various types, it is, of course necessary to make sure that correct filament voltages as well as filament current is supplied to the tubes and in general the chart given in Fig. 2 covering "Operating Data for Vacuum Tubes" will be found variable. The lettered notations as regards the suitability of the tubes has been described with neutrodyne receivers particularly in mind.
The volume obtained using UV-199's or other dry-cell tubes is generally less than the volume obtained using UV-20 1 -A or C-30 1 -A
OPERATING DATA for VACUUM TUBES
TYPE
OF TUBE
FILAMENT VOLTAGE
FILAMENT CURRENT (AMPERES)
"A" BATTERY SOURCE
PLATE VOLTAGE
USED AS
DETECTOR
R.F. AMPLIFIER
A.FAMPLIFIER III STAGE
AE.AMPUFIER Z«2 STAGE
WD12
/. /
0.20
/ DRY CELL
22!/z TO 90
A
X
C
D
UV-199
3.0
0.06
3 DRY CELLS
72'/z TO 90
D
A
c
D
UV-201-A C-30/-A
5.0
0.25
6 VOLT STORAGE BATTERY OR 4 DRY CELLS
45 TO 120
C
A
A
A
UV-20! C-30!
5.0
1. 00
6 VOLT STORAGE BATTERY
45 TO [20
D
A
3
B
UV-200 C-300
5.0
1.00
6 " " "
13 TO 22l/2
A
Y
Z
Z
VT-1
4.0
1. 10
G " " "
22'/2T0G7'/1
A
Y
B
B
VT-Z
G.O
1.35
G " » "
90 TO 350
D
8
B
A
2!6-A
6.0
1.35
6 n n u
tf!/2 TO 120
D
B
B
A
UV-202
8.0
2.35
10 " " "
90 TO 500
X
D
B
A
LEGEND
A EXCELLENT B= VERY GOOD C-GOOD D = FAIR X— POOR Y = VERY POOR Z = UfVSU fTABLE
FIG. 2