September 1934 Radio-Craft
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics.
Radio-Craft was published from 1929 through 1953. All copyrights are hereby acknowledged. See all articles
Here are the schematics, chassis layout, and service info for
the Howard Explorer Model W Deluxe 19 Tube All-Wave Superheterodyne
radio. The Radio Service Data Sheets that were published in
Radio-Craft usually seem to have more information included
than those published in other magazines, at least in the same
era (1940-ish). It might have to do with how much material is
provided by the manufacturer rather than a decision by the magazine
editors. Believe it or not, there are still people searching
for such data.
Howard Explorer Model W Deluxe 19 Tube All-Wave Superhet
Radio Service Data Sheet
(Uses single-purpose tubes to secure extreme circuit stability:
wavelength range, 13.6 to 2,142 meters; provides for either
inverted-L doublet antenna; neon resonance indicator; zero-beat
oscillator; variable Q A.V.C.; tone control; variable A.V.C.
parallel push-pull output 245s.)
A 19 tube radio receiver in its home. Airplane-type dials
are used; only the tuning dial sector of the band in use is
illuminated. as the band switch is turned.
Schematic circuit of the A.F. amplifier and power pack chassis.
There are 9 tubes in this section of the instrument. A "theatre"
type dynamic speaker is used,
Until very recently the general practice has been to utilize
the new tubes at their maximum capabilities. Consequently, a
slight change in characteristics would greatly affect the operation
of the complete receiver. However, this 19 tube set is designed
to utilize its tube complement very conservatively, with the
result that great stability has been achieved which, after all,
is a major factor in securing satisfactory reception, especially
on the short waves.
Note; it is inadvisable to attempt to realign the set except
as a last resort. The recommended procedure, only to be used
by expert radio Service Men, is as follows:
To align the I.F. circuits feed the I.F. service oscillator
test signal into the control-grid of V2.
When aligning R.F., I.F., or oscillator circuits turn A.V.C.
adjustment (slotted shaft) to extreme left. The I.F. trimmers
are very critical, greatly affect the performance of the set,
and must be carefully resonated.
Aligning R.F. and Oscillator Circuits
Adjust A.V.C. control to extreme left position. It is unnecessary
to remove the set oscillator tube. Align the circuits only in
the sequence given.
To align the set oscillator turn its trimmer all the way
out and then select the strongest signal when turning it in;
set insensitivity near the center of the dial will result if
the wrong oscillator signal is used.
Bend the variable condenser plates for kc. dial alignment
only in the broadcast band. Before adjusting any band, make
certain that the pointer of the station indicator is set on
the last black line when the dial is turned all the way to the
left on the broadcast band just above 0.55 (Maximum capacity
of the variable condenser).
Turn the band indicator to 0.15-0.35, set the dial to 0.35,
and feed 350 kc. into the antenna post. Resonate the trimmer
(not green coded on the trimmer washer) in the long-wave oscillator
can. Align the R.F. and antenna stages. Reset dial to just above
0.17 and resonate the green coded oscillator trimmer at 175
kc. Recheck the 350 kc. setting.
It is necessary on the broadcast band only, that a metal
plate with holes in line with the trimmer nuts be used so that
the circuits are not detuned when the regular base plate is
screwed back on.
Turn the band indicator to broadcast 0.55 to 1.5, set the
dial to 1.4, and feed in 1,400 kc. Resonate trimmer 14, R.F.
trimmer 7 and the antenna trimmer (knurled knob extending from
top of antenna coil can). Now rotate dial to 0.55 and resonate
trimmer 10 at 550 kc. Re-check the setting at 1,400 and bend
plates of variable condenser at 950 and other points where necessary
to secure kc. reading on dial.
Short-Wave Band No.1
Turn band indicator to 1.5 to 3.5, set dial to 3.5, and feed
in 3,500 kc. service oscillator signal. Resonate trimmer 13,
R.F. trimmer 6 and antenna trimmer 3. Rotate dial to 0.55 on
broadcast hand. (The short-wave dial calibration may be inaccurate
at this point and the 0.55 figure corresponds to 1.5 on short-wave
band No. 1.) Feed in 1,500 kc. and resonate trimmer 9. Recheck
at 3,500 kc.
Short-Wave Band No.2
Turn band indicator to 3.5 to 9, set dial to about 8.9 (due
to off-calibration this corresponds to 8.5), and feed in 8,500
kc. Resonate trimmer 12, R.F. trimmer 5 and antenna trimmer
2. Rotate dial to 3.5 and resonate trimmer 8 at 3,500 kc. Recheck
at 8.5 (8.9).
Short-Wave Band No.3
Turn band indicator to 9 to 21, set dial to 20, and feed in
20,000 kc. Resonate oscillator trimmer 11, R.F. trimmer 4 and
antenna trimmer 1. The alignment at 9 is obtained by use of
the fixed condensers which should not require change. To insure
band sensitivity in the region of major foreign program reception,
turn the dial to 12 and resonate antenna coil trimmer 1 at 12,000
Note that since all adjustments are made with the A.V.C.
inactive, extreme care must be used to attenuate the input signal
low enough so that there will be no overloading of tube amplifiers
while making adjustments.
After these high-frequency adjustments have been made, the
service oscillator setting should be advanced 930 kc. and the
output signal strength considerably increased; non-reception
of the image signal indicates incorrect set oscillator adjustment.
For example: a service oscillator signal of 20,930 kc. should
be perceptible at 20 on the dial after alignment to 20,000 kc.
Beat Oscillator Adjustments
Turn the main dial to receive a service oscillator signal
of 4,800 kc., and make sure that the band on the "beat oscillator"
(Frequency Meter V17) falls on 1.5 when the 2 gang condenser
is at full capacity.
Turn Osc. Sw. to the right ("Mod."), and frequency dial to
4. Resonate the trimmer on the 2 gang condenser to main dial
setting. Turn band indicator switch to short-wave band No. 1
(1.5 to 3.5), set main dial to where 1,500 kc. comes in, turn
frequency dial to 1.5, and then resonate trimmer 15.
Connect one side of a high-resistance voltmeter to A. V.C.
potentiometer terminal which connects to the "high" side of
the 0.2-meg. resistor and to the 0.1·mf. fixed condenser, and
the other (positive) to chassis ground.
Adjust the receiver for reception of a signal intensity of
3,000 to 4,000 micro-volts, and vary for maximum voltmeter reading,
in a given locality, the adjustment in the top, next to the
neon adjustment, of the coil can assembly in the upper right-hand
corner (facing rear of tuner).
In certain localities close to a broadcast station it may
be necessary to readjust the A. V.C. (slotted shaft) control.
Exactly resonate the receiver. Then, if the station's signals
sound "fringy" or rough, turn the control to the right only
sufficiently far to correct this condition.
Neon Tuning Indicator and Q.A.V.C.
Facing the back of the tuner chassis, extending through one
of the tall shielded assemblies in the upper right-hand corner,
will be found a small, black knurled knob used to adjust the
neon resonance indicator. It is advantageous to be able to set
this adjustment if excessive fading is experienced due to locality.
Adjust the receiver dial to a powerful station during the time
of day in which it is received strongest. Then turn the neon
adjustment until the light just fills the opening in arrow dial.
Readjust the tuning dial of the receiver; should the light become
more brilliant, leave the dial at the point of highest brilliancy
and again readjust the neon indicator until it just fills the
arrow opening. (This adjustment need be made only when the set
Since the interstation noise suppression system or Q.A.V.C.
is a proportional function of the neon light, the Q.A.V.C. system
will be correctly adjusted.
Note that the neon light system is not intended to work on
the short-wave stations. However, it will usually indicate resonance
to more powerful signals.
Resistor X is an oscillator suppressor in short-wave band
No.3. Its value is determined by individual requirements.
Locations of trimmer condensers in the new 19 tube all-wave
superheterodyne. This illustration furnishes the necessary information
to complete the data In the text.
Schematic circuit of the tuner chassis. There are 10 tubes
in this unit. The 2·gang condenser mentioned in the text is
located at the right of oscillator V17.
Radio Service Data Sheets
These schematics, tuning instructions, and other data are reproduced from my collection of vintage
radio and electronics magazines. As back in the era, similar schematic and service info was available
for purchase from sources such as SAMS Photofacts,
but these printings were a no-cost bonus for readers. There are 187 Radio Service Data Sheets as of
May 2, 2017.
- Radiola "28" Super and "104" Power Speaker
- Sonora Model TW-49
Models 1020, 1120, Series 10
- Air King Model 4604D
- Sparton Models 526, 526X, 526PS
- Truetone Model D2624
- Admiral Models 6EI, 6EIN
- Detrola Models 571A, 571B
- General Electric Model
- Howard Model 920
- Colonial Model 652 5-Tube Broadcast-Short-Wave
- Fairbanks-Morse 9-Tube
All-Wave Model 91
- International Model
500 5-Tube Dual-Range Battery
- Emerson Model 678 "Auto-Dynamic"
Nos. 230 and 231 Series
- Atwater Kent Model 649
- Howard Model
G-26, and "Airplane 4" Model AA25
Ward "Airline" Series 7GM 7-Tube High-Fidelity Receiver
- RCA Victor Model T5-2 5-Tube,
2-Band A.C. Superheterodyne Receiver
- Majestic "Models
50," "51" and "52"
- Bremer-Tully Model
7-70 and 7-71
- General Electric
Model M-49 4-Tube Radio-Phonograph Dual-Wave Superheterodyne
- RCA-Victor Radiola "Superette"
Model R7 Superheterodyne
- Crosley Model AC-7 and AC-7C
- Westinghouse "Columnaire"
Models WR-8 and WR-8-R (Remote Control)
- Characteristics of
Metal Tubes - and Other "Octal" (8-Prong) Base Types
- Kolster K20, K22, K25, K27 and K37
Nos. 62 and 63, 8-Tube High-Fidelity Chassis
- RCA Model 103, 4-Tube A.C. Compact
- FADA "Special" Model 265-A
and FADA "7" Model 475-A
- General Electric Model
C-62 6-Tube Battery
- Emerson 5A Automotive
- Zenith 666 Automotive
- Motorola 100 Automotive
- Crosley Roamio 4-A-1
- American-Bosch 524A
- Crosley Model 1316 (in Model
- RCA Victor "High-Fidelity Electrola,"
- AMRAD Model 81 ("Bel Canto"
- Fada 103 Fadalette,
Stewart-Warner Series 108, DeWald 54 Dynette Sets
- RCA Victor R-27 and Philco
53 Ultra-Midget A.C.-D.C. Radio Receivers
Models Fairfax and Sheffield 8-Tube
- Stromberg-Carlson No.
29, 9-Tube Superhet
- International Kadette
Model 400 4-Tube Battery-Operated Superhet
- RCA Victor Model 5M 5-Tube Auto
Model 11 Short-Wave Converter
- Silver-Marshall Model
727-DC Battery-Operated Superheterodyne
- RCA Victor Model VHR-307
Home Recording - Phono-Radio Combination
- Delco 32-Volt
Radio Receiver Chassis Models RA-3, RB-3 and RC-3
- Majestic Chassis Models
380 A.C. T.R.F., and 400 A.C.-D.C. Superheterodyne
- General Motors S1A, S1B
- Admiral Model 7C63, Chassis
- Westinghouse Model H-133
- Arvin Models 150TC, 151TC
- Kadette Model 90 Duplex
- RCA-Victor "Magic
Brain" Model 281
- Grunow 11A Chassis 11-Tube
Sears, Roebuck & Co., Silvertone "Rocket" Models 6110 and 6111
Electric Model GD-52
Models 6D302, 6D311, 6D326, 6D336, 6D360
Allied Radio, Knight Model E10913
- Arvin Model 140P
- Emerson Models 501, 502, 504
- Crosley Model 56TD-W
- Hoffman Model A500
- Stewart-Warner Model
- Zenith Models 6D014,
- Coronet Model C-2
- Sparton Models 7-46,
7-46PA, 8-46, 8-46PA
- Stewart-Warner Models
9001-C, D, E, F
- Zenith Models 5D011-5D027
- Bendix Models 636A, C, D
- ECA Model 108
Model 66 and 666, 6-Tube Superhet
- Ford-Philco Radio,
Model FT9, 6-Tube Auto-Radio Receiver
- Howard Explorer Model W Deluxe
19 Tube All-Wave Superhet
- RCA Victor Portable Table
Electrola Model R-95
- Atwater Kent Model 305Z
5-Tube 32 V. D.C. Superhet
- Kadette Jewel Model 40 Chassis
3-Tube Ultra-Midget Receivers
- General Electric Model
N-60 6-Tube Auto Superheterodyne
- Sparton Model
40 6-Tube T.R.F. Automotive Receiver
- Clarion "Replacement"
Chassis, Model AC-160 A.V.C. Superheterodyne
- Emerson Models 20A and 25A
- General Electric K-40A
- Pilot Model B-2
- RCA-Victor Radiola Model
M-30 Automotive Radio
- Motovox Models 10A All-Electric
and 10E Battery-Operated "Moto-Tetradynes"
- Kennedy Superheterodyne
- RCA Victor Model R-78 B1-Acoustic
- Philco Model 15 Series,
11-Tube Superheterodyne Chassis
- Zenith Challenger Model
Electric Models G-105 and G-106
- Silvertone "F," "FF," "G," "H," and "J"
Stewart-Warner Model 03-5A1 to 03-5A9 (Chassis 03-5A) Senior Varsity Radio
- Radiola Models 61-6, 61-7
- Westinghouse Models
H-104, H-105, H-107, H-108
- Farnsworth Models EC-260,
EK-262, EK-263, EK-264, EK-265
- United Models 980744,
(R-127 Chassis) Models 1271 to 1279 All-Wave
- ERLA Model 4500 Dual-Wave T.R.F.
4-Tube A.C. Receiver
- Clarion No. TC-31 5-Tube A.C.-D.C.
- Detrola Model 105C 5-Tube Dual-Band
- Zenith 6-Tube All-Wave Chassis
- RCA Victor Model 261, 555
to 107 Meter
- Philco Model 38-116; Code
"Ferrodyne" Chassis Model R-136
- American-Bosch Model
43OT 5-Tube 3-Band Superheterodyne
- RCA Victor Model C9-4 9-Tube
- Kennedy "Model 826B" Combination
- Steinite 50-A and 102-A
- Pilot Model 63 All-Wave 6-Tube
- Stromberg-Carlson No.
69 4-Tube All-Wave Superhet. Selector (Converter)
- RCA Victor Model 102 4-Tube
A.C.-D.C. T.R.F. Receiver
- Bosch Models 60 and 61
- Atwater Kent Models
30, 33, 35, 48 and 49
- Crosley Model 120 Senior Superheterodyne
- Columbia Screen-Grid
- General Electric
Models A82 and A87, 8-Metal-Tube All-Wave A.C. Superhet.
- Colonial 31 and 32 D.C.
- Zenith 5-Tube Triple-Wave Chassis
nos. 5508 and 5509
- Remler Model 46 ("Scottie")
- General Electric FA-60
- Stewart-Warner Series
- Howard Model B-5 (715),
Series 1 and 2 (Sheaffer Radio-Clock-Pen Desk Set)
Car-Radio Models F-1440 and F-1442
Model 31 Combination Radio and Panatrope
- Emerson Models 38, 42 and 49, 6-Tube
Dual-Wave (Chassis U6)
Motors Chevrolet No. 601574 Automotive
- RCA Victor M-104
(and M-108) Automotive
- Arvin-Ford 17-A Automotive
- Westinghouse Model WR
207 & WR 208 5-Tube Dual-Band Superheterodyne
- Radiolas "Super VIII" (AR-810,
"Semi-Portable" (AR-812), 24 and 26
- Howard Model 45 A. V. C.
- Majestic Model 25
Motorola Model 61
- Arvin Model 6
- Admiral Models 7T06, 7T12
- Garod Model 5A1
- Hoffman Model A301
Model E10716 Battery Portable
- Arvin Models 555, 555A, 552N, 552AN
- Grantline Models 605, 606
- Truetone Model D2616
- Belmont Model 5D128
- Arvin Models 444, 444A
International Kadette Model 1019
Models 97-561 to 97-569
- General Electric Model 280
- Zenith Models 5R080, 5R086
- Truetone Models D1747, D1748
Roamio Automotive T.R.F. Models 90, 91, 92
Roamio Automotive Superheterodyne Models 95, 96
- Emerson Model AZ-196
- Belmont Model 5P19
- Crosley Model 56FC
- Emerson Models 507,
509, 518, 522, 535
- Garod Model 6AU-1
- General Electric Models 219,
"Chairside" Model 567
Model 408 Battery "Farm"
- Wards Model 74BR-1055A
- Farnsworth Models EK-081, EK-082,
- Philco Model 200-X Radio
Admiral "Aeroscope" Models 161-5L, 162-5L and 163-5L
- Philco Model 59, 4-Tube A.C.
- Zenith Farm Model 6V 27,
- Ward 10-Tube All-Wave High-Fidelity
Superhet, Series ODM
- Philco-Packard Deluxe
- Canadian Westinghouse
- Crosley Model 1155
- Philco Models 39 and 39A
- Arvin Model 35
- Hetro Air-Ace Series M
- Westinghouse Models H-161, H-168,
- Garod Model 5A4
- Arvin Models 152T, 153T
- Belmont Model 5240
- Mantola Models 92505, 92506
- General Electric Models 102,
102W, 107, 107W, 114, 114W, 115, 115W
- Crosley Model 555 (A.F.M.)
- Crosley Model 515 (Fiver)
- Crosley Model 425 (Travo)
- Fairbanks-Morse Model
81 "Farm" Set
- Clarion Model 423, 470, 471, 472,
Radio Corp. Model 90
- Belmont Model 578 Series A
Posted October 6, 2015