FRANKLIN MODEL 94 ALL - WAVE RECEIVER
Designed by Design-Mumma-Engineers Drwn by Desch
Franklin Radio Corp'n - Daytona Ohio - U.S.A. Oct. 12-1923

ALIGNMENT OF FRANKLIN MODEL 94 ALL - WAVE RADIO RECEIVER

Receiver should be circuit tested, and any high or low voltages should be corrected. This will reasonably insure the correct use of the resistors. However a visual inspection of the resistors and condensers, should be made so that the alignment operations which are to follow will not be frustrated. A table or voltages which are to appear at the various terminals is appended. When circuit testing is completed, proceed as follows:

(1) Set up signal of exactly 450 Kc, 30 % modulation, 400-1000 cycles, oscillator to be very stable.

(2) Either apply high resistance voltmeter (AC) across plates of 59 tubes, or insert 15 MA DC Meter in the common cathode lead of the I.F. tubes (in lead to rotor of sensitivity control), or if tuning meter is used simply observe tuning meter variations.

(3) Apply I.F. Osc, signal lead to grid of #2 I.F. tube.

(4) Adjust trimmers on #3 I.F. Transformer for max. signal and max. reading on sensitivity indicators,

(5) Apply I.F. Osc. signal lead to grid #1 I.F. tube and repeat operation #4 adjusting trimmers on #2 I.F. Transformer.

(6) Apply I.F. Osc. signal lead to antenna post and adjust trimmers on #1 I.F. Transformer and observe as in #4.

NOTE: Speaker is never disconnected so that audible signal is always present to aid peaking operations.

(7) Set wave band selector switch on B.C. Band (Farthermost clockwise position).

(8) Set tuning dial at 1500 KC., checking that dial reads 100 when gang condenser is completely closed,

(9) Apply 1500 Kc. Osc. signal (30 % mod. 400-1000 cycles) to ant-gnd posts.

(10) Adjust trimmer on osc. section of gang condenser (section #1) for maximum signal.

(11) Adjust trimmer on first detector grid coil (Trimmer on section #4 of gang) for max. signal.

(12) Adjust trimmer on B.C. Preselector circuit (Trimmer on section #3 of gang) for max. signal.

(13) Set tuning dial on 570 Kc. and adjust osc, signal to exactly 570 Kc.

(14) Adjust series osc, padding condenser for max. signal (condenser C-3 on circuit diagram) (this condenser is located beneath chassis but is adjusted from top of chassis thru hole in chassis. It is the trimmer located nearest to front of set).

(15) Check peaking at 1500 kc and make minor adjustment if necessary repeating operation 10.

(16) Check alignment at about 800 Kc to see if osc. and 1st det. are tracking.

(16 - A) If when checking alignment at 800 Kc. and it is found that 1st det, does not track with oscillator, necessitating an increase of trimmer capacity on section 4 (also then on pre-selector section #3) then proceed as follows:
(a) Turn dial to 1500 kc.
(b) Loose set screw on dial and turn dial on the condenser shaft about 1 or 2 degrees counterclockwise and re-lock with set screw.
(c) Then proceed with operations # 8, 49, # 10, # 11, # 12, # 13, # 14, # 15 and # 16.
Alignment should now be better at 800 Kc. or perfect. If not, repeat operation set down in # 16 - A. Of course if in 16 - A it was found that trimmer condenser had to be reduced in capacity on section # 4 (also then section # 3) then reverse the direction in which the dial was slipped on the gang cond. shaft (move it clockwise in this case). Repeat the same operations as outlined in 16 - a-c above,

(17) Move band selector switch to next higher freq. band (1550-4200 Kc.) counterclockwise one notch.

NOTE: AFTER COMPLETION OF OPERATION 16 - A DO NOT TOUCH TRIMMERS ON SECTIONS # 1, # 3, and # 4 OF GANG CONDENSER.

(18) Set up 4000 Kc. Osc, signal and connect leads from oscillator to ant-gnd posts on set. Turn dial of set to max. signal (will be close to 0 or 1500 Kc. on tuning dial).

(19) Adjust lst det air-trimmer (located on control panel, second knob from left) for max. signal. It max, signal is secured at either extremity of this control travel, than it will be necessary to make coil adjustments.
(a) If this trimmer peaked or attempted to peak at its max. capacity then 1st det coil lacks sufficient inductance (too few turns or coil diameter incorrect).
(b) If this trimmer peaked or attempted to peak at its min. capacity (farthermost counterclockwise position) then 1st det. coil has too high an inductance (too many turns). Remove 1 turn and repeat operation 19 until this first detector trimmer peaks the 4000 Kc. signal at 1/4 of its total travel from its farthermost counterclockwise position.

(20) Set up oscillator signal at 1550 Kc, and turn tuning dial to farthermost counterclockwise position (max. capacity).

(21) Adjust series osc. trimmer (C - 2) (second from front of set, located beneath chassis but adjustable from top of chassis) until max. signal is secured. 1st det. air-trimmer should paak this 1550 kc. signal somewhere in its range.

NOTE: If in operation # 18, tuning dial did not pick up 4000 Kc. signal at 10 or nearly 10 on dial, then oscillator coil for this band is in error having a wrong number of turns. This difficulty must be corrected before proceeding with operations # 19, # 20 and # 21.

(22) Move band selector switch to next high freq. band (CC one notch) (11000 to 4200 Kc.).

(23) Set up oscillator signal at 11000 Kc. Move tuning dial and gang condenser to furthermost clockwise position (min. cap.). adjust cap. C-1 for max. signih. (For operations which are to follow set must be standing on LEFT END. Condenser (C - 1) is mounted on rectangular coil and switch shield beneath chassis.

(24) If 11000 Kc. signal cannot be tuned in with gung condenser at min. cap. even after adjusting C-1, then osc. coil inductance is either high or low. If inductance is low then 11000 Kc. signal can be tuned in by increasing gang cond. cap. (rotating gang). If osc. inductance is too high then this fact can be determined by varying Oscillator signal to some lower frequency until signal is audible in receiver.
If this osc. coil inductance is incorrect, examine the coil for correct turns and diameter. Inductance can be lowered by sliding last turn or last 2 turns away from rest of turns of coil.

(25) check at what position the Ist det, air-trimmer peaks this 11000 Kc. signal. Max. signal should be obtained at about 1/4 total travel of this condenser from its min. cap. setting. If this does not occur, then first det. coil has wrong inductance value and must be adjusted by sliding end turn or turns. Sliding turns outward away from main body of coil decreases inductance.

(26) Set up 4200 Kc. Osc, signal and move tuning dial and gang to Max. Cap. Signal should be heard close to 100 on dial. Check 1st det. trimmer to see that it peaks this 4200 KC. signal within its tuning range.

(27) If in checking in # 26 the 4200 Kc. signal cannot be heard (receiver does not tune to 4200 Kc, signal) then the osc. coil inductance for this band is too low and consequently C-1 in operation 24 was adjusted to too high a capacity so that the facts in the case are that the osc. ind. is too low and distributed cap. too high. Therefore add 1 or 1/2 turn to osc. coil and repeat operations 23, 24, 25 and 26.

(28) Check 1st det, trimmer at several points in this band to see that it peaks properly.

(29) Move band selector switch to next higher freq. band (22000 kc. to 11000 Kc.) (farthermost CC position).

(30) Set up osc. signal at 21800 Kc. and move gang condenser to min. capacity setting. adjust trimmer on # 2 section of gang cond. until signal is heard.

(31) If signal cannot be tuned in then osc. coil has too high an inductance and must be corrected and same procedure followed is in # 24 except that in this case higher frequencies are used.

(32) Peak 1st det. trimmer at 21800 Kc. signal. (Be sure that # 5 trimmer is set at min. cap.). Should peak at 1/4 trinner condenser travel from min. setting. If this does not occur then ind. of 1st det. coil is incorrect and must be corrected. If air-trimmer closes more than 1/4 its travel the inductance of 1st det. coil is too low and conversely too high if trimmer cond. does not close 1/4 its travel adjusting of coil by sliding turns inward or outward.

(33) Set up osc. signal at 11000 Kc. and move tuning dial and cond. toward max cap. At 100 or close thereto the signal should be heard. Be sure the signal received is the fundamental of osc. First det. trimmer should peak within its tuning range. No trouble should be encountered here unless some high distributed or lumped capacity has been introduced in 1st det. circuit which should not be prosant. This must be corrected if 1st det. trimmer does not peak correctly at 11000 KC. signal freq.

(34) If signal is received at a much lower (5 to 10 div.) than 100 on dial then osc. coil inductance is too high and should be reduced. Then repeat operations #30, # 31, # 32, #33 which will give a high capacity se ting on trimmer on section #2 of gang.

(35) Check air-trimmer of 1st det. in various settings of gang between high and low freq. extremes to see that trimmer peaks at these points.

NOTE: When performing operations set down for the two high frequency bands no violent or sudden changes should occur in 1st detector air-trimmer settings. If such is experienced then operator has peaked trimmer on frequency on wrong side of oscillator.

CIRCUIT TEST VOLTAGES FOR MODEL 94 ALL-WAVE

Normal "B" Voltage DC from filament 5Z3 to C.T. HV Trans. - 400 volts
Potential between cathode of 2B7 and cathodes of 58 tubes - 3 volts
(Use 300 volt range) This is effective grid bias (no signal)
Also observe this polarity. Cathodes of I.F. Tubes should be positive with respect to cathode of 2B7.