Porto-Server Inc. PF-511 Schematic

Porto-Server Inc. PF-511

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Product Information:
Model:PF-511
Manufacturer:Porto-Server Inc.
Description:9022-F

Schematic Pages

PNG: Page 1 Rider Manual Volume 15
PNG: Page 2 Rider Manual Volume 15

Schematics Content

Page 1:

I.F. 455 KC.

Lettered terminals in 11 lastrations correspond to similarly lettered terminals on the circuit diagram.

DIAL AND POINTER DRIVE CORD ARRANGEMENT
To string dial cord, turn the main drive drum to maxi mum counter-clockwise position and use following parts:

114955 Clip on end of cord
117057 Cord (55 inches)
119087 Ring for dial cord
161384 Tension Spring

SOCKET VOLTAGES Measured with voltmeter having sensitivity of 1000 ohms per volt except where indicated by (*).

VOLUME ON FULL WITH NO SIGNAL DIAL TUNED TO 540 KC.

Page 2:

ALIGNMENT PROCEDURE 1. Remove choses and loop from cabinet. Solder approximately 8 " of insulated wire to any B connection (see voltage chart on opposite side for convenient B location). Then reinstall chassis and loop in cabinet. The B lead should extend from under the chassis at the back, 2. Connect ground lead of signal generator to B lead. 3. Connect output meter across the speaker voice coil (terminals at back of speaker.) 4. Turn the tuning control knob clockwise as far as it will go (tuner mechanism is now in maximum open position with tuning slugs almost completely withdrawn from coils). Dial pointer should then point to 1600 Kc mark on scale. If it is set incorrectly, release pointer clip on dial cord and reposition pointer. 5. Set volume control at maximum volume position and use a weak signal from the signal generator.

Coating of speaker cement at top of each tuning core stem to prevent movement,

AUDIO OSCILLATION The audio system of this receiver utilizes a two stage type of inverse feed-back arrangement and, should it over be necessary to replace the speaker or output transformer, it is important to maintain a definite phase relationship in the feed-back circuit. If the connections to the out. put transformer are reversed or it the feed-back connection is made to the wrong side of the output transformer secondary: the system will become regenerative instead of de. generative. Under those conditions audio oscillation may result. If that occurs, oscillation may be prevented by reversing, the connections to the secondary of the output transformer.

APPROXIMATE STAGE GAIN DATA Be sure R.F, and I.F, stages are accurately aligned before measuring gain. R.F. gains can be measured with a " channel " type instrument containing a tuned and calibrated R.F. amplifier. A vacuum tube voltmeter may be used for audio gain measurements. Observe following precautions:

1. For all gain measurements connect signal generator as shown. Use 600 KC. signal with 400 cycle modulation (use nearby frequency if local station interferes.)

2. For R.F. and I.F. measurements connect negative terminal of a 3 volt battery (two 142 volt cells in series) to A.V.C. lead and positive terminal to B This provides a definite operating point. IMPORTANT: Disconnect battery when measuring audio stage gains.

3. Be sure radio is carefully tuned to generator signal { use weak signal for sharp tuning.)

4. When using a " channel " type instrument carefully tune it for maximum output at desired frequency before making measurements,

Ments. The R.F. and I.F. stage gains shown below are less than under normal operating conditions due to the use of 3 volts fixed bias in order to establish a definite operating point. Therefore, these values are not intended to indicate the full capability of a stage,

Differences in tube characteristics, tolerance of parte, adjustment of tuned circuits, and variations of line voltage will influence stage gain. Accuracy of measurements is dependent upon careful tuning of receiver to generator signal and experience in using your equipment. These factors may create considerable variation in gain measurements.