Info

To the B line, by-pass with a 0.001 microfarad disc ceramic condenser. A disc ceramic is recommended because it is series resonant in the TV range. 2. Unwind the output coil on the amplifier's plate form, counting the number of turns and noticing the direction of winding. Insulate the plate coil with several layers of Duco cement or any Polystyrene liquid insulation. Solder a small stranded wire to a copper, brass or silver ribbon the width of the antenna coil and long enough to wrap around the...

Model Tek Trf Tuner

This Unit available Assembled or as a Kit from your Local Distributor One bracket and pulley assembly, 06282 One 4 gang variable condenser, 21-5223 One gang condenser shield assembly, 25-8208 One 500K volume control with switch, 29424 One 100 ohm hum balance control, 29260 One length of braided shielding, 12491 One 20-20-20 mfd. 250 V. electrolytic condenser, 34102 One .1 mfd. 400 V. paper condenser, 28113GT One .05 mfd. 600 V. paper condenser, 28115GT Two .05 mfd. 400 V. paper condensers,...

Part No

Chassis 06401 Filter Condenser 16124 Variable Condenser 21-5203 Socket 8 Prong 9309 Socket 5 Prong 29316 Crystal Socket 29628 Phone Jack 19470 Switch 19475 RF Choke 19-1996 Line Cord 12434 Terminal Strip 21723 .01 600V Paper Condenser 28101 .1 600V Paper Condenser 34158 100,000 Ohm 1 Watt Carbon Resistor 20 RC30AE104M 18,000 Ohm 2 Watt Carbon Resistor 20 RC40AE183M 2 Ins. Tie Point 16752 30K 10W Wire Wound Resistor R-1637 Knobs 23-8221 Ceramic Insulator Sets 27-1000 * Hardware Kit 06411 10-32 X...

Calibration

The Signal Calibrator is adjusted at the factory to have the appropriate harmonic at zero beat with the Standard Frequency transmission from WWV but it can be expected that this adjustment may change slightly during shipment and handling. It Is desirable therefore to check the calibration when first set up and at intervals thereafter. The Signal Calibrator has been built in accordance with the best engineering practice short of temperature control on the crystal which was avoided because of...

Model Bk Tube Student

2 Miniature tube sockets 1 5-prong coil socket 1 Tie-lug, 2 insulated terminals 1 50,000 ohm regeneration control 1 100,000 ohm fixed resistor, R1 1 220,000 ohm fixed resistor, R2 2 1 megohm fixed resistors R3 & R5 1 .1 ufd. 400 volt paper cond. CI 1 .01 ufd. 400 volt paper cond. C5 1 25 ufd. electrolytic cond. C6 4 2-56 X 5 16 screws 10 6-32 hexagon nuts 11 6 Lock washers 1 Extruded bakelite washer 1 Micoid washer 2 Metal spacers 2 Bakelite knobs 1 Dial pointer 1 Regeneration control nut, 3...

Dual Tone Control

Thordarson's development of this Dual Tone Control was prompted by the many requests of sound men for an effective tone compensating system to boost or attenuate the bass or treble frequencies independently of each other. Examination of the schematic diagram will show that the final circuit is simple and not at all complicated to construct. It is constructed on a small chassis, making it adaptable to practically any existing amplifier. Operation is based on degeneration in the cathode circuit...

Alignment Of Receivers

Modern radio receivers employ from two up to eight, ten or even more circuits to achieve the selectivity desired. These circuits, however, are of little benefit unless all of them are working at their proper frequencies simultaneously. Only someone acquainted with the alignment of receivers in a radio production department, or someone engaged in radio service work who has adjusted a receiver on which someone has tightened all of the adjusting screws, can realize how dead a receiver can sound...

Oscillator Coils

(The conventional oscillator coil is an even simpler device than the average antenna or RF coil. The method of checking the coil itself need hardly be explained. An ohm-meter is usually all that is necessary. To prove that an oscillator is working, it is only necessary to touch the probe of the Oscillator channel of the Analyst to the stator connection of the oscillator tuning condenser, and at the same time, with the Attenuator set for maximum sensitivity, the dial of the Oscillator channel,...

Volume Indicators

ONE OF THE MOST IMPORTANT PHASES OF RECORDING IS CLOSE ATTENTION TO THE PROPER RECORDING VOLUME. THE BEST OPERATION IS OBTAINED WHEN THE NORMAL NEON BULB IS LIT AS MUGH OF THE TIME AS POSSIBLE WHILE THE OVERLOAD NEON INDICATOR FLASHES ONLY AT RARE INTERVALS OR NOT AT ALL. A close control of program level is required to achieve such results but every bit of effort expended in the attempt will be well worth while. If the volume is too high, the recording amplifier is overloaded and impresses a...

Tracking

Early models of radio receivers usually used only one tuned circuit per receiver, but as the number of circuits was increased to provide better selectivity, tuning a radio set became a problem beyond the grasp of the average citizen, and confined the sale of receivers to the DX hunter who spent innumerable midnight hours listening for new stations. To make the receivers commercially more acceptable, simplifications in tuning were imperative. To this end, designs were produced that had a nominal...

Analyst

The manu facture and sale of the Meissner Analyst has been discont inued since the War. However the in formation below is given since it is applicable to all instruments of this type. The Meissner Analyst is a tool for the rapid solution of difficult Service problems. It is a device to permit the rapid location of faults in defective radio receivers or sound equipment without measurements, complete voltage measurements on all tube elements, or tedious tracing of circuit wiring. The fundamental...

Gang Condenser Servicing

F. amplifier is aligned in the usual manner. Connect a service oscillator between the chassis and the grid of the 6A8 tube, using a condenser .0005 mfd to .26 mfd. between the grid and the high side of the generator output Do not remove the,grid clip for this operation. Set the dial near 600 KC, and proceed with alignment at 456 KC. Turn the audio volume control on full. Increase the output of the service oscillator until a signal is just audible. Adjust each I. F. trimmer so that...

Complete Parts List

1 Broadcast and short wave antenna coil No. 14-2860 1 Broadcast and shortwave oscillator coil No. 14-2862 1 PM speaker with output transformer No. 25274 1 Variable condenser No. 26128 1 Filter choke No. T-20C65 6 Octal sockets, 25-8209 1 500K ohm volume control with switch, 19701 1 Band switch, 25273 1 Dial mechanism plate, 02865 1 Trimmer base assembly, 17738 1 Dial drum, 19706 1 Dial cord and spring assembly, 02869 1 Dial Shaft, 19703 1 C washer for dial shaft, 16653 1 Bakelite washer for...

Output

Output terminals are provided on the back of the chassis see Fig. 2 . Two output impedances are provided, one for output into high impedance loads 30,000 ohms or higher and one for output into a 500 ohm balanced transmission line. The high impedance output may be used for feeding an amplifier located only a few feet from the tuner and whose input impedance is 30,000 ohms or greater. If the amplifier impedance is greater than 30,000 ohms and if the cable capacity approaches 1000 uuf., then the...

Horn Type Loudspeakers

Diagram Horn Type Loudspeaker

A second general type of moving-coil loudspeaker is known as the horn type loudspeaker. Here the vibrating structure, usually known as the diaphragm, is relatively small in size and does not radiate directly into the air. Figure 2 illustrates the functional nature of such a loudspeaker. A flaring tube called a horn is connected to the diaphragm so that the sound energy created b the diaphragm enters the small end of the horn, called the throat from the sound chamber which is the space directly...

Checking Band Edges

The Signal Calibrator is an excellent device to spot the edges of either CW or Phone bands. It may be coupled to the receiver and set at such a level that the markers at the band edges are just audible and operate continuously. The level of the markers may be changed instantly to make them strong enough to be picked out of the strongest interference or to be just as quickly eliminated so that a 'weak signal on the band edge can be read. The amateur who has a good electron-coupled oscillator...

Accessories

The Meissner Model 9-1091C is supplied with knobs and control panel escutcheons and requires no additional parts except mounting screws for mounting in a console cabinet. For rack panel mounting, a hardware kit is available consisting of 1 8 steel panel in gray or black, side mounting brackets, bottom cover plate and dust cover. Also available for table top mounting is a steel cabinet and panel. For a most excellent combination of units and one which will satisfy even the most discriminating...

Singletuned If Transformers

The single-tuned IF transformer has taken two important forms, the bi-filar coil and the double coil tvpes. In the former case, the two wires constituting primary and secondary are wound simultaneously, forming a coil that is a single physical unit yet having two independent circuits. The start of the primary was usually the plus B connection and the start of the secondary was ground. The outside of the primary was the plate connection and the outside of the secondary was the grid connection....

Interelectrode Capacity

It has been pointed out, in the section on Single-Stage Oscillation, that the coupling medium for such oscillation is the inter-electrode capacity of the tube. The method of measuring such small capacities in the presence of much larger capacities in a network that cannot be opened to measure the desired capacity directly may be of interest. Fig. 23 represents the capacity network that exists in the tube as far as feedback capacities are concerned. The method of measurement is to have a similar...

Alignment Am

The AM alignment may be carried out with an AM signal generator and an output meter. Connect a 500 ohm resistor across the 500 ohm output terminals of the tuner. The output meter may be connected from the high impedance output terminal to chassis. For IF alignment introduce a 455 kc 30 modulated signal into the signal-grid of the 6BE6 Pin t 7 through a .1 ufd. coupling condenser. The output of the signal generator should at all times be kept as low as will give a satisfactory reading on the...

Rfif Channel

The RF-IF channel is a high-gain three-stage tuned RF amplifier employing three 6SK7 tubes. This amplifier is followed by a diode voltmeter tube and an electronic indicator tube. The signal is fed to the input jack through the special input cable, and full control of the level is provided by a four-position capacitive Multiplier and a resistive Attenuator. Three frequency ranges are provided, selected by the Range switch. The bands covered are 600 to 1700 kc, 240 to 615 kc and 95 to 250 kc. The...

Baffles And Enclosures For Loudspeakers

Preferred Dimensions for Bass Reflex Cabinets It can be seen that sound waves will normally be radiated from both sides of a vibrating diaphragm. Now the sound waves radiated from the back of the diaphragm combine with those from the front of the diaphragm and the low frequencies tend to combine so as to mutually cancel. Therefore a direct-radiator loudspeaker must be placed in a baffle or enclosure of some type so that these components cannot cancel in the region of interest. The...

FIG

Because of this reduction in low-frequency velocity it is necessary to. build up the low frequency response on playback to compensate for this effect. This is called equalization. It must be pointed out that equalization Is needed for the record characteristic, and not for the pickup. Any compensation which may be added to correct for deficiencies in a given pickup must be treated separately from record equalization. Since a crystal pickup responds to the amplitude of displacement of the...

Doubletuned If Transformers

The double-tuned IF transformer is, by far, the most popular type. It is simple in construction, has negligible leakage, no measurable hum transfer into diode circuits and can have its selectivity curve made as sharp as two single-tuned transformers in cascade, or can be considerably broader at the Nose of the selectivity curve than two cascaded single-tuned transformers, yet on the broader part of the selectivity curves maintain practically the same width as the cascaded single-tuned...

GENERAL

The Meissner Model 8CK is designed to provide superior reception in the 88 to 108 mc FM band. It is a direct application of the circuits of the famous Meissner Model 8C receptor. A double converter system is employed which greatly reduces image responses. A ratio detector system is employed in this tuner to provide distortionless and noise-free reception with a minimum of tubes and parts. The RF section, consisting of the oscillator and two mixers, together with the 3-gang variable condenser is...

Alignment Fm

Discriminator

For FM alignment a frequency modulated generator 60 to 400 cycle modulation, 400 kc sweep and an oscilloscope are required. Connect the modulation soiree on the signal generator into the horizontal amplifier of the oscilloscope. It may be necessary to connect a phase shifting network in this line between the signal generator modulating source and the oscilloscope horizontal amplifier in order to get the correct pattern on the oscilloscope. Connect the tuner output to the vertical amplifier...

Microphonics

In the original design of receivers one of the most exasperating and illusive problems confronting the radio-engineer is that of preventing Microphonic Howls. First-class radio manufacturers usually do everything economically practical to minimize this trouble but, even in spite of these efforts, this trouble still produces many service calls. The cause of the trouble is easily understood, but finding the offending item is usually a difficult job with many apparently correct answers proven...

Single Channel Loudspeaker Systems

In the usual radio receiver, a single direct-radiator loudspeaker is used. This unit must reproduce the complete frequency range required. Stated in another way, the frequency range resulting is no greater than the loudspeaker can reproduce. It is unfortunate that in general much too small a portion of the total cost of the receiver is alloted to that vital link - the loudspeaker. The usual loudspeaker used for this application has no special characteristics. However, single direcWadiator...

Iigeneral Information Circuits And Applications

Radio Frequency Television Test Construction, Testing and Use of Audio Phonograph III-CONSTRUCTION OF THORDARSON-MEISSNER KITS By Order of Difficulty Construction Model 2 BK - 2 Tube Student Model 3 BK - 3 Tube Student Model T-4 EK - TRF Model 10-1191A - 5 Tube AC-DC Model 10-1199 - 6 Tube AC-DC Model 8 CK - FM Receptor Model 6 BK - 3 Band AM Model 2 CW - Novice

Variable Dc Supply Employing Thyratron Rectifiers

C. power supply shown in the schematic diagram finds its main application in amateur phone and CW transmitters and in laboratories where a variable source of D. C. voltage is frequently desired. This circuit does not require the usual primary variac or a voltage dropping resistor to obtain control of the output voltage. In amateur transmitters the variable voltage feature is advantageous for tuning up operations, where a low plate potential will aid in preventing damage to...

Tube Ac Trf Receiver

This receiver is presented in this manual only as a general guide in receiver construction. The essential parts which are available from Meissner or Thordarson are noted by in the parts list. The Meissner 5 tube TRF receiver kit No. 10-1106 was designed to fill the requirements for a receiver kit very simple to build yet possessing performance such that it will continue to give satisfying entertainment long after the thrill of successful construction has worn off. This receiver tunes from 550...

Pictorial Diagram

A pictorial wiring diagram of each kit has been prepared with great care to show what no circuit diagram can show the physical arrangement of parts and leads, which, in many cases, Is more important tnan some of the values of circuit elements shown in the schematic diagram. If the arrangement of parts shown therein is followed closely, your kit will work with the same freedom from trouble that characterizes the finished original Master Models leaving the engineering department of the Meissner...

Amateur Speech Amplifier Utilizing The Tc Speech Filter

The circuit diagram illustrates the application of the Thordar-T-20C73 Speech Filter in a typical amateur speech amplifier and driver unit. This compact audio band pass filter has been specifically designed for amateur, police, and emergency radio service. It provides several worthwhile operating advantages when installed in the speech section of transmitters employed for voice communication. The main requisite for communication work is signal read-abiliyt and intelligibility, not broadcast...

Calibrating Trimmer Band Frequency Position

The black test lead is used in the operation above to get enough sensitivity to operate from the signal generator. Ordinarily when checking the voltage from an oscillator tube, the brown test lead should be used. The RF-IF channel requires practically the same accuracy in frequency calibration as the Oscillator section. Accordingly, a signal generator should be used in adjusting the RF-IF channel so that it has an accurate frequency calibration. The connections from the signal generator to the...

Wireless Phonograph Oscillator

The Meissner Wireless Phonograph Oscillator No. 10-6380 Is a device to permit any radio receiver to be utilized as an electric phonograph without any'wires connecting the Wire-less Phonograph Oscillator to the radio receiver and without In any way altering the receiver. WIRELESS OPERATION The Wireless Phonograph Oscillator Is actually a radio transmitter of very low power. Federal laws prevent raising the power output. It will radiate a signal in the broadcast band that can be picked up by any...

Gang Condensers

Gang condensers are instruments of precision that should be looked upon with respect. They are made and adjusted by experts to very close limits of uniformity to that your kit may have the best possible tracking and accuracy of calibration. To give them the best protection when handling them or working on any chassis on which they are mounted, keep the condenser closed, that is, plates fully meshed. Never bend a condenser plate unless you are very sure that you Know what will happen.

Amplifier Construction Procedure And Suggestions

Whether an amplifier is to be used for home music installations or for public address work, the following suggestions will help toward producing a superior audio system. The first step is to determine the parts layout and the chassis base size that will be required. .When constructing any of the audio equipment described in this manual, it is suggested that the chassis view photo be followed in determining the placement of the major components. The size of the standard chassis base employed on...

Advantages Of Inverse Feedback

IN AUDIO AMPLIFIERS A beam power amplifier to be truly modern should incorporate inverse feedback. It is a commonly recognized fact that low plate resistance tubes such as the 2A3 are superior from the standpoint of low distortion and good quality. With inverse feedback the high plate resistance beam power tube may be made to take on the characteristics of the low-mu triode, yet retain most of its high power sensitivity. The important advantages obtained by the use of inverse feedback are as...

Dial String Diagram Meissner 8c

All parts listed above plus the following 1 Punched aluminum chassis, 05965-A 4 Miniature tube sockets, 29477 1 2-terminal strip, 16731 5 Special locking washers, 26658 1 Condenser-tie lug assembly, 05449 1 Volume control with switch, 29424 1 Length plastic tubing 1 20-20-20 ufd. electrolytic condenser, 34102 1 25 ufd., 25 volt electrolytic condenser 28105 1 .05 ufd., 600 volt metal clad condenser, 28172 1 .05 ufd. 600 volt paper condenser, 28115 1 4 ufd., 25 volt electrolytic condenser, 34147...

High Fidelity Watt Phonotuner Amplifier

This amplifier is presented in this manual only as a general guide in the construction of amplifiers. The power and output transformers and the filter choke are available. This high fidelity amplifier has been designed for home music installations or other applications where quality reproduction is required. In addition to accommodating AM-FM tuner or crystal pickup signal sources, this amplifier includes a 6SC7 pre-amplifier. This stage provides the additional voltage amplification and bass...

Alignment Without Test Equipment

If no test equipment is available, connect an outside aerial to the receiver, advance the volume control to maximum and tune in a local station between 1400 and 1500 KC, adjusting the trimmer condensers on the gang condenser, retarding the volume control as the receiver becomes progressively more sensitive, using always a small output signal because more accurate alignment can be made with a weak signal. Only those parts followed by are available from Meissner or Thordars Parts Supplied for...

Alignment With The Analyst

For alignment purposes, the Analyst can be conveniently used either with a calibrated test oscillator or with a received signal of known frequency. If the receiver to be aligned is of the TRF type and has merely drifted out of adjustment it will probably have enough sensitivity to operate the speaker when the signal is fed into the antenna and ground terminals of the receiver. In such a case, the Audio prod is connected to some convenient point in the audio system furnishing audio voltage, and...