Dynatuner FM-1 어셈블리 정렬 작업 지침 - 페이지 3

{카테고리_이름} Dynatuner FM-1에 대한 어셈블리 정렬 작업 지침을 온라인으로 검색하거나 PDF를 다운로드하세요. Dynatuner FM-1 20 페이지.

페이지 인쇄

DYNATUNER FM-1

DESCRIPTION

In sclCl'ting the Dynatuner for your FM receiver you

have chosen one of the most intensively engineered high

fidelity components on the market today.

The Dynatuner is a fresh engineering concept, not an

adaptation of an existing- production design, To produce a

tuner having optimum performance. every portion of the

circuit has been carefully investigated in terms both of

performance maxima and' of the overall stability of opera-

tion and simplicity of adjustment required of a kit design.

The result of this effort is a tuner which provides the

same top performance in your home as it does in the

Ik1boratory. Without any test equipment -just following the

simple adjustment procedures in this manual-the kit

huilder will achieve the high performance normally obtain-

able only with laboratory test and alignment equipment.

There is no longer any question whether adjustments

have shifted during shipping and handling as frequently

happens with FM tuners. In the Dynatuner all adjustments

can be easily checked; and, of course, the periodic: main-

tenance required of all tuners is simply and easily made

without a trip to the serviceman. This adjusting technique

has been obtained without any sacrifice in tuner per-

formance, In falt. the converse is true. The care and control

necessary to make these adjustments absolutely reproduci-

ble h8.s

rm;ultA~d

in a significantly hi/1;her level of performance

comhined with the required stability.

In addition to the adjustment requirements, the basic

Aengineering objective was to produce a tuncr design of

•

adequate sensitivity for fringe area reception, with dis-

tortion levels of the recovered audio signal coml1arahle to

that measured on the best of audio amplifiers.

The significant advantages of etched cireuit construction

in terms of reliahility, reproducibility and durability are

amply demonst.rated in the Dynatuner. Their use has

further accomplished the ultimate goal of improved per-

formam'e, In no ot.her t.unerkit or factory wired

has

exact component placement and lead layout been so

accurately defined. The excellent specifications of the

Dynatuncr arc possible, and guaranteeablc, unit to unit,

lab model to production kit, because of the extraordinary

uniformity which etched circuits provide, and the inherent

Htability of the circuit mn.(iguration.

Therc has been no intent to enter the sensitivity specifica-

tion race (claims often engineered by the advertising

department).

However. uHing the sensitivity standards

proposed by t.he Inst.itute of High Fidelity Manufacturers,

this tuner belongs in the highly sensitive class and, in fact,

will provide listenable reception of mOl'e stations than

tuners of ostensibly higher sensitivity rating.

The concentration of effort to reduce distortion has also

produced a tuner which is unquestionably the lowest

distortion receiver on the market today.

There are many parameters in addition to sensitivity

and distortion which are part of a completely satisfactory

tuner design, Some are measurable; some are intangible.

Extensive field testing under adverse and marginal con-

Aditions has proven the Dynatuner to be as fine a tuner as

"can be obtained today regardless of price or specification

claims,

The circuit consists of:

Cathode coupled tuned R.F, amplifier stage

using a 6AQ8,ECCB5 high conductallce dual

high frequency triode.

2. Screen coupled oscillator-mixer stage using a

6ATBA high conversion triode-pentode.

3. Four I.F. amplifier stages with progressive

limiting using two 6BA6 and two 6AU6 tubes.

4. Balanced wide band discriminator with makhed

semi-condudor diodes.

5. Cathode follower providing detector isolation

to the de-emphasis network and multiplex take-

off using one half of a 12AX7/ECC83.

6. Plate follower wide band feedback audio output

stage using the other half of the 12AX7,'ECC83.

7. Tuning indicator 6FG6/EM84.

8, Power supply and rectifier 6V 4, EZ80.

The Antenna Circuit

Provision is made to match either a 75 ohm unbalanced

or a 300 ohm balanced transmission line thus accommodat-

ing any standard antenna array used for FM reception.

The

R.F. Stage

The cathode coupled dual triode R.F. amplifier circuit

was chosen for the input stage. It combines the high gain

and low noise figures of the commonly used grounded grid

input with a tuneable input

a necessary feature to prevent

overloading from strong loeal signals when tuning weak

signals,

Other more complex circuits have slightly better theoreti-

cal noise thresholds. However. galactic noise levels at 100

megacycles are of sufficient magnitude to prevent complete

utilization of this theoretical difference and the less com-

plex cathode coupled stage closely approaches optimum

field result.s.

The Oscillator-Mixer

The triode section of the 6AT8A is used in

1.1

"tickler

feedback" tUlled grid oscillator circuit. Careful temperature

stabilization and choice of operating parameters result in

an oscillator circuit with sufficient stability to obviate any

need for automatic frequency control with its inherent

degradation of the audio signal.

The pentode section of the 6AT8A is used as the mixer.

The tube is self-biased for maximum conversion efficiency.

The oscillator is injected into the screen circuit to provide

complete isolation of the oscillator tuning circuit from the

signal tuning circuit at the mixer grid. Oscillator drag

(change in oscillator frequency as the mixer tuning is

adjusted) is nonexistent, greatly simplifying the adjust-

ment and tracking of the front end. This isolation also

reduces re-radiation of the oscillator energy into the

antenna which might cause interference in other nearby

receivers and television sets.

Circuit constants of the oscillator and mixer circuits have

been adjusted to give uniform sensitivity over the entire

FM band.