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INSTRUCTIONS FOR ASSEMBLING DYNAKIT MARK IV

DESCRIPTION

The Mark IV Amplifier uses a circuit arrangement

based on that of the Dynakits Mark II and Mark III

which have become world famous for superior quality

while essentially simple and trouble free. The new

7199 tube is used as a pentode high gain voltage am-

plifier directly coupled to a cathodyne phase inverter.

All parameters are adjusted for minimum distortion.

This type of phase inverter has the unique advantage

that its operation is independent of tube aging so that

no adjustments are required in maintaining optimum

performance.

An internal capacitive feedback loop balances the

phase inverter at the highest frequencies, and the

arrangement provides accurately balanced driving

signals to the output tubes, which are EL-34's oper-

ated well below their maximum ratings. The output

tubes use a fixed. bias arrangement which is set

through use of Dyna Biaset (patent pending) which

provides optimum linearity of the tubes and mini-

mizes the effects of unbalanced components. The

connection of the output tubes includes a small per-

centage of screen loading which improves the regu-

lation of the output stage and makes it comparatively

uncritical of load impedance.

The impedance match and bias conditions utilized

in the output stage provide minimum distortion over

a very wide dynamic range. In addition, 20 DB of

negative voltage feedback lowers the distortion to an

unmeasurable proportion at normal listening levels

and to less than 1% intermodulation distortion at

40 watts output.

The use of a minimum number of phase shifting

stages along with careful transformer design makes

it possible to have unconditional stability at both

high and low frequencies. This feature of the design

means that there is no tendency toward motorboating

or oscillation under any condition of use.

The inherent linearity of the circuit, its absolute

stability, and the prefabrication of all critical wiring

on the printed circuit assembly make construction

completely non-critical. The use of conservatively

operated, highest quality components insures supe-

rior and dependable operation over a long period of

time.

GENERAL WIRING PRACTICE

Assembly of the Dynakit Mark IV is quite simple

compared to general kit assembly requirements. This

is because all critical parts of the Dynakit are factory

assembled for you on the printed circuit assembly.

Other parts are out in the open in a free and unclut-

tered layout so there is easy accessibility for wiring

or trouble shooting purposes. Con<;truction of your

Dynakit should not take more than three hours be-

cause of these simplifications.

Upon opening your kit, check the components with

the parts list. Familiarize yourself with the compo-

nents; they can be identified by comparison with the

pictorial diagram and by specified color coding.

Tools required for easy assembly of your Dynaldt

are a soldering iron (small tip) or soldering gun,

long nose pliers, screwdriver, and wire cutters. Al-

though not essential, a low cost wire stripper and

cutter of the type which can be purchased for less

than a dollar win greatly facilitate cutting and strip-

ping the various leads in the kit.

c,;ood

soldering technique is valuable in obtaining

satIsfactory results from any electronic equipment.

ALL SOLDERING MUST BE DONE WITH

ROSIN CORE SOLDER. There is no warranty on

any equipment in which acid core solder has been

used. Make sure that the solder is plainly marked

"Rosin Core."

you have solder on hand the origin

of which is doubtful, it is wise to obtain new 50/50

or 60/40 rosin core solder. Whenever soldering is

required, the assembly instructions specify it by

"(S) ".

this symbol is not shown after a connection

is specified, it indicates that further connections will

be made at that point before soldering.

Soldering is accomplished by heating the joint with

the iron until solder is hot enough to flow when

touched to the joint. It is not desirable to feed the

solder to the iron.

should be fed to the junction of

iron and joint. After the solder flows, the iron should

be held in place for a few seconds and removed when

it is seen that the solder has contacted both parts of

the connection-the lug and the wire connected to it.

It should not show a ball of solder, hut a smooth

transition from solder to component lead.

Before applying solder the joint should be c1e.an

and the lead should be crimped in place so as to have

mechanical security. It is not necessary to wrap leads

around contacts many times. A single turn and pinch-

ing together with pliers is suitable. After soldering

there should be no play at the joint if the )Pad is

wiggled with a pair of pliers. It is practical to do all

soldering with a pencil type iron

wi~h

a low wattage

:ating. A small tip is extremely useful when working

III

confined space.

a soldering gun is used it should

be used with discretion since the amount of heat

available is far more than required fOl' soldering light

wires.

Component leads should be trimmed as they are

used; the length should be such that the proper con-

nection can be made from point to point without

strain on lugs or components. Care should be exer·

cised not to allow wires to touch one another unless

they are actually connectf::.j to the same point.

The instructions which follow have been arranged

for simplified procedure in which the work can be

done without interference between the various por-

tions of the wiring. It is recommended that the in-

structions be followed on a step by step basis, check-

ing off each step as it is completed. The pictorial

diagrams should be used for reference and all con-

nections Checked against these before going on to

tlw

next step.

the wiring is done methodically and

each step checked carefully, your amplifier should

work without difficulty as soon as it is completed.