Philips 337 a service manual

Page 1

337A

STRICTLY CONFIDENTIAL

FOR PHILIPS SERVICE
DEALERS ONLYA
I

COMONY 1936

Al

gllfill Ii] 11h Ill HEW

S ERVICE DO CUMENTATJ ON

OCTODE-SUPER

337A

mum.

Receiver 331A is a sulmhhnterollyne set with
built-in moving-coil loudspeaker. for reception

of the follomng' f en bands: 18.18 Nit-5.38
MC (16-3-51 m)r::|{:ll 1563/3 Kc-nanL Kc (199-
580 in).

The set his four control hollt The small knob on
the left amen volume cuntroL whilst the large
knob fitted concentrically to it operates the
continuously variable tone-filterr The small knob
on the right serves for tuning and the large one
opontes the wavechange- and mine-switch. The
receiver is provided with A.V.C.. connections for
a moral-one pick-up Ind [or In extra loudspeaker
with a high impedance. A ufety contnct an the
buck ensures that the receiver is entirely den: "
when opened.

Ducn'pfim of the circuit. :
We will first describe the circuit ding-n: for in;

medium-wove bnnd, nnd afterwards for the sho -
wlve bond. The voltage on the aerial comes acr . s

511 end in induced in 512, which coil forms a pail-'1!

of the tuned circuit of grid 4, of L1 comprising C23.
512. the tum; condenser C7 and the trimmer C11.
The vol e over C? in conducted vin R30. which
is of signi canoe for nhon woves only, to the 4th
grid of L1. The circuit C8, 517 with the parallel

oddmg condenser C11 and the eerie: ad '
gondenlcrs C16 and C29 is connected to tlhe :11:
grid of L1. The padding oondmers ensure that
the frequency of the mentor is nlways 475 Kc
higher than the frequency to which the H.F. cir-
cuits are tuned in. The plrdlel condensers do this
for the higher frequancies and the series padding
condensers fur the lower frequencies of the wave-
hind.

C26 is the grid condenser and R10 the leak resis-
tnnce. whilst R9 has been fitted to prevent plus-
itic oscillltiou. 518 is con led with 517, which
causes oscillation. The end: e the first and second
grid of L1 are to be considered as n triode oscil-
luringt in a frequency 475 Kc higher than that of
the .F. tuning. Converrion takes lnce in L1 and

, V Gina n e enciu of

I the KEEN-d IheZeneutor e sun In
w v_difi9rme. frequenciw vi than}! dqgnals, The
circnitSlQ grill; and 'to the difference
frequent. Mi-4375 S_ ducts in 520 the voltage
with aegeq-nency 475 19.1 520 u. 521 form
81h _ first band-

poss filter.

The strength of the coupling between 519 and $20
determines the hand-width oi' the hand-pus
filter. The voltage over C18 is further nmplifierlin L2
and then reaches the hand-pass filters before and lifter

04- M. JILH-l-M

Page 2

337A

L3.eothntheI.F.volu50.een-'d0nhl amplified
end Iced W 6 dronitx, a whee
thednde. whet-detection taken 0. 05%
theLF.hend-pue film-chef owingmuu

hemdflhe hetweenthe ' udthe
wonder, it firmly inductive. which

uuflornmdofthemomnecmeilohmned
inehieuneyit'neleo impouihle
form" hmmdynmg uni-atoms
untunltofupeddveeoupling.0flendw
fomeltheoeoondhmd-puefihetetn ' on

innit. 817. 816. 526. 527. undo. R13 emu?
uttedinynmhnmmted lefilnde.
' Ohm In 0.1 M. Ohm.

mu.volle5emnl7,illppliedvlnc37
totheemunlfldofuendiefnnhaemplified
vie a Wu ' dent-t h 15. 531.
049.041 endcfllfonne tertocut frequencie-
ebov0SOOOeydaForehortwev0eG40iielee
mneeted in eel-lee, to enppreee low frequndel
in wh'mh way better reproduction of epeeoh in
ohtlined for Alum-Wm reception.

The A.V.C. 0 ea u follwe: When vi- C38
emote eignlreeeheethemonddinde-
mdeeleqercumtooemhtheeirmitenede.
uthnanLRleleuuingeIn-Frnqn-

A2

ive emu 322. R14. This negative volt:
hep ' vinR7toLl.vlnR20endelto
end vi- R12 to L3. L1. L2, L3 end L4 elso receive
e fixed n rive bin 'ecroee R1. which is up lied
Vin R14, 13 end 315 to the control grid PM.
C23. C24. C30. C34. C35 end C39 ere the vex-ion:
decoupling coed-Merl. L1 end L5 mpeetively
receive negative grid hire from the drop of tension
man R8 and R , which ruin-nee: ere deeou led
hy C25. C3. The continuum!
cuneiltn of CM. R26 and R2 .
:6. C6 ie an eeriel filter which in tuned to 475 Kc.
tynAll' of this frequency In conducted direct!
u: earth end an therefore not rate into thz
LF. action. For short wens e wiring of the
circuit: of L1 is quite difl'erent. 57 ie the uriel
coil: 58 with the trimmer C9 Ind the tuning eon-
denser C7 vie C27 form the grid circuit. The
oeeilletot eoneieu of 313. (:12. CS (grid circuit)
Ind 514 (reaction coil).
For shortwave reception the aniline: Ire ueney
it 475 Ke lower then the fielueney on which the
HI. circuit is tuned. This method wu selected
to prevent dumping end to enum eoneunt won
king of the Ouodo. upecially for high fie';nencies.
The guiding condomere have been included in
the .F. seed-m. C9 in the penile] padding Ind
C2? the eerie- pedding condenser. R6 eetvee for
connecting the 4th d to the duesie. The LE
eection is the some or Ihon- Ind medium wavee.
CAD in tehen uy in the LE. eectiom the result
of which is thet the union of the low notes
in somewhat weaken . L6 is the fullweve rec-
tifying velve; the mouthing filter nomieu of Cl,
55 end C2.

variable wne ler