Tandberg TPT 3001 A Brochure 3

Page 1

TANDBERG

Technical Paper

TUNERS

TPT 3001 A

TPT 301 1A

The front end

Programming
unit

The new analog tuners TPT
3001 A and TPT3011A are the
result at a long term develop
ment in the Tandberg labs.

The tront ends employ

ganged, tuned circuits where
DC voltage controlled capaci-
tance diodes are used as lun-
ing elements. and Dual-Gate
MOSFETs are used in the RF

Both tuners employ the same
ingenious tuning system

In addition to the main tuning,
there is a second stage which

stores 8 pre-tuned FM stations

in an electronic memory. This
pre-tunlng system IS based on
a voltage synthesis princrple
combined with a last analog
servo loop to achieve max.-
mum SN ratio and irequency
stability.

Tuners TPT 3001A *TPT 3011A

Although they are designed for

dilterent market segments
they do have one major com
mon denominator: The musr-

and Mixer slages. This
achieves respectively; stable,
accurate tuning and excellent
sensitivity combined wnh su-
perior headroom.

Pr ramPreset
{9 2

. o
Output Level

caltty ol the reproduced sound
This is ensured by their many
des>gn Similarities.

The TP'T 3001 A utilizes B
tuned CllCUiIS, the TPT 3011A,
5.10 prevent Mirror image
(21,4 MHz) and other out of
band distortion

Program Signal

Store Prograrr

Page 2

IF selectivity

The limiter

The detector

The stereo
decoder

The audio circuit

The IF amplifier oi the tuners is
where the adjacent and the
alternate channel selectivity is
created.

In TPT 3001 A the selectivity
can be switched to three ditte»
rent band-widths; WIDE, NOR-
MAL and NARROW, each one
optimum for its particular com
bination oi station density and
conditions at reception

In WIDE and NORMAL the lil-

ters are discrete LC types with
6 and 20 poles respectively.

In NARROW two symmetrical
high selectivity ceramic filters
are added to the 20 pole LC
filter 01 the NORMAL posrtion,
resulting in an unsurpassed
combination of selectivity and
distortion free sound reprodue
lion.

In TPT 301 1 A the selectivity ot
the IF circuits is determined by

W Programebte HA Yiiner 3001 A

MP! Mam ANC

Both limiters have exceptional-
Iy good AM suppression and
interterence rejection. Moreovr
er they guarantee a constant

Important tor lite overall quality
01 a tuner is the pencirriarice
oi the detector both with re-
spent to linearity. bandwndth
and signal to noise ratio,

In TPT 15001 A a hilly dluu ete.

Equally iinpoltant a: all other
stages ' lie slaieo decoder
for the lit .l result The most
common deficiency at a stein
decodei is the generation 0!
beat tunes on heavy mod
iilated signals This propeir,i Li
never Specified tor a turret but

in man .i git/0U unmi Llltf i ti
spei iat kin lWleithi Ali l sidio f.u
queue/t chririlugy. but in
many Hm dtltltl set mi.
isvit.gli-r lull iiit. iinsi limit
pklllnlll Haialii, alui .li-siiiii
Clii'ullit

lil..tlil.illliilv. .iiiiiiu m.

servo

muting

Mmlrigle

signal level output over avery
wide range of signal input
level

modified Foster Seeley" de-
tector is used having a band
Width of more than 4 MHz, to
avoid any distortion caused by
bandwidth limitations.

in TPT 301 1A the detector is

w it, well audibly annoying for
a discerning listener

i.i airriiil ihlS beat tone geii

ei ration and to allow use of
Tandbergs unique Automatic
Noise Cancelling Circuit, a dis
crate stereo decoder is used in

Hull lli. l lrllltl :otint'lqnniily

' l M l. g muted. and not as
tnmnnly believed that FM
i. lllllt'ftiltlly an lutenorsoiirce

rl:i;.i., 'le :liiiii lt'l Gloom
and I nil in liytlaltlijihr}
:mriiu tiiiilt il.i.itiiirzls rifmmr
iimiiznt sui'iiinnsi iprilyuziter

a computer designed filter
whose characteristics are
slightly narrower than the
NORMAL posnion of TPT
3001A with four. selected. high
quality ceramic filters of con-
stant group delay. This to take
advantage of a high selectivity
combined with a bandwith that
permits undistorted reception
also at strongly modulated
broadcasts.

33m]leth

part of the limiter with adjust-
able LC tillers ior perfect
matching to the iF amplifier.

the TPT 3001A. more complex
in desgn than most complete
tuners.

In TF'T 3011A a spectally
selected IC is used for optimal
periormance

and polypropylene caps. malal
film resistors) and design phi-
losophies (minimum negative
feed back applied in short
loops. eh: )

As in the series 3000 audio
components