Leak Trough Line II Service Manual

Page 1

H. J. LEAK & CO. LTD.

TROUGH-LINE 11 FM. TUNER

INSTALLATION, OPERATION and MAINTENANCE

Connecting the EM. Tuner.

1. This unit may be used free-standing on a table.or it may be mounted on a panel of any thickness, through a cut-out
of log x 3% (27 cms. x 985 cms.). To mount on a panel: remove the rubber feet by pulling smartly out of their
retaining holes: pass the body ofthe tuner through the cut-out until the front plate butts against the panel. then pass
the U-shaped bracket over the back ofthe tuner and fix it by passing the wing screw through the hole in the bracket
and into the threaded hand-bush in the centre ofthe rear panel on the tuner. Tighten the wing screw just enough to
prevent the metal backing on the front plate of the tuner from slipping on the panel.

2. The mains transformer primary is wound for voltages between 210 and 250 (50 to 60 c/s) or on the alternative model
for voltages between HO and 124 (50 to 60 c/s). The circular voltage selector (situated at the back of the tuner)
should be withdrawn to its fullest extent, rotated to the voltage nearest to your supply and reinserted.

3. When used with a LEAK power amplifier the mains supply for the tuner can be obtained by inserting the A. C.
POWER" plug into the A. C outlet socket on the power amplifier. The tuner is switched on by turning the volume
control

4. The 300 ohm aerial input is balanced to earth. When using 300 ohm twin feeder, the conductors should be
connected to the outer aerial terminals. When using an unbalanced 70-80 ohm feeder, the inner central conductor
should be connected to either of the outside terminals and the outer screening connected to the centre chassis
terminal.

In many localities (covering perhaps 80% of the population) good reception of the BBC. transmissions will be
possible with an indoor aerial. but it should be remembered that the signal/noise ratio will always be better with an
efficient outdoor aerial. Even with a very sensitive receiver such as this it is desirable to use an outdoor aerial
correctly orientated, the optimum position being indicated by maximum closure of the tuning indicator pattern.

5. The output voltage from this tuner is approximately 1 volt. Due to the use of a cathode follower output stage the
output impedance does not exceed 12,000 ohms. This means that up to 20 ft. of low-loss co-axial screened cable
can be used to connect the tuner to its associated pre-amplifier without audible loss of high frequencies.

6. This tuner unit is earthed to its associated pre-amplifier via the screening of the AUDIO OUTPUT lead, and no
additional earth connection should be made to any part of the tuner.

REL IOI

Page 2

Sen icing.

On no account should the pre-sct trimmer capacitor CK or the prc-set tuning slugs be tampered with or HdJuSlcd
in any way.

It is not possible for an F.M. tuner of this calibre to he HCCurnlcl) aligned \iilhoul using a double beam
oscilloscope. F.M. signal generator complelc with an accurate marker oscillator and a DC valve voltmeter.

These requirements should be emphasised to a potential service engineer. and if all the above cquipmcm is not
aiailable. work should not be started.

BLOCK CIRCUIT DIAGRAM _0F TROUGH-LINE lI PM. TUNER

was:
IDtuOl
(new: moo: vmou _ amour mum when-um." was: °/'
It ullll I! 1 MMHEE Mum! DNCIMlvu two-t-
l
moist um
oscuuio- uc
'~ Y" Ian-
. l S l I In unm- .x { X
on m .u - m u: w an a
l,

.1:le ®
00 , ° (3.3.

L6) CD

El

"El@g ' w

; e; : : :
ll u h .5»... '(E t: k
- v ..u . M.
mun" no.
$ij #1.. 2%;- ......~ _ .._.. m. «~-

a...-

-32!"

who unvvl
un

UNDER CHASSIS TOP CHASSIS