Two Valve Transceiver - Eddystone Short Wave Manual

(40
EDDX61?0NE; SHORT: WAVS."MANUAIL
TWO VALVE TRANSCEIVER
COVERING THE 56 TO 60 Mcis
One, 0f,.the advantages of &""tnetire work
sinsll p9k8r_necessary
oljtain results,
and so praptical 'pparatus
is,: quite
p4105fe' can ,lje.built.,
Here, we,i;lesqibe .a
.W,metre
band
transmitter and
reeiyer =combined, built from standat$' parts
proba,bly. the .Siallest
bulk
,asi`ble; consistent with efficienq." . A 120;v4
battery,
a 2
volt .L.V accumulator,
',phones and .a 'telescopic aerial,
.1.61
i
6.. complete eqUipthent which can be
carried anywhere by one person.
-.transceiver. .has giyen
good
and
.consistent-
results over.;a
tilrolonged
.test
period and has .aphieved RQ. 2 -way. working
-over. a..:distance of . abpv.e ,.W miles.., under
favourable outdoor conditionsi., In the, centre
of a. city, its range is reduced, accordingi to
circumstances, but- 2 mile working,,,1as beep
accomplished consistently
under, :ordinary
:conditions and 2 -way communication llias,been
,curied out. between. two travelling. cars,.
Underside' view of chassis.
The modulation
choke, modulator valve, send, receive switch,
quench coil unit and microphone transformer
are all clearly seen.
BAND.
Top view of Transceiver showing oscillator
vaAve, tuning control and condenser, and coils
.
L2 sank L3, which, are .each.3 turns of 14g:.
copper-Wirei wound on a 1.1 corL
The coils are
atippbrt4d in the wiring except the aerial coupling
(centre) whichlis fastened on the paxolin panel to
the feed out terminals.
Most: transceivers employ the 'squegging
grid leak- selfqnerich &theft* for reception,
but
(thii'inoder; the"dbtectbr. is not called
upon 'to 'dog' both operations,
' the peritbde
modulator being Utilised as a separate quench
,Valve 7 Using'. qUe4-ich. cOilS.
Change over
send or receive is made by a 3 -pole shortirig
switch. A Mazda P220 small power valve is
used as an oscillapr for transmission. and a
;detector for tepeptiOn.
The second valve .is
a MUllar51,PM.22 pentode,
used as a modulator
for pending .and as quench valve for receiving.
The action of. the switch is as follows..
In the
receive position, all points are open, the ..grid
leak value being 3 megohms plus 10,000 ohms,
'phones: in circuit, quench coils operative ,with
d.rop resistance in H.T. feed. .-Qn send position,
the grid leak value is 10,000 ohms, 'phones
and quench coils .short circuited,. full H.T.
in use. A microphone transformer is fitted,
the microphone being .plugged straight into
back.of set and: the L.T. battery is used for
*energising it.