-
8/10/2019 T 60 Transmitter 3 62
1/3
=
Roy E Pe fenberq W4WKM
316 Stretford Ave nue
Peiriex Virgini
/ll
.
.
..
.
.
.
-:
-.
. :
.
73 Tests
The Knight T-60 Xmitter
A
60 watt AM
and
CW transmitter
with
, full 80 through 6 meter amateur
ba
nd
coverage fo r
less t
han
50.007
It
's ha rd to be
lieve
but
th is is
what
Allied Radio Corpo
ration
ha s
ac
complished
in their
new
transmitter kit.
The Knigh t T -60 is a completely se
lf
-con
tained nea t l it tl e p ac ka ge t hat
put
s
out an
amazi
ng
s
ig
na l fo r its size.
A quick check of th e specificatio
ns
will ver
if y that th is ea sy to a ssemble kit is a r ea l
bargain
on today s amat
eur
equ
ipment
market.
How does
th i
s
Knight-Kit
provide
so
many
features at
th e price
of 49.95? Par t of
th e
reason
is,
of cour
se,
that
it
is a
kit; yo u
su p
ply
th e
ma jo r ity of t he labor. Tha t is, if you
c
al l the
in
terest i
ng,
easy as semb
ly of t he
tr
ansm
itt
er
labor.
The de
sign
concepts
that
provide high performance at lo w cost i
nclude
a silicon rectifier pow
er
supply, use of a ma ss
produced
high effici
ency TV
sweep tu be in
the
output stage an d a h
ighly
effective, controlled
carri
er
scr een modulation system th at provides
good quality speech with plenty of pu nch. Th is
aud io s
ys
t em allows th e final to l
oaf
al on g
at
about
%
normal power input an d s till
ap
pr o
a
ch th
e
C' V
input
of
60
watt
s on voice
peaks.
.
.
.-
I @ ,
..
.
r
0 '
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.
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.
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@
e
~ J l t
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42
13 MAGAZINE
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8/10/2019 T 60 Transmitter 3 62
2/3
5. Wh
at is
my Ref l e
ct
ed
Power?
6. Do I have h igh RF resist
ance in splices, connec-
to r s a nd in series with t he
radiating element?
7. W ha t is my RF Power
A mplif ier E
ff i
ciency? .
8. How muc
h power am I
was ting
in
relays, f
il t
ers
and feed l ine?
5
NTENN
N LYZER
-
-
.
. .,..
42 .
9 5
NET
e
S EC O E LE CT RO NIC S
INC.
I
5041 Penn Ave. se Minneapolis 19, Minn. I
I
I
I
I
I
I
N ME _
DDRESS
_
CITY ST T _
Please se nd me full informatlon on
the
Seco 520
0 als
o s e
ce
e lectroni c equipment catalog folder.
,r
WaJ
. nalyze Y
our
ntenna and R Power
_t mplifier With the
520
3 YSWR scale
interpre
ta tion
s I :
I
to
8:I S
tand
ing Wave Rat io- antenna system efficiency
GOOD
BAD
sca le.
3
Fo
rwa rd and 3 Re
fl
ected Power scales accurately
calibra ted (3.5 to 180 mc)- ra nges
0
10, 0-100
and
0- 1000 watts.
Directi
on
a l
Co
upl
er
and
Me
ter are matched p
air,
ac
curately
ca
libra
ted
.
Single
compact
case
6
x
2Y i
x 5
1A
-
no
c
ha
rts
or
graph
s
to
read .
Scales a rc cal ibrated for50 ohm line (simple multiply
r
ead
ing by 1.4 for 72 ohm lines).
Co nt inuous duty m ay be left in line
as
RF monitor.
I
1. Is my antenna ra
di
ating all
available power?
2. A re
there
Hot
Spo
ts In
my feed line?
3, Is my antenna-feed li ne
match actua lly
teste
d, or
only computed?
4. W ha t
is
my F o r w ar d
Power?
HAMS this Seco a point
antenna and power
amplif ier
check
gets more
from your rig
P
I
I
I
I
I
I
I
I
The
se
same features make compact con
struct ion possible and th i s little
transmitter
is no
larger
t han a man-size shoe box. The
gray
wr
inkle fini
shed
, rugg
ed
steel
cab
inet and
the two-tone panel provide a very attractive
a nd practical hou sing. Despite th e compact
construction, a ssembly is ea sy.
Th
e 218 sepa ra
te
as
sembly st
eps
are
a
r
ranged in ea
sy to
und
er
stand
, check -off
order
in the large 8 x 11,well p rinted i
ns
t ruc
tion manua l. This 32 page booklet conta in s 19
clear illustration s in addition
to
the schematic
diagram
and complete illustrated
part
s break
down.
As a further cons t r uction a id, 6 of the
major assembly illustration s are duplicated in
15 x 20 wall chart form. \Vith all
of
th is
a ssi stance, it is indeed difficult to goof.
Good quality
par
t s a re used
throughout
the
tran
smitter
and packaging of
th e
parts is
geared
to conveni
ent a s
sembly.
Res istors are
ca rd
mounted
and
a
re
marked
f or
ready
selec
t ion. Other small
part
s a r e supplied in trans
parent plastic
ba
gs for ea sy
identifi
cati
on .
These
feature
s,
along
with the illustrated
part
s
breakdow
n, detailed
draw i
ngs
and
se lf
checking in structions
mak
e for rap id a ssembly
by even the mo
st
i
ne
xper ie
nc
ed individual.
The schematic diagram
of
the T-60
tran
s
mitter is shown in F igure 1. The circuit con
s
is
t s of a 6HF8
tr
iode sect ion (VIA) o
pe
rat
in g
a s a
Pierce
c
rys
tal oscilla
to
r os a s a VFO
ampli
fi
er . The
pentode
section of
the
6
HF8
(V I B ) is u
sed
a s a
buffer
amp
lifier
or
fre
quency mul t
ipl
ier,
d
ependin
g on t he
band in
use. An
adju
stable
pi
ne twork t uned cir cu it is
used to couple the bu ffer-multiplier st age
to
the g rid of the
6DQ6B
(V4) power amplifier
stage. The plate of the
6DQ6B
is shun t fed
a nd a
pi
network us
ed
to provide
the
proper
match between t he
hi
gh
imped
ance p
la
te cir
cuit and
the ant
enna.
Anten
nas with impe
dances ranging be twe
en
40 and 600 ohms ca n
be matched with th
is network . F igure 2 char ts
t he
frequ ency
cove
ra
ge of t
he
tran
smitter
a long
with th
e r ec
ommended
cr
ys
t a l
or
ex
t
ernal
VFO
f
re
q
ue
ncies f
or
eac h
band.
The metering ci rcuit of the T-60 f ollows the
trend e
stabli
shed in several recent
tran smit
t ers . A cry sta l diode,
CR
I , is used
to
rectify
a porti
on
of the RF present a t th e output of
the antenna
ne
twork. Th e filter
ed output
of
the
diode is applied
to
t he meter and a shunt
re
sistor may
be switched in to avoid off-
scal
e
deflection of th e met
er
when feeding high im
pedance
load
s. The
DRIVE TUNE, PLA
TE
TUNE
a
nd
LOAD controls
are al l adju
sted
for
maximum meter defle
ct
ion with
the FUNC
T
ION
switch
in
th
e t u
ne
po
sit
ion. T
he
switch
is th
en
t hrown to
th
e CW position a
nd th
e
controls peaked for max
imum
output. \Vhile
th is may appea r
to
be a q
uic
k and dirty
method of me tering a 3 stage transm itter, it
rea lly
works
well and
per
mi
t s ea
sy , accurate
t
uning by
inexperienced opera tors .
MARCH 96
43
-
8/10/2019 T 60 Transmitter 3 62
3/3
rf qu
li :K1I
T n
u m i U Ii 'T
Cry,U11
or
VFO
reo&In
(Md li T )
(M
(
M
80
3.5 toU
3.5 t
04
.0
7.0 to 7.3
7.0 to 7.3
20
7.0 to
7.175
14.0 to 14.35
J5
7.0 to 7.150 21.0to
21.4
5
10
7.0 to 7
.42
5
28.0 to 29.7
6
8.334 t0 9.0
SO O
to 54.0
The cathode circuits of the oscilla
tor,
buffer
multiplier and power
amplifier
stages are con
nected to the key
jack
. When the
key
is closed,
th ese points
are
a t
ground
potential. I n the
key-up co
ndi
tion, a 2.2K
ohm
res isto r is in
se r
te
d in th e ci
rcu
it. The c
at
hode
cur r
en
t of
t he 6DQ6B deve
lops
a bias voltage acr oss the
res
is tor wh ich is suffici ent t o r edu ce
th
e 6DQ6
pla
te
and screen current s to a safe value and
comp
le
tely cu t off the osci lla t
or
and
buffer
stages
. Th is design f eature
re
du ces the volt-
age
across the open key to a s
afe
value and
provides excellent key
ing
characte ris tics . Th
er
e
is one disadvantage to this keying
circu
it. If
an
external
VFO is used, it must run con-
t inuously and keying must be accomplished in
th e transmitter.
I n the AM mode , a
casc
aded 1
2AX7
(V2
is used as a speech am pl ifi er which drives the
fi rs t section of the
6DR7
(V3 )
modula
tor
stage . Th is section of the modulator is O
p4
e
rate
d a t zero bia s and
grid
rectification of
the applied au dio sig nal occurs . Thi s
in
crease
in bias causes the
plat
e
vo
ltage to r ise, va ry
i
ng
with
the
modulat ing signal. The g
ri
d
of
the second section is conn ected t o the plate of
the
input section and th is positive vol tage r ise
incre
ases the
cathode
current, and thus the
voltage, of the output stage. A
po
r tion of this
voltage
is applied to the 6DQ6B
scree
n. This
voltage
r
ises wit
h modul
ati
on
an
d var ies
at
a n
au
dio r ate, modu
latin
g
th
e sc
ree
n of t he
r f ou tpu t amplifier and
in
crea sing the average
de p
oten
t
ial
of the screen. In the TUNE posi
t ion of the FUNCT ION switch,
redu
ced sc reen
volt
age
is applied to
th e
6DQ6B and
out
of
reso
nance plate current is
red
uced to a safe
value.
Th e
power
sup
ply
is conventio
na l
a
nd con.
sists of
a power
tra nsformer wit
h
plate
and
filament
windings. A full wave volt
age
doubler
circuit, using silicon
rectifiers
and a n RC fil
te
r
develops 440 volts de for the plate and screen
circuits.
The comple ted
tr
a
ns
mitter w
as be
nch tested ,
us i
ng
an \ C. J one s T
yp
e 625 wattm eter a s
a 50 ohm load with th e in ternal indicator used
to mea sure
power
ou tput on 6 meters.
Sin
ce
the
dir
ectional coupler used in
th
is in
strum
ent
is frequency sens itive, a Hewlett-Packa rd 41
OB VTY::\ was used to
measure the
voltage
across
the
load and power output computed
fo r
th e o ther
bands. P A
stage
input power was
metered a nd,
wi t
h the transmitter tuned fo r
max im
um
ou t put in
accordance
with the in
str uctions , found to range between 63 watts
on 80 met ers and 76 w
atts
on 10 meters .
Us
ing active
cry
s
tal
s, C\V po
wer
ou t
put
r anged
b
et
ween 40
watt
s on 80 meters
and
26
watt
s
on 10 meters. Effi cien cy on 6 me
ters
is
of
cours e greatly reduced si nce the PA is opera t
ing as
a
doubler.
Measu
re
d power
output on
6
meters was
13
wat ts w ith
80
watt s input
.
must be
emphasized
that
these
measurements
were
made
by
tuning
in accordance
with the
ins truct ions, l et ti ng the ope ra ti ng conditions
fa
ll as they would.
A 1000
cy
cle tone was
applied
to the micro
phone in
pu
t and a scope connected to mo
nit
or
the r f envelope . The
gain
con trol was ad.
vanced to the point where distor t ion was ap-
parent. Th is occu rred
at
between 90 and 100%
modu
lat
ion, dependin g on tun i
ng
and load ing.
Mea
sure
d p k power
output
was
roug
h
ly
equa l to t he CW output
for
identical
tu
ning
a
nd
loading conditions.
On
the air tests produced good results. No
attempts
were made to establish any DX rec
ords,
the
objective being to obtain critical
re
por ts on s ig
nal
quality. Commen ts on the
controlled c
arrier
modulation system we
re
t ypic
al .
Y our aud io quality is good, 01\1
,
b
ut
your carrier see
ms
to be
go
i
ng
up a nd down .
Those
op
erators
familia
r wi t h controlled car -
r iel' Al \l s igna ls
gav
e good
repo
r
ts
. Co
nstrue
-
t ive, on t he a ir he
lp
in
fi
ndi
ng the
proper
sett i
ng
of the audio
gain
co
nt
ro l was di ffic
ult
to ob ta in. The proper po
in
t, ver ified by
th e
scope, is
just
below the
sett
ing
where
audio
distortion becomes noticeable .
T here
are very
few compla in ts
with the
t rans
mitter
. T he comments on
the metering
sy s
te
m ca n n
ot
be taken too serio
usly
si nce
the sy stem work s a
nd wor
ks
we
ll. The
reduced
ou t put on 6
met
ers is more serious. However ,
since 6 meter coverage is a bonus anyway , we
can afford to be philosophical and not look a
g ift horse
in
the
mouth. The writer has per -
sona l objection to
the
RCA
phono
j ack used as
the mike connec to r and
it
is suspected that
ma
ny
wi ll change
it
to a type to
fi t their
mi
cropho
nes.
A
ll in all,
the Knight T60
is
a
very
good
buy
. F or the Novice, it is an ideal
first
trans-
mit
t er and it is very attrac tive to
the
more
expe rienced ama teur as an eme rgency or
standby
uni
t . The r ugged construction a
nd
simplicity of the unit
mak
e it probab le
tha
t
thi
s little rig will be in se rvice long after
more sophis t icated equ ipmen t is down for
ma
in tenance.
, W4WKM
13 MAGAZINE
