convert cb radio for ham bands
DESCRIPTION
This is a collection of articles from 73 magazine, which appeared over the course of 4 decades. The series is called CB to 10 but there are a few parts/issues that didn't make it into this compilation. There are a few other relevant articles like the CB to 6 series. I created this compilation because CB radios can still be purchased for incredibly cheap at Swap meets, Garage Sales, Antique Stores, hand-me-downs from the family, etc. I'm not sure how the 10 meter band is looking currently, or if the use of AM within the channelized band plan created through these articles still exists, but for the avid RF homebrewer, I believe these articles will be of great interest as CB radios are a complete and fully working QRP+ transceiver, while a transceiver for a particular ham band can be extremely expensive (and Ham Radio is really only fun if your learning, building, Home Brewing). Many SSB CB's exist and I believe the AM CB radios can be adapted for other other modes as well. So before you scrap out that old CB for parts (which I did with the first few I acquired), give conversion a try. 73 Aum Namah Shivaya 73TRANSCRIPT
-
5/19/2018 Convert CB Radio for Ham Bands
1/81
ob
Wilder
W
NVH
Route 4, ox 230-Z
heodore AL 36582
- - part I: bandplan and crystal info
C
to
1
ig 1
NOTES:
>=
Channels 1 through 1 and channels
17
through
23
in the CW segment are
not
authorized
at
this time for Novice or Techni
ci
an class use
>=
Channels 17 through 23 in
the SS segment are the same frequencies as channels] through 6 and channel 8 of the M
segment
28.505
28.5
15
28.525
28.545
28 .555
28.565
28.575
28.595
28.605
28.615
28.625
28.645
28.655
28.665
28.675
28.695
28.705**
28 .715**
28.725**
28
.745 **
28.755 -
28 .765**
28.795**
gest some standard blocks of
cha nnels (frequencies) that
cou ld be used to increase the
effectiveness of these low
powered ri
gs
. With both the
Novice and Technician class
license holders on 10 meter
CW it can be seen that there
28 .705
28.715
28 .725
28.745
28 .755
28.765
28.775
28
.795
28.805
28.815
28.825
28.8
45
28.855
28.865
28.875
28.895
28.905
28 .9
15
28.925
28
.945
28.955
28.965
28.995
Conv
erted Ten
Met
er Frequ
encies
AM Phone Ph
on e
Frequency (MHz)
Frequ
en cy (MHz)
idea of
gett
ing low power
transceivers to work is to
establish some simple ground
rules. If every person con
ve rting a
CB
rig for 10 meters
picks frequencies at random,
very little acti vity will result.
I would like to therefore sug-
Origina l Novice /Tech
Channe l Frequen
cy
(MHz ) Frequency (MHz)
1 26.965
28.005 *
2
26.975 28.015*
3 26.985
28.025*
27.005 28.045*
5 27.015
28.05
5
6
27 .025
28.065*
7
27 .035 28.075*
8
27 .055 28.095
9 27.0
65
28.
105
10
27 .075 28.115
11 27 .085 28.125
12 27 .105
28
.145
13 27 .1
15 28
.155
1.
27. 125
28.165
15
27.135
28. 175
16
27.
155 28.195
17
27.165 28.205
18 27.175 28.215
19 27.
185
28.225 *
20
27 .205 28.245 *
21
27.215 28 .255*
22
27.225 28.265 *
23 27.255
28
.295*
eg l lternative
fut ure. Now is the t ime to
drag out that old
11
meter rig
and convert it to 10 meters
on crystal controlled channels
that cou ld become standard
all
over the
country.
The first th ing that has to
be done to make the whole
F
or some time now, there
has been an ever-grow
ing concern
over
the outcome
of the ten meter band. The
ham use
of
the
band has
dropped over th e past several
years due to sunspot activity
to
a
point
where other ser
vices,
mainly
Citizens Band,
feel that the frequencies
could be put to better use. I
remember when 1 used to
work
into
Europe daily with
five Watts and a dipole on CW
and AM and even into
ZL
and
VK
land after I got up a
3 element plumber 's de
light beam.
The sunspot cycle, though
probably no t as good as the
one back in the late 1940's, is
about open the band up
again Many groups
r
pr s
-
ently getting ready for better
act ivity
on ten
with th e estab
lishment
of
nets and even
new repeaters.
The above is the whole
idea behind this article: an
easy way to get back on 10
meters with low power with
a small outlay of cash.
When the FCC announced
that
they were increasing the
Citizens Band from 23 chan
nels
to
the cur rent 40 chan
nels effective January 1,
1977 the prices started to
drop on the 23 channel units.
If indications here apply to
the
country as a whole, a lot
of hams started picking up
these cheap rigs with the idea
of first going
on CB
in their
cars to keep track of t raf
fi
c,
and secondly , someday con
verting the CB rig for use on
other
bands, namely
10
meters.
Also, there seems to be a
large influx of former CBers
giving up the ranks of CB and
going on to amateur radio.
Over 80 of the new hams in
the Mobile, Alabama, area are
former CBers who wanted to
get away from the QRM on
11 meters. Most
of
these
former CBers still have their
old CB rigs stored away in
their junk boxes. They have
picked up the ham habit of
never throwing away any
thing that might be usable
some time in the far distant
106
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5/19/2018 Convert CB Radio for Ham Bands
2/81
28 .505 MHz Output Used To Show Example of Crystal
Frequency
Tran
smit
Crystal
Frequenc
y Transceive Crystal
Frequen
cy
Both Transmit and Recetvel
PART
II
ORIGINAL
CRYSTAL
FREQUENCIES FOR CB OPERATION
ig
2.
NOTE: W
it
h this many different
i f
combin
t
i
on
s being
used it is necessary that exact specifications of
th
e t
r
nsceiver
to be converted arek nown
F
28 .505
MHz
F 5010
23
.495
MHz
14 .25250
MHz
F 5010 33.515
MHz
3
9.50 16667 MHz F l 0000 18.50 5 MHz
.z
4
7.
126250 MHz
F
5995
34
.500 MHz
F 6200 3
4.7
05 MHz
F 10635 39.140
MH
z
F
-456
12.52450
MHz
.E.. pll
12.418 33 MHz
F - 10700
3
5.935
M
Hz
Receiye Crystal
Frequency
F -
265 28
.2
40 MH z
F 455
28 .050
M
Hz
F
455
28 .960 MHz F 1365
27 .140
MHz
F
1650
30.155 MHz F- 1650 26.855 MH z
F 1680 30 .185 MHz F - 1750
26.755 MHz
F - 1755
26.750 MH z F2310
26.195
MH z
F - 3580
24.925 MHz F 4000 32 .505 MHz
F 4300
32
.8
05 MHz
F
42
24
32.730
MHz
F -
4455
2
4.05
0
MHz
F
55
00
23.005
M
Hz
F
6000
34.505 MHz
F
600
0 22.5
05 MHz
F 6500
22.005 MHz F 6685 35.190
MHz
F 7500
36.005
MHz
F
8000
36.505
MH z
F - 10000 18.
50
5
MHz
F
10700
39 .205 MHz
F -
20635
7.870
MHz
F 23505 5.000
M
Hz
31955 - F 3.450 MHz F 455
2
14.025 MHz
f
455
2
14.4
80 MHz F 4 55
3
9.350 MHz
F - 455
4
7.0125
MHz
F
1650
2
15 .0775 MHz
F
1640
3
10.
04
8333
MHz
quency. This type
of
trans
ceive r can be modified for use
on 10 meters, bu t the ex
pense would probably be
mo re than buying or b
uil ding
a
si
mple 10 meter transmitter
and simple conve rte r for use
with an existing receiver. The
possibility
of
building a
si
m-
ple VFO to replace the
crysta
ls
in the transmitter and
rece
iv
er sections
of
this type
of transceiver would solve the
problem
of
the large numbers
of crysta
ls
needed.
Th
er
e a re two other
Channel Numbers
123-4
5-67-8
9-10-11-12
13-141516
17-18-
1920
2122-23
1-4
5-8
9-12
13-16
17-20
21-23
1-4
5-8
9-12
13-16
17-20
21-23
1-4
5-8
9-12
13-16
17
2
0
21-23
1-4
5-8
9-12
13
16
17 -20
21-23
See Note 1
See Note 2
See Note 3
See Not e 4
See Note 4
See Note 3
See Note
2
See Note
1
See Note 1
See Note 2
See Note 3
See Note 4
See Note 1
See Note 2
See Note 3
See Note 4
See Note
1
See Note 2
See No te 3
See Note 4
See Note 1
See Note 2
See Note 3
See No
te
4
Transmit TX }
Heceive AX
See Note 4
See Note 3
See Note 2
See Note
1
L
S8
A M
and
USB
AX Oscillator
All Frequencies
23 .290
23.340
23.39
0
23
.440
23 .49 0
23.540
37 .6
00
37 .6
50
37.700
37 .750
37 .800
37.850
11.705
11.755
11.80 5
11.855
11.905
11 .955
8. 1
59
8. 20
9
8 .259
8.309
8.359
8.409
11.740
11
.790
11 .
84
0
11.8
90
11 .940
11.990
14.950
14.960
14 .970
14 .990
10.595
10.6
15
10.62 5
10.63 5
7.4585
7.4685
7.4785
7.498 5
7.46 15
7.
47
15
7.4815
7.5015
11.003 5
11.01 35
11 .0 235
11.
043
5
7.
4225
7.
4325
7.4425
7.46
25
11 .27 5
11.730
10 .140
1
0.16
0
10.1 70
10 .1 80
7.8015
7 .7985
7.3
435
7 .8025
Crystal
Frequency
MHz
USB)
A
o
H
LSB)
E
8
F
c
G
K
L
J
M
o
N
Crystal
are fai
rl
y broad. To fulfil l the
requ irement of being channel
se lectab le without being tun
able by the ope rator, most
CB rigs on the market today
wi
gi
ve
close to 4 Watts
ou tput at both extremes of
frequency, that is, at chan
ne
l l
and channel 23.
Afte r revi ewing the crystal
requirements of over 1200
different CB transceivers, I
was
able to arrive at the
common configuration for
both transmit and receive
crystals. Every tr ansceiver re
viewed fell into one of the
configurations shown in
Fig.
2, where F indicates the
output frequency desired.
The frequency
co
mbina
tions shown in
Fi
g. 2 are fo r
CB
tr ansceivers that use a
single crystal fo r each trans
mit channel and another
crystal fo r each received fre-
must be a block
of
channels
that they can use when they
convert a
CB
rig
to
CWopera
tion. There is unwrit ten use
of
SS
B only on the low fre
quency end
of
the 10 meter
phone band, so t he
SS
B CB
rigs
th
at
are converted should
have a block and, of
co
urse,
the bulk of the converted CB
rigs being inexpensive AM
ri
gs
,
wil
l need t
hei
r channel
allocations. Fig. 1 lists a
three of the groups of 23
channe
ls
th at could be used.
The very nature of the
basic CB transceiver makes
this ty pe unit one of the
simplest to convert to ten
meter operation. In the case
of o ther ty pes of low power
surplus equ ipment that has
been avai lable in th e past, the
tunab
le stages have been fair-
ly narrow, but in the case of
the CB rig, the tuned stages
10
7
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5/19/2018 Convert CB Radio for Ham Bands
3/81
PART II I
CONVERSION
FACTORS FOR
10 METER OPERATION
ig
3.
NOTES:
1
= Channels
1, 5, 9,
13 17 and
21, 2
= Channels 2 6 70 14
18,
and
2
2
3
=
Channels
3, 7, 1 1 5,
and
79. 4
= Channels
4, 8, 12, 16,
and 23
PART I
See Part I II fo r Crystal Formula
Manufacturer
Model Numbers Shift
Tx
/RX Main OSC
B & K (Cobra)
19
, 21 29 L
F
A
B & K (Cobra) 130
,1
31 & 132 LSB N
H
C
USB
N
I
C
8 & K
(co
bra 138 & 139
0 J
D
8 & K (Cobra) 132A & 1328 L
SB
N
H C
USB
N
I
C
Pace 123A
M
G
B
Pa
ce (SS81
10008
,
l000M
0
K
,
Pace CB143, CB-144
M G B
Midland 13-8808,
13
885 LSB
N H C
USB N
I C
Midland
13-895 0 J
0
Realist ic
TAC
-238 , TRC-40,
TR
C-49 M
G
B
Robyn T 1238
L F
A
R
obyn T12
3C, K-123
M
G
B
AMGT VII
R
oy
ce 1-602 M
G
B
L
1
0.235 MHl TX L 9.735 MHl TX L 9.535 MHz TX
L
10.69
0 MHz
AX
L-10.190
MHz AX
L=9 .990 MHz AX
(Frequency groups A & F remain the same)
TX ' 38240 - Freq. of l
ow
end.
AX 38240 - Freq. of l
ow
end + 455 kHz
H=8498 .5 kHz H=899
.5
kHz H 9198.5 kHz
(Frequency groups N & C remain the same)
H ' Low end frequen
cy
minus 19506.5 kHz
1=8501 .5
kHl
19001. 5 kHz 1=92
01.5
kHz
(Frequency groupsN & C remain the same)
0 ' L
owen
d f requency minus 19162.5 kHz
B-38640 kHz 0 =39140 kHz 8
3934
0 kHz
(Frequency groups M & G remain the same)
+
1040 kHz + 1540
kHz +
1740 kHz
The above is the
frequency
8
must
be raised for
each frequency group for operat ion in the
10
meter
band.
0 8842 .5 kHz 0 =9342.5 kHz
0=
9542.5
kH
z
{Frequency groups K & E remain the same}
0 =
Low end frequency
minu
s
19162.5
kHz
1000B, or the Pace 10QOM
should prove fi ne choices for
conversion to 10 meter SS
B
In each of these, the origi nal
7.8025
MH
z crystal is the
only crystal that needs to be
changed.
It
seems logical that
a multiple deck crystal
switch/socket package cou ld
be used. This arrangement
would allow several 23 chan
n
el
arr angements over the 1
me
ter SSB segment. For ex
ample: Selection of the lower
end frequencies of
28503
kHz, 285 05 kHz 28507 kHz,
and 28
51
0 kHz would require
only 4
cr
yst
al
s for a
tota
l of
92 channels between 28503
kHz and 28
8
kHz.
There are several linear
amplifie
rs
on the market to
day which are smaller than
mo
st
CB
t ransceivers and
have output of 50 to 100
W
at t
s. Of cou rse, most of
these un its are rated as 3 to
30
MH
z ha
m
amplifie
rs
which actually on ly work
well be
tw
een 26 and 3 MH z.
These small amplifiers could
be used
to
increase the mo
bile or fixed capability of the
converted
tr
ansceiver.
The final type of CB trans
ceiver that can be modi fied
for 10 meters is
the
PLL
type. These are more expen
sive than the ot her two types
fo r several reasons. The PL L
is the easiest to modify by
the
CB
er for operation on
frequencies other
tha
n the 23
or 40 channels for which the
uni t was built. This type
of
unit is th e easiest fo r the
manufacturer to convert to
4 channel operat ion. This
ease is, of course, the major
reason t
ha t
th
is
ty pe of trans
ceiver lends itself
to
mod i
fi
ca
tion to the 1 meter ham
band .
I have selected 8 different
models
of
PLL transceivers
that are avai lable to show
what can be
do
ne to modify
this type of t ransceiver for 10
meter use.
Fi
g. 4 lists the PL L
transceivers and the crystals
that are presently used for
ge
neration
of
the necessary
signals fo r 11 mete r
CB
oper
ation.
By r
ef
erring to the original
frequ encies
of
th e CB trans-
(see Fig. 1)
28.705
MHl
The crystal combinatio
ns
listed in Fig. 3 are examples
of some
that will
be encoun
tered when trying
to
sh ift an
eleven meter CB transceiver
to
the 1 meter band. I have
found that the simplest way
to ca lcula te the frequencies
needed is to use only channel
1 to determine a simple for
mula. Once a formula is ob
tained , each crystal frequency
can be found. The be
st
way
to se lec t which oscill
at
or you
want to shift is to select the
one that requires the least
number of crystals
to
make
up the greatest number of
frequenci es.
Th
e Cobra
138
, Cobra
139, Midland 13-895, Pace
plete schematic and parts
st
for the unit from the manu
facturer or one of the
CB
service
typ
e books on the
market listing your t rans
ceiver . Though the synthe
sized type is cheaper
to
mod
ify th an the type using crys
tals for each frequency, there
could be problems in obtain
ing the necessary information
to determine the crysta ls
needed.
In Fig. 3, I have listed
several of the more common
synthesized units available
and crystal data necessary to
convert the uni ts to 1
meters. Fig. 3 is divided in to
3 parts for ease of under
standing.
Low t
Frequency fo r Channell
28.005
MHz 28.505 MHz
MG
B
OK
N H C LS8
L F A
N I C US8
/AM
From
Part I
Key
Letter
Sequence
groups of transceivers avail-
able on the mark
et
at th e
present
tha
t could be mod
ified. First of
the
se is the
synthe sized uni ts which use
combinations of a sma
ll
num
ber
of
crystals
to
obtain
all
of
the tr ansmit and receive fre
quencies desired. The second
class
of
transceiver avail able is
the phase locked loop or
PLL type
that
uses v
er
y few
crystals and digital frequency
gen eration
to
obtain the fre
quenci es needed.
The combinations used for
the synthe
si
zed units are al
most without limit.
When
conver ting a transceiver of
th is type, it would be of
necessity to obtain a com-
lOB
-
5/19/2018 Convert CB Radio for Ham Bands
4/81
celvers as li
st
ed in Fig. 1,
various shifts in oscilla
to r
fre
quencies
a
n be obtai ned.
The intent of th is article is
not to
give a step-by-step
conversion of CB
tr
ansceivers
to 10 m
et
ers,
bu t
instead
only to tell what can be d
on
e
wi th the available units on
the market.
ln the
case
of
the PLL
transceiver, it wi
ll
be
co m
e a
matter of experimentati
on
to
determine
th
e exact fre
quencies needed. I recom
men d
th
at anyone
attempt
ing
to
co
nvert a PLL transce
iv
er
bec
om
e very famil iar with
PLL circuits in general. In the
type of transceiver requ iring
o n
ly
c
ry s
tal changes to
change th e
output frequency,
Manufacturer
Pace
Teabe
rr
y
Teaberry
Standard
E
Palomar
Royce
Realistic
Model
CB1
66
Stalker One
Sta
lke
r Two
Horizon
29
SBE
26C
B
Digico
m 100
6
01
T RC57
Crystal
Fr
equency
10240 MHz
44 73 MHz
13
1325
MHz
78025
MHz
7
797
5
MHz
1000
MHz
Same as the Sta l
ker One
10 24 MHz
5 5
75
MHz
10240 MHz
12
8 03 M Hz
12
800
MHz
107 MHz
10
69
7
MHz
Ie 14 MHz
10 695
MHz
36
38
MHz
13 1325
MHz
44
73
M Hz
7
8025
MHz
7
7975 MHz
10000 MHz
Ag
Oscillato r Use
A
ll
Frequencies Reference
AM
OSC RX
8 esc -
RX
USB Ca
rr i
er OSC
LSB Carr
ier
OSC
REF
esc
REF esc
Tra
ns
mit
A
ll
Fr
equencies Ref erence
USB
REF esc
AM
S8
REF esc
AM
L S8 Car
rie
r esc
LSB
Carrier
esc
REF
esc
10
MHz
OSC
37 MHz OSC
13 M Hz OSC
A M RX OSC
LSB
OS C
USB esc
PL L
REF
esc
the processes are simple. In
the case
of
the PLL circuit,
the problems
that
can be en
countered in d igital develop
ment
of
th
e frequencies
needed are best solved by the
more expert in the ham
ranks. The
co
nversion of a
PLL tr ansceiver is
no t
a pro
je
ct that
should be tackled by
th e
new ham or one with
little or
no
knowledge of
so
li
d
st a
te devices.
There are several th
ings
tha t must be taken into ac-
count before you at tempt
conversion
of
any CB trans
ceiver for operation on the 10
meter band. Ma inly these can
be grouped in
to
a few simple
questi
on
s:
1. How much do I want
to spend if I have to buy a
new or used CB transceiver?
2. Does
th e
CB transceiver
I presently have lend itself to
easy and cheap c
on
version?
3. How much electronics
knowledge do I have to solve
the
pr
oblems I
will
encou n-
ter?
4.
Do
I feel
that
10
meters is worth a ll
th
e effort
to c
on
vert a
C8
rig to that
band?
If all of these questions
can be answered in such a
way to ind icate that your
nex t project is
to
be the
co
nversion of a CB trans
ceiver
fo r
1
meters, then get
started before
th e
band starts
to
open up for some rare
. -
Harry
MilJer
42n d
St
Sarasota
FL 33580
ave
Your
ld
peakers
how to remove the beehive
wall
op
. In effect, you are
recentering a misaligned voice
coil. Result is usually a dear
up
of
the ratt le. -
where th e scratch was heard.
Don t
g
et
ove
r
ambitious with
pounding. A few
li
ghter raps
are far be
tt e
r than one hef ty
- -
Then use a heavy rubber mal
let to str ike the magnet end a
sharp blow or two
at
a point
directl y opposi te to point
I
n the old days, service
technicians did a lot of
speaker cone rec
en t
ering to
clear up annoying ratt les,
which was at th e time a tedi
ous
bu t
possible job.
Current speakers generally
make speakers thr
ow
-away,
due to thei r modern design,
so they re go or no go
devices. There is, however, a
possible cure if the rattl e is
due to an off-eenter voice coil
and it s a fast repair.
Remove the speaker. Hold
it close
to
your ear and
gently, with fingerti ps, alter
nately press and release the
cone abou t an inch from the
rim toward
th e
voice coil and
listen f
or
scratchy sound.
Rotate the speaker while do
ing this. If
th e
speaker is
capable
of
this fast cure,
yo u
will
find
th e no
ise
li
mi
ted to
one poi
nt
on th e circumfer
ence. Carefully note t
ha t
point. Lay speaker
on
a solid
flat surface, with magn
et
up.
1 9
-
5/19/2018 Convert CB Radio for Ham Bands
5/81
part
II
: conversion data
Legal
ltern tive
Tobie
1.
requency
coverage
of the
29.95
OX transceiver
twice the price. There are 2
ICs, 12 diodes, and 15 transis
tors in a double conve
rs
ion
receiver and AM transmitter
con figuration. The manufac
turer claims 0.5 microvol t
sensitivity at a
10
dB signal
plus noise to noise ratio. Pow
er ou t pu t from the 2SC799 rf
ampli
fi
er is
lis
ted
at
4
Wa
t ts
and the spec sheet advertises
90 modulation. Loaded, the
transmitter draws 1.4 Amps
at up to 13.8 vol ts
easi
ly
obtainable from th e cigarette
ligh
te r in you r car o r from a
small ac supply). The rig has a
built
-i
n squelch circui t, bu t is
not equipped with an rf
tuning indicator or receiver
Sm erer.
When the Citizens Band
was created in the 1950's, the
early ri
gs
used 23 pairs of
crystals to tune both transmit
and receive on all 23 chan
nels. Converting one of those
rigs to 10
ph
one would cost a
s
mall
fo rtune to crysta l up,
but I was prepared to pay it
until Norm Lefcourt
W6
1RT
mentioned that th e newer CB
rigs
use crvstalplex, replacing
the old 46 crystals wi th 14
new crystals and still covering
all 23 channels. Norm point
ed ou t tha t by replacing the
six master oscillator rocks, I
could cover 23 frequencies
simplex on the 10 meter band
with just a little tweaking of a
few
L
circuits. W6IRT,
WA6QPL, K6JUA, others and
1 al l started working on the
co
nvers ion. K6HY, K
6LJL
and
WB
6QKF he lped with
advice.
t
sounds pretty easy, bu t
there was a pro
bl
em - de
ciding on which frequencies
on
10
phone to use. The
phone portion of the band is
gigantic when compared to
the othe r HF bands, and we
wanted
to pick a segment
where there would be some
activi ty . We
d idn 't want
to
cause difficulties for other
services, yet at the same time
we wanted to stay near the
low end so that retuni ng from
the CB frequencies would not
require a rewinding of coils.
Afte r an awful lot of discus
sing on the landline and two
meter FM , we decided to stay
away from bo th
th
e very top
end of th e 10 phone segment
(because of OSCAR) and
from the very bo tto m end,
too (because of the SSB DX
activity just above 28.5) . We
finally sett led on a sta rting
frequency of 28.76
MH z for
channel one, with the other
22 channels tuning upward
from there. The decision was
based on two practical con
siderations: First, the pres-
39.495
39.
64 5
39.595
39 545
39 395
39.445
M a t e r
Qs.ci
llato
r
Fr
eq
uen
cy
28
.
76
28 77
28 78
28 80
28 .81
28
.82
28
.83
28 85
28
86
28.87
28.88
28.90
28 91
28 92
28 93
28 95
28
.96
28.97
2
8 98
29
.00
29.01
29 02
29 05
Fr
eq
ue nc y IMHz)
1
2
3
6
7
8
0
11
12
13
15
16
17
18
0
22
23
10 Meter Cha nne l
the FCC approved 40 channel
C8 for use after January 1,
1977. When a lot of manu
fa cture rs started dumping
their o lder model 23 channel
sets on the market at bargain
prices, I got reinterested in
recycling a CB radio up onto
10 phone. 1 watched the ads
and fi nally bought a
J.
C.
Pen ney transce ive r model
981
6201.
t
is a quali ty piece
of gear that usually se
s for
H
OW
abo
ut
a brand new
DX transceiver that s
rock stable, plugs into your
cigarette lighter, and tunes 23
frequenci es on 10 phone for
less
than 30?
f
course,
there are a couple of draw
backs - power ou tput 4
Watts, and an emission type
the sideband guys call An
cient Mod ulation - but those
problems are hardly w
or t
h
menti on ing. Just ask any old-
timer who worked the peak
of the '46-'48 sunspo t cycle.
You
can
do wonders with just
a few Watts on 10 phone, and
the technical specs on the
29.95 transceiver make it a
superior performer to wha t
was avai lable in 1
94
6.
For several years, I've been
watching the want ads and
goi ng to swap meets in search
of the perfect junk C8 rig. I
had plans for picking up one
for just a few dollars, chang
ing a few crystals and
presto - getting on ten phone
quick and dirty. I never really
found what I wanted for a
cheap enough pri ce (CB SSB
was always too expcnsivel]
and I soon lost interest. And
besides, I was busy getting
on
to
tw o
meter
FM
plus I
didn' t want to give up work
ing the low bands on
CW
or
SSB. All of that was before
Alan S. Kaul W6RCL
9731 ~ d
v nu
Chatsworrh CA 91311
CB
162
-
5/19/2018 Convert CB Radio for Ham Bands
6/81
(f)
e
cr
- - -'-
, , -
f-
'
I
~
-
F . ..
lSI CO>tv
~ .
IST f '
.
2 0
~ ,
C ( ~
I
n ~
m G j rc n
..
I I
~ -
.,
.
,
;
5
MHz in 10 kHz steps. The
master oscillator fr
eque
ncies
range fro m 37 .600 MHz to
37.850 MHz in 50 kHz steps.
In order to co me up with a
worka ble plan and in ord er to
purchase th ewest number of
crysta ls, I decided to cha nge
the frequency of th e master
oscillato r by 2.0 3 5 MHz. Th is
puts channel 1 on 29_000
MHz. Thi s is a nice round
number, and it seems t
ha t
the
higher frequenci es formerly
were used for AM opera tion.
This is accomplished very
easily by changing th e crys
ta ls as shown in Table 1. The
new crystals can be purchased
from Int ernational and other
ma nufacturers for aro und
4.9 5 each. This puts th e rig
o n frequency in th e ten m
et
er
band,
COAX BRAID
FASTENED TO
TOWER WITH
GROUND CLAMP
would be an excellent candi
date for convert ing to ten
meter M and, at th at price,
I cou ld butcher t he rad io all I
wanted to and still
not
fee l
bad abo ut it. Let me say
at
this poi nt th
at
, alth
oug
h I
thin k I made a good buy for
the amount of ele
ct
ronics I
was getti ng,
I
have fo und ou t
t hat th ere are better deals to
be had. The used CB market
is virt ually n
on
existent and
an en
ter
prising ham can find
a bro ken CB rig for 5. 00 or
less. At th ese prices,
it
will be
hard to go wrong when pur-
chasing a CB rig fo r co n
vers ion to ten meters.
With
new two meter rigs
INNE R CONDUCTOR TO
>
8f t
l in STRANDED /
m
Fig
t.
Leland H Agard KSLUW K5SA
ROil
te
5, Box 735
Starkville MS
9759
T
he C
oo m is just
abo ut over. The sup
pliers are tryin g to unlo ad
wa re ho uses full of new
23-channel CB radios
at
any
price th e market will pay. In
ma ny insta nces, the CB
antenna wil [ cost more than
the radio - amazing but tru e.
I was in th e local Rad io
Shack stor e and noti ced
tha
t
t he new Realistic Mini 23 CB
radio was selling fo r 29 95.
This had to be a bargain, as
thi s radio normally sold fo r
10 _ 95. I
thought
th is rad io
138
-
5/19/2018 Convert CB Radio for Ham Bands
21/81
Fig 2. Realistic Mini 23, btt view
also a goo d proj ect for a
co uple of guys who just want
a littl e privacy to discuss the
stoc k market or whatever.
For under $60.00, this is a
good way to keep ten meters
alive. See yo u on ten AM
Indeed, it seems t
hat
gro und
wave on this band is about
equal to line-of-sight pat hs on
two meters. Thi s is a great
club project to bringa ll th
ose
members back together on
some
comm
on groun d. It is
SQUELCH
CRYSTAL
SWITCH
VOLUME
CONTROL
To
3
9.635
MHz
39.685 MHz
3
9.73
5 MHz
39.7
85 MHz
39.
835
MHz
39
.855
MH z
[ [ [
T4 T5 n
ATTAC H PROBE
FOR RCVR TUNING
Table
From
37.600 MHz
37.650 MH z
37.7
00
MHz
37 .750 MHz
37.800 MH z
37.850 MH z
[ [
T2
n
Crystal
Xl
X 2
X3
X 4
X5
X6
middle of the group of fre
q uencies yo u are using. In my
case, it worke d
ou t
t o be
eight fee t and one inch fo r
just a little below 29.000
MHz. The inn er conductor of
th e c
oax
fee dline is attached
to the quar ter wavelength
radiator, and th e braid of the
coax is clamped to the tower
leg using a ground clamp.
This system works quite well
and cuts the length of the
sloper in half.
Resu lts
The te n mete r AM rigs
compare very favo rably with
the two meter rigs. The cost
is dr astically lower, but range
seems to be abo ut as good.
Mobile-tomobile coverage is
ab
o ut t h r e e miles, and
mobile-to-base coverage is six
to seven miles. With base
station-to-base
stat
ion co n
tac ts runnin g four Watts
ou t put and sloper antennas
up
forty
feet at bot h ends of
the path , co nsistent gro und
wave coverage of better than
20 mi le s is main ta ined.
trimming the whip un til I
reached an swr of 2:1 while
operating on ten meters. On
the whip I was using, I too k a
littl e more th an two and a
half inches of f. Th is will vary
wit h d i f ferent types of
mobile ant enn as, of cou rse,
and a good method is to
inser t the swr bridge in line
and trim until a good match
is obtained. Th e fr equency
change of 2
MHz
or so should
work out okay with most
mo bile whips tha t are base
load
ed
.
For a base s ta tion
setup
any ex ist ing ten mete r ante n
na could be used, even a
tr imm ed down
CB
gro und
plane. I wanted an indepen
den t rig and did not want to
tie up my ten me ter beam
with the tittl e rig, so an extra
ten meter antenna was a
must. I fi nally decided on the
sloper-
type
anten na s
how
n in
Fig.
1.
Thi s antenna is easy to
ins ta ll, is small, is cheap to
build, and is ver t ically polar
ized for working mob iles. The
sloper should be cut for the
The
ULTIMATE
in CW Reception
ACTUA L SIZE
3 1j, WIDE
2
J
/s
HIGH
.4 3/8 P
COpy
ON
99 95
COPY ONE IS
NOT
A FILTER This stat ion access
ory
is a
must for
th e d iscr
imin
...ting
amateur who
op
era tes CW, whether he is an a
vid
CW op or on e
who
engages in CW
fo r pro fi ciency. The CW signal is processed (not fi l tered) in am anner
whi
ch allows
tru e
ULTIMATE
STATION REJECTION, a
mod
e wh ich has been previ ousl y
unavailable . The circu
i try
is totally
unique
(patent pendingj.a
must
fo r emergency
C
Wop
erations. If you haven't had the
opportun
ity to operate a COPY ONE, ORDER
YOURSTODAY
COPY ONE CW PROCESSORSPECIFICATIONS & FEATURES:
lt
imate sta tion rejection almost unbelievable but truet)
itch
&
volume independent of rece iver or tra nsce iver
Full quieting
(i
e .. no ba ckground noise) with
out
sque lch
.COPY
ONE
is not a filter.
t here is
absolute ly
no ringing or
background no ise
.Plugs
into transceiver or receiver/ transmitter combo
wit hou t modificati on
Discriminates signals in80 to 100cycle incr
emen
ts
Full b reak -In Cw opera
tion
Incl udes 115 vo lt AC power supplyor may be
batte ry operated
ui l tin code pract ice osc illator
LEO lock-up controls front panel mounted
ORDER YOURS TODAY
send $99 .95 by
check
or money order to:
3135 North Cole Road Boise,
Idaho
83704 [208]377-1562
L
l
139
-
5/19/2018 Convert CB Radio for Ham Bands
22/81
Cliff Wigin ton,
Sr
W SG
R FD
1,
Box 208
urnsville MS 38833
to
p r t
XI: Gain s rigs
A
lmos t every late-model
CB
rig on the mar ket is
capable of operating on 10
with excellent sensit ivity and
output. No mod el requires
very ext ensive changes to
modify. I picked an inexpen
sive and easily co nv
er t
ed rig
for my fi rst research run and
ach ieved some rather gratify
ing result s. A litt le fancy te le
phon e wor k go t me in
touc
h
with Char lie C
onn
ers KliNG
in Nebraska, who
I
knew had
spent many hours in design
work on PLL circuits. As it
tu
rne
d out, Charlie has do ne
exte
nsive work on 10 meter
co
nversions, and , without his
advice and know ledge, my
conversion
cou
ld have been
very painful th e first t ime.
T he Hy-R an ge model
681A, I which I chose for
conversion, can be modified
in about an hour and per
forms well (be
tt
er th an manu
facturer 's specs], Is it phase
loc ked loop? You be t - it
only requ ires the pu rchase of
one
cry
stal instead of two,
fo ur, or possibly six o n some
rigs, and
the
receiver sensi
tivi ty is right on with a lit tle
re a
lig n m en t . No ci
rcuit
changes are necessary, and
there is no com
prom
ise o n
sensit ivity.
Do I have you i
nte
rested ?
Get out your alignmen t to ol,
VTVM, and signa l generato r
172
(necessary equ ipment), and
set aside one ho ur of your
day 's schedule.
Finding your way inside
should be no pro blem. Loc
at
e
X10 l and rep lace it with a
new cry
st
al which is de ter
mined by the form ula: (N
/2 )
+ 9. 51 0 MHz, where N = kHz
above CB channe l l (26.96 5)
tha
t yo u wish to o pera te.
For example, suppose we
move up exactly 2 MHz to
28. 96 5 for channel
1.
Then ,
28.965 -
26.965 =
2000 kHz;
200 0/2
= 1000
kHz or 1
MHz; 1000 kHz
+
9.51 0
=
10.510
MHz for new crystal
f requency.
With the new crystal in
stalled , se t the channel
sel
ecto
r to channel l , attach a
VTV M to TP8 on the PC
board (junc t ion of R114 and
Rl1 5), and ad just T
l01
for
1.5 V de .1 vo lt. This step is
critical and must be done
carefully, as it allows the vco
to
opera
t e withi n cap tur e
ra nge of the PLL circuitrv.
Th is accomplished, loosely
coupl e an accu rate signa l
source to the a
nte
nna jac k,
fl ick the channel sel
ec t
or to
channel 11, and carefu lly
peak T104 , T105, T106,
Ll l 2, and Ll 15 fo r maxi
mum receive sensit ivity.
Next, a
ttac
h a power
meter and du mmy load to th e
output and key up th e trans-
mitt er, Watch the power
meter and tu ne T 102, T103,
L103, Ll 04, Ll 06, L109,
a nd L110 for max imum
power out put If th e power
outpu t exceeds 4 Watt s at
thi s point, read just L
110
count erclockwise until it is 4
Watt s or less. Th is last ste p
will assure an output free of
s pur ious radiat ion. Also,
reme mbe r that these adjust
ments are i
nte
racti ve and
shou
Id be gone over more
than once fo r peak perfor
mance.
And there you are It' s . .
first c lass 10 meter rig in
anybo
dy s
boo k - in about
an hour.
Now you need an a
nte
nna
fo r the littl e jewel. There is
one
CB
antenna on the
mar ket tha t -wi
-operate as
is o n
10
with less th an 2-to
1 SWf th rough a full mega
h e r t z. The M400 Star
du ster made by Antenna
Specialists is a natu ral, the
only modification necessary
being to change the coax co n
nector fro m the CB rig to the
10 meter rig. But, for the
ham who s got to have everv
thing just ri
ght
, slip the
capacita nce hat
of f
the top
radiator , pru ne the rad iator
to 96 and the three radia ls
to
98
, and you have a fine
vertica l ant enna which will
show unity gain with a goo d
dipole.
A mobile antenna presen ts
litt le m
ore
difficul ty th an a
simple retuning. Most com
mercially produced mobi le
CB
antennas fall int o three
categor ies, and all can be
mod ified succe ssfully with
very littl e effor t. Qu arter
wave whips are simply pruned
to resonance wit h an swr
me te r in the line. Center- and
to p-loaded antennas usua lly
have an adjustable me tal whip
wh ic h
r e
qu
ir es a
slight
sho rte ning.
Helica lly wound antennas
may be carefu lly shor tened
a nd resealed against the
wea t he r. There 's no th ing
really difficul t about the con
version, and most can be
acco mplishe d in 30 minutes
or so.
By th is poin t. yo u should
have under $100 and about
an hour and a hal f worth of
time invested in a slick 10
meter sta t ion . -
Reference
1. Hy-Gain
mod
el 682 uses
th e
same co nve rsion .
Mode
ls 2680 ,
268 1,
268
2, and 2683 req uir e a
di ff
erent c
ryst
al fo rmu la: Crystal
X10 1
=
N/ 3
+
11 .80 666 MHz, but
t une-up is
exac
t ly the sam e. Ser
vice manuals (ve ry c
om
p rehen
sive are avai lable f rom : Hy-Gain
Electro nics. 4 9
00
Supe rio r
St
. ,
in o ln , Nebraska 6850 4, f or 5
each.
-
5/19/2018 Convert CB Radio for Ham Bands
23/81
Hans Peter Baumeister
DFiSP W
JJ8D Windsorshjre Dr
Rochester
NY
14624
p r t
X the Lafayette e sat
558 75
ig
1.
Te/sat
558-75
par ts location diagram
10
X205: 24.865 MHz
X206
: 24 .905 MHz
X207: 24.945 MHz
X208, 24.985 MHz
X209, 25
025
MHz
X21 0, 25 .065 MHz
No o peration is possib le on
28 .720 MHz between
cha
nnel 22 and 23)
because
of the switching a rrange
ment .
If you wan t
to
listen oc
casionally to OSCAR 7, just
use a 25.835-MHz
crystal
fo r X210. Thus, cha nnel 23
rece ives the 29.502MHz
bea c
on
, and cha nnels 21
and 22 receive 29 .480 MHz
and 29 .470 MHz, respec
t ively, in the CW
subband
.
you prefe
r
th e
73
Magazine
band
plan chan
ne l 1 at 28.965 MHz), you
need
to
replace only th e
following crystals:
X205, 25330 MHz
X206: 25.380 MHz
X207: 25.430 MHz
X208: 25 .480 MHz
X209, 25.530 MHz
X210, 25.580 MHz
Crys
ta
l X204 remains un
cha
nged , so
de
lete step 1 in
th e follow ing instructions.
This set
of
crysta ls gives
you
th e
firs t 23 channels
of
the 73 band plan.
Some portions of the
t ransce iver must be
rea
lig
ned
,
hut
t
he
o
nly
co
mponents tha t
must
he
cha
nged a re th e crysta ls. A
sa tisfactory a lignment
ca
n
c rys ta l shou ld be replaced
by a 14
.94o-MHz crystal in
or
de r
to g
et even
1o-kHz
spac ing fro m cha nne l to
cha nne l orig inal ly 10-10
2010 kHz), Every crys ta l of
th e fir st group yields fou r
cha nne
ls on 10 m
et
er s.
The fo rmu la fx
fo p +
11 .275 MHz - 14 .910
MHz , w
he
re fop re
qui red operating frequen
cy in MHz, gives the fre
qu
ency fo r the crystals in
t
he
24-MHz r
ang
e . Remem
b
er
: Each of t
hes
e crys
ta
ls
give s fo ur o pe r at ing fre
quen
ctes.
Example ; The frequency
28.500 MHz sh a ll be on
channel o
ne
,Which c rystal
is necessary? f
x
28.500
MHz
+
11 .275 MHz
14 .910 MHz 24 .865
MHz . This
crysta
l replaces
X205 as shown in th e parts
locat ion diag ram, Fig. 1 .
This c ry
stal
is in
ac t
ion
f
ro
m
che
nn
lt
to 4 o n the
selec tor sw i tch . X206
re spond s to cha nne ls 5-8;
X207 to c hannels 9-12;
X208 to 13 -16; X209 to
17-20; and X210 supp lies
21 , 22, no ope ration, and
23.
you
want all 23 chan
nels in an unin ter rupted
o rder, all you
do
is add 40
k
Hz
to
the
p
revious
c
rysta
l
s
f
reque
ncy
.
Exam ple: For 28,500 to
28.730
-M Hz
coverage ,
yo ull need:
crystals , which ar e d ivided
i
nt
o
two group
s for fre
quency
synthe sis: a grou p
of six c ry st a ls in
th
e
24-MHz
range
with 50-kHz
spaci
ng, and a g
ro up
of 4
c rys ta ls from 14.910 MHz
to
14 .9 50 M
Hz
.
Afte
r
c hecking
th e block
dia
grams fo r t he differe
nt
modes , I decided to re
pla
ce
th e 24-MHz crystals .
Also , the 14
.950-MHz
T
his tig makes a very
ve
r
s til a l l-m od
e
mob ile t ransceiver when
co nve rted to 10
meters
.
The pr ice has come dow n
remarkab ly from its or
ig-
ina l offe ring . It s basic
spec
ifications are : 23 chan
nels, all
mode
s US
B
lSB ,
AM), minimum 12 W PEP
output,
an
i-f c rystal fil te r,
and 600-Hz
fine
-tune
capab il ity. The rig has
10
86
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5/19/2018 Convert CB Radio for Ham Bands
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be ach
ieved
usin g on
ly
a
wattmeter
and a 10 m
et
er
tra
nscei
ver.
Y
ou
s
ho
u ld
have no p rob lems if you
fo
l low the
se instructions.
1 .
Rep
l a
ce X20
4 w i t h
14 .940
-M
Hz crys tal.
2. Repl ace X205 throug h
X210 as re
quired
.
3. Set mode sw i
tc
h to USB .
4. Plug in
the
mi
cropho
ne
and
turn th
e
rig on
. Turn
t he squelch full y counte r
cl
ockw
ise.
5.
Co
nnect a 10
meter
an tenna
throug
h t he
watt
m
et
er.
6. Prov ide a st rong signal
on one
of
the
pl
anned
operat ing f r
equen
cies.
7. If you hea r the signa l
a l r ead
y,
ro t
at
e
l201
c
lo ck
w ise
unti
l t he signa l
d i sa
ppe
ar s, an d t h e n
coun te
rclo
ckwi se until the
signa l return s. Cont i nue
o ne-h a l f t u rn
co
u nte r
cl oc
kw
ise past t he
po
int of
return of the signal.
Go to
ste p 9 if yo u were able to
co
mp
le t
e th i s step.
If
not ,
con
t inue w it h ste p 8.
8.
If you don ' t hear t he
signal, rotate l
201
count er
clockw
ise
un t
il yo u hear it,
o r ch
ec
k
th
e f req ue n
cy
and
st rength of your
refe
rence
signal.
Go
back
to
step 7.
9.
Redu
ce th e 10 me ter
reference signal
ampli
tu de
un t
il
you bare ly hear it.
10.
Adju
st 1202,
l2
03, and
l204 fo r best recep t ion .
Redu
ce
refere
n
ce
signa l
le
ve
l as required .
11.
Ad
just l
18 and l1
9
fo r
best rece pt i
on
.
12. Repeat steps 10 and 11.
13 . Set
mod
e sw i
tc
h
to AM
.
14. Press
mi
crophone pu sh
to-talk bu
t t
on and a
dju
st
l2, L3 , L4, L5, L7, and L6 fo r
m ax imum i nd
ica
t ion on
the
watt
mete r.
15. Repe
at
step
14
unt il
powe r o
ut
p
ut
is be
tw
een 4
an d 8 W atts.
16
. S
et mo
de sw i
tc
h to
LSB .
1 7 . I ncre a se r
ef
e r ence
signal level u ntil a wea k
signal is received, A sli ght
f re q
ue
ncy c o rr
ec
t io n
m ight be necessary .
18. Ad just L12 th rough l 17
fo r best reference signa l
recep
tion
.
19 . Rem ove referen
ce
sig
nal and repeat steps f 'l and
18
fo r
m ax
imum
n
oi
se.
That ' s
it
I f you fi nd it
co
mpl i
cated
- t
ry
it . I t ' s
r
eall
y no p
rob
lem .
The ret uning w as suc
cessfu l if th ere is p ractical
ly no d
iffe rence
in
noi
se
received w hen you sw i t ch
ba ck and
fo
rt h be
tw
een
USB and LSB and power
o
utpu
t is nea r ly
co
nsta nt
whether
on
u
pper
o r low
er
sid eb an
d.
Better results
mig
ht be o
btain
ed, how
ever, if you have ac c
ess
to
sophist i
ca
ted te st equip
men
t .
Th
e time required fo r th e
co nve rs io
n/a
l i gn
me
nt i s
less
th
an one hour.
Original ly, th e fine tu n
in
g contro l varied onl y t he
rece ive
fr
equency . So lder
ing w ire a
to
w ire b (Fig. 2)
provides f ine tun ing fo r
tr ansmit , as
wel
l.
I
found
th is conversion
ve ry hand y fo r stric t ly
mob
i le use. F
or
po rtab le o r
f
ixed
u se , h o w e v
er
,
rep
l
aceme
n t o f X2 01
t hro ugh X204 w ith a 14 .91
0-
to
-15.010
MH
z
vfo
is fea si
b le and certa in ly wo rth
whil
e. This w i
ll
prov
ide
a
100-kHz-wide segment fo r
e
ac
h o f c r
ys
t a ls X20 5
t hrough
X2
10 .
You wi
ll
be su rp r ised
how o
fte
n y
ou
get a DX
contac t w
it
h onl y 10 W
PEP
. Tal
kin
g w
it
h W6s and
W 7s w hile d riv ing around
in u psta te New York is
no rm a l,
and
a contact
w it h South America , the
Car ibbean, o r even South
Afr ica is n
ot
a rari ty . Good
DX
Fig
2. Fine tu ning
po
ten-
tiometer.
v G12
HEATH OX
-I 00
M
od
i .. , ..
9 5
H
EATHH
X l0Pow
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5/19/2018 Convert CB Radio for Ham Bands
25/81
p r t
XIV
a
Realistic
rig
Rubert rochowsky KflQL
3553 S it ssi err
Topeka KS 666
A
grOw in
g
inte re st in
CB
to
10
conver sions .
combined
with a close out
sale at Radio Shack re-
su
lted
in t
he
re ce nt pur-
c h ase
of
a Reali st ic
TR
C 4
52
4D
channel CS. I
had
e a rlie r o b ta ined a
23 c hanneJ
Royce
set fo r
conversion
.
but
felt
the
cost
for crystals was
not
justified to obtain
only 23
channels. I must admit to a
ce
rta
in
amount
of blind
fa ith in the TRC 452 pu r-
chase
bu t
I
fig
u
re
d a rig
wit h on ly two c rysta ls had
to be both
easie
r a nd
cheaper
to
convert Th is
was late r found to be
true
on both counts.
Although I
had
read all
12
the earl ier
conve
rs ion ar-
t icles in
73 Magazine I
had
not stud ied t hem in g
reat
detail
except
for my pass-
ing
interes t in th e Royce
.
Another review of th e ar
-
ticles showed
l it tl e info
r-
mation on conversio
n of a
phase-locked-loop
PLl)
rig. Th is m
ea
nt a great dea l
o f s
tu
dy ing digital freq ue n-
cy
sy n
thes
is a
nd
m
an
y
hours spen t in technical
discus sions
with
Gene
Godsey K0BXJ
and ot
he
rs.
This a
rticle
is
intended to
share the information
gathered a
nd
he lp
ot
he rs
converting
th
e
PLl-type
rigs .
Crystal Control
With crys tal
prices
in-
creas ing an d i
ntegra te
d ci r-
cu it p
rices
dec
reasing,
it
was
only a
matter
of
time
before someone came up
with a be
tt
er way to sy n-
thesize
t
he necessa
ry fre-
q
uencies
for CB. Crystal -
plex
reduced
th e
crysta l
count from 46 to 14 bu t
th e advent of the phase
locked loop reduced th e
co u n t to just
2 crysta
ls in
mo
st of t he newer rigs. At
fir
st
gla
nce,
it m a y seem
t hat th e se rig s a re no
l
on
g
er
crystal controlle
d,
but furthe r study s
how
s
that
they
are .
Since th e
reference frequency is
derived f
rom
a
crystal
oscillato r th e tolerance
and p recision
of the
reference
freq
uency and
th e
o
utput
freq
uency
will
be
t
ha
t of a c
rysta
l.
Miller Circui ts
In orde r to unde rstand
ll circuits
an under
standing
of
mixer ci
rcuits
is
necessary . In th e most
basic
terms a m ixer has
two input frequencies and
fou r output f requencie s.
The frequency
we will be
interested
in is
ei the r the
sum of th e
original fre-
quencies o r the
difference
between
th e
origina l fre-
quencies . It is impor tant to
rem emb er that either
th e
sum o r d iffe rence
may
be
use d a nd they
may be
used if ferent ly i n
separate
circuits
within
th e
fig .
Even
the simplest
single-
conversion receiver in CB
will no rmally use
two
mix-
er s
tages
to
arr
ive at
th e
desi red
inte rmed
ia
te
fre-
q
uency
It f
of
455 kHz.
Two frequencies are mixed
to a rrive
at
the
sum
and
this signal,
either
455 kHz
above or below the
re-
ceived signal, will be
mixed
with th e
received signal to
-
5/19/2018 Convert CB Radio for Ham Bands
26/81
ig 1. Block diagram
of
the PLL components as used in the
TRC452
The key to th e whole fre
quency c
ha
nge is t ied to
the 15.36-MHz re f
er
ence .
We ca n t
change
the refer
e nce di vid er , and we
do
n t
wa nt to d isable the who le
re fer
en
ce d ivi
de
r, as we
wo u ld kil l o u r 10-kHz
re ference to the phase
detector.
let s disconnect
the 15 .36-MHz reference
from th e mixer and replace
it
with
a new
oscillator
se t
for 16.955 MHz . The vco
will
now be
d riven higher
by th e phase detector until
th e
d ifference
of
1 .82 MHz
is reac hed. The new veo
o ut p
ut frequ
en cy will be
16.955 MHz plus 1 .82 MHz ,
or 18.775 MH z . M ixing
18 .775 MHz with the 9.785
MHz
in t
he
t
ran smitter
gives us a new frequency
o f 28 .560 MHz for channel
1. which is right where
we
want to
be
. Mix ing
18.775
MHz with th e incoming
signa
l
of
28
.560
MHz
also
kee ps our fi rst receiv
er
i-f
at
9 .785 MHz, rig ht where
it
was
bef
or
e . Everything
e lse chec ks o
ut
, and a ll
t ha t we changed
was
the
frequency
re f
er
en ce
ap
plied
to the mixer.
This work
s we ll in
theo ry, so let s see how it
wo rks in practi
ce
. Fig. 2
shows th e schematic for a
s imple crystal os
cillator
with no
tuned
c ircuit . This
c irc u it an d
others
a
re
desc ribed in olid State
Design fo r t h e d
io
Am
ate ur (ARRl ). Th is
121
12
.. ....
12
.. ..
:16...
-
ve c
C [
2U .. ..
I
, STD
1 1
.
J
.. ..
.
- -
-------------
---,
I
[ >[ U
C[ LTER
I
D,v D[
lI[He o lO I
i
I
I
.
i
LH R
I
I
I
I
i
[ E
E ~
P..OC A .... . BC[
I
0 C ,c cA10
D,v DE
I
I
I
L
-
LL
C 8 2 TO n
.J
- -
I
~
0 24 M
things ar e dependen t on
this freq uency . We a re us
ing a divide-by-1024 to pro
vi
de
th e 1
00kH
z r
eferen
ce
to th e ph ase d
et
e
ctor
, so
any change in
th e
refer
e nce f requency will ad
ve rsely
affect
o u r d ivider.
We are
a lso usi ng a d ivide
bv z
to p roduce
t he
15
.36
-MHz
harmoni
c
whi
ch
is mixed with
th e vco
output.
By now, th ings seem
pretty comp lic a te d. Any
change in the 10,24-MHz
re feren c e c
hanges
the
ma t
hem
at
ica
l re la ti
on
ships be tw een q uite a few
components . Ther e s
eems
to be no easy w
ay
t o
change th e freq
ue
ncy of
t his rig. But fu rthe r analysis
shows tha t
there
is an easy
way .
le t
s look at
th e
way
the vco changes
frequen
cy
agam .
10 .24 MHz is divided by
1024 to
pr
odu ce a 100kHz
inpu t to one side of th e
ph ase de
tecto
r. If the chan
nel se lecto r swit ch is
se
t to
cha nne l l , wh ich program s
the div ider to di vide by
182 , then th e resu lt of mix
ing the vco output wit h the
15.36-MHz reference must
be
1.82 MHz to divide to
the 10
kHz
needed
fo r
th e
other
input
to th e phase
detector
. The phase detec
to
r will
detect
any f
requen
cy dif ference , hig h o r low,
and ad jus t the
vco
up
or
down until th e mi xed o ut
pu t
is
exac
t ly 1 .82 MHz .
through a filter whi ch
se l
ec
ts t he harmonic pro
du ced at 15.36 MHz . The
vco frequ en cy is mixed
with thi s 15 .36-MHz sig
na
l,
goes th
rough
IC2 int e rface,
and is then divided to 10
kHz by the l IN divider .
This is app lied to th e ot her
i
np
ut
of
th e
phase
de
te
c
to r. The ph a se
detec
to r
detec
t s t
he
diffe ren ce of
the
se
two
i
nput
signals and
produces a vo lta
ge
which
controls the vco frequ en
cy . When the pha se of th e
two input signals to
th
e
pha se
detector
is
th e
same .
th
is loop is lock ed.
As mentioned earl ier.
th e
output
frequency from
th e vco is N times th e input
fr
equ
en
cy. 10 kHz . By
va
ry
ing th e consta nt
N
th e ou t
p
ut
fr equ e n c y ca n be
va
ried one 10-kHz ste p
at
a
time . The cons ta nt N is
co
nt rol l
ed
by
th e chan
ne l
selector switc h (from
182
to
226
).
Another output of th e
10 .24-MHz ref
erence
oscil
lator, not s
ho
wn. is used to
mix with th e first i-f for the
receiver. The incom ing sig
nal fre
que
n
cy
(26 .965
MHz
fo r channell) is mi xed with
the vco
outp
ut frequen cy
1 7.18 MHz for c ha n
ne
l
l) ,
wh ich wi ll pr
odu
ce 9.785
MHz as
th e
first i-f. This
9.785 MHz is th en mixed
with th e
10 ,24OoM
Hz
out
put
of the
referen
c e
osci lla to r to produ
ce
the
455 kHz seco nd i-f.
Al
so
not
shown is
th
e
tran sm it lo ca l
oscillator
,
wh ich is se t at 9.785 MHz .
This signa l is m ixed with
t he v
co
o
utpu
t frequ ency
to prod uce the tran smi t
frequ ency, 17.18 MHz p lus
9.785 MHz equals 26 .965
MHz , whi
ch
is the c hanne l
1
frequen
cy .
Now t ha t we ar e familiar
with
Pll
circuits,
let s
take
a look at
thi
s ci rcuit and
see wh
at
we ca n change to
prov ide the new operating
frequency .
The first imp ulse is to
cha nge t he 10 .24 MHz
c rysta l. Bu t too m any
arr ive a t 455 kHz .
Du
al-conv
er
sion re ceiv
er
s use
an
additional fre
quency conversion sta
ge
for low er no ise and le ss
distortion of t
he
recei
ved
sig
na l.
N
ow we
have two
i-ts. a nd
we
may have ad di
t iona l amp lifie rs for
ea ch
i-f. The
fi
r
st
i
f is
no rmally
around 10 MHz and may
be
dete rmined by
clo
se ex
aminat ion of t he
sche
matic .
Phase Lo cked Loop (PL
L
Cir
cuits
Mo
st PLl
c ircuits
co
nsist
o f
4
ma jor componen
ts
: a
pha se
de
tect
or
, a filter
amplifier. a voltage co n
tr olled oscilla
to
r Ivcol, and
a
l i
divide r, pl us o th e r
suppo rting
compo nent
s .
Fig. l shows t
he
diagr
am
of
t hese componen ts as used
in th e TRC-452.
The pha se
detecto
r p
ro
du ce s a vo ltage
propo
r
tiona l to the ph a se diffe r
en ce o f two
input
sig
na
ls .
The low
-pass filter
(filter
amp
)
integrates th e output
vo ltage of th e phase detec
to r
and al so filters har
monics o f frequency com
ponents given
to
the pha se
detecto
r. Then it produces
a continuous
vo
ltage com
ponent in proport ion to the
phase diffe rence . The
vfo
is
an
osci llator whose fre
quency is co nt
ro
lled by
the
vo ltage appli ed
to
it. The
vco frequency is
fed
bad
t o the pha se det e ctor
th rough
th e
l i
divider
.
(The constant.
N
is given
by
th
e c ha nne l se lec to r
sw itch.) So. the
output
fre
q
ue
ncy from the vco be
comes N times the input
frequ e ncy.
The referen ce div
ide
r
has two sections :
One
is a
divide-by-2 ci rcuit which
produce s 5.12 MHz ; th e
ot
he
r is a di vide-by-l024
ci rcuit wh ich produ
ce
s
10
kHz whi
ch
is appli
ed
to
on
e input of the pha se
d
et
e
ct
or
. All Pl l c ircuits
studied use 10 .24 MHz a s
the re fer ence f
reque
ncy .
The 5.12-MHz output from
the ref
eren
ce divider goes
-
5/19/2018 Convert CB Radio for Ham Bands
27/81
-
ig
2. Oscillator used for f i ) e d ~ c h a n n e l operation of the
TRC 452.
resistors are
14
Watt.
11.380 MHz. remove
co
u
pl ing
capa
citor
C212 from
the
receiver , and use a
se pa ra te oscillator se t at
11 .835 MHz to feed into
the
receiv
er
mixer. Trans
mitte
r and rece iver align
me nt shou ld pro ce ed as
previou sly
out
lined .
Wel l,
that
s it.
Replace
the
cover
s
and
you
re
se t
for a lot
of
activity
on 10
meter
AM. Or if youre like
me
. you ca n start planning
fo r mo re
modifi cation
s
and ac
ce ssories . A linear
amp lifier in
the
20- to
25-Wat t range wou ld be
nice. A va ria ble crystal
oscillator (vxo) ci rcuit
would allow
shi
ft
ing
10
kHz
to
completely cover
this segment o f the band .
The rf g
ain
could
be hard
wired to all
ow
using
the
co ntro l for
the
vxo. The
PA
function
can
be
dis
ab
led and the sw it ch used
to app
ly a s
ma
ll a
mo
unt o f
signal f rom
the
9.785MHz
oscillator into the receiver
to provide a
be
at frequen
cy for S
SB
re
ception
. And
the
list goes o n.
W ith
out
a
doubt
.
the
TRC 452 pro
ved to be
b
oth
cheap
and
easy
to conv
ert.
The crystal was my only ex
pe
nse as
the
junk box pro
vided all
other pa
rts.
One
last word
of
warn
ing 1 0 meter fev
er
is con
t
agiou
s
and qui ckly
spread s On
the da
y I co n
ve rted my rig,
I used
2
meter
s to tell K0BXj to
listen for me on 1O. This im
mediate ly p
rod
uced 2
hams talking
back t o me on
10 meter
AM
.
One
ham
who listened got curious
enough to visit me. and
a
bo
ut
6
o thers
wh
o lis
tened on 10
gave
reports
a nd s ugg e s t i o n s o n 2
meter
s.
References
CB 10 10 series, 73
Magazine
May,
Ju l
y, December, 1977;
February, August, September ,
October, 1978.
eafistic TRC45 Service Man-
ual
Radio Shack .
SoUd State Des ign for
the
Rad io
mat
e
ur
AAAL, 1977.
sion . For this. I
deviated
slightly from
the procedure
given
in
the ser
v ice
manual. Conne
ct
either a
wattmeter or swr bridge to
the antenna jack
and
con
ne
ct
a
dummy load
. Again
us ing channe l 20, key the
microp hone
and ad
just
L214 for maximum
output
.
This will br ing
the
final into
reson
ance and prevent
damage during extended
key-down periods . Now ad
just . in
order
.
l208
.
l209
.
l210
.1211
.l212 . a nd again
adjust
l 214 . These shou ld
al l be tuned fo r max imum
output. On the last adjust
ment of
l214
. detune
slightly to extend
the
life
of
th e final tr an sistor. To
co
mplete transmitter align
ment
, m
odul
ate
the
transmitter
with a l -kHz
signal
at
a level
of 100
millivolt
s . and
adjust
VR207 t o s
how 100
modu
lat ion on
the
oscil
loscope
.
The rig is now se t up for
10 meters . a nd we
mu
st
give
so me serious co n
sidera t ion to pla
cement
o f
the os
c illa to r within
the
rig .
Adequate
sh
ielding
c a nno t be ove r
-emph
a
sized. and fo r this re ason I
c
hose to
mo
unt
t
he
oscil
lato
r on
the top cover
of the
Pl l
board
.
Some
angle stock and the rig
cove r will provide
sa t
isfac
t
ory
shie lding from
rf .
The
sh ie ld ed lead fr
om the
osc
i l l a t o r may
be
run
down . and into. the
Pll
box between the two
pr inted ci rcuit boards .
Since the osci llator has its
own ze ne
r diode for
vo
lt
age regulation .
the power
lead may be run to the
swi
tc
hed
12
volts on
the
on /off volume control.
Whether you choose to
co
nv
ert.a TRC-452 or some
ot
he r Pl.I -tvpe
rig .
th e
tec
hnique presented here
sho uld allow a quick. easy
conversio n.
If
the
v
co
refuses to
drive
up to the
frequency
n
eeded
,
an alternative
is
to
repla
ce th e tran
smitter
crys ta l with
one
cut for
frequency counter will prob
ably not show any output.
but
don
t be concerned
.
Set
the
channel selector
for c h a n n e l 20 .
Now
ca
refully
adj
ust l2 on the
P
l l
boa rd and
se t
it fo r the
midpoint of the range
where oscil la tion
occurs
.
The frequency co un t e r
s
ho
u ld indi
cate 19
.115
MHz .
Start
with channel l
and
chec k all 40 c hannels.
If the
vco
circuit
, including
L2 . is
functioni
ng properly.
we
s
hould
show fre
quenc ies sta rt i ng w it h
18.775 MHz
fo
r c hannel 1
and
following
norm
al CB
channel
spa
cing
up
through 19 .21 5 for channel
40
.
If the oscil la tor drops
out
on
either end
. slight
read
justment of
l2 may be
needed
.
Now
proceed
with
receive r alignment. Co n-
nec t a signa l
gene rato
r
to
the antenna jack
and se t
it
for 28.800 MHz with l -kHz
modulation
. Turn
the
c ha n
nel se l
ec
tor
to
c
ha
nnel 20.
Connect either an
audio
VTVM
or
oscilloscope to
the
external
speake
r
jack
.
Now
adjust
l201 for max
imum output . Set the chan
ne l se
lector to
channel 40
and the
signal generato r
to
29.000 MHz .
Adjust the
pr imary of l202
(black
vinyl
tub
e) for maximum .
Set
the
c hannel se l
ec
to r
to
channel 1 and
th e
signal
generator to 28.560 MHz .
This t
ime
.
adjust the
secon
darv o f L202 (red viny l fo r
maximum. Set up aga in for
c
han
nel 20
and adj
ust L203
for maximum output. This
co mp le t
es th e
re
ceiver
alignment.
Transmitter al ignment is
the
final step in conver-
0.
I
I
00
: r ~
1
,9(14
0 .
.
r-
.
E.. U
00.
oscillat
or
is used for fixed
channel
o pe r a t i o n.
For
those
who desire
tuning
capability . a var
iable
crystal
oscil la tor may be
used.
A
lt
hough so
me would
say the osci llator output is
dirty. I prefer to
think
of
i t
as
being rich in
harmonic
content. The c ir cu it ry o f
the TRC
-452 is set
up to use
the
third
harmonic of
5.12
MHz ,
so
a 5 .651MHz
crystal will give a usable
harmonic at 16.955 MHz .
The combi nation of C3/L3
on
the P ll board will
filter
al l but the desired frequen
cy but it may
be
ne
cessary
to
change the value of
C3
to
30 pF
to peak the filter at
16 .955 MHz .
The
first
step
in
conver
sion is to remove the
covers and
locate
the
Pll
boa rd. It wil l
then
be
necessary to remove
the
Pll
board . In the
TRC
-452,
the
Pll
board and
side
co v e r are soldered in
place
. lo cate coupling
capaci
to
r C4
on
the
Pll
board
. R
emove and
dis
card
thi s capacitor. Small
shie
lded
ca ble from
the
osc
illator is now
inserted
in
t
he C4 hole nearest the
edge of the board and
solde
red in
place
. Reinsert
the
Pll
board and ta
ck in
place . Be sure to co nnec t
all pins. as mos t
of the
se
are used
in c ircuits as well
as providing mounting
stabil ity .
Next. connect
th e
oscil
la tor to a well-regu lated
supp ly and apply power to
bo t
h
the
oscillato
r and t
he
rig. A
frequency
counter
should
be
connected to
the
output of the 1st local
oscillator. At this point.
the
122
-
5/19/2018 Convert CB Radio for Ham Bands
28/81
Tommy
M
Murphy
KSUKH
RI. 1, Box 3
A
Ethel MS 39067
- part
xv
a
Realistic
Photo by Jam es Clegg
Walkie-talkie using external anenna con nection to watt
me
ter and dummy load. Unit showed 1 /
output of over 1.5 Watts at 29.000MHL.
238
T
he CB frequencies were
rcccrutv expand from
23 to
to
channels to handle
the
increased number of chi
lens
using the band. Since
many
firms
bCC IOle well
of f
from the sa le of the
23-chJnnel
un
it s, t he
thought
WJS
that
the
gold mine
wa
s
going
to
>tril..
e a
new
ve
in
and
that th e new -tu-channcl units
would be th e holiest thing
going. So, cvcrvcnc began
dumping th
e 23'chJnnei units
a t very
an ra
cuv
c pr
ices.
Many barns were
quick
to
grab t
he
oppor
tun ity
of
gc
u orne
first
etass co
m
municatlon
gear at a good
pri
ce,
and th e CBers bought
them
up also
a t a fa t r
at
e.
N
ow
e
nte
rs J pr
oblem
:
So
rr
unv
tr
ansceivers
of 23
ch
annel capacitv
had
been
s o l d
t
h a
t
when th e
40-chJnnei units came
ou t
,
t here ju t WJnot
the anucl
pated demand for t
hem,
so
now even au channel units
can be found
at
low prices.
Tho
c who
did buy the new
-tu-channcl radios qu ickly
found o ut
tha
t the high
p
owered
skip-land boys
had
been up there for
vc
ar
s,
so
th
e
additional 17
channels
were
just
about
useless f
or
the
purpose
for which
the
Citizens
Ban
d Serv ice wa
c..tabllshcd
The word i
appar n t y
o ut
that
many
manuf
a
ctu
rer ..
now bel ieve that the m
arke
t
is saturated, and tT\J
ny bar-
gains arc appearing in CB
gea r. This is h
ow I
carne to be
the
po scssor
of a couple
of
wal kie-talkie units
to
co nvert
to
10
meters. The radio is
a
3-channel
, 2Walt input ,
l-wan output walkie- talk ie,
the
Realist ic TRC-1 80. My
unit
s
ho
wed an output of
s lightly
mor e
than 1 .5 Watts
o n a
wattmet
er
into
a
dummy
load, using fresh
batteries.
The unit
normally
sells for
40.95;
I
pu rchased
th
ese at
24.95 each,
al
mo
st
a
50
sa
vi
ngs.
Spec ifica tions s
how
tha t
th
e
un it has
exce
lle
nt
sensi
tivity . 5
mV
for 10 dB
5 N N n spuriou s
emission down -SO dB or
bett
er. The receiver
dr
aws 25
-
5/19/2018 Convert CB Radio for Ham Bands
29/81
Smithe
s
new HF Ban /am
Dipole.
New
Products
to 150 rnA, depend ing
on
squelched or received signal
condition, and
the
trans
mitter uses 250 to 500 rnA
The walkie-talkie comes with
CB channel 14 already in
stalled, plus a set of AA
batteries.
Checkout
showed
that
the unit
was working
perfectly.
Some
plus
features
include an earpho ne jack, an
externa l antenna jack (to use
a mobile or base station
a
nte
nna), a power jac k that
a
ows you to
connect
to a 12
V de so urce
s
uch as a ca r
ba tt ery), a charger jac k for
recharging
nic
k
el
cadmium
batteries without removing
them, and a battery tes t
button with LED indicator to
show the condition of th e
b
at t
erie
s.
Ther
e is
no
guess
w
ork
o n the LED: If it lights,
the batteries are
okay;
if
th ey're not alright, there's
simply no light
T he walkie-talkie was
easily converted to
10
meters
with just a
substitution
of
crystals and th e retuning of
the transmitt er and receiver
from
{ i g 22
1
keys t
he
transmiller.
Program ATTY ha s two
mod
es:
send
and
receive. In
the
receive mode, the mark and
space tones
will
be decoded
and the res ulting text displayed
on the video monitor. Either
stages. After looking at a
numbe r of schematics
on
the
general run of uni ts of this
natu re, th e majori ty have th e
basic
455
kHz i- f, so co nver
sion of most should be fair ly
simple. I desig nated
th
e
channel A posi
tion
to be
29.000 MHz, whic h calls for
th
at
frequency
for
th e
trans
mitter,
of co
urse,
and
a
28.545 MHz crystal fo r t he
receiver. I st ill have two addi
tional channel s
to
add, when
the need arises. The built-in
an t
enna measures
39Y:o
inches
long extended and has an
interna l loading
coi
l. Rather
than messing with
the
coi l, I
just reduced
the
length
of
the
wh ip by
almost
3 inches
(using a f ield
streng
t h meter
to
find
the
poin t
of
maxi
mum outpu t o f rf) m
ak
e it
resonant at 29 MHz. To
ensure tha t I
retu