Cdr.
Goy Milius W4 NJF
Robert Webb K4ASU
421 Soddle Rock Rood
Norfolk, Va.
Heath 88400 Modification
The lI e a th SB~OO and SB300 work well to- band can be heard while he is called, up in
gether in tranceive but there are times, usually the American phone section without delay .
working D X, w hen it is necessary to operate The entire affa ir is done by the installation
them apart from each other. I t then becomes of a double throw, 2, 3 or 4 pole rotary switch
a chore and takes time to shift plugs and with two wafers. A common surplus item was
cables in the SB400. The Collins S Line makes used here but others are readily availab le in
a similar cha nge by simply throwing a switch tile market. The />oles of the rotary switc h are
011 the front panel of the exciter when the re- attached to the eud from the mixer and arc
ceiver and exciter have been cabled together thrown to the lead to the receiver L~ IO or to
for truuceive operation. However, at times, the lead to the transm itter L~ 10 . At the same
this ca n cause h avoc, and pi nk tickets, should time, usin g the second wafer, when in sp lit
the operator neglect to check the band seg- operation, the dia l li gh ts of the 5B400 are en-
meut in which the exciter was set. T his is what ergized to indicate that the transmitter is being
has happened when the C \V operator sud- operated separately and the receiver L ~ IO is
denly hears SSB signa ls from American sta- gro unded out.
tions down in the 20 meter C\V band. It This is (Illite cheap, easy and simple because
cannot possibly happen here with the SB400 beside the rotary switch all that is required is
and SB300 if the following modification is a length of HG-58A/ U coax, a small piece of
made, because a complete split of the tw o aluminum , th ree phone -plugs. a piece of hook-
units has been accomp lished by the turn of a up wire and a 100 ohm ~2 watt resistor. Most
switch and they are not interdependent upon of the wiring call he done before the rotary
one another as in Collins. Furthermore, a swi tch is installed. The only modification to
messy mix-up of cables is eliminated. T he the original 5B400 is a minor change in the
elusive DX station down in the fore ign phone wiring of the two d ial ligh ts which are fed
normally from two different sources. To control
them with one switch, the dia l lights, of
course, must be fed from one source and wired
in parallel.
T he accornpunying photograph clearly
shows the placement of the rotary switch for
which a small bracket is constructe d fro m the
piece of a luminum. The screw which holds the
bracket is a lready in the L~ lO cover of the
5B400. It is loosened and run through a hole
or slot in the bracket and put back into its
original hole. The bracket is bent sufficiently
to permit the rotary switch being used to fit
comfortably in the space to the right of the
UfO.
The w iring is re lativel y sim ple afte r the
cables have bee n prepared. All of them call
be soldered to the rotary switch before in-
stallation. L ay aside the two cables which
came w ith the SB400 and w hich were used
to make the transfonnation to transceive. Save
Location of the new switch. them, as they may come in handy at a later
74 73 MAGAZIN E
WAFER N~ 1 Top
•
WAFER N~
_ 26oTTOM ---:;::.-==:: "'IVS M J TTl
I ,\,_'; : Tit
0" , " . m
If
~'~~\:. TO' " .. , ./wt
'I 0 I ...
'N . 11." 0";
~
...~
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R
-----i 1t• •
JI "'''''''''''
.,.slf4."
, .. ;:H 0)
SHOWN IN TRANSCEIVER POSITION
Fig . 1. Wiring of the new switc h for the Sli-llne.
date. Cut four cables from the RG-58A/U. It
is suggested that, prior to cutting the coax,
yo n d eterm ine the le ngths req u ired by usin g
a piece of so lid wire which ca n h e threaded
between the com ponen ts and thereby oh tai n
fairly accurate dimensions. Enough cab le
shou ld be used to be dressed professionally TWO CATEGORIES TO CHOOSE FROM
around the components on the chassis. Length Sta ndard Dut y Guy.d in HOfa vy Duty S. 1f Supporting
is not critical. In the photograph the cables H.iihh of 37 _ 54 · II - 105 and Guy.d in H. iihts of
and 122 f..t 3 7 _ 54 f•• t ISS)
a ppear to he rather lon g; but they were short- 71 - BB f..1 19uy.d)
ened for neatness after the picture was
snap p ed .
Two of the cables just cut are fitted with ROHN has these 6 IMPORTANT POINTS:
phone-plugs at one end whi le the remaining Eo, . of Operation- roller guides between sect ions assure
easy, safe, frict ion-free raising and lowering. SI•• ngth -
e nd of each of the two is stripped to solder to welded tubular s teel sections overlap 3 feet at maxi.
the lugs O il the rotary switch. One cable, mum height for extra s turdiness and strength. Unique
which w ill go between the rotary switch and HOHN raising procedure roi,., 011 , -ction, tog.th.r- uni.
forml y w ith an equal section overlap at a ll heights!
the transmitter L~ IO has the 100 ohm resistor V.uatilily- d esigned to su p por t the largest antennae
inserted in series with its center lead and a with co mplete safety a nd assurance at any h.ight d."redl
phone-lug is fitted immediately after the re- 5impl. Indallotian- insta ll it yourself-use eit her flat
b ase or s pecial tilting base (ill us t ra ted above) depend.
sistor. ( T h is is the same arrangement as on ing o n your needs. Rot.d and r.,t.d - e nt ire line engi-
one of th e origina l cab les w hich came wit h neered so you can get exa ctly the right size and properly
the SB400. ) The other end is a lso stripped rated to wer for your antenna. The HO HN line of towers
is campl.t• . Zinc GalvaniJ.d- hot dipped galvanizing a
for attachment to a lug 011 the rotary switch. standard-not an extra-~-jth all RQ HN towers! Prices
T he fourth cab le is rather long and has both
ends stripped. One end of that cable will be
soldered to a lug on the second wafer of the
start at less than $100.
SEND FOR ROHN TOWER HANDBOOK
-$ 1.25 Volu.
-
-ONLY $100 postpaid (,~cial to readers
rotary swi tc h. The other end w ill be fe d of Ihis magazine). Nearest
throu gh the rear of the cab inet and joined in so urce of suppl:r se nt on request. Repre-
sentatives wert -wide to serve you. Write
an d at the phouo-p lug a lready on th e cab le today to:
which comes from the receiver L~ IO. T here
is a small hole in the back of the SB400 cabi- ROHN Manufacturing Co.
net w hich req uires only a little enlargi ng to P. o. ... 2000 Peoria, IlIinoi,
adm it RG-58A/ U. This concludes the p re\>ara -
"World', Largest EXCLUSIVE Manufacturer
tion of the cab les and th ey should be sole ered of ToWfTl; designerl, f!rlgineers, and i1l81allus
to the proper lugs on the rotary switch as set of complete oommunitutwn ~r I)',u".,.,"
out in Fig. 1.
NOVEMBER 1966 75
At first glallcc it will appear as if one se g-
men t of the top wafer on the rotary switch is
not necessa ry because a ll the connections
th ereto go to ground. H owever, not h ing will
h e saved b y co nuecfi ng the sh ie ld s of all the
cab les together. Nothi ng bu t all u nwieldy m ess
result s, and there will he saved on ly one seg-
ment of the rotary sw itch- two sections o r
wafers are still necessary. The rotary switch,
th erefore, becomes an exce llen t tie point for
all cable sh ield s.
0 11 the lower wafer of the rot ary switch a
d iscernin g eye m igh t he led to believe that in
place of the 10ll g cable which goes out through
the rear of the cuhiuct, con nect ions can be
made d irectl y at the rota ry switch, thus elim-
inatin g the lon g cab le. T his was tried and the
Over 215,000 QTH's in the United States edition resu lts were quite unsatisfactory. Spu rious
plus other leatures $5.95 emissions appeared. As the purpose of this
The Foreign edition lists over 121,000 QTH's cab le is to ground out the receiver L~ IO w hen
plus other leatures $3.95
the transmitter L .\IO is in use and berebv
See your favorit e dealer or order direct (add 2Sc f or mail-
in g in U.S., Possessions & Ca nada. Elsewhere add SOc). elim inate or p reven t beat notes from the com-
binat ion of both L:\ IOs, it is logical that the
gro u nd in g shou ld be m ade away from the
Radio Amateurs Reference library , tran smitter a m I outs ide of th e receiver.
of Maps-Order Your Set Today! As for the d ial ligh t modifica tion, view the
...-
- -- ~ - -:::.--:-..:.= - -I.
ligh ts from the front of the SD400. Disconnect
the brown lead co m ing from the base of the
mixer band-pass circuit hoard at th e left-hand
dia l light. Lengt hen this wire so that it will
reach p in # J on lower wafer of the rotary
switch a nd solder it to pin # 1. ( See Fig. l B.)
Discon nect a ll th e leads on the righ t dial ligh t.
Th ere arc a good number a ttached th ereto
becau se it h as been used as a tie point. Solder
WORLD PREFIX MAP - Full color, 40" x all those lead s toget her and tape them we ll.
28" shOwS prefixes on !!~ch coun~r~efer: T hey can han g free. Run a lead from the left
OJ( iones. time zones. clt,e~s~~~fd $1. 00
ented tables • •• ••• •• . . p dial light to the right dial light. Run another
RADIOEAMwAoT.EluoRSfr~~E~~eC~:~t~~ ~r~~~ lead from the left dia l light to pin #4 on the
OF TH - 9" 25" lIst- lower wafer of th e rotary sw itch. You now
~nnit~~e~1a~1~~I~U~~;~~lrit~~ro~~~~~~i~~~ have p laced both li gh ts in parallel fro m one
six major UM·.S. ~lts~~'tt1e San Francisco sourc-e of power and the switch w ill com p lete
ton , D.C., I tarm, ' postpaid $1.00
& Los Ange es • • •• • . • • • . the circuit on ly w hen it p laces t he transmit-
OF NORTH AMER-
RADIO AMATEURS M~Px 25" _ in cl udes ter L ~ IO in to operation. T he connections to
ICA! Fu ll cOIt;H, 29 d th e Caribbean to
Central amenca ~~n call areas. zone th e switch ca ll be m ad e after th e cab les h ave
::o~n~~~~et~.rpr:~~es :nrn:~~~alt~~:S in~~~- been attached and before the rotary switch is
freque ncy char,t . fl~~e 50 United States attached to the bracket on the L .\IO cover.
mancn on eac o. $1.00
and other Countnes . To embellish the job you can make a little
WORLD AtlAS- Only ~tla s comf~le~o~ti~ d iagram as seen in th e photograph to tell you
amateurs . Polar proJectlon' t s full where the point er lies. This, of cou rse, is not
nents , prefixes on each cOpuons:~aid· $1 .50
color, 16 pages . • . ..• . . too necessa ry beca use if everyth ing is working
Complete reference library 0\ ~rg$3~~J co rrect ly yo ur d ial ligh ts will light when your
of 4 as listed above . . . . pos P . tran smi tt er L~ I O is takin g over.
See your f avon'1e d"I er or order enect . An yone who has th e two pieces of gear can
imm ed iatel y discern the inconvenience which
WR/TEFOR
I ' RAD IOAMATE UR 116 k this modification removes. Now, a ll you have
to do to leave transceive operation is to lift
~
FREE ca 00 INC the transm itter c-abinet cover and sw itch to
BROCHI/RE! Dept. 8,4844 W. Fullerton Ave. sp li t opera tion]
Ch icago, III. 60639 • • • K4A SU, W4 NJI'
76 13 MAGAZ I NE
