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Bulletin issued by the horthern PO Box 1010
Branches of the \Wireless lInstitute Launceston
of Australia, Tas. Division. Tas. 7250
. °rch 1974
v.1l.% No 11
- ——— v m—
kep.s-ered at GPO Hobart
for transmission by post Price 20g
as a meriodical. Category B.
It has been suggested that as QRM is a news bulletin it should
not be cluttered up with anyone's private opinion, including
that of the editor.
So this month I am not going to say anymore but 1 would like
to hear from you whether you agree with this private opinion.
73 John
Here is a list of offices that will have to be filled at this
months Northern Branch Annual General meeting.
Also listed are the names of the people presently holding
that position.
President - Peter Frith VK7PF
, Vice President -~ Joe Gelston VA74GJ
; Lindsay Dowl VA74LD
Secretary - Norm Richardson VK7NR
Treasurer - Kevin Henricks VK7ZAH
Editor - John van Staveren VK7JV
Equipment store manager - Kevin Henriciks VK7ZAH
Q8L Officer - Col Wright VK7LZ
Auditor = Carl Waldon
Lecture and Publicity Officer - Reg Emmett VK7KK
< o —s
MEETINGS
o4 e
March 5th North W:.
t Branch, Lakins Hall, Ulverstone.
Lectur 7 Graham VK7ZAQ on solid state.
Varch 8th. North- Sranch, AEB rooms, High st.
Lecture (- Ken VK7LX, introduction of colour TV
March 10th Port Sceoe .l mini Hamfest, start 1100 AM
March z2rd WIA Tas. Dive. AGM and Dinner. Note new venue
Beltana Hc?el, Main rd,Lindisfarne
March 9 + 10th YulS ¢‘~ses, room 38 Kings Meadows High school
April 5:h Norih.* t:i:nch, AEB rooms, High st.
One wee . 3r'ier than usual, due to GoodFriday.
Q.— ;M. MaPCh 197Ll-
Northern notes by Reg VAL7KK. Page 2
It always brings a crowd! This time around 40 persons joined our
February meeting for the auction and helped raise 85,85 tfor
the clubroom account.
Our auctioneer /J. was entertaining and really in his element as
always when he's selling or raising money.
Equipment donated ranged from complete mobiles , wall clocks and
magnets to nylon rods. A mantle radio sold for 3,00 and a number
of rubber mats were apportioned out for 50¢£ each.
Noticed Richard Tanner at a recent YkCES class proudly displaying
micro switches, relays and so forth capturea in a 20¢ box of "junxk!
Thanks all, for the material you donated and the way you spent
your money.
Two most important happenings at our Larch meeting.
A talk by Ken Briggs Vi&/7LX, Chief engineer of TNTY9 on the introd=
uction of colour television is a must. This is a different area
of the subject than that discussed by wsen at the LkKws lecture,
80 1s bound to be of interest to many.
The second event is our election of officers for the next year.
Its your task to ensure the best people occupy positions on the
executive. Look around and see if there are others who deserve
a chance in a position or who may give present workers a well
earned rest.
Remember the Annual dinner in Devonport last year ? Think of the
members attending from the North and North \est, remember how
one looks arcund and adds up those attenaing from the South ?
Now it's their turn. DOW'T LET US DOww. Lets have a mighty turn
up in Hobart on March 23rd.
Money will not be received on the night of the dinner and final
acceptances are reguired 2 weeks before the date. Sec you there.
73 reg.
SIrsE RTINS gk
YRCS classes started on 23rd February. About 20 youngsters attended
and will be working in two groups.
The advanced class is under the direction of wally VK7ZwX and
is studying for the intermecdiate certificate,
Others are in a group lead by Reg VK7aK and are aiming for either
junior or elementary certificates.
Further helpers are always welcome particularly between say 11
and 12 o'clock to assist in the trouble shooting department, or
help supervise on air operations.
Surprising how much electronics one learns in trying to ensure
a crystal set detects or an electronic organ oscillates.
sk ojee 3l
whe
oie s sle ate
afs ate a¥s it
sie ok
oK e ae s sle sl sk ala ok
Wle W LTl uls ats als sk sl
At legst three members sat for AOCP exams in February.
We hope that Malcolm Weldon, Peter Guenther and James Powell Davis
had some success. If they do, five licencees at the Launceston.
Matriculation College will rival that of the PMG departments.
MK MO SR NS B N S R SR ate
ale ale st wbs 2t ute 0 3wl
NS mieSR ats
Y Wl
SR 2l
sk s
el
If the xtals arrive this week the repeater will have changed
frequency by the time you read this.
This means that without a new receive xtal on 147.000 Mhz you
will not hear the repeater but as the transmit frequency remains
the same you will trigger it.
It is hoped that the change be made on 2nd March, Make a point
of listening to the broadcast on Sundays for tarther information
if the change isn't made on the above date.
QeR. s March 1974
North West notes by Max VK7MX Page 3
-
First of all I must congratulate John 7JV on his forthright
statement last month concerning membership. 1 have rarely seen
so much meat in a small parcel and it left little to say.
I could add that if you dont feel lige Jjoining in WIA activities,
at least give your financial support. Help to swell the
membership as the greater our representation the more notice is
taken of us. Dont make a mistake, frequencies are limited and
if you like using them do something towards preserving them.
Give it serious thought and join the gang again, after all its
only the cost of a night out.
I wonder who the funny man was who hid my rig at the meeting,
I saw the funny side after I sorted the speaker out, sort that
out. QSL cards again . Our Branch receives @SL cards from the
divisional officer monthly and they can be picked up from Harold
VK7MZ on payment of a small postage fee, so please collect them
as accomodation is limited. If you prefer you can send some cash
to Charles 7CH who will then post them to you direct.
Our meeting was a jolly affair with Reg 74£:{ and John 7JV in
attendance. John's mini-computer was ably demonstrated to the
multitude and I suppose it won't be long before he pulls it to
pieces to see what makes it tick.
The report of last councel meeting was read by the secretary
and it is interesting to hear what goes on.
1t was decided to hold the annual field day on 10th March at
Port Sorell, a combined North - North West affair.
So get the picnic baskets out mum and prepare the harmonics
for a day out. (dont forget the aeroguard.) Anything from
evening dress to bikinis are acceptable, it is most informal.
More information on the broadcast later.
It was pointed out during the meeting, that with new postal
regulations it is important to make sure that your mailing
address is correct. This applies particularly to A.R. so if
you change your QTH be sure you advise the necessary person
immediately.
Summing up the final item dealt with at the meeting sufficient
it is to say that the 3 FM units are now privately owned and
will be on the air soon.
Tony 7AX has been in the news, got himself involved in an
international wedding and was heard on 2 metres complaining of
a car full of confetti, in other words the best man copped
the lote.
We look forward to seeing all our N.W., members at our meeting
on 5th March.
- W
RNoale ale
NG RSN s s TR Ll N
ale ale Wl cs ats Wt ot e st ale als
.
FOR SALE
Pye Ranger low band FM, not converted. £10.00
AWA low band carphone , not coverted ¢ 8.00
1674, with xtals for ch.A, B, L. $35400
Power supply and modulator 700V per side 500ma 350400
VK3-2 Metre coverter with xtal $14.00
Miscellaneous, transformers,relays, high wattage resistors,
wire wound pots and about a dozen meters various types and
ranges. See Ross and haggle about the price.
Ross Broomhall, 27 Suncrest pl. Ravenswood. FPhone %91515
QlR..‘rl. MarCh 19711-
Page 4
AQ6 Orbit data by Peter VK7PR
Times are for the closest South - liorth passes for each day the
satellite is on. Other passes can be heard 1hr 55min. earlier
and later with 29 degrees less or greater,
For those without a calculator add 1hr 42min. to give the centre
of a pass. The satellite should be heard for 20 minutes centred
on these times.
—— e ——
e+ e et
e
Date Orbit Time Z ©u vate Orbit Time 2 OWw
March May
2 6295 0920 1838 18 7260 1050 210
4 6320 0915 187 20 7285 1045 209
7 6358 1005 199 2% 7322 0940 193
9 0383 1000 198 2b 7347 0934 191
11 6408 0955 196 27 1372 0929 190
14 6446 1044 209 30 7410 1019 202
16 6471 1039 208 Tune
1 7435 1014 201
18 6496 1034 206
3 7460 1009 200
21 6535 0929 190
6 7458 1059 212
23 6558 0924 188
8 7523 1053 211
25 658% 0919 187
10 7548 1048 210
28 6621 1009 20U
30
13 7585 0943 193
6646 1003 199
April 15 7610 0938 192
1 6671 0958 197 17 /635 0933 191
L 6709 1048 210 20 7673 1023 203
6 6734 1043 208 22 7698 1017 202
8 6759 1038 207 2Ly 7723 1012 201
14 6796 0933 191 27 7761 1102 213
13 6821 0927 190 29 7786 1057 212
15 6846 0922 188 July
1 7811 1052 211
18 6884 1012 201
L 7848 0947 194
20 ©909 1007 199
6 7873 09l 193
22 6934 1002 198
8 7898 0936 192
25 6972 105 211
11 7936 1026 204
27 6997 1046 209
13 7961 1021 203
29 7002 1041 208
May 15 7986 1016 202
2 7059 0936 192 18 8024 1106 214
L 7084 0931 190 20 8049 1101 213
6 7109 0926 189 22 8074 1156 212
9 7147 1016 202 25 8111 1021 203
11 7172 1010 200 27 8135 1016 202
13 7197 1005 199 29 3161 1011 201
16 7235 1055 211
March 1974
Q-R.M- Page 5
Uses for an electronic calculator by VK7PF
The following rxamnlies are for one particular calculator chip,
but no doubt ovners of other type calculators can adapt the
techniques to Ior use with their a achine.
Large power of_a number. Divide ghe power into two or more factors
eg, to find 3 first calculate % then make this the constant
and find the cube. o
3(=)(K) (X) (X) (X)(X)(C)(K)(X)(X) = 14348907
Reciprocals. By making a number a constant and using (4)twice
we can produce its reciprocal.r'he first(4) divides the number
by its self to give 1, the second(+)will divide 1 by the number
to give the answere.
4(=)(K)(+)(+) = .25 further use of (+)will give the
reciprocal of the square, cube etc.
This method is useful if the number is the result of previous
calculations.
Square root. This that a guess be made of the result and applied
in this equation a2=1 éN
+ ail § when a1 is first suess
2 (a1 a2 is result of equation
and next trial number.
- a3 next and so on
H is number.
Find square root of 5 the first guess being 2.2
enter 2.2 (=)(X)5(+) (+)(C)(+)2(=) 2.236363%6 which is put in
as a constant (K)5(+)(+)(2)(+)2(=) 2.2360679
(K)5(+)(+)(2)(#+)2(=) 2.2360679 no change so is answere
Sum of products. This usually requires the use of a memory or the
writing down of individual results for later addition. This method
requires enterin: some numbers twice but does give 2 result with-
out the use of pen &paper.
(pXP) + (@ X Q) + (r XR) is calculated as
P(X)P(+)q(+)Q(X)q(+)r(+)R(X)r(=)
example, 5 items at $3.55 plus 4 items at 32.41 plus 9 items at
-~
35.90
5(X)3.55(4)4(+)2.4(X)4(+)9(+)5.9(X)9(=) $30.49
Another use is parallel resistances.
1 =1+ 1 + 1
R R1 R2 R3
R=1(+)R1(X)R2(+)1(+)R2(X)R3(+)1(+)R3(=)(K)(+)(+)
Compound interest #1000 at 7% for 5 years 5
T.07T(=)(X)(X) (X)) (X) gives 1.07
(C)(X)1000 zives 21402.,5517
Mortfiage and loan repayments The annual repayment P is related
to e sum borrowed ¢ the annual ra.e of interest a and the period
of years over which sum is borrowed n .
P = a Xy . Suppose Y= "5000
1—§1+a§3 a= 9,5
(1+a) n= 25 vears
(K)(X)(X)(X)(X) gives 1.095).
1.095(=) .
(CH)K)(X)(X)(X)(X) gives 1.095 or (1+a)
(C)(E)1(=)(+)(C)(X)(-)(-) evaluates the denominator
(C)éK)0.095(+)(C)(X)BOUO(=) 847.67520
The monthly rate is thi.s divided by twelve.
Decimal to binary conversion Enter 2(=)(XK) followed by %he
number whose binary representation is required,repeatedly press
(+), if the fractional part of result is greater than previous
write down 1, if less write down O.Stop when no whole numbers left.
2(=)(K)653(+)326.5(1),(+)163.25(0),31.625(1)40.8125(1)20.40625(0)
10.203(0)5.1015(0)2.550(1)1.275(09 0.A37(1)
so result is 1011000101
Q.R.Li. Pageb liarch 1974
This generates the binary bits from the least significant
to the most siimificant.
Nth Roots. This is an extension of the square root
solution.
a2=1 (N .4 + al(r-1) ) al= first approx.
r ( al ) N= number
r=root
a2= second approx.
5
V20 is calculated a2s Tollows
a2= 1 ( 20 + 2424242 )
5 ( z . é ° z ° E
to give the finalresult of 1.320-641 after four tries.
bR N vSR X
FOR SALE ‘
Heathkit 303 Amateur band receiver, solid state 3250400
Heathkit 401 SSB transmitter 175V PiP fiZO0.00
1 only Wattmeter SWR bridge dual range 200W, 2«W @ 20,00
High Gain Vertical antenna 18AVy, 60 to 10 ketres &5 40400
Ray Els VK7US, 20 Jillian st. Launceston. Phone 442513
Whpste
sl N RS R IR Ieate sTey
o ate s
R
SN
Branch Fees and g.K.M. subscriptions.
North and North West Branch members pleacse note that Sranch
fees are now due,
Remember, your Branch provides many facilities including QRN
and it does this through your subscription.
Yearly subscription :£1.00 , all grades.
Hon WIA members may subscribe tc ki at - 2.00 per year and
students $1.00 per year.
Tear off or copy and sent to,
North VWest members Northern members and QRN subscribers
WIA Tas. North ‘West Branch WlA Tas. Northern Branch
PO Box 12 kast Devonport PO Box 1010 Launceston
Tas. 7310 Tas, 7250
Name cecceeocaooos o0 o s sreis Sleiw eistelerno Call e sions e
coess
AQATESS cooeooecsoosccooscsasosscsscsscsssssscoosssscass
® ¢ 0 0 0 00 6000 6 060 0 0© @ 6 00600 0 0 00 0 e o s
0605 0 0 s 0 00 e o 0 0 0 o
If not a member of the VW.l.A. are you interested in joining?
YES/NO
QeRoM. March 1974
DX notes by Den VK7DK Page 7
The last month has been quite productive in the way of DX.
KEurope has still been coming in from late evening to early morning,
and the following calls have been heard, PA@,&l,SP,GW,HA,O0H,LL,0Z,
YU,GD,ON and G being among the many that have been copied here in
Launceston.
S.E.A. (South East Asia) Net operates on 14.320 ikhz at 1200 Z and
will bear watching each night. This is usually conducted by L4S7PB
(Paddy), HSLAGN (Pete), or VG9R (Carl).
Many rare calls may often be heard on this net, such as 5Z24,5U07,9K£2,
XU1,A51,XV5,9M2,9M8,
V9,XW8, P2, ET3,A4,A6,A7 and 8ub6 to name some
that may wet the apetite. Father loran, 9N1MM Nepal's only Ham
representative used to be & regular on SEA net but has not been
heard since his trip to W land. Listening to the net will soon
accustom you to its operation, so how about joining in when VK7
is called, and maybe work a few new countries.
Palmyra lslands, KP6 was activated by WA7IXk/KP6 from 14th to 19th
February, this gave a new country to many as this is the first
operation from this group of islands for many years. John,the op.
is on board the L5 ft yacht "Wandering Star'" and 1 believe their
next stop is the island of Truk.
The QSL information is via KS6DY, PO Box 1618, Pago Pago.
Trinidade, PYZ was to have been activated on February 12th.
I would be pleased to hear if anyone worked him in VK7, sure was
not heard at this QTH.
The VP's are always news here, and a VP2SAZ was about on 14.195 Mhz
at 2300 Z early in February, no @SO with VK7 that I know of,
China will be activated by a WIGEY who has been given special
permission to demonstrate amateur radio to the people of Peking
University on April 19 - 21, 197.4.
As BY has not been activated for so many years, 1 can imagine
the QRM problem as many thousands hams around the world call this
one station. As a demonstration of ham radio, it may fall
somewhat short of anticipation.
73, Den
S sk g 3¢ SNl SR e sk s n s sk sk
VHF notes by Joe VK7ZGJ
Finding news is very difficult this time of the year.
Activity is very low with the most consistent stations operating
being, Kevin 7ZAH and Danny 7ZDA both having obtained their
Yeasu FT620's and can be contacted almost anytime on 52,050Mhz.
Ron VK3ALC can be worked most of the time on 144Mhz providing
conditions are reasonable across the Strait. Other V£3's worked
on 144Mhz this month include VK3ZgC and 3ATN.
February. 3rd provided good conditions to Geelong, Kevin worked
Ron twice on 1296, 432 and 144Mhz.
Although activity is low construction of equipment is taking
place, Bob 7ZRF has, after much frustration, completed his solid
state carphone, "sounds nice Bob"!
Kevin 7ZAH has completed a 6/40 afterburner for his FT620 and
I am in the process of completing a 4y32Mhz transverter.
If you want something to listen to in the late evening around
1200Z, try sitting your receiver on a beacon frequency for an
hour or so, you will eventually hear it, I have found VK5VF
on 53Mhz the most consistent. You can hear it for several
seconds ata time, this is Meteor scatter.
73 till next month Joe
sl oks sk sk s ok
sk eksk ok
QeR.M. March 1974
Reprinted from 6UP ‘ . Page 8
6 & 2 METRE DOUBLE-SIDEBAND, BOAC STYLE
Carl Palmer VK2ZGX
With the ever-increasing number of SSB stations evident on the VHF bands,
many stations may be seriously looking to sideband to "get amongst it". Certainly, on
six metres at least; S°T iz the predominant mode. Unfortunately, homebrew SSB is
beyond the resources of many, either in time or experience. Commercial equipment is
either expensive,or not a consideration,for others., Double-sideband is effective,
easy to build quickly and fgets you on sideband?. lMost SSB receivers can resolve DSB
perfectly well as an SSB signal, being able to reject the opposite sideband. Even
receivers having relatively wide IFs can be used to resolve DSB. It requires careful
tuning, and the operator has to put up with a certain amount of phase distortionj the
signal however is perfectly copiable, Another point - the unit described is cheap.
Any AN transmitter could be easily modified to run D32, pr, if like the author,
you wish to build a separate final and modulator, the following circuits and design
layouts should be of interest.
The Modulator
The modulator is a straight-forward audio amplifier with about 10W audio
power outpute. The dcsign presented need not be used, but remember thot the output
transformer necds to be the same configuration, Looking at figure 1, note that a
ferrite bead is slipped over 'he input lead. This is to prevent RF fecdback and is
quite necessary. A slug froir a coil is quite suitable. A low pass filter on the mic.
input and a top cut circuit on the output staze help to reduce the transmitted
bandwidthe A 'specch weirhting filter! employing bass roll-off and rapid high frequ-
ency cut off would be ideal (see VHI Comrmnications, internatioral edition, nov. 69
and may 69). This is currenily being experimented with. Construction follows standard
audio practice. See figeHe
’he arrangement of TRl is important as
the final is a balanced modulator. The screens
mast be driven in push--pull. 1f a centre-
X tapoed transformer is not available, either
X arrangement as shown in fig.2. =t the left
W ie
TR1b 47k TR1b can be used, The left hand circuit, with the
anode anod» resistors, is inefiicient and less output
voltage results. The right hand arrangement
is preferable, The dioces can be any power
rectifier having a reverse voltage rating of
400 volts or nore. Current rating is not
important -.s peak screen current is lowe
not very X TRla is o driver transformer with a
efficient X primary impedance of about 8z and secondary,
20k centre~tappede TRla can also be a power
Fig.2. ALTERNATIVES FOR TRla transformer with 240V primary and either a
560/0/560 or 385/0/385 seccondary. TR1b can
be any suitable transformer with similar
pri.-sec. ratios.
The Finals
Both fincls talie the form of a high level balanced modulator. The grids are
fed in parallel and the cnodes con:ected in push-pulle. The screens are fed with audio
in push-pull., The carrier is balanced out in the anode circuit and no R}" appears at the
output until screen voltage appearse. As this is audio, D3B is the result. Note that no
neutralisation is necescary. luch simpler than Al3 The output tuning capacitors can be
trimmers. The Anode tuning cnpacilors are cplit stator uaits from the AVA KR3 etc FN
carphones but any suitable unit of about 15pf maximui capa01txnce hOdld do, providing
the voltage rwtlngsare aceruate. _ I - i
RESULTS; 6 Metres 2 Metres
6146 valves 2E26 valves
150 Watts PEP input 50 Watts PEP input
700volts on anodes 500 volts on anodes
4 ma grid current from 3/12 driver L4 ma grid drive from 3/12
Carrier: about -504db Carrier: about =-45db
Total width approx. 10Khz
The 1P supply on .o can te from 450 %o 750 volts, while on zm the I can be from
300 to 500 voltsz,e Ioicr Nouwers are ~chieved with the other v-lves tientioned.,
The circuit of ench amplifier is shown in figures 3 & 4 re,pectlvelj for 6m and
QeRe M. pPage 9 March 1974
2me Note the different grid circuits. No bics supplies. Much simpler than AMI Grid
current is measured across the lk resistor in both cases.
Tune up is best accomplished by feeding a low level tone into the mic. input.
Better still, two tones, about an octave ~part but not harmonically related. Say, at
850Hz and 1.4kHz or 400Hz and 90UHz. low tune for maximum smoke.
12AX7 12AU7 6006
~-
001 : .001
N
100k
™ 47k
Tk i !
rocking /)
armature TV
mic. width coil — 9 [)
o= 27R A
e 39k
! Bu I&u ) /ISU
B+
7 ' / 300V
low pass filter
paur of 16146
or 2626 Fig.3. 6m FINAL
L2
ouT
N a
meter © 2 turns (8q on HT
220 .1 wati
<IN
L LG4
pair of: 6146
or 2626 | . __ 238
-001u
C1 L4
ouT
L2
- 50
L1
.00%u ;! P
D> X
RFC
23 (i
'&.." II
e’ \o”
2 turns 189 on Fig.4.2m FINAL
220, fwatt
D HT
March 1974
Page 10
feedthroughs
b
05
075" ¥
! l ' 125!
e— 05—Pbg——
15"
output tuning
‘
075—> capacitar %
15"
|
e 125> | e 2"
_ I _,4?_ “___4¥, - valve
| sockets
$ anode tuning atode crreit grid tuning
capacitor teedthrough | capacitor
? c0ax input
socket
fe— 075"
.
Y4!
e coax outpu'
*‘*?‘ ‘f socket
grid cuecutt
teedthrough
1
0-75" ,
Fig.6. CHASSIS
LAYOUT
maod.
trannie
chassis
2" deep
Constructicn
The amplifiers are constructed on pc board (blank) as shown in fige6e,
according to the template in fig.H. The HT, 6.3V, meter feedthroughs and the input
socket are rcversed in position on the 2m board. See fig.6.
Good VHF technicues should be used in constructing the finals. See 6UP for oct.
1973 p.20. for a suitable method of wiring the 6146 sockets. Same will go for 2E26
valves, etc.
COIL DATA
2 Metres
Ll 2 turns,ecarthy end of L2,18swz 3/8" dia. Ll 2 turns,earthy end L2,3" dia. 18swg.
L2 5% turns 3/8" dia. 18sug. L2 > turns #' dia. 18swg.
L3 8 turns 1" dia. 18sugs. L3 1% turns 2" dia. 18swg.
L4 4 turns 1" dia. 18svg. L4 1 turn %" dia. 18swg.
Ccl split stator type,sec text. cl split stator,see text,
The amplifiers are constiructed,with the copper side down,on the pc board and
ihe aszemblies mountied on an a2luminium main chassis. The moaulator is mounted in
the middle. The mod. trannie output is switched between each unit by a DPLUT switch
on the front panel, inclose it in a cabinet to keep those high voltages out of harms
‘vaye CQ DX §
QoRoMo March 1974
rom Hobart to Page 11
VK1 Miles kn VKL Miles m
Canberra 535 861 Rockhampton 1364 2195
Mt.Ginini 516 30 Toowoomba 1090 1754
Townsville 1639 2638
VK2
Albury L72 760 VK5
Armidale 889 1431 Adelaide 722 1162
Bathurst 665 1070 Bordertown 572 921
Deniliquin 524 843 Ceduna 1053 1695
Lismore 1031 1659 Millecent 518 834
Newcastle 132 1178 Mt.Gambier 490 789
Orange 671 1080 Murray Bridge 686 1104
Pt.Macquarie 839 1350 Port Pirie 8L0 1352
Sydney 656 1056 Renmark 700 1127
" <
®
Tamworth 839 1350 Sterling U 1149
Wollongong 617 993
5
VK6
VK3 Albany 1665 2679
Ballarat L1 661 Carnarvon 2273 3658
Bendigo u53 729 Geraldton 2058 3312
Frankston 349 562 Norseman 1572 2530
Geelong 363 584 Perth 1873 3014
Melbourne 372 599
Mildura 663 1067 VK7
Mortlake 407 655 Burnie 146 235
Morwell 326 525 Devonport 132 212
Mt.Cowley 351 565 Launceston 103 166
Mt.Waverley 366 589
Tahara 463 U5 VK8
Traralgon 328 528 Alice Springs 1534 2469
Wangaratta L55 732 Darwin 2332 3753
VKL ZL
Biloela 1296 2086 Auckland 1508 2427
Brisbane 1126 1812 Christchurch 1274 2050
Bundaberg 1282 2063 Dunedin 1161 1868
Hughenden 1537 2473 Wellington 1409 2268
Ipswich 1098 1762
Mackay 1507 2425
Nambour 1169 1881
QsReM, March 1974
Distances from Burnie to Page 12
VK1 Miles dm VKL Miles km
Canberra 434 698 Rockhampton 1252 2015
Mt.Ginini yi2 663 Toowoomba 992 1596
Townsville 1511 2432
VK2
Albury 348 560 VK5_
Armidale 795 1279 Adelaide 581 935
Bathurst 563 906 Bordertown 429 690
Deniliquin 384 618 Ceduna 916 1474
Lismore oLy 1519 Millecent 381 613
Newcaséle 648 1043 Mt.Gambier 352 566
Orange 56l 908 Murray Bridge 54l 875
Pt.Macquarie 755 1215 Port Pirie 697 1122
Sydney 571 919 Renmark 554 892
Tamworth 742 1194 Sterling 572 921
Wollongong 533 858
VK6
VK3 Albany 1577 2538
Ballarat 265 426 Carnarvon 2159 3474
Bendigo 309 L97 Geraldton 1953 EYFTY
Frankston 206 332 Norseman 1465 2358
Geelong 217 349 Perth 1777 2860
Melbourne 229 369
Mildura 517 832 VK7
Mortlake 262 y22 Devonport 20 32
Morwell 196 315 Hobart 146 255
Mt.Cowley 205 330 Launceston 67 108
Mt.Waverley 223 359
Tahara 321 517 VK8
Traralgofi 200 322 Alice Springs 1388 2234
Wangarstta 325 523 Darwin 2186 3518
VKL ZL
Biloela 1185 1907 Aucklend 1571 2528
Brisbane 1033 1662 - Christchurch 1373 2210
Bundaberg 1181 1901 Dunedin 1273 2049
Hughenden 1402 2256 Wellington 1496 2408
Ipswich 1004 1616
Mackay 1389 2235
Nambour 1075 1730
Qe ReMe March 1974
Helical antenna for 70 cm Page 13
by Col VK7KW
As an ERP of 300 watts is required to operate through the 432Mhz
repeater of AO7, it was decided to reprint this Helical antenna
from QRM of July 1971.
As one of the two repeaters in AO7 uses the 70cm band, the
problem arises as to what type of antenna to use for space
communication.
With the following considerations it was decided to construct
a 6 turn Helix.
a) Could be easily duplicated by other amateurs.
b) Built from locally available components.
c) No complicated matching devices.
d) High gain, 12-13 db with good beam width.
e) Circular polarization.
The materials used to construct, consisted of 6mm Pyrotenax
cable for the Helix, 22gauge sheet metal for the groundplane
(galvanized iron), 3/4 inch PVC conduit and 2 tee fittings
for the helix support, 6mm Pyrotenax saddles and cadmium plated
self tapping screws. The following dimensions were calculated
for 432Mhz. Ground plane 513mm diameter, helix 181mm diameter,
spacing between turns 146mm, matching stub length 114mm.
The Pyrotenax cable can first be wound on a 1 gallon paint tin,
then transferred to the supports. The cable is held in place by
the saddles and self tapping screws.
If a match to 75 ohm cable is required a 114mm length of 75 ohm
cable 3/8 inch diameter is required, first remove the centre
conductor and replace with a piece of 20 swg (0.036) copper wire.
19mm L-%;) CowduiT
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My STUB 7Jqm / Sapples
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