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Bulletin issued by the Northern P,O. Box 1010
Branches of the Wireless Institute Launceston
of Australia, Tas. Division Tas. 7250
October 1974
Vol.4 No 7
Registered at GPO Hobart
for transmission by post Price 20¢
as a periodical., Category B.
MEETINGS
October 8th North West Branch, Lakins Hall, Ulverstone.
There will be a demonstration of colour T.V.
October 11lth Northern bhranch, A.E.B. rooms, High St. ‘
Equipment Display Night. Here is a chance -
to show off that piece of gear you've built.
October' 12th Council meeting, 2 p.m. at the QTH of VK7PD
77 Talbot Rd, Launceston. .
YRCS
October 12th & 26th i >CSMJ“1'
-~/ room 38, Kings Meadows High School. ybv
Z:i:zf’+'7c% L;QLvpr - M-
9,3, CONTESTS
October 5/6 VK/ZL contest phone - -
October 12/13 VK/ZL contest CW -
B RSGB 21/28 Mhz phone cotest :
¥dc£obervl9/20 RSGB 7Mhz CW contest “ -
) J.0.T.A.
October 26/27 CQ WW DX phone contest )
November 2/3 RSGB 7Mhz phone contest - LT
November 10 Czechoslovakian CW & Phone contest
—r)
November 23/24 CQ WW DX CW contest
»
Q.R.M. October 1974, 2
Pages
Northern notes by Reqg VK7KK,
Meeting attendances are on the up again, around 37 members
last month. Perhaps, however, meetings are tending to be a
little overloaded. Business transactions took rather longer
than normal, this meant that by the time the lecture was
completed and members had a go at the disposal gear, it was
past 11 o‘clock. Hope that this doesn't become the normal as
it rather stiffles the eyeballs.
One of the most significant reports presented was Ed 7HE's
clubhouse committee report, Ed had obviously put much effort
into pricing a suggested clubhouse. What could be built for
$7000 with our labour would seem to fulfil our requirements.
Ed's committee's progress with further investigations will
be awaited with interest.
An item carried forward for future discussion was a
suggestion for a weekly levy to boost clubhouse funds, 20¢
a week was suggested. Any ideas or further thoughts please.
Brian Greenwoods talk on T.V. translator networks gave
an insight into design problems from the other side of the
fence. A point of major interest was his mention of the
North West system to use channels S5A and 1 from Table Cape
to serve the Burnie area. Whilst one can appreciate the
reasons mentioned for choosing these particular channels
it seems unfortunate that they are to be utilized in such an
area.
Scout groups in Launceston have made requests for
assistance for J.0.T.A. on October 19-20. It seems there won't
be a co-ordinated request from scouts so anyone who can assist
a group would be appreciated.
Two forward dates to put in your diary, Xmas Barbegue at
the QTH of ED VK7HE to replace the December meeting, is on
December 7th. A New Years Eve celebration is also planned
for Evandale,
The meeting this month is to be the annual equipment
display night. There wasn't a reminder at the last meeting
but it is hoped that you've been working towards this and
have a project to bring along. If not, there might be an
interesting piece of commercial equipment to show off.
000000000000000000000
The Northern Branch has obtained a quantity of AWA, MR6A
low band FM units. These are for sale to W.I.A. members
at $8.00 each, with a limit of one per member for a start,
if any are left over in say 2 months time, a second unlt
may be purchased. a
"These units are sold on the condition that theyare not to
\
bé re-sold or put to illegal use.
Modifications for 52.525 should take no longer than 30
minutes, instructions will be supplied.
000000000000000000000
Peter Feltham has passed the LAOCP exam, congratulations Peter.
Danny VK7ZDA is all prepared for the morse exam in November,
very confident too, he already has an FT101B sitting on the
shack bench waiting for the big day. Good Luck to you Danny.
Q.R.M. October 1574, Page 3
North Western notes by Max VKTMX.
Our September meeting went off vervy well with a good attendance.
A lively meeting took place followed by a meeting of the Hamfest
committee. Full details will be found elsewhere in this issue.
The boys are really working overtime on the project. Note that
the date shown in QRM last month was incorrect.
Following business some morse practice was dispensed by Harold
VK7MZ, and to round the night off after supper Sid VK7SF showed
some all moving, all colour, all talking pictures. A good night
all round.
Proceedings were enlivened somewhat by Bob VK7ZJS who
produced some goodies which were snapped up. Which reminds me
Bob is now pushing a very strong signal from Somerset on 2 metres.
Anyone passing through Somerset should call on Bob and view his
all steel, all welded, twin diesel powered pleasure boat of
very large dimensions. A very fine effort.
Coming to our next meeting we hope to have a demonstration
of colour T.V. with servicing equipment explained. With colour
T.V. round the corner we look forward to this lecture.
We have had a number of visitors through our area recently.
Possibly the most famous was Col VKZASF with his XYL Jean.
Col was mobile on 40 metres and says he is coming back.
We also saw John VK5DJ en route to Hobart with his family.
Ian VK3YAY also departed from Devonport.
A most unusual series of contacts took place via the 2 metre
repeater on 9th September with Hal ZL3WJ M/M, A number of VK7
stations were contacted as his ship moved out into the Tasman
and he was last heard when 150 miles from Mt. Barrow.
Several N.W. members were involved.
The 2 metre beacon is now complete and being tested.
Some trouble is being experienced in matching the complicated
antenna but we are working on it.
Everyone appears to be normal in our area so 1 can not
find any personal titbits to throw in.
CUL VK7MX
-0-0-0-0-0-0-0-0-0-0-0-
ADHESIVE SEALANT. "SILASTIC 732RTV"
This is a one part silicone rubber compound which will cure
at room temperature, yet has the special properties of;
1) Excellent dielectric characteristics.
2) Thermal and chemical stability.
3) Cures to a tough rubbery solid.
. 4) Retains flexibility from -65 to 260° C
¥ 5) Resists weathering, moisture and ozone
6) Electrical strength (puncture voltage) 550 volfs per mil,
7) Dielectric constant 2.8
It can be obtained in four colours, black, white, aluminium
and translucent. Tubes containing 150 grams are available
from Repco, but only in one colour, black.
It can be used for all sealing and bonding applications in
electronic equipment including the sealing of coax plugse and
antenna connections. Col VK7KW
Q.R.M. October 1974, Page 4
LADIES PAGE
Hi there
I have been meaning to add my little bit for some time,
but time passed. The remarks in last months Q.R.M. acted 1like
a needle you know where, and the fact that I have, I think,
something to rave about.
As was mentioned in Q.R.M., we are moving again. This will
be my 22nd move in my life time and Normans 12th, I hope it
will be our last. I said this when we moved to 69 Georgetown Rd.,
but you can see what has happened. I'll say this though, where
we are going we don't stand much of a chance of being flooded,
stranded maybe, but never flooded.
We haven't quite got to the stage of looking for a thing
and realising we are pursuing a fruitless search because the
damn thing is packed, and we are not yet at the stage of one
plate, knife, fork per person.
The 0.M. worked out where the shack will be before
anything else. We have had the shack nearly everywhere, even
like Phil and Joe, in the bedroom, but we slept with it.
Thrilling, believe you me! It wasn't the melodious of lullabies,
but when I could stay awake I joined in.
We have lots of plans for the house, but untill we are
actually there, we are doing a mild stagnation bit.
I have been putting on quite a bit of weight this winter,
but as the 0.M. has said, after I have run (run, he must be
joking) up the drive a few times the pounds will drop away.
When we have moved in we hope you will all drop in to
see us. The view is fabulous winter and summer.
The address is: 11 Fort Street
North Riverside
Launceston,
Well 73s,
proudly 7NRs XYL Ann,
P.S. Oh, when we had a mobile home
to go wherever there was to roam
This was very handy e
not to mention fine and dandy,-.:
providing we found the land.
When youth did pursue me,
my feet were quite itchy.
But now I pursue youth,
with the itch I get B.....
Q.R.M, October 1974, P§ae 5
D.X. notes by Den VK7DK.
September is now over, and what a mixture of conditions
we experienced. During the weekend of the 14/15, there was a
severe burst of solar disturbance, and for two weeks
following this, conditions were very poor, particularly above
14 Mhz. I had arranged to take twc weeks leave as from that
weekend to try and work a few rare ones, but Murphy's law
decided otherwise. On the credit side though, 3.5 and 7 Mhz
were not affected as badly and some reasonably strong signals
were heard from the Pacific area. Before the solar activity
7 Mhz was really good, as is usual in the beginning of
September (and March). The following were logged on phone:
C2l..XWw8.. KX6.. XE.. JA,. TU2.. VR1., EI8.. G.. ZKl.. EAB,..
TI2.. W.. DJ.. 5Wl.. KS6.. GI.. PAg.. I3.. UI8.. UAgZ.. and
for the short time I listened on CW, 4X4.. LZ.. W.. were heard.
3.5 Mhz was also good. On phone: FO@.. YJ8.. KP4,. KL7..
and W's. Most were above our band and could not be worked
without split frequency. I also heard a very weak EABCR.
On CW, HA3.. UL7.. UT5,.,. OH.. OK.. UB5.. UPZ.. . These are
extremely hard to work, maily due to the terrific QRM the
Europeans suffer.
An all YL DXpedition is all go for Chatham Isl. for one
week, from October 26. They will be on 3.5, 7 and 14 Mhz.
VE6JL/SU is active till the middle of November approximately.
QSL via his home call or via the bureau. He is engaged on the
task of clearing the Canal.
An Island much in the news lately has been heard. This
one is a little odd, as he is WN3VEX/VQ9 on Diego Garcia and
was operating on 14 Mhz. I should think this would count as
Chagos Isl. as far as DXCC goes,
The latest predictions as to the sunspot minima, and
this is an unofficial one, is June 1975. So cheer up, it
seems that conditions can only get worse.
Now for the stations heard on 14 Mhz:
0200/0400.. KP4.. TG9.. OA4.. HR1,. YV.. ZL4NJ/A Cambell
0400/0600.. 5¥X5.. W,. EP2,. XE,., VE.. UF6.. 5Wl.. SV.. OB,,
u8.. LZ.. HC.. I.. PJ9.. HR.. ZS6..(short path)
0600/0800.. DK.,. LZ.. SV.. YU.. YO.. G.. HC.. F.. UT5,.
SP.. ON.. SM,. KH6.. OE.. TG9.. EA.. DM.. ZB2..
1000/1400.. UK2.. UK9,. SM.. UQ2.. VS6.. 9M2.. YB.. HS..
4S7.. XU1DX, DJ.. BV2.. HL.. VS5.. DM8..
VK9XW (Cocos), A9.. XW8.. VQ9.. OH.. G.. JA..
9M8.. F..
1400/1800.. SP.. G.. JA,, DL.. OH.. I.. SM.. UK9.. GW..
1800/2400.. JA.. CX.. KG6.. DL.. OH.. I.. VP2S.. F.. SM..
- PY,. W.. C21.. YV.. .
21Mhz has shown a little activity from W land around
23/24002, and of course the JA's are still there but very
much weaker than they used to be in years gone by.
Well thats it. I would still appreciate any DX reports
from other sources.
73 and DX.
dhkkhk
kA hkkhhkkhhkhkkrh
kokkk ok
WANTED WANTED WANTED WANTED WANTED WANTED WANTED WANTED
Wanted to buy an FT200 or FT101 in good condition, details
and price to; Ross Broomhall, 27 Suncrest Place, Ravenswood.
Q.R.M. October 1974, Page 6
CAMERA : 12V POWER SUPPLY
24 N + 12V
@
{3 <'\» 2;
‘
3
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- ks
3 3 .
= _Iflflp
2100/ >
sov |~
ov
IKS
= 22/o/,
-2V
(1) DTS310 and 2N3055 mounted on a heatsink within camera
(2) 24-0-24 volt transformer is mounted externally to the
camera.
(3) OV should not be grounded except in camera power
supply card.
) Power supply card is similar in size to the-horizontal
and vertical deflection cards. No art work is available.
Parts Available. (check with Frank VK7ZFR)
7038 Vidicons (new) $20.00
Vidicon Yokes (new) $ 8.00
Yokes do not have a focus coil, this can be easely wound.
Q.R.M, October 1974, Pagews7
CAMERA INTERCONNECTIONS and VIDICON CIRCUIT
412V
V. DRIVE
3
B, ov L
MESH
e N OUE
ViD. TARGET TARGET D 7 I
— 12V ) i
B Vioco o/m
Vip ofF -
'lI
VID. £RRTH
% o .
VipEo Heap AMP
(1) All components surrounding vidicon except focus, beam,
and target controls are mounted on a small p/c card.
(2) Circuit is suitable for either normal vidicons or
seperate mesh vidicons. If no 600V supply is available
tie mesh supply back to +300V.
Q.R.M. October 1974, Page 8
4
Reprinted from "THE RADIO BULLETIN" Jan.-Feb. 1972
TRANSISTOR REGULATED POWER SUPPLY DESIGN.
by John Reynolds, VK3ZMU..... Part Two
5. Overload Protection Circuitry.
The circuit diagram given on p.13 of the last bulletin is
the complete voltage regulator, except for the d.c. rectifier
and filter. However, the circuit as it stands is not protected
against excessive current drain.
- Fig 8 shows the characteristics of three types of current
limiting that may be employed.
X
X X
(a) Crowbar (b) Foldback (c) Cutout
Fig.8. Current Limiting Curves.
(a) The crowbar type is the simplest to arrange. The supply is
reset by removing the load. However, a disadvantage is that
under short circuit conditions the controlling transistors
pass the FULL current with the FULL input voltage across
them; i.e. the output transistors must be made larger than
required for normal operation so that they may survive under
short circuit conditions.
(b) The foldback characteristics is a more desirable form of
crowbar where the dissipation under short circuit conditions
(at point X on the curve), is reduced due to less current
being drawn. For fixed voltage output and at moderate
currents, this is easily obtained; but it is not so easy
with a variable voltage, high current power supply. The
current limit condition is removed by the removal of the
load.
(c) The cutout method is easy to incorporate. With this system,
the power dissipated in the output transistor with short
circuited output is ZERO, since the current and voltage
are both zero. A slight disadvantage is that the power
supply will trigger exactly on the preset output current,
and if switch-on surges etc. exceed this level, the overload
will be activated.
Referring to Fig.7 (page 13 last issue), if the base of Q3 is
shorted to the negative rail, the voltage driving current into
Q3, Q2 and Q1 is zero, and thus they switch off.
If-an SCR is used as the short circuit, its saturation (on)
voltage is about 0.8 volts, and the current required to hold it
in the "ON" state is about 20 mA (for a small SCR). Since the
resistor in the collector circuit of Q6 will only pass 1 mA,
the base of Q3 is not a suitable point to which to attach the
SCR, since it would not stay switched on. But if the SCR is
connected to the emitter of Q3, the available current is
B 3 x 1 mA, or greater than 25 mA.
By shoring the Q3 emitter to a point at a level of 0.77 volt,
the maximum available voltage across the B-E junction of Q2
and Q6 is 0.77 volt. Since that voltage must exceed 1.2 volts
to turn them on, they will be cut off, and the output voltage
Q.R.M. October 1974, Page 9
-
and hence the current will be zero.
When the SCR is switched on, Q3 will have a collector current
of (say) 30 mA, and its Vce will be about 22 volts. This
corresponds to a Q3 dissipation of about 7 watts. To reduce the
dissipation of this transistor, a resistor could be inserted
between the emitter of Q3 and the junction of the Q2 base and
the SCR anode.
Unfortunately, however, such a resistor would degrade the
regulation, and there are therefore practical limits to its
size. The circuit of Fig. 9 shows the method used to solve the
problem.
+22_28V 1 I load
Fig.9, Current
Limiting Circuit
I load
By making LP1l a 24 volt lamp rated at about 50 or 80 mA, when
current limiting occurs, the light goes on and can be used as an
overload indicator for the front panel. The voltage remaining, a
small amount between 0.6 and 4 volt will be dropped across the
transistor, reducing its dissipation by more than 75%. To reset
the SCR, the anode must be disconnected from the base of 02.
In order that the voltage does not rise straight away with the
SCR disconnected, the base of Q2 is connected to the negative
rail during the reset.
To fire the SCR, the gate voltage must exceed the cathode
voltage by about 0.6 volt. The manufacturers state that there
should be a resistance of 1-2K between gate and cathode to
protect the gate. At 5 Amps load current, the voltage across
the 0.33 ohm resistor in the negative line is about 1.6 volts.
A voltage divider across this resistor will allow the current
limiting point to be set with a potentiometer. The current
limting point is dependent on the pot. setting, and thus the
trip point can be marked on the front panel. A good feature
of this system is that the trip point is constant for all
*cutput voltages.
'The complete circuit is shown in Fig. 10.
6. Transformer and Diodes.
For the raw DC supply, the transformer used dropped 4 volts
from 28 volts when the full 5 amps were drawn.
The diodes used in the bridge rectifier are not critical,
Types 1N1199A were used in the prototype; they require
heatsinks. Filter capacitors totalling 10,000 uF would be good.
The on-off switch should disconnect both arms of the primary,
Q.R.M, October 1974, Page 10
ol
and the static shield on the transformer should be earthed.
7. Final Remarks.
Actual regulation is better than 0.3% at 6 volts, rising
to better than 0.9% at 16 volts, for a load of from zero to
5 Amps. Measured voltages and currents are in close agreement
with theory.
At first switch on, the current limiting may fire and will
need to be reset. This is normal. Output ripple is less than
30 mV.
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Fig.10. The Completed Power Supply Circuit.
Q.R.M. October 1974, Pagewsll
HAMFEST LOCALITYMAP
FORTH RIVER
AVYMHDIH SSvd EAST
TO DEVONPORT
B
E
A
C é_———
H TURNERS
>B | BEACH
n
i
| )
Gl
g
RAILWAY =
CROSSING R
WEST
— TO ULVERSTONE
CLAYTONS
RIVULET
i
Q.R.M, October 1974, Page 12
HAMFEST PROGRAM (proposed)
- W.I.A. HAMFEST 16th and 17th November 1974.
Hall will be open at approx. 9.00 A.M. Saturday.
Setting up of equipment etc.
1.00 P.M., Reception of peoples, Registrations. Nametag issues.
2.00 P.M. Guided tours departures. Tour & inspection of
MERSEY FORTH POWER SCHEME
.
OR
Tour of LEVEN CANYON, (South of Ulverstone)
Tours redquire your own transport arrangements.
6.30 P.M. Evening meal (Smorgasbord, spplied)
At conclusion of meal, the cabaret style social
will commence, refreshments etc. will be supplied.
A fashion parade is scheduled during the evening.
9.00 A.M. Sunday. Open Hall,
9.30 A.M. Weekly News Broadcast from VK7WI/P
10.30 A.M. to 12.30 P.M. Fox Hunts (Various)
2m Ch. 40 (B)
6m 53,032 Mhz. A.M,
om 52.525 Mhz. F.M,
40m (transistor portable required)
CHILDRENS ENTERTAINMENT, FILMS ETC.
12.30 P.M. Lunch (supplied) Barbequed Hamburgers, Sausages
etc. Salads
1.30 P.M. to 3.00 P.M, Various Fox Hunts etc.
. Childrens entertainment.
2.00 P.M. Anticipated small excursion for the ladies
2.30 P.M. Auction of surplus equip. (bring your old gear
10. 3.00 P.M. to 4.00 P.M. CLOSING, PRIZE GIVING.
During the entire Hamfest there will be, Frequency checks,
R.,T.T.Y. Display, A.T.V. Display, Commercial Equipment Display,
Antique Equipment Display, Best Home Built Equipment Section
(PRIZE)
. Operational equipment on 80m, 40m, 20m, 6m,52.525.
2m Ch.40 & 48/60.
We invite you to bring along any item for use or display which
you consider may be of interest to others.
Q.R.M. October 1974, Page 13
REGISTRATION FORM
W.I.A. HAMFEST 16th & 17th NOVEMBER 1974, TURNERS BEACH HALL
I wish to advise I/We will be attending the above function.
NM.'..................... PP{ONE t‘IO-ooo..- CALI-J SIGNI........'
(if any)
ADDRESS............I....I....‘.Q‘ ..................... e & & & 9 & 0 8 s
No ATTENDING RATES
cseesesss Doubles Family group $10.00
cesssssses Singles Double $ 8.50
esssessss Students Single $ 5.00
esesscess Children under 1l2yrs: Student S 3.00
essessses Children over 12yrs Sunday only $ 2.00 per
person (children free)
Enclosed please find a cheque for ......... .
I Will/Will not require accommodation. (tick as required)
Ulverstone Beachway Motel $12.00 Double, $7.00 Single
Bed and Breakfast.
Children $3.00 Extra
Stones Hotel $9.00 per adult.
Children under 12 (% price)
Devonggrtr Gateway Hotel/Motel
$17.00 double or twin
$13.00 single. $2.50 extra
for Children
(Please enclose $5.00 deposit on Hotel/Motel accommodation)
Caravan Parking Caravan park adjacent to Turners Beach Hall
Power and all facilities $1.00 per day.
WE WOULD APPRECIATE YOUR INTENTION OF ATTENDING BY 10th NOVEMBER
PLEASE.
FORWARD TO: Mr. I.Ellings
87 Bel-Air Crescent
East Devonport. 7310
e
Jal. GUNN PTY. LTD. . .
-
50 brisbane Street,launceston, ' 5. 7
Telephone 2 2251 g ° ) .
& BULLDERS HARDWARE
BOMESTIC
MARINE & PLUMBING SUPPLIES
PAINT & TOOLS
SEDDON PRESS
35A GRAUVILIE STREET, LAUNCESTON. 7250
Telephone 31 6191
for all your printing
Business and Personal
™ ' QSL cardg ##e#
o
N@EW”NQS
— 7360
1540
, ELECTRICAL FENGINEERS
SPUGIALISING I MOTOR REWINDING AND ASSOCIATED WORE
27 SUHCREST PLACE, RAVENSWOOD
TELEPHONE 391515
Muwj Lawes Elee fisf“fi@
135 HODART ROAD,
KINGS ITRADOVS, LAUNCESTORN
; Telephone 443119
TRY U3 POR YOUR NEXT AFPLIANCE
' YOU WITT FIND IT FASY ON YOUR POCKEZ 8 8 §