QRM
Recognised text
Text below was produced by optical character recognition and may contain errors. Check it against the original.
4
‘.
“WHMBRWWM
Bulletin issued by the Northern P.O. Box 1010
Branches of the Wireless Institute Launceston
of Australia, Tasmanian Division Tas. 7250
June 1977
Vol.7 No.?2
Registered at GPO Hobart
for transmission by post Price 40¢
as a periodical. Category B.
MEETINGS
June 1l4th North West Branch, Lakins Hall, Ulverstone. 8 p.m.
June 10th Northern Branch, S.E.S. rooms, Charles St. 8 p.m.
A.0.C.P. CLASSES
Kings Meadows High School, Block B, room 35
June 13th Receiving Systems
¢ June 20th ! "
June 27th Transmitting Systems
July 4th ! "
Y.R.C.S. CLASSES
YRCS classes are held every Tuesday (during school terms)
from 4 p.m. to 5.30 p.m. at
Kings Meadows High School, Block B, room 33.
- CONTEST
¢ June 11/13 VHF Mid Winter Field Day Contest
June 20th Deadline for the July issue of QRM
We badly need articles for future issues, can you
help ? How about circuits with a note what it is
and what type of transistors, IC's etc. ?
Page 2 ORM June 1977
Northern Branch notes by Mac VK7CCC.
Twenty nine members and visitors attended the recent
monthly meeting and discussion/film night held at Northern Motors
in Launceston.
Amongst business discussed were the 3 motion put forward
by Bill VK7AK, the first two were defeated, the last one '"that
the business of Branch General meetings not proceed beyond 9.15
p.m." was carried.
Peter VK7PF advised that Col VK7LZ, our QSL manager is up
and about in hospital and progressing satisfactorily. A card has
been sent from the Northern Branch members.
WICEN; Two meetings have been held recently, both were very poorly
attended, should we continue ? Are you interested ? Contact Ed
VK7HE 1if you want to become part of a very interesting and worthy
group.
Our Lecture Officer Wally VK7ZWX, reminds you that at the
next meeting the topic for discussion will be "Temperature
Inversions" We look forward to a full house on 10th June at SES
rooms Charles St.
Treasurers Report; The revenue statement for the year was presented
by Peter VK7PD, a copy is to be found elsewhere in this issue.
A combined Annual Junk Sale come Barbecue is to be held at
some future date at VK7CCC's property (a winter barbecue !)
suggestions for a date please 2.
We must thank Northern Motors for the use of their facilities
plus the eye opening innovations provided in their range of cars
to reduce pollution. I wonder if pollution is not the lesser of two
evils, the obvious initial and future servicing costs might
produce a situation where no one can afford cars and our recreat-
ional lifestyle will be drastically curtailed - food for thought !
RTTY;
0 MMy
Anyone interested in purchasing circuit boards for ST5
demodulator, autostart and powersupply please contact VK7CCC.
Probable cost around $12 - 15 for 3 boards.
Congratulations to John Doolan VK7NJD and Mark Nightingale VK7NAM
on gaining & pass in the May Novice examinations. As you can see
they didn't waste any time getting call signs or to get ~n the
air, John can be heard operating on 80 and 11 metres and Mark
1s operational on 11 metres but it wont be long before tre'll
show up on 80 and 15 metres.
WOULD YOU LIKE A NOVICE LICENSE ?
A Novice Amateur Radio course commencing Thursday 23 June at
7.30 p.m. Kings Meadows High School, room 23, is aimed at the
October examination.
Enrolment via Adult Education Board offices. Fee payable
to them is unknown at present. The instructor will be Reg VK7KK.
June 1977 QR M Page 3
North West Branch notes by Wayne Gibson.
The April meeting was held on the 12th. Once again there
was a very good attendance of members. The president was in the
chair aided by a standing secretary Max VK7MX. Most items of
business were of a routine nature. Ian VK7ZIE gave a short report
on council activities. Ian said that R&L denied that the Novice
License was of only two year tenure he also noted they were
considering allowing novices to use part of 10 metres. Ian
briefly outlined the agenda for the Federal convention and
judging by the thickness of the wad of paper there will be little
time for sight seeing.
It was officially announced that a repeater was now
operating on repeater 3 from the Loonah site. The unit is not
the NW repeater but the old repeater from the Southern Branch.
This unit is on loan and operating on low power, about 10Watts.
A report was submitted to the meeting,in the form of
the minutes of a meeting of the Repeater and Beacon Committee
held on the 27th March, of current activities of that committee.
A brief summary is as follows; a) 2 metre repeater, work is held
up through inavailability of adequate cavities and poor receiver
front end performance. b) 70 cm beacon, a design study for a
solid state unit is being carried out. It is intended to replace
the present valve unit as soon as possible. <¢) 2 metre beacon,
nothing is proposed for this unit at this stage except to shut
it down while testing the 2 metre repeater to avoid desensitisation
problems. Please note that Ian VK7ZIE is the committee's spokesman.
The main motion of the April meeting was initiated by
Brian VK7ZBL. The meeting passed the motion, that Council should
be informed that the N.W. Branch would be willing to hold the
1977 Hamfest if requested to do so by Council.
A fly from the shack wall of one of the not so young
members reported that, while trying to electrically restore an
elderly wireless very many volts appeared on the sets tuning
gang, I guess it must have come as a bit of a shock.
73 Wayne Gibson
VHEF Notes by Joe VK7JG
Once again I have nothing to report on activity. "The
6 metre rig is always monitoring 52.050MHz when I am in the
shack and I usually give at least one CQ during the evering but
no results for the past month.
Dont forget the Mid Winter VK2 VHF Field Day to be held
on the week-end 11lth to 13th June. Start 1200 East Sat. 11lth and
finishes Monday 1200 East,13th June, this is a long week-end.
For further information refer A.R. May '77 page 24.
I have no reports of 2 metre SSB activity but I did hear
John VK7JV using the Geelong repeater during the month.
If you have any old operational 2 m FM equipment for sale
please let me know as there are several new "Z" calls looking for
it.
73 Joe
Page 4 QR M June 1977
H.F. Notes by Frank VK7BC and Col VK7LZ.
Conditions have been similar to those experienced last
month with the longer openings on the 10 and 15 metre bands
tending to take some of the load off 20 metres.
The ITU contest on the 15th and 22nd did not generate
the expected DX activity one would have hoped for and most stations
participating commented on the fact. The C.W. section seemed to
draw most activity from the Easern European area.
The I SSB'ers QSO party held over the 21/22nd weekend
did bring some DX into the open, mostly on the top end of the
20 metre band.
28 MHz. KM6FC, 4Z4TT/VR1 plus JA's and W's as well as a few weak
ZS5's.
21 MHz. KA1IOW, VS5MM, KZ5PM, 4Z4TT/VR1l, VR3AK, VR1X, EA4QB with
many W's, JA's and Europeans.
14 MHz. 7P8BC, VE8MA, ZM7AT, CR9, VR1l, VR3, VP9, KM6, 9M8, ZKl
and the usual DX from Europe on CW.
7 MHz. Has not been worked from this QTH this month.
3.5 MHz. W's and Europeans heard with good strength both on SSB
and CW. The ZL's continue to provide much of the activity
with the various awards being looked for and with the
increasing number of N calls, some healthy pile ups can
be observed.
Col should be back on the bands again with a vengeance and compile
his usual HF notes for next month.
73 de VK7BC
For those DX'ers who wish to keep their DXCC countries
list up to date, the following amendments will be necessary.
DELETE; the three following VQ9 countries, Aldabra, Desroches,
Farguhar. These are deleted as from 28th June 1976.
These three Islands were returned to the Republic of the
Seychelles upon its independence last June. FH8 Comoro
Island deleted as from July 6th 1975.
ADD: to your Countries listing, D6A Comoro Islands, FHB8 Mayotte.
For QSO's made on or after July 6, 1975.
These actions bring the grand total on the ARRL countries
list to 363. This is made up of 319 current and 44 deleted
countries.
73 de VKTLZ
sk 3k okokokok kK koK K
FOR SALE _FOR_SALE FOR _SALE FOR SALE
IC-202, 2 metre SSB transceiver, very good condition, had very
little use. $170.00 or offer.
contact, John Mc Culloch VK7CCC
June 1977 OR M Page 5
_NORTHERN BRANCH W.I.A. TASMANIAN DIVISION
Sales $15 161.44
Less Cost of Sales
Opening stock 1/3/76 $ 1 313.95
Purchases $15 432.21
$16 746.16
Less closing stock 28/2/77 $ 2 007.44
GROSS PROFIT §14 738.72
422.72
Add other income
QRM $132.00
Subs $232.50
Repeater refunds $ 34.00
Progressive dinner $205.00
Interest $ 40.17
Hamfest $411.65
Commission $ 26.51
Advertising $160.00
Barbecue $ 19.00
$ 1 260.83
$ 1 683.55
Less Expenses
License fees $ 24.00
ORM $178.00
Petty cash expense $ 55.64
Hamfest $401.11
WIA Federal $ 54.00
State library S 4.80
Barbecue $ 18.65
Cheque books $ 12.80
Twentieth Century Fox $ 17.10
Repeater power $ 67.00
Australia Post $ 15.00
Progressive dinner $ 94.90
Change cash tin $ 20.00
Initial petty cash advance $ 15.00
S 978.00
NET SURPLUS S 705.55
Plus standing cash float S 20.00
Plus petty cash on hand S 10.40
NET ADJUSTED SURPLUS § 735.95
BALANCE SHEET AS AT FEBRUARY 28, 1977
Liabilities Assets
Acc. funds $2 671.60 Stock $2 007.44
Net Profit S 735.95 L.B.S. $1 369.71
Cash float $ 20.00
Petty cash S 10.40
$3 407.55 $3 407.55
CLUBROOM ACCOUNT
Balance 1/3/76 $2 069.49
Interest received $ 179.93
Fund raising $100.00
Balance 28/2/1977 $2349.42
AUDITED AND FOUND CORRECT. B.C.Proverbs, A.A.S.A., F.C.I.S.
12/5/1977.
Page 6 QR M June 1977
LOW 1LEVEL R.F. AMPLIFIER. by Trevor VK7TB
On building a digital readout system for a new communications
receiver I found a need for a low impedance wide band voltage
amplifier (50 - 75 Ohm input output impedance). A pre-amplifier
that would amplify a level of about 20mV (across 50 Ohm) and have
a voltage gain of about 15.
Initially this problem seemed quite straight forward, but
after some investigation I came to the conclusion that trying to
amplify low impedances over a wide band width in one stage
presented results with gain often less than unity. The problem o
was diagnosed to gross impedance mismatching, using e.g. grounded
source F.E.T.'s, grounded emitter bipolar stages etc. Why not a
grounded base configuration ? it has low input impedance (typically
biased for 50 Ohm input) but a very high output impedance(typically
500K or greater). This high output impedance was stepped down by
a 9:1 wideband transformer, not the perfect impedance match but
sufficient to give a gain of 15 at the impedances shown.
An increase in gain can be achieved by allowing the stray
capacitance plus the collector capacitance to broadly tune the
output transformer. Terminated in these low impedances a band-
width of at least 30MHz was achieved (10 - 40MHz).
L1, L2 & L3 are three windings
BF /80 each consisting of 5 turns
B¥ Zoo connected series aiding. Imped-
.0l ance transformation is
9 : 1
5
50-7L
oUT Py7
The small toroid I had on hand was of unknown grading (it came
from a piece of VHF equipment). This situation often results but
with some experimentation with the number of turns soon gives
optimum results.
Two important points when winding a transformer of this
type is to see that the wires are twisted,at least 4 twists per
inch and wound in a trifiliar form.
Possible uses; Low noise wide band R.F. amplifier for receivers,
Amplifier for pre-scalers, frequency counter etc..
June 1977 QR M Page 7
NORTHERN BRANCH EQUIPMENT STORE.
Resistors Transistors
L and ¥ W 4c¢ 2N3563 29¢
per 100 $2.50 2N3564 20¢
. BC108 20¢
Capacitors ON3866 95¢
microplate 5¢ BD135 62¢
ceramic 8¢ 2N3055 $1.25
electrolytic 4.7ufF 16V 15¢ mounting kit 12¢
10ufF 1lev 16¢ F.E.T
47uF 16V 16¢ ——
100uF 16V 22¢ 2N3819 65¢
220uF 16V 50¢ 2N5245 60¢
1000uF 25V 58¢ 3N210 90¢
2200uF 25V 70¢ U310 $2.00
tantalum 10uF 16V 30¢ Diodes
1, 2.2, 4.7uF 25V 25¢ 1N914 9¢
greencaps .22uF 100V 18¢ EM408 10¢
.1, .047uF 100V 12¢ 1N4002 l4¢
.01, .0047, .001luF 100V 8¢ HP2800 95¢
Trimmers 3 - 9 pF 40¢ I.C.'s
2 ‘i2 pe ioz LM380 audio 2W $2.10
-40 p 0 LM741 op. amp 40¢
Crystal Sockets MC1550 RF/IF $1.20
LM11lh V/Comp. $4.40
D, Style xtals Sie MC1496 Bal/Mod. $1.35
Style xtais Ua723 Volt/reg. $1.05
Coil Formers LM556 Dual/555 $1.85
Neosid single bases 10¢ Co-axial fittings
double bases 1l1l¢
bakelite formers 8¢ B&L stand. plugs 20¢
. PCB sockets 54¢
single cans 10¢ h .
double ‘cans 11¢ chassis mount 40¢
F16 and F29 slugs 8¢ UHF PL259 plug $1.40
2 - 300MHz balun core 12¢ 50239 sockets $1.20
. . . reducing adapt. 37¢
Printed Circuit Board RCA - S0239 ad. $1.90
single sided per sq ft $3.25 angle and T ad. $1.80
double sided per sq ft $3.55 BNC stand. plug $1.30
socket $1.20
Relays
4 c/o $5.00 Log books +2.00
sockets 86¢
relay driver $1.70 BF200 transistors
(just arrived) 50¢
Also available, on order only, all ARRL and RSGB books,
subscriptions to all magazines as advertised by Mag Pubs WIA
in Amateur Radio.
Equipment advertised by Vicom is available,on order only,
at advertised prices.
Je&
T GUNN PTY. LTD. |
50 BRISBANE ST. LAUNCESTON
Telephone 222 51
DOMESTIC & BUILDERS HARDWARE
MARINE & PLUMBING SUPPLIES
PAINT & TOOLS
SEDDON PRESS
35a GRANVILLE ST. LAUNCESTON 7250
Telephone 31 61 91
FOR ALL YOUR PRINTING
BUSINESS AND PERSONAL
QSL CARDS
NORWIND
g
ELECTRICAL ENGINEERS
SPECIALISING IN MOTOR REWINDING AND ASSOCIATED WORK
27 SUNCREST PLACE, RAVENSWOOD
TELEPHONE 391515
Atho! Lawes Electrics
135 HOBART ROAD, KINGS MEADOWS, PHONE 444710
FOR ALL ELECTRICAL APPLIANCES, SPECIALISTS IN,
HI-FI SOUND SYSTEMS
CAR RADIO AND STEREO
SEE US FOR A BETTER DEAL, WE SERVICE ALL WE SELL.