QRM

1970sDocument1976QRM Vol 6

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QL RB
Bulletin issued by the Northern P.O. Box1010
Branches of the Wireless Institute Launceston
of Australia, Tasmanian Division Tas. 7250

October 1976
Vol.6 No.7

Registered at GPO Hobart
for transmission by post Price 40¢
as a periodical. Category B.

MEETINGS l I .

Oct. 8th Northern Branch, S.E.S. rooms, Charles St. 8 p.m.
Oct. 12th North West Branch, Lakins Hall, Ulverstone. 8 p.m.

Y.R.C.S. MEETINGS

Oct.: 9th & 23rd Kings Meadows High School, 10 a.m.

A.0.C.P. Classes
Oct. 4th Kings Meadows High School
11th block B, room 35
18th CW 7.30 p.m.
25th Radio theory 8 p.m.
Nov. 8th

_Contests
Oct. 9/10 VK/ZL Oceania CW
Oct. 16/17 Jamboree on the air
Oct. 16/17 RSGB 7MHz CW
Oct. 30/31 CQ WW DX Phone
Nov., 6/7 RSGB 7MHz Phone

Nov., 13/14 VK7 HAMFEST AT EVANDALE

THE NEW FREQUENCY OF THE SUNDAY NEWS BROADCAST IS 3570KHz

October 22nd Deadline for the next issue of QRM
Page 2 QRM Oct. 1976
Northern Branch notes by Joe VK7JG.

Before mentioning last meeting I must congratulate
the organisers of the progressive dinner. Everyone I spoke to
at the dinner agreed that it was one of the better functions
held by the Northern Branch. Our visitor from the North West
coast namely Ian VK7ZIE and XYL was overheard refusing a drink
late in the evening saying '"no thanks I'm driving .... I'm
driving etc.”
Now to the meeting held at S.E.S. rooms Sept. 10th.
It was well attended with 34 persons present. After the
preliminaries were dealt with we had the election of two
officers following the resignation of our Hon. Sec. Norm VK7NR
and the need for an equipment store officer to help Daniel
VK7ZDA with his work with the equipment store. Graeme VK7ZGG
was elected to the position of equipment officer and myself
Joe VK7ZGJ as Hon. Sec.
Turnover was down a little on last month, Peter VK7PD
reported sales of $946.00 and purchases of $1685.00, it was
requested that persons owing money to the store clean their
slate as soon as possible.
The most heartening news of the evening was that
John VK7JV withdrew his resignation as QRM Editor "thanks John",
so how about doing your bit for our publication and write an
article to help fill the pages of QRM,
I could write a page full about the discussion that
took place concerning the Bourke St. premises, at this stage
the executive is to obtain lease details from the Launceston
City Council and present them to the meeting as soon as they
are available.
The meeting closed at 21.20 and was followed by a
most interesting lecture on the history of the VK7RAA
repeater and repeater requirements by Peter VK7PF. Peter
thanked Bob VK7ZRF, Col VK7KW and DCA for their help in making
the repeater visitors say "the best in Australia”.
By the time you read this there will be two new Full
call signs on the air in the North, Byron VK7BD (ex VK7ZBD)
and myself Joe VK7JG (ex VK7ZGJ) we both passed the last
CW exam.
The lecture this month is by Professor R.H.Thorpe
chairman of the Australian Consumer Association. So come
along and make his time worthwhile.
Next month is equipment display night, so once again
dont leave it to the usual few, last time only two exhibitors
were present, so bring your new toy along, it need not
necessarily be home brew, and make the evening worthwhile.

till next month Joe VK7JG

FOR SALE, from Joe VK7JG, 40 Lavender Gr. Phone 443882
Marconi HF signal generator 85KHz - 25MHz $25.00
Playmaster quad amplifier must sell, kit cost$145.00 will
take $130.00 , 15 Watts per channel, built in attractive
wooden cabinet, R.F.I. proofed.
October 1976 Q.R.M. Page 3

Notes from the North West Branch by Lindsay Johnson.

The monthly meeting was held at Lakins Hall Ulverstone
on Tuesday l4th September. The meeting commenced at 8.15 p.m.,
with 9 full members, B8 associates and one visitor present.
Ian VK7ZIE the President and Max VK7MX the Secretary Treasurer
in their chairs. Apologies were received from, Ken VK7KH,
Brian VK7ZBL, Kirby VK7KC, Bob VK7ZJS and Charlie VKICF, A
visitor, Jim Lewis was welcomed by the president who thanked
him for attending and expressed the hope that he would come
again. The minutes of the last meeting were read by the
secretary and were duly passed. The inward correspondence
dealt mainly with requests from several scout masters asking
for assistance from North West Branch members in the forth-
coming Jamboree On The Air. Several members agreed they would
be happy to help out and would advise the scout leaders of their
decision.
The meeting was advised that Tony VK7AX would be doing
a rebroadcast of the Sunday morning broadcast on a frequency
of 27.125MHz. The treasurer reported on a stable bank balance.
Graeme VK7ZAQ the technical officer who is logging up endless
hours of work on the new repeater reported that, the commercial
gear used for the repeater is still giving troubles thus holding
up the progress of getting it on air. He also would like the
donation of several 30 inch lengths of hard drawn 4 or 5 inch
copper tubing, this would be very much appreciated, he is also
looking for assistance fiom members for the construction of new
aerials.
A long discussion was held about the forming of the
Mersey Vally Radio Club. Associate Jim Davies who is known
State wide for owning a very fine collection of vintage radios,
has offered the use of his amateur gear and there is plenty of
that too. Several members are anxious to get this club on air,
provided that a fully licenced member is in attendance when
members are on air. Max VK7MX is donating much of his time
holding fortnightly classes over Latrobe way, so who knows,
some of his pupils may be on air members of this proposed club
in the near future.
The meeting closed at 9.50 p.m. and was followed by
supper with Burnie and Penguin members being hosts, this was
followed by the raffling of a big box of something and that's
exactly what it turned out to be, much to the surprise of the
winner when he opened it later.
After next months meeting Jim Davies will give a talk
on? well I will leave that to Jim, we are all looking forward
to seeing or hearing what he has for us.
Following the usual after meeting talks the evening closed off
at 10.15 p.m.
73 Lindsay
Ahkhkhkkhkdhhhhhhhbhkhhhhr

Bill VK7TE requests that more amateurs visit Mark Addison in
Cosgrove Park, Mark has only had two amateur visit him, no he
didn't complain but Bill VK7TE does and he is right! I cant say
anything I live across the road from Mark and don't know what
he looks like, He is trying to learn for the AOCP but obviously
cant attend classes as the only bodypart that moves is his head.
Page 4 Q.R.M. Oct. 1976

HF and DX notes by Col VK7LZ.

This month very little listening has been done due to
being away from home part of the time but from reports received
it appears that conditions have been very similar to the previous
two months, however considering the low sunspot count we are
extremely lucky to be hearing as much as we are as the old timers
well know.
Bill VK7AK has a theory that if one can hear VKé's on
3.5MHz during our evenings it is advisable to listen on the short
path for Europeans on 14Mhz and 21MHz, this proved to be true on
the 18th September when Frank VK7BC worked several including
Scandinavian countries short path on both 14 and 21MHgz. Franks
log reads like an extract of 4 or 5 years ago with the following
goodies,
14MHz - 0600 to 14002, ZS6APO, A4XGQ, A4XFA, A4XGH,VU2ACD, OM6KT,
also OH, SM, G, PA, F and I.

21MHz - CROAJ, VS6HI, also 4X4, JA's and several European
countries (all of the above were on SSB)
Europeans occasionally come through afternoons local
time long path on 14MHz, whilst W's, VE's and the odd Pacific
stations are regulars.
On 7MHz G's appear on SSB most days, also the odd ON, CT,
DL, F and XE whilst on CW YU, DM, DL, GW, HB9 and ILX
SM, ON,
have been heard as well as W, VE and Pacific stations, ZB2CD was
339 on CW at 10.30Z one evening.
No reports are to hand regarding 3.5MHz but 1.8MHz is
showing signs of life again, several W's are now coming through
around 1000Z but signals are not good and only one QSO has been
made. VR1IAA has again put in an appearance and VE3EK has been
listed on these evenings. KL7HAQ and JATNI have both been QSO'ed
but only with 449 signals.
With the DX season hopefully approaching, several of the
DX gang are working on their antenna systems. Col VK7KW now has
his 20 metre beam on top of his tower again, Frank VK7BC has a
new tower ready to raise and Den VK7DK sports a brand new
204BA also a 15 &10 metre beam all assembled but with no tower
as yet - any offers ?
And to end on a note of optimism, in an interesting and
enlightening treatise into the mechanism of the sunspot cycle
in the July issue of '"Radio Communications'" G8KG comes up with
some extremely interesting observations well worth studying, he
predicts that in spite of the story of gloom most writers are
forecasting that Cycle 21 will be at least equal to the one
just ending and may reach a peak in the region of 150,

dhhkkhkkkkkhkkik

FOR SALE. from Alex VK7CS
VHF communications 1973 $5.00
Galaxy 5, Mrk 3, SSB transceiver $300.00
40 foot wind up tower in 2 sections. $50.00 o.n.o.
The transceiver and VHF communications are at the QTH of VK7JV
Oct. 1976 Q.R .M. Page 5

VHF notes by Kevin VK7ZAH.

Band conditions during the previous month has not been
very favorable for working DX. I personally have not heard any
DX on the 6 metre band. On the lower portion of the 2 metre
band I had only a couple of contacts probably because I have
been working away from Launceston for the last two weeks. Noted
that the 2 metre band was open on the 17th and 18th but nothing
was heard on the low end of the band however I did manage to
work VK4UX portable in VK3 on the Ch2 repeater, quite surprised
to hear the callsign on 2 metres.
The dedicated 6 metre operator in Launceston Joe ex
VK7ZGJ now has the full call VK7JG, which takes a bit of getting
used to, Joe has already been using the key on six but to no
avail.
I have recently erected a Ringo Ranger antenna up about
55 feet with very good results, being heard at Ulverstone by
VK7TT unfortunately Terry was not strong enough to be heard in
Launceston with his 10 Watt (I was running 60 Watts). Terry
intends making his aerial arrangement a bit more efficient so
in the future it may be possible to work him direct at any
time. Also since ercting the Ringo I have been able to trigger
the Hobart repeater but my signals are to weak for a contact.
I think the repeater mute has been recently wound on a little
harder to eliminate noise opening the receiver,l have come to
this conclusion as now it does not open on noise and I can no
longer trigger the device.
Whilst on the subject of the North West Branch and in
particular VK7EM, Winston has under construction a 2 metre
transverter for SSB, his converter is completed and he was
able to read my SSB signal at Penguin. So with a bit more
power from Winston there is a good chance that he will be able
to work into Launceston. Winston also told me he is able to
receive a good picture on UHF TV channel 56 at his parents
OTH at Ocean Vista Burnie.
73 de Kevin Henricks VK7ZAH

Dont forget that we still have two amateur satellites
circling the Earth, giving us at least three passes every
evening and six when Oscar 6 is switched on. Oscar 6 had its
4th birthday during the week, which is a magnificent record
for an amateur satellite with an expected life of 12 months.
This was made possible by switching the unit off 4 days a
week to help preserve the batteries, it has certainly paid off.
Oscar 7 is coming up to its second birthday and is
still functioning very well although very few VK7's take
advantage of its facilities. On an overhead pass the 2 metre
downlink is S9 on a % wave whip. So why not take advantage of
these satellites when other modes of propagation are not
favourable for working DX
73 de Joe VK7JG

EQUIPMENT STORE
As from the issue of the new telephone directory,Graeme VK7ZGG's
phone number will change to 44 66 36
Page 6 Q.R.M. Oct. 1976

FINE TUNING FOR YOUR FRG7., by Bill VK7AK

| WATT

Solder the zener and 50uf to the earth lug adjacent
to the filter choke located underneath the chassis, solder a
100 Ohm 1 Watt resistor direct from the grey wire to the zener
cathode, the whole lot is then self supporting.
Immediately above the audio gain control on the front
panel at a height squared off with the MHz knob, drill carefully
through the front panel with a 1/16 inch drill, repeat with a
3/16"and then a 3/8", file out carefully to take a 10K linear
pot.
The BAl02 and the ceramic capacitor and the 6K8 % Watt
resistor can be mounted on or near the tuning gang. Point B on
circuit connects directly to the stator (the rear section).
Run a wire from the wiper of the 10K pot to the 6K8 resistor.
It will be necessary to set the pot to centre and readjust C
on the printed circuit board to correct frequency AT THE LOW
FREQUENCY END OF THE MHz DIAL. Having now got the fine tuning
working you will probably now notice the lack of selectivity
becomes more obvious. You will now be able to tune signals on
reverse sideband to that normally used. On 80 metres tune in
signal on LSB, switch to USB and with the fine tune you can
resolve the signal again without difficulty, provided of
course that the signal is about 5/4 or better in the first
place. Anyway it is still a good receiver for the money.
e Je ok e ke de d ke de ke ko keok kokok k

We Boobed

In the parts list of the 144MHz linear amplifier in
the September issue a couple of errors crept in.
R1 should be 3.3 Ohm 4 or % Watt
R2 should be 22 Ohm % or % Watt
D1, D2, D3 - EM402 etc.
X1, X2, X3, X4, X5- Ferrite bead 5mm x 3.5mm, 4Bl ferrite.

Y e dede de kKde deokok Kokokokok okok
Oct. 1976 Q.R.M. Page 7

AUDIO FILTER: (SSB reception) by Trevor Briggs. VKJTB

The circuit shown consits of three stages of low pass
and two stages (one at each end of the low pass section) of
high pass filters. The high pass results in the low frequency
slope on the curve and the low pass results in the high
frequency slope.
The inductance and capacitance values listed can be
plus or minus 10% with no real serious bandpass distortion.
One reasonably important requirement is that the filter be
terminated into a 600 Ohm impedance. This is satisfied by
the low noise isolation amplifiers and diode switching.
The bandpass curve drawn is typical of what can be
achieved using rather low Q inductors. Some surplus potcores
have a higher QO and will produce even steeper results than
shown. (John VK7JV has a few sets available)
The purpose of the isolation amplifiers is to enable
unity gain to exist with the filter switched out. Adjustment
of R6 is to enable a gain value of the filter loss.
The transistors should be of a low noise type and
arranged into a configuration so that they will handle a
reasonable amount of signal.
The pot cores available should be rewound to about
100 - 130 turns for 88mH inductance. The exact inductance is
found by the circuit shown.
Equipment required is, 1) a calibrated audio oscillator
2) a C.R.O.

RAudio
oscillATOR

By parallel resonating the inductance, the value of inductance
can be easily found.

55 v° C
L= 2T ——3 LC
Ple 2T
e.g. 1
L 88mH = —~——*———————~—————————‘——*———€~
4 x 10 x 780 x 780 x 0.47 x 10~

From the parallél resonant equation it can be seen that
88mH with a 0.47 capacitor placed across it has a resonant
frequency of 780Hz. The 4.7K resistor in series with the audio
generator is to stop the low impedance of the audio generator
from loading down the tuned circuit.
Page 8 Q.R.M. Oct. 1976

AT PARALLEL RESONANCE THE IMPEDANCE OF THE TUNED CIRCUIT
Is MAXIMUM.
The value of inductance is adjusted by removing or
replacing turns untill the correct resonant frequency 1is
obtained. (maximum deflection on the C.R.0.) If a C.R.O.
is not available then a sensitive A.C. uA meter may be
placed in series with the tuned circuit, resonance can then
be noted by minimum deflection. (high impedance, low current
at resonance) My experiments realized a change of 1Hz was
clearly detected on the meter.
The number of turns for the 176mH inductors is around
about 190, this varies tremendously depending upon the
permeability of the ferrite material in the pot cores. I
think you will agree that the slope factor is excellent for
audio filters.
You need not interfere with any circuits in your
commercial gear, just cut the leads at the volume control
and insert. The circuits listed should handle a wide
impedance variation without any effect on the filter shape
or the commercial gear circuits.
Your filter (of course) should be installed at a
practical point of the lowest possible audio level.
NOTE Particular care must be taken with earth loop returns.
Any form of feedback from input to output of the filter
will of course degrade the filter shape. A low impedance
power supply is a must. The board layout given, complete
with the complex diode switching, proved succesful without
any degradation resulting.
MAKE ONE EARTH POINT ONLY FOR SHIELDED CABLES AND POWER LEADS.
Wire gauges used were, 88mH 26 B&S, 176mH 30 B&S.
Any further constructional information can be obtained from
Trevor VK7TB,
Nivh yaidt1dvy asrlQy
Page 9

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Page 10 Q.R.M. Oct. 1976

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Oct. 1976 Q.R.M. Page 11

VKT
HAMFEST
1976

EVANDALE
NOVEMBER 13 & 14
The Wireless Institute of Australia, Tasmanian Division wishes
you and your family to attend the Tasmanian Hamfest to be held
on 13th and 14th of November,1976.
The programme for Saturday will consist of registrations,disylays
of home constructed and commercial eguipment, carphone checks,etc,
Also something for the ladies and children., A Buffet Dinner and
Cabaret will be held at the Hamfest site on the Saturday evening.
On Sunday transmitter hunts, yes/no hunts, ecuipment displays,
cuessing competitions, Barbecue Lunch, etc.
The success of the Hamfest depends on a large number of people
participating, so we hope to see you at Evandale on the 13th znd
14th of November, 1976.
Further information can be obitained Ifrom :-
B.Yeoman, Bus.918288 Home 918218,0r L,Dowl, Bus.321273Lome 444690
GUIDE TOHAMFEST “7°
Page 12

MEMORIAL HALL

REGISTRATION FORM

Name Phone Home

Address Bus.

Callsign
Registration Fee
Single $5-00 _____
Family/Double $8-00 __
SUKNDAY ONLY per adult $-00
Please find enclosed chegue for

I will require Hotel/Motel/Guest House accomodation f{or
persons. Devosit of $5-0CU is enclosed.
Please Return Form to P.0.Box 1010,Launceston,Tu35,7250
MODERN SOLID STATE CONVERTERS
VHF Modern solid-state, high performance converters
for 28/52/144 MHz bands. Featured in Feb
GONVERTER ruary E.T.l. p.63.
; 28 MHz/ET17078B $1
KITS TadMARET
| IZO0A
MPRI2Y MPHI2
These converter kits are simple, easy to construct and align.
® Ja's? MHz (ETI 707B)
t < ¢ tried ana proven design and was featured in the January
sue v FLECTRONICS TODAY INTERNATIONAL. Noise figure
oo 6 omoas g littte meaningless but this converter produces a
s igure o around 2 dB. Gain is 20 dB or greater, bandwidth is 3
Mie on 6e 0 Mbaz on 10m, spurious responses — 50 dB or better.
Chowce o iF trequencies to suit yourself. Piease specify 28 MHz or
© ML Hperat-on Crystal not supplied. Fibreglass p.c. board. Value
at 911 or just the p.c. board $3.10

3lly another simpie converter. An original 6 UP design, this was
s ured in the January 1976 issue of ELECTRONICS TODAY
NTERNATIONAL This converter was designed for low noise (3
better) and iow crossmod. performance. Gain is adjustabie,
vt maxaimum of about 20 dB. Bandwidth is also adjustable
eiween ibout 0.5 MMHz and more than 1 MHz. Spurious responses
re down 50 dB or better. Choice of IF frequencies to suit yourself.
™ eutralization Crystal not supplied. Fibreglass p.c. board. What
"ore could you want for $14 or p.c. board onily . . . $3.50
> MH2z (6UP-004)
€
mous design by VK5QZ —~ now a standard of sorts! improved
bouard This is probably the simplest way to begin on the UHF
o m;m 1nd straightforward design that produces good
c notse figure approx. 4 dB, JFET front end, gain of
15 IF t 28 MHZz or 52 Mz although some constructors
nave used 146 MHz successfully for FM net operation. Bandwidth
iporox 4 MMz Fibreglass p.c. board. Crystal not supplied.
e with str uqhtlorward instructions. Head for the frontiers
tor s 14 or p.c. board only ... $3.35
e © MARKER (6UP-006)
orovides harmonics to 1296 MHz from a 1 MHz crystal or to
M from a 100 kHz crystal. Can accept crystals to 15 MHaz.
jset 5 transistors. Crystal not supplied. Find the band edge
tor $7 or p.c. board only . . . $2.55

PACK & POST on kits is 60c per Kkit.

CIRCUIT

send s.a.e. for details on coil components,toroids,baluns & other
e | kits and components

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