QRM
Recognised text
Text below was produced by optical character recognition and may contain errors. Check it against the original.
BULLETIN 1I55UsD BY THE NORTHELRN PO BOX 1010
BrANCHLS OF THE WIREIZSS INST1iTUTa LAUNCESTON
OF AUSTRALIA TAS. DIVISION. TAS. 7250
bl 1973
VoL. 3 o 9
REGLISTERED AT GPO HOBART
for transmicssion by post
as a periodical. CATEGORY B. PRICE 20c
Here it is again, the December issue. They seem to come around
gulcker every year, maybe its the pace of life with insufficient
time to do all that needs to be done, let alone some of the things
we would like to do, or maybe its that we are getting older and
slower.
Looking back on this year, we have had some sad moments with the
demise of some of our pioneers in amateur radio.
But life goes on, and they would have been proud of the work that
has been done in the Livision as well as the Branches.
Firstly the Anual General lieeting and the Constitutional changes,
this seems to work very well, maybe even better than we had honr~d
for, even some of the arguments it inadvertently caused brought
some of the disinterested amateurs back in the foreground.
The Annual dinner in Devonport and the Jubilee dinner in Hobart
were a pleasure to attend and credit must go to the people that
organized these functions.
There is no need to say anything about the Hamfest other than
that a combination of proven as well as new ldeas plus your
support made it the success it was.
The Northern eguipment store is having 1ts best year yet, with
sales for the first 7 months allready exceeding last years total.
As for QR we have recently made some changes that are being
appreciated by the members, these include an increase in the
number of pages, offset printing and a better quality paper.
In the near future we may also change to a commercially printed
cover to further imprcove its appearance.
At this time 1 would like to take the opportunity to thank all
the people that have contributed articles and helped with the
production of QRM.
On behalf of these people and myself, I wish you all a very
happy Christmas and a prosperous new year,
John VK7JV
_MELTLNGS
Dec. Lth North Yest Branch, Lakins Hall, Ulverstone
Dec. 15th orthern Branch BBg at the QTH of Joe VK7ZGJ
LO Lavender gr. sSummer Hill, West Launceston. '
bring your own meat, refreshments supplied,cost £1.00
Jan., 11th Northern Branch, AEB rooms High st, Launceston.
There is no meeting in the North West in January.
YRCS classes, dates for 1974 will be given in
the February issue of QKM
Page 2
37 members attended the November meeting.
Graham 7ZAQ had taken the trouble to drive down from Devonport
to be our only visitor.
¥
Business discussed included the increase in subscriptions to the
division,quite a lot of time was taken by members to speak against
the desirability of the division becoming a collection agency for
what in the past has been purely a branch levy.
The usual reports were tabled and the meeting closed at 20.10 hours,
after which some 30 glides, showing the workings, testing and
launching of Oscar 6, were screencd.
Joe 7ZGJ spent a few days in Sydney on business but managed to
do some scrounging in his spare time, resulting in an RTTY
machine looking for passage to Launceston.
Congratulations to Peter 7PF and Col 7LZ on having managed to
accwiulate the required number of points for their Oscar 6 award
applications, Peter's certificate is in fact the first in VK/ZL.
Notable characters seen in Flinders Island during the month were
Wally 7ZWX, Tom 7AL and Joe 7ZGJ, no we wont tell you which was
flirting with the air hostess on the way home.
As you may have noticed we now have HF notes written by Den 7DK
and VHF notes by Joe 7Z2GJd, 1if you have any information that could
help them compile these notes please let them know and help others
to work some of that rare stuff.
I had hoped,that after the few lines in last months QRM about the
broadcast, some of you would have made an effort to supply Reg
with some information, but I should have known better.
A couple of years ago Ron 3AKC came to Launceston to attend the
annual dinner and finished up spending a couple of days in the
Launceston General Hospital. This time Ron came over for the
hamfest and everything went well untill he wanted to leave and
found that his flight had been cancelled, after many phone calls
he got away at 00.15 hours and upon his arrival in Melbourne had
to take a taxi to get home in Geelong, he made it by O4.00 .
Robin 7RH aeronautical mobile in a light aircraft over the Western
Tiers was having a ball on ch B, working amongst others Peter 7PS
in Hobart.
Bevan 7CX has bought himself a 30ft yacht and will very likely be
operating maritime mobile on HF as well as VHF.
Listening to 11 metres the other day made me wonder wether this
band is going to finish up in the same sort of chaos as in the
i
USA, there were two blokes talking using the usual type of invented
call signs and describing their equipment, FT101‘'s,makes you wonder
doesn't 1it%
>
sesp sk s sk e sl ok sk
2le s ale wta aby as ate afs als als ale
Cont. from page 5. The charging of NI-CADS
Tricxle and float charge. Sealed N1-CAD batteries can be trickle
Efigfged or floated. Maximum continuous over charge current sbould
not exceed the 50 hour rate. The trickle charge current required
to keep the battery constantly in a fully charged condition should
not exceed the 100 hour rate.
Notes. Charging rate data varies with different size cells.
Check manufacturers recommendations for the size cell you use.
Do not connect cells in paralell for added capacity or charging.
It is usually easier to arrange a charger with sufficient termlpal
voltage for series charging ie: arrange cells of the same capacity
in series to suit terminal voltage source.
Ni-Cads are available in high rate and standard rate cells and
range from capacities of 1.6 AH to as high as 23 AH with discharge
currents to 2,3 Amps per cell. )
Cut off voltage averages 1.1V on most sizes of available cells.
Charging voltage per cell averages 1.35 Volts to 1.5 Volts over
the Ni-Cad range.
ReReMs | December 1973
byVK/MX
Notes from the North West Branch Page 3
Thought Provoker for the month. Good on Alpha Romeo Jackson for
his letter concerning the use of phonetics. However 1 think this
subject is one best judged by active hams who often work under
very difficult conditions. Regulation 128 of the official handbook
for radio stations in the Amateur service states '"For the purpose
of uniformity it is desirable ,though not compulsory, for Amateur
station licensees to adhere to the phonetic alphabet given in the
preceeding paragraph'".This refers to an alphabet which is also
used by a number of services, and a very good one.
However the object of the exercise 1is to communicate and get
information through. Having been through this countless times and
battled to pass information 1 have found that often a change of
phonetics dees the trick. Example, my call sign 7 Mike Xray has
been finally understood when | switched to Mexico Xray or to
Musical Xylophones. It depends on the conditions and the type of
interference etc. 0.K. use official phonetics untill they fail
then switch to a desperation alphabet.
Now the News. Drama of the month. Time, Sunday night.
Scene, Devonport Airport. 7MX receives a call per twisted pair,
7AX here 1've locked my keys in the car, can you contact 7Z1E .
He 1s contacted promptly and takes of for Ulverstone for spare
keys. In one hour flat 7AX 1is presented with a bunch of keys.
Have you ever waited around a deserted airport for your car keys?
Also a 2 and 6 Meter rig doesn't seem of much use in a locked
up car.
The monthly meeting went of like a rocket once again with Steven
7Z8F present from the North. Important business was dealt with
and at the conclusion a colour slide exhibition was held, with
a prize for the best set of slides. This was carried off by
associate Bernard Turner for some very fine night shots.
Later some slides showing Oscars innards were well received ably
described by Steve. It would be interesting to know who slipped
the art studies into the box of Oscar slides.
71S donated a door prize for the night which was won by 7AX
Tony went home with a pumpkin roughly 20 over 9 .
We were pleased to hear Bob 7ZJS come up on 2 metres F.i. fron
Somerset, quite reasonable copy in Devonport, so we have Burnie
communication at laste.
Ken 7£H has been looking for final tubes for his SSB rig.
Seems he dashed out and left the rig on Tune. When fused tubes
become antiques Ken will be in the big time.
We have discovered several young lads in our area who are taking
more than a passing interest in radio. We are making a move to
asslst these boys in their hobby.
Finally a shot at council. Why the 224% increase in Subs 9
How does this compare with other Divisions ? Is it dictated in
retrospect or anticipation ? Our Branch and possibly others
would be interested. Well this is QRM isn't it %
73 MAX VK7MX
From the estate of the late L.R.Jensen (VK7LJ) the following
items are listed-
1 AWA Voltohmyst %90.00
1 Antenna noise bridge %15.00
1 Coaxial switch 51 0. Q0
Various meters
Quite a collection of miscellaneous pieces and components for
which I understand offers will be received.
Any inspection or negotiation can be made by appointment with
Mrs L.R.Jensen , 313 Park st. New Town 7008 Phone 281369
Qs RalMe December 1973
H.F. DX Notes by Den VK/DK Page 4
This is the first of the DX notes for QRM.
I only hope conditions hold well enough to enable some of us to
work some, but as you know the sunspot cycle is approaching a
minimum and we may have a bleak winter period in the coming year.
We have just been through a period of high contest activity.
Two very popular 'tests are the VK/ZL and the CQ world wide contest.
The VK/ZL yielded a good quota of DX, the 20 mx band being open to
most parts of the world during the contest period.
The CQ is a good contest, no matter if you are interested in
hunting zones, prefixes or rare bX.
Some of the prefixes heard are listed together with the normal
prefix. HGH (HA), CV4 (CX), SL2 (sM), 924 (9Y4), LC9 (XE).
Other rarer ones were FL8, 574, FS7 .
Ever noticed how quit the band becomes after a contest? Where do
all the stations go ? During the above test the 14 mhz band
was wide open to all parts, but the following day nary a signal
was heard.
There is a rumour that 3Y-Bouvet iIsland is to be activated by
WBHBID and group. Unfortunately 1 have no info as to date, time
or frequency. KLamaran Island VS9K is to be activated on Nov. 24
and 25 on 14.177 and 7.085 mhz. Bhutan is to be visited by Venkat
VU2KV, using the visitors prefix of A55.
After many years of being the most wanted country in the world,
it is rumoured that the French authorities may grant licences to
French stations to operate from Clipperton Island. 1 do hope this
comes to pass. Whilst on French stations, they are permitted to
use the prefix HW for an unknown length of time, in commemoration
of the first French-American radio contact .
The Hamfest committee would like to thank all those manufacturers
and suppliers who contributed to the interest and success of the
Hamfest by their generous donations of trophies and the supply
of technical literature and catalogues.
To Fred Bail of Bail Electronic Services who came over in person
to display and demonstrate a wide and interesting range of
equipment the committee would like to egspecially express their
appreciation and thanks.
And to the following firms who heightened the interest in the
various contegts conducted at the Hamfest by their donations of
prizes the committee gratefully acknowledges their gestures of
goodwill to the amateurs of this State.
Dick Smith Electronics Pty. Ltd., 162 Pacific Highway, Gore Hill,
N.S.W. Suppliers of all amateur from a screw to an integrated
circuit.
Watkin. Wynne Pty. Ltd., 32 Falcon st. Crows Nest, N.S.W.
Well known by all amateurs over the years for the tried and tested
JABEL range of accessories.
R.H.Cunningham Pty. Ltd., 493 Victoria st. West Melbourne, Vic.
Australian distributors for the world famous range of Eddystone
receivers.,
8.TeCe_- W.&G.Genders Pty. Ltd., 53 Cameron st. Launceston.
State distributors for the well known and comprehensive range
of S5.T.C. products.
J.&T.Gunn Pty. Ltd., 50 Brisbane st. Launceston.
Suppliers of all your hardware requirements.
QR M, December 1973
THE CHARGING OF NI-CAD BATTERLIES by Va/NR Page 5
Last month we looked at some of the more important characteristics
of NI-CADS and it is hoped that the notes have been of assistance
to our members.
Charging Ni-Cads. We firstly state the obvious and say that the
basic requirement for a battery charger is a source of direct
current having a voltage higher than that of the fully charged
battery. The positive terminal of the charging source is connected
to the positive terminal of the battery so that the charging
current flows through the battery in a direction opposite to that
of the discharge current.
Constant current charging is not only the cheapest and simplest
method but is recommended to prevent the possibility ofthermal
runawvay. Constant current charging is obtained by making the
supply voltage much greater than the battery voltage and limiting
the current flow with a large amount of series resistance.
D R
The above circuit is a typical half wave constant current charger
and no filtering is required as the Ni-Cad cells have a large
equivalent capacitance.
This circuit can be used for currents up to 0.5 amp only.
R
240V
AC
For charging currents above 0.5 amps this circuit should be used.
The charging factor is 1.4 . For fully or partially discharged
cells, 1.4 times the capacity removed must be replaced.
Charge currents should not exceed the 10 hour rate, 14 hours
charging at this rate will fully charge a discharged cell.
To determine circuit components calculate the battery voltage
as 1.5 volt per cell to find Edc.
Use a transformer with at least twice this voltage and an =
current rating about twice the DC charge current value.
Select diodes (silicon or selenium) with a conservative PLV rating
and able to handle at least twice the maximum anticipated current.
Subtract Ede from Eac and use this value for E, and the 10 hour
rate for the value of I and then find R using R JU
-1
The wattage rating of R should be at least twice the product of
E times I . Adjust the value of R if the DC charge current
exceeds the 10 hour rate at the end of the charge time.
continued Page 2
Sorry about that, but couln't fit
it in anywhere else.
Q.R.1M. December 1973
Choosing an Electronic Calculator by VKTPF Page ©
The choice of a suitable calculator for your particular needs
is made very much harderby the rapidly expanding range of models,
together. with reduction in prices, of calculators on the market.
Some months ago I looked into what was available; I wanted one
that I could use for calculation of OSCAR orbit times which are
mostly tedious repetitive calculations. From my studies I would like
to pass on some pointers to watch for in buying a calculator and
also show some functions that can be done on a simple four function
machine that the instructionbooks do not include.
Number of digits This means the number of digits used in the
calculations which is at times more than the display shows,
Decimal point This can be fixed,pre-set to 2,3,4,etc or fully floating
This latter means that the most significant digits are shown first
before any decimal and read from the left hand side of the display
whereas with the pre-set ones the number displayed is around the
decimal point position.
Under and overflow This is the loss of all or portion of an answer
or entry. Some lock up and go into an error display if too large
a number is entered while others just stop when full, During
calculations you can loose portion of a number due to underflow
and quite some differences can result in the answeres depending on
the order of calculation in chain calculations.
In overflow answer conditions some just give an indication and
all calculations are lost while others will give the most significant
digits and indicate that the decimal point is to the ri;ht,out of
the display,either by a fixed amount or ways can be used to find
its position.
1'11 give some examples of what can happen when calculations are
limited by one of the above factors.,but nothing can take the place
of actual sammple calculations of your own.Do not go by samples
given in the information sheets,they do not show what can't be done.
Example 1 Using 8 digits with fixed or floating dec. pt.
32.,50(X)1.452(x)253(=) 12197.496 floating dec. pt.
(=) 12195.64 2 dec. pt.
¥xample 2
356.56X 634,13 X 6.14
256.%2
35A.56 (X) 634.73 (X) .14 gives overflow if 2 dec. pt.
ucsed but if a different order
used in the calculation
354,56 (X) 634.73 (+) 256.32 (X) .14 (=) 5421.32 2dec. pt
(=) 5421.3505 floating.
Example 3 3.56 X 6.66
1.5
(a) 3.56 () 1.32 (X) 6.66 (=) 17.92 2 dec. pt.
(0)3 56 (%) 6.66 (4) 1.32 (=) 17.95 " n
(=) 17.961817 floating dec.
4ith the 2 dec. pt calculations the errors are due to
under-flow losses the amount depends on the order of calculation.
Example 4 Crystal frequency calculations.
146.4 (+) %6 (=) 4.06 mhz. 2 dec pt.
chech 4.06 (X) 36 (=) 14~ .14 mhz " " (zrossly in error)
145400 (+) 35 (=) 40AF.56 Xhz. 2 dec pt.
check 40475 ,66(X) 36 (=) 1456%93,99 m moonm (better)
QeR.M. December 1973
Electronic Calculators cont. Page 7
146.4 ()36 (=) 4.06A6A66 mhz, floating dec.
check 4.06A6666 (X) 36 (=) 146.%9999 mhz.
These examples show that for scientific use a calculator should
have the most number of digits as possible plus floating decimal
point to give the correct answer with the least trouble.
Now to other functions,take the calculation of a 3.9K resistor
in parallel with a 5.6k .
R = 3.9 X5.,6 % 10°
«9 + 5.
This can not be done on a simple calculator,without committing
to peper the intermediate result,it requires one with a memory or
at least a constant function that can be used for temporary storage.
step 1 3.9 (+) 5.6 (=) 9.5 (X) or (M)
step 2 3.9 (+) (X),rel K,or (+) (MR). (X) 5.6 (X) 1000
(=) 2298.9473 ohms,
K or constant function. This function enables you to enter a
constant for use in (X), (%) and in afew calculators tobe used in
(+) or (=). IN the four function X , only the the number is entered
the funetion is entered in during the calculations while with the
two(fgnction type the initial entry includes the instuction to (X)
or (+,.
Example of four function K calculations,
256 (=) (K) puts 256 into store
36(+) giges 292
2(X) " 512
56(+) " 0,21875
56(=) " — 200
The powers of the store can also be found eg
(X) A5536 (X) 16777216 this being 256
Example of two function ¥ calculations.
(¥)256 (=) (K) puts X256 into store
2237612
(+)256 (=) (K) puts + 25f into store
56 (+) 0.21875
The powers on the store are found by using (=) (=) ...
Now after all that I will describe the calculator I finished up
buying. It was one put out as a kit by SCS of U¥. and uses a chip,
made by General Instrunent l'icroelectronics,which appears to be in a
class on its own and probably represents the kuropean side of
calculator techniques.
Here are some of the specifications.
8 digit, fully floating decimal point.
4 function with a constant on all functions.
Does not limit on over or underflow,provides 8 signiéécant
figures plus dgcimal point in range 1.0000500 X 10 ~ to
9.9999999 X 10779
Raising to power, partial results can be made a constant,
For those that may be interested I believe from the specifications
that the SINCLAIR cambridge calculator kit, advertised in sveral UK
publications, could be using the same chip. The landed price less
sales tax (they are free of import duty) would be about %50.
to bhe continued
Qe Re Mo December 1975
THE JUBILEEHAMFEST by a Participant. Page 8
As I came onto the Western Junction rd. from the Midlands Highway
I noticed a sign "HAMFEST" on a post. Following that I arrived at
the Hall where another sign turned me into the gates.
As I drove in my eye caught sight of the vast antennae array, it
would sure do credit to any home installation.
With dipole, TH3JR beam, VHF beams, cloverleaf etc. it was very
impressive and what a feat of work.
Wondering in through the side door I stuck my head into the kitchen
with a hello and was greeted by a chorus from a cheerfull army
of XYL's already working on the evening dinner, and what a meal.
Continueing into the hall with a request from Kevin 7ZAH to sign
the book, it was certainly a sight to gladden the eye of any Ham
at the far end of the room was an array of some of the finest and
most sophisticated gear available today, one could fiddle devices
to get the feel of a possible Xmas present from Mum.
Round the corner and along the side was a range of home brew
apparatus and a complete amateur station in operation.
It makes me envious to see such examples of beautiful workmanship
done by various chaps on amateur gear, HF, VHF and ATV were all
in evidence,
Opposite along the stage, great panels were devoted to history,
with old pictures, articles and photographs, producing mixed
feelings, it created a lot of attention.
Everywhere one saw groups of amateurs in earnest conversation
including locals, VK3's, VK5's and a ZL, and every opportunity
was taken to meet as many as possible. XYL's and harmonics were
there brightening things up with splashes of colour and lively
conversation. I felt that the outstanding feature of the whole
show was a universal desire to communicate and this we did,
face to face.
One could not help but notice the hard, quiet efficient work that
went on behind the scenes, there is no need to mention names, we
all saw them and appreciated their efforts.
To illustrate, the time taken to set up tables and present a
meal must have been something of a record.
After dinner we all enjoyed the cabaret and couples dancing
appeared to be having a wonderfull night.
On Sunday the enthusiasts dashed off to fox hunts etc. while
those remaining carried on with the eyeball QSO's.
The wonderfull weather made a perfect setting for the midday
barbecue and the multitude was fed once again in record time.
Later in the afternoon as 1 drove away, thoroughly satisfied I
mused to myself that a lot of work remained for the organizers,
taking down the multitude of antennae , packing up and leaving
the place ship shape, but I'll bet they not only did it cheerfully
but got a great deal of satisfaction 1in doing it.
Thanks everybody and I trust that 1 am around for the next effort.
R6LA SRR
P s SN
e sl STr s
s we
v st sl
R Rs SR
sk s slR ste
More Hamfest by Re KK,
For those who couldn't «eep up with events, following are some of
the highlights. 148 persons were recorded in the visitors book.
As this included wives and children some sorting out of these
figures would probably be interesting.
There were 14 interstate and overseas licenced visitors.
Fred Bail 3YS and assistant Greg 3ZYT, Rob 3AUk, Harry 3AJE,
Gil 3AUlI, Norma 3AYL, Phil 3APO, Ron 3AXC, Lionel 3NN,
Trevor 5NC, David 5Z00, Chris 5MC, Phil ZL1BMC now also VK7MC.
Licenced VK7's totalled 51 ( 16 Southern, 5North Western. and
30 Northern Branch ) 27 associate members, 39 XYL's and YL's,
and 27 children.
Fox hunts produced much entertainment, hiding places ranged from
»
JeR. M December 1973
. bPage 9
sitting in a shelter watching a2 cricket match, river swamps
and cattle sale yards (hold your nose)to behind the piano in the
hall. Embarrassing moments for a few, Peter Feltham walked over
the rig which was buried under a pile of leaves, yet didn't find it.
Airport security guards got the impression something was lost and
didn't seem convinced when told that we were looking for a trans-
mitter hidden in their rose garden.
EA 7HE asked Norm (the fox) if he was within 15ft of the highway
foxy Norm had to whisper his "yes" into the microphone as he was
hidden in the hedge less than 6ft away from Ed.
Congratulations to the following prize winners:
Fox hunts, 1) Jimmy Henry, a winner at 9 years old.
2) Tony Polowy
3) Lionel VK3NM
Raffle for SWR bridge, donated by Fred Bail. Brian VK7TX
Guessing competition, Frequency (L4.5. mhz) John VK7JV
Weight (1005 gr) Lionel VK3NM
Capacity of PC board (300 pf) Kevin VK7ZAH
Best home constructed gear, 1) Brian VK7Z2BY (receiver)
2) Bob VK7ZRF (TV camera)
Good to see the organizers got something for their efforts.
VHFnotes by Joe VK7ZGJ.
52 mhz. The 6m DX season is bacg with us again and Ian VK7ZIF was
about the first to take advantage of it by working VX5SU very early
~in the month. Since then we have had several good openings to
VK2, 3,4,5 and ZL. VKJ was worked on the 21st of November by
Malcolm VK700 and a few others. On the 18th the band opened around
01.00Z and stations in Launceston were very active, these included
VK's 7ZAH, 72BY, 700, 7LZ and myself mainly VK2 andVKL being worked
The 27th little DX although CH@ Brisbane was watchable on and off
throughout the day, the band finally came good around 11.,30Z with
an opening to VK2 for about 15 minutes then VLZWW popped up, he
said the beacon VK@WI would continue running as there is another
amateur going to the Island.
144 mhz. Things have been rather guiet although Kevin 7ZAH and
Ron 3AKC have been maintaining regular skeds, they are on every
evening at 8.30Z. Daniel 7ZDA has also been operating on 1U4l4.54mhz
so when tuning the band take a look above 144.5 or you may mis a
contact. CHL4 still provides us with an early warning beacon and
VK3's are quite familiar to us at this time of the year.
432 mhz. Activity in this area is very low with £evin 7ZAH being
the only active amateur on these frequencies in Launceston although
Daniel 7ZDA hopes to be operating on 432 this season and has an
1296 mhz converter going with a 5 el. yagi mounted on top of it.
Our cogratulations go to Ron VK3AKC for his record breaking contact
with W2NFA on the 6th of October,1296 mhz moonbounce contact.
Signal reportes were 549 to Ron and 559 to W2NFA. Ron runs 160 Viatts
DC input using a pair of 3CPX100A5's,
Best of DX, till next month. 73 , Joe T7ZGJ
FOR SALE
®ICO 750, 80, 40 and 20 metre S$SB tranceiver complete with
heavy duty power supply, speaker and microphone.
For quick sale $140.00 0.1.0.
J.0liver VK7JO, 2 Luxmore Pl. Launceston. Phone 443314
Write an article for QRM in 1974 . How's that for a lew Year's
RESOLUTLON
Q. Ko Mo December 1973
Reprintedfrom 6 UP. page 10
THE WEISS FM DISCRIMINATOR
from various sources
A simple disoriminator for NBIM can readily be attached as an adjunct to
many tuneable IFs.But the difficulty that usually arises is one of availability of
special components that inevitably accompanies many such circuits. These days of
course ICs are available that can perform the function of FM getection. Either
phase locked deteotion or quadraturs detection (amongst others) is obtainable with
ICsythe principal drauback here being cost in most cases. Availability can present
its problems in this case also.
The Weiss FM discriminator is simple and uses readily available parts, not
using a centre-tapped detector transformer or one with a tertiary winding. This
detector has been used in much commercial eguipment but has not attracted much
attention in amateur oircles,
This detector would find plenty of use in beginners' receiversy,such as those
SWLs or YRCS lads with an interestin VH¥. Adding this circuit to almost any tuneable
IF takes but an afternoon's work. The old B/C ~ SH set or more modern transistor
receiver is easily modified and good results are obtained. With more modern receivers
the IF may be a little too narrow for best results with the Fif standards used in
this country so that it should be connected after the first IF stage but befores the
last, Construction can follow the cirouit diagram and no problems should be
experienced. Coils L1 & L2 should be shielded from one another or a shield placedas
indicated on the circuit digram. These coils can be any suitable IF transformer
winding with its appropriate capacitor. The resonating capacitor for L2 will have
to be made up of the two 680pf capacitors in series plus a parallel capacitor as
indicated on the circuit. In operation,Ll should be peaked on an unmodulated:
signal for maximum RF voltage detected at TP (transistor collector) and L2 adjusted
for best clarity on a modulated sigmnal. The audio control shown can be a set pot. or
a fixed resistor and the audio amplifier in ths receiver switched from the normal
detector to the FM detector thus enabling the receiver audio gain to be used.
details taken from Radio-REF july 1969 ( article by F9JR)
and Radio Communications september 69,p.617.
Ql....BF115,BC107/8,2N3564/3 etc.
Capacitors marked with an asterisk may require adjustment.
THE WEISS FM DETECTOR
e etet
Subscriptions to 6UP are $3.00 per year.
Write to: The Editor 6UP
L7 Ballast Point Rd.
Birchgrove. NSW 2041
Qe R. M. December 1973
Page 11
® Courtesy Geelong Amateur Radio-Television Club Newsletter,
QQREO6-40
X o
'
i @ g
CONCVDAE
= INPOT
28nuz
= (6inS)
IAS,
|
ineouT| Y Y FRECAY™
CONV. o]P
!
212AT7 19 5lAT7 LIO 12BY7 Lt Jueud qee .t:
V6 C : ¥
#1N 00 LN oo £LN
3'30 i i 8 j
XTAL T3 ' 3BT3 ~y |
S woTe. e 100K | .ogst-£-{ O
MIXER DRIVER FINAL 12v
X SPARE
TX-RX
CONTACTS
X OF TRANSCEIVER
X
Y
-~ BLOCK DIAGRAM -
~ VK3IASQ ~
M.R. TRICKETT.
<o
GeRelMe Decenber 1973
2 METRE TRANSVERTER. by VK3ASQ Page 12
Courtesy Geelong Amateur Radio-Television Club Newsletter.
COMPONENT DETAILS.
VCH1 5-50pf compression trimmer.
VG2 2x2-10pf split stator.
VC3 2x2-10pf split stator.
VC4 2x2-15pf split stator wide spaced.
VC5H 2=-20pf trimmer.
RFC1 2 turns 28 swg enamel wire through Neosid slug.
RFC2 20 turns scramble wound on 1 watt resistor over 100K value.
FT 1000 volt .001 feed through capacitor.
XTAL 29.000 Mhz, multiplied by 4 = 116 Mhz.
%y 2 turns of hook-up wire wound on L2
L2 15 turns, 7 inch dia. 20 gauge air wound & close wound.
L3-L4~L5~1L6. see diagram. .
L7 2X 15 turns, 14 gauge, 1 inch dia. spaced 1 wire diameter.
18 2 turns, 14 gauge, 1 inch dia., adjusted in conjunction
with VC4 and VC5 for more RF out.
Ly, Lo
2X2 turns
L3,L5 - 4 turns 5 inch dia. E L8
% inch dia. 20 gauge
20 gauge
space by 1 wire
diameter L7 2x1% turns
split stator
Oscillator chain
19 10 turns, 26 gauge, Necsid former with slug, glued to
centre spigot of valve.
110 5/16 inch former in can, 4 turns, 22 gauge spaced 1 wire
diameter, slugtuned.
L1 L turns, 22 gauge, on 5/16 inch former with slug.
112 2 turns, on same former next to L11.
113 2 turns, on same former next to I12. L11 closest to chassis
Coupling C on L12 inside can comes out to bottom tag.
Series C on 111 , comes out to common earth,
Converter oscillator injection co-ax comes out through
hole in side of can, ®ARTHED INSIDE CAN.
ninent details.
Plug in V6 and V4
2 Adjust L9 for oscillation
3 Adjust 110 for reading at TP1, which should be 1V equals 1ma
drive to V4
L4) Reset L9 and remove xtal, in and out to assure stable
oscillation and reliable starting.
5% Measure oscillator injection by means of probe or lamp,peak Li11.
Plug in V1,V2 and V3, switch tranceiver to TX position.
? Adjust VR1 for -4V on centre tap, adjust VR2 for =20V on tap.
8 Check Final bias on zener diode as =-35V.
9 Switch tranceiver to TUNE position and peak for maximum output
at 28 Mhz. This should be approx. 1W P.E,P.
10) With absorb.Wave meter approx. 1 inch from L2 adjust VC1
for maximum at 28 Mhz.
11) #ith absorb. Wave meter at 144 Mhz coupled to L3,adjust VC2
for maximum.
12) With absorb. Wave meter coupled to L5, adjust VC3 for max.
Cont. Page
Q.R.M, December 1973
Cont. from Page Page 13
13) With a wattmeter connected to the output, adjust VC4 and VC5
and coupling for maximum power out.
Repeat and adjust coupling on all intermediate stages.
Power output should be more than 50 Watt P.E.P.
NOTE. * 4.7 Ohms; ** miniature pot.; *** suitable meter.
These three items can be varied to suit available meter.
Prototype used 10 ma. 1t is advisable to bypass meter and
fit a silicon diode in forward direction across it to avoid
damage in case of bias failure or faulty final.
12 volt supply into EM4OL4 for the relay is AC from filament
supply. Filaments wired for 12 volts.
Connections for use with FT200 and FT101,
These two units have the same connections and set up with their
accessory socxet. By removing the dummy plug the final heaters
are disconnected, power for the transverter can now be taken
from this socket. A cable with 9 conductors was used with the
same type of plug (11 pin) at the end.
ACCESSORY PLUG CONNECTLONS.
PIN No PIN No PIN No
1 no connection 5 + 600 volts 9 Relay TX
2 12 V heaters 6 - 100 volts 10 Relay common
3 + 150 volts 7 ALC no connection 11 Relay RX
4 +300 volts 8 KEarth
Relays. X Pye aerial change over relay.
Y 2 pole WIA disposals.
Receiving converter modifications,
The receiving section of the transverter uses a WIA VK3 VHF group
2 metre converter, modified to use external oscillator injection.
While this is not strictly necessary, it is most desirable as it
ensures that the transverter actually transmits and receives on
the same frequency, it also saves the cost of one xtal and gives
the converter a little more oscillator injection, improving
performance a little.
Fig. 1 gives the original circuit, while Fig 2 shows the modifications
required.
FIG.1 L7 FiG.2
Original l Modified
The L6 coil form etc. is replaced with the 270 ohm and .001
utelizing the holes in the PC board where the coil would go.
The gate circuitry is added in place of L5, again using the
existing holes in the board. The coax which comes from ILi11
comes through the side of L11 can, across the chassis and is
soldered to the bottom of the converter, which is mounted on
stand-offs above the main chassis.
JeT. GUNN PTY. LTD.
50 Brisbane Street,Launceston.
.‘
Telephone 2 2251
DOMESTIC & BUILDERS HARDWARE
MARINE & PLUMBING SUPPLIES
PAINT & TOOLS
SEDDON PRESS
35A GRANVILLE STREET, LAUNCESTON. 7250
Telephone 31 6191
for all your printing
Business and Personal
QSL cards ¥****
NORW'NDS '
ELECTRICATL ENGINEERS
SPECIALISING IN MOTOR REWINDING AND ASSOCIATED WORK
27 SUNCREST PLACE, RAVENSWOOD
TELEPHONE 391515
Athol Lawes Electrics
135 HOBART ROAD,
P
KINGS MEADOWS, LAUNCESTON
Telephone 443119
PRY US FOR YOUR NEXT APVLIANCE
YOU WILL FIND IT EASY ON YOUR PO $ 83
i | o ,: =i eswnn e