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March 1985

Beechlog
 
The on-line magazine of the Burnham Beeches Radio Club.
INDEX AND ACKNOWLEDGEMENTS


ISSUE No.13 MARCH 1985


Page 1................Index
Page 2................News & Views
Page 3................News & Views
Page 4................Letters
Page 5................Tech-eds Notes
Page 6................Tech-eds Notes
Page 7................SSTV
Page 8................First Byte
Page 9................First Byte
Page 9................For Sale & Wanted
Page 10...............Technical Index
Page 10...............Library
Page 11...............Diary of Events
Page 11...............Club Equipment
Page 12...............Membership List
Page 13...............Membership Form





Editor................Dave Chislett G4XDW
Technical Editor......Dave Lomas G4XOW (New)
Printer...............Dave Ayres G6GBC
Computer Editor.......Mike Brown G4RAA (New)

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B.B.R.C. COMMITTEE

Chairman..............Dave Bentley G6LKZ
Secretary.............Paul Robinson G6DVC
Treasurer.............Lynas Newton G6LYN
Member................Mike Brown G4RAA
Member................Martin Heaver G4WSW

Library...............Dave Bentley G6LKZ
Club Equipment........Dave Bentley G6LKZ

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New Club Rooms...........Haymill Community Centre
112 Burnham Lane
Slough. SL1 6LZ

NEWS & VIEWS


Questionaire 1........There was a good response to the questionaire
on Beechlog. Thankyou to those who gave them back to me. It seems
that most people are quite happy with the magazine and most felt
that little change was necesssary, if you mentioned a change in
your form we will try to incorperate those changes in the forth
coming issues. On the subject of change see elseware for changes in
the editors etc.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Just recently some members of the club have bought Compact Disc
Players. Apart from the goods sounds to come from these Lasers, I
was particularly interested to find a low level of RF radiation
from the model I bought. Contrast that with the computer this
magazine is being compiled on. In the workshop recently we had a
Sinclair Spectrum made for the Spanish market when opened it
contained a screening paint and when closed a low level of RF
radiation. Once more we find that we are the poor relations of the
world with high levels of RF coming from everything we buy.
Elseware in this issue are details of a paint which could help
with not just computers but with all those other things that
contain the dreaded CHIP.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

In this issue we say goodbye to Gerry G8VNA who retired as Tech-ed.
Gerry and Carroll have decided not to rejoin the club this year due
to pressures of work and the extra distance to the club house. I
would like to say thankyou to both of them, both contributed so
much to the magazine in the early issues, later Gerry became the
Tech-ed not an easy job. I think you will all join me when I say I
hope they will return to the club in the future.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

This issue sees Dave G4XOW taking over from Gerry as Tech-ed please
direct all technical articles to him. The final date for all items
for inclusion in the June issue is May 10th. Please, if you can,
give items to the editors as soon as possible this does help reduce
the load in the weeks up to publication. A new page appears this
issue suggested by Mike G4RAA on computers in radio. Mike will be
editing this page so items of interest on computing to him.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

NEWS & VIEWS


Hot on the trail of my tale of G4VRK and his RTTY mailbox I
recieved a printout of yet another mailbox heard at various places
up and down the 2mtr band. This station G8ATS seems not to have
heeded the words of the RSGB and BARTG and is running contrary to
his licence. What I think is more worrying is that others are
planned if not already up and running. What do you all think about
these Mailboxes please let me no and I will print some of your
thoughts next issue.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Taking of mailboxes I received a letter from a club member see next
page for details. Mike got onto the Prestel computer within minutes
of reading that I had a mailbox number I was at the time accessing
other pages and as I was about to sign off I was told of a
message. Eileen had delivered the magazine to Mike that evening.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

As mentioned previously I have found out more about the paint shown
on 'Tomorrows World' for screening computers. The paint is called
MS-485 RFI Conductive Coating (Black), manufactured by
Miller-Stephenson Chemical Co, Inc. Quoted attenuation for a
coating is 105db at 150Khz to 44db at 1000Mhz. Worse fiqure appears
at about 100Mhz with only 21db attenuation. In this country the
cans can be obtained from:

D.Frazer and Company
129 Kylepark Drive
Uddingston
Scotland.

Price is about #5.50 a can with a can and a half suitable for doing
a TRS-80 computer. I have a leaflet and test report on the product
so if anyone is interested please contact me.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Too late for inclusion in the last issue may I say congradulations
to Greame and Gale on the birth of their daughter Emma Jane. Born
on the 9th December.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

LETTERS TO THE EDITOR

Dear Editor,

I should like to express my disgust at remarks made by B.B.R.C.
members and committee members during the Extraordinary General
Meeting held in November last.

It has always been my belief that Amateur Radio provides the
opportunity to bring together peoples around the world in a common
interest. Hence the delight and interest shown in making difficult
contacts in obscure tangents of the globe, not to mention floating
around in space. Yet, at the EGM several people openly expressed
extreme racist views, indicating in no uncertain terms that anyone
not white would not be made welcome. Well I suppose Mr. Ghandi
wouldn't want to come anyway.

I am quite aware that we all may hold whatever views we like
personally, in our society where we are allowed freedom of speech.
However, in a club which purports to be open to anyone with a
genuine interest in Amateur Radio, the remarks passed openly at the
EGM were offensive. I don't imagine that any of these people can
bring themselves to do much but snigger at this letter, but I trust
that I will have no further cause to be offended by any comments
made in public by my fellow amateurs.

Yours Eileen Chislett G6EIL



TECH-EDs NOTES


"You've got a BBC Computer and Word Processing facilities, haven't
you ", asks Dave (G4XDW). "YES" I say. "How would you like to be
our new Technical Editor?". (not a lot, seemed a good answer). But
seriously here we are and firstly I am sure I will be speaking for
all of the club in thanking Gerry (G8VNA) for all the work he has
done as previous Tech-Ed.

In order to avoid repetition, I have made an index of all
technical articles to date; this will be included in the
magazine. If anyone wants a copy of any of these, I am sure the
Editor will oblige.

My latest venture has been to construct a simple SSTV adaptor for
the home computer. Thanks to Dave (G4XDW) for typing in a program
from an article and getting it working! I managed to get what is
best described as a J.L.B quality picture. Some way to what Tony
(G4LQD) has been achieving. Apparently, the pictures on tape that I
was using are frame sequential colour so with some off-air B/W
signals, hopefully, Ann (XYL) will think this #1000+ worth of gear
is justified.

Some of the you members will be aware of my local interference on
the H.F Bands. I thought it would be worth reporting the events in
case any of you face a similar problem.

On finally getting the G4 (after a struggle with the dreaded morse
best forgotten about), I purchased a DNT CB rig and modified it to
10 metres. With no aerials up at this time I put it in the car
along with a G-Whip antenna. On turning on I could hardly believe
the result, S6 on every other channel with this horrible droning
noise. Driving down the road it faded away so I started using 10
meters mobile making sure the contact was over before reaching
home. The other phenomenon I noticed was the source was not too
stable and so one could not simply avoid certain channels.

After eliminating everything in the house and checking at 3 a.m.
one morning, I concluded it was not local domestic equipment.
Eventually, I decided the factory across the road could be the
source.

TECH-EDS NOTES

Now what was this large diameter cable (the size of coax I wish
my down lead was), that B.T. had installed when the activity
changed from fixing fork-lift trucks to an export business! I
managed to catch a director one day and taking the rig (nicads
strapped to the case) up to their office, there was about half a
dozen phones and a large steel cased super microprocessor battery
backed up system. Flicking around the channels it was hard to get
the meter off the end stop.

Anyway he agreed to contact B.T. and I eventually decided to fill
in a form obtained from the Post Office to the D.T.I. interference
investigatory division. Unfortunately, this is only intended
for reporting broadcast band interference, but it is all that is
available. Unfortunately (again), it was sent to the Reading
Division, which was about to close, so apart from a telephone call
later from an engineer who had given up trying to locate our
house, we heard no more until the Oxford Division took it up. I was
told on the phone that they normally have to charge for anything
other than interference to broadcast bands, but he would take a
quick look.

The result was that the installation is known to cause this problem
and B.T. would be advised to fit filters to the lines, a procedure
only taken when a complaint is made. Well the equipment is in a
screened box, but like my transceiver with a long wire attached, it
radiates nicely.

This was all several months ago, has anything been done?

73 ' Dave G4XOW

P.S.

Question----- How far will 27 mhz go under water?

Answer------- A colleague at work (C.Gross, who organises radio
control demo at McMichael Rally) runs a model submarine which he
tested in an 18 foot deep tank; it was controllable at the
bottom. (Editor's comment?) However, it is only controllable to a
depth of about 6 inches in sea water!

Dave G4XOW

SLOW SCAN TELEVISION


As many of you are aware, I have for the past year or so been
active using SSTV, mainly on the 20 metre band, using my computer,
a Tandy Colour System, together with a simple interface which
separates the sync from the incoming video and feeds them into the
computer via one of the joy-stick and the RS232 ports. This
system, together with some very complex 6809 machine code
programmes, has been very effective.

Recently I was able to acquire a purpose-built converter - the SC-1
- made by Volkes Wraase Electronics in Germany (DL2RZ). This is a
"state of the art" converter giving 64 grey levels and can also
receive and transmit FAX.

For black and white pictures it can receive the following:
8 second (128 lines by 128 pixels) and store 6 pictures
16 second (256 lines by 128 pixels) and store 4 pictures
32 second (256 lines by 256 oixels) and store 2 pictures

The quality of the received 32 second picture does not differ much
from the definition on your normal TV set.

For colour pictures, it can receive and transmit 2 different
systems.
1) Frame sequential - red,green, and blue pictures are transmitted
as 3 individual SSTV frames and then combined.
2) Line sequential - here, red, green, and blue lines are
transmitted alternately, the memory is switched automatically and
the picture appears on the screen as it is being transmitted. The
sequence lasts 24 seconds (3x8).

The converter can also receive FAX (both AM and FM) at 280/120/60
lines per minute and will automatically start and stop on the
appropriate phasing signal.

I hope to be able to give you more experiences of this unit in a
later issue.

Tony, G4LQD

(P.S. Dave G4XDW has done it at last)


FIRST BYTE

This is the first of a regular column on computing and radio. I
hope that I will find topics that interest not only computer
owners, but everyone else too. As always though, it is difficult
working in a vacuum. So, if you hate the column or know of
something worth including, please let either myself (Mike), or the
editor, know.

I took delivery of a new Shinwa CTI CPA-80 dot-matrix printer just
before Christmas, and I'm very happy with it. It has 9 different
typefaces and sizes of print, 4 different 'weights' of type, user
definable characters, proportional spacing, high res. graphics and
a 4K print buffer. And you thought you were confused! Just to add
to the chaos, I've been given a copy of a telesoftware program
which can print in a 'handwritten' typeface.

Hopefully things are going to get even more exciting on the
radio/computing front in the near future. Of course, many people
are using computers to generate RTTY. (Including me, since last
week.) Whilst this has the advantage of being a well known
standard, there are other, more efficient methods of sending text
(or data) over an R.F. path.

One way that's very popular, particularly in the States, is Amtor.
I'm sure most of you know that this is a form of RTTY. The baud
rate is faster than standard RTTY, at 100 baud and, even more
importantly it is error correcting. It shares with RTTY one
disadvantage, though. In both modes there is a transmitter on the
air at all times. This means that, when sending an over, your
transmitter is radiating full power all the time. Obviously
transmitters designed for SSB need to be severely derated if asked
to radiate a continuous carrier. Also, of course, the frequency can
only be used by one QSO at a time.

There are many specialised terminal units available which will
handle Amtor, RTTY and ASCII. (The latter being data sent using
RTTY tones but ASCII rather than Murray code.) These black boxes
are rather expensive, when you consider that you also require a
computer and a rig! Naughty but nice?

Fortunately there is more than one way to skin the proverbial cat.
Software can often provide the solution to a hardware problem.
There are, for instance, a few RTTY programs which need no terminal
unit at all. Likewise there are programs to run Amtor with only a
normal terminal unit, like the ubiquitous ST5. Hopefully there will
be one available for the BBC B shortly. (Three guesses which
computer I own.)

BIT TWO

The Real Thing however, is Packet Radio. Gerry (G8VNA) and I have
conducted some very interesting experiments with a BBC B program
written by two hams from Cambridge University Computer Laboratory.
The program is a bit rough and ready (like it doesn't really work
as supplied!) but has some very interesting features. It does not
need any sort of terminal unit, just a lead going from the computer
cassette socket to the rig. Audio from the computer goes to the rig
mic socket, and from the rig speaker socket to the computer. The
cassette control relay is used for RX/TX switching.

Both of us were surprised how well such a simple system worked.
Signals were decodable until there was quite a lot of noise on the
audio, corresponding to about S 0.5 on my rig! The major advantage
of the packet system though is that it is error detecting. It works
like this......Station 1 transmits a packet of data addressed to
station 2. If station 2 receives the packet then it transmits an
acknowledgement back to station 1, which will then send the next
packet. If, however, station 2 does not receive the packet then no
acknowledgement is sent. Station 1 then automatically re-sends the
last packet. It will do this up to ten times before giving up in
disgust!

That's it for now, I'll keep you posted about further leaps in
technology (Quantum, or otherwise!).

Mike (G4RAA)

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

FOR SALE & WANTED

Bits and pieces to go in this slot!!!!!!!!!!



TECHNICAL ARTICLES INDEX

MAR 1982 A 24 Hour Clock (using junk sale module)
Mobile Boom Microphone

SEPT 1982 Base Station Microphone (using SL622 or SL1622)

DEC 1982 Making Printed Circuit Boards

MAR 1983 6 Amp 12 Volt Power Supply

JUNE 1983 Transistor Tester

SEPT 1983 Testing Transistors with a Multimeter

DEC 1983 T.V Circuits - UHF Diplexer & 600Mhz
(radar) Filter
Simple 2 meter Dipole (using 300 ohm ribbon cable)
Tone Burst Generator (using CMOS 4060 device)

MAR 1984 Converting ICOM 1050 to 10 meters
Tapping a Banana-Tree to receive T.V signals
(not that useful in U.K!)

JUNE 1984 A Wavemeter for 144 Mhz.

SEPT 1984 Dry-Fit Battery Charger

DEC 1984 Noise Bridge Circuit

MAR 1985 Technical Index

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
CLUB LIBRARY

HF Antennas for all Locations Moxon
1981 Call Book RSGB
1984 Call Book RSGB
Radio communications Handbook RSGB
R.S Components Cataloque
Confidential Frequency List
+Suppliment
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


DIARY OF EVENTS

4th Feb..................G3CWI Slide Show Antarctic
18th Feb.................G3JKV Auroras
4th March................A.G.M.
18th March...............G3RZP ATUs & SWR

23rd March...............RSGB VHF convention Sandown Park
(Saturday)
1st April................FoxHunt (Please note usual start
Upton Court Car Park)

13/14th April............RSGB National Convention Birmingham
15th April...............G8DPH A.T.V. Demonstration
6th May..................G4CGS H.F. propagation
18/19th May..............Spring Picnic (Sat/Sunday)
20th May.................G4END Slow scan TV & colour
3rd June.................G3CWI Slide show ?
17th June................G4PHS R.F. filter design
30thJune................LongleatMobileRally
21st July................McMichael ARS Mobile Rally

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Further evenings planned but not confirmed..........

Moon-bounce
6Mtr operation
PMR equipment

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CLUB EQUIPMENT

1. 25ft Telescopic Mast/base/guys & pegs (G4XGD)
2. J-Beam 2mtr+70cms Beam/cables (G4XGD)
3. 4x23 ele JVL 23cms Beams (G4XDW)
4. Tent+Awning pegs (G4XOW)
5. G5RV HF Aerial/cable (G4XGD)
6. AM. HF Tranceiver 'valves req' (Club Rm)


MEMBERSHIP LIST



001 Eileen Chislett G6EIL Sl.21896
002 Dave Chislett (Editor) G4XDW Sl.21896
003 Tony Alderman G4LQD Fc.3286
004 David Ayres (Printer) G6GBC Md.28108
006 Paul Shayler G6TSF Sl.41396
007 Bill Perkins SWL Sl.32171
008 Lynas Newton (Treasurer) G6LYN Bn.66759
009 Mike Brown (Committee) G4RAA Bn.4262
011 Dave Lomas (Tech. Ed.) G4XOW Lt.Grn.2847
012 Ann Lomas SWL Lt.Grn.2847
021 Peter Harman G4XGD Sl.28826
027 Graeme Platts G4XOF Sl.78495
030 Richard Ashberry G6RTM Sl.46012
031 Ted Swaby G4XOE Sl.75099
033 Dave Hemmins G6DRP Bn.64436
034 John Williamson G4XJN Sl.24008
038 Paul Robinson (Secretary) G6DVC Rslp.72125
043 Bruce Gilson G4WVX Bn.64415
047 Peter Melling SWL** Sl.29025
048 Mike Gathergood G4KFK 0895 834167
049 B. Mockett G1DSI ********
050 T.Kay G6LRZ Bn.4255



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Please note if your details are not correct please use the form on
the back of the magazine and hand to a committee member. This will
help us to keep the records up to date.

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THE BURNHAM BEECHES RADIO CLUB

G3WIR G6WIR

The Burnham Beeches Radio Club, affiliated to the Radio Society of
Great Britain, serves the Slough/Windsor area, although it got its
name from its original meeting place - or that vicinity.

We meet twice a month, and our activities cover a wide range of
topics related to radio communications, such as lectures,
demonstrations, and club operating nights; there is also a keen
interest in home computing among our members.

We welcome members of any age and sex, who have an interest in
Amateur Radio, whether they be licenced amateurs or 'Short Wave
Listeners'.

Meetings: 1st & 3rd Mondays of each Month at 8.00pm
Haymill Community Centre
112 Burnham Lane
Slough. SL1 6LZ
Secretary: Paul Robinson G6DVC. Telephone. Ruslp72125.

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MEMBERSHIP DATA FILE

NAME:.................................... CALLSIGN:................
ADDRESS:................................. DATE:....................
................................. TELEPHONE:...............
................................. POSTCODE:................

BANDS WORKED: HF( ) VHF( ) UHF( )
MODES USED: CW [ ] SSB [ ] FM [ ] RTTY [ ] ATV [ ]

MAIN INTERESTS: (Building, contests, ATV, RTTY etc;)
...................................................................
...................................................................
...................................................................

SUGGESTIONS FOR CLUB ACTIVITIES:
...................................................................
...................................................................
...................................................................

COMPUTER INTEREST:...................... MODEL:...................
[All details held in confidence by the committee]

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