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December 1985

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


ISSUE No.16 DECEMBER 1985

Page 1................Index
Page 2................From the Chair/The Word
Page 3................News & Views
Page 4................Tech Eds Notes
Page 5................Eleven to Ten
Page 6................
Page 7................Radio Haymill
Page 8................Bits & Pieces
Page 9................
Page 10...............GB0TTT
Page 11...............G4PHS Filter Design
Page 12...............
Page 13...............
Page 14...............Club Events
Page 15...............Membership List
Page 16...............Membership Form


Editor................Dave Chislett G4XDU
Technical Editor......Dave Lomas G4XOW
Printer...............Dave Ayres G6GBC
Computer Editor.......Mike Brown G4RAA

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B.B.R.C. COMMITTEE

Chairman..............David Ayers G6GBC
Secretary.............Vacant
Treasurer.............Lynas Newton G6LYN
Member................Dave Lomas G4XOW
Member................Dave Chislett G4XDU

Publicity.............Eileen Chislett G6EIL
Library...............Dave Bentley G6LKZ
Club Equipment........Lynas Newton G6LYN

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

Meetings: 1st and 3rd Mondays each month

FROM THE CHAIR.....

It's that time of the year again. You know, the next Beechlog is
due out! Oh, and I think there is something else
happening............. oh yes, that's right Christmas is coming!!
The time of year when you see hundreds of busy shoppers ( last
minute? ) trying to avoid the 'Brahms & Liszt' drivers being chased
by the Boys in blue muttering about one episode of 'The Bill' and
they start thinking were just like the 'Hill St Blues' boys!!

Well, my family have got organised this year. All but one of us has
chosen and in some cases bought, one "large" present, which the
others merely donate towards via another member of the family-Good
eh? well it don't half make Christmas shopping easy!

Seeing the word 'donate' reminds me to thank everone who helped in
any way with the BBRC ( what do you mean? Thames?!) Telethon. At
the time of writing ( about 8.30pm ) we have collected well over
#400.00. I think this is terrific - well done.

As usual these days, I have to thank Eileen and Dave for their
special efforts in organising the BBRC for this worthwhile charity
event. Perhaps again next year? Talking of next year, I have to
remind everyone that nominations for next year's committee are
required before the second meeting in February '86. See Dave G4XDU
for a nomination paper - and get the nominee to sign it please. The
good news is that I will not be standing for Chairperson next year
and the even better news is that the Haymill Centre now have a full
time Barman! Hic! Mine's a double!!

I must finish on a sad note. As you will see elsewhere, we have
lost one of our "regulars" Bill. He was always a keen and
interested short wave listener. He will be missed by many, but I
trust he now has a Gold 'A' licence.

73 Bill...........David G6GBC
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SPREADING THE WORD

I hope there are plenty of entries in our "Design-a-Logo"
competition so that I can go ahead with posters in libraries etc.
That will be a great way to start the New Year. I'm sending
articles and piccies of our marvellous Telethon effort to various
magazines and local papers, so I hope the extra publicity for the
club helps to swell our numbers in 86. Don't forget to invite any
amateurs or anyone interested in amateur radio to come along to a
meeting. New faces are always welcome. Happy Christmas to all and a
peaceful New Year. 73 Eileen G6EIL

NEWS & VIEWS

First this issue, for those who have not yet heard. On the 22nd
November Bill Perkins died suddenly from a heart attack. Bill was a
long serving member of the BBRC and although never being licenced
enjoyed just listening in to the QSO's of others. He attended most
meetings of the club and though not taking part in many of our
outside activities said he enjoyed the companionship of the club.

I know you will all join me in sending our deepest sympathy to Flo
and her family. The club has sent a card to Flo and a wreath to the
Funeral which was held at the Slough Crematorium on Thursday 28th.
To represent the club Eileen G6EIL attended the Funeral. The club
has made a collection which will be handed on to Flo in due course.
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The rally is on! The BBRC took the initiative and called the old
Rally committee together. The meeting held at Dave G4XOW hammered
out the organising of McMichael '86 as it will be known. Although
the site has not yet been confirmed the show is on the road.
Traders have already been booked and all members of the committee
went away with things to do and organise. The date for the rally is
20th July 1986.
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QSL cards......This week I took delivery of the QSL cards for the
special events station, if you contacted the station during the
event see me G4XDU for your card. If you didn't contact the station
and want a card there should be sufficient but you will have to
wait until the cards have been sorted. While on the subject of
QSLs, I received from the Post Office 500 cards; they did this time
get the call-sign right Hi Hi...
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What is the cost of an evening of morse practice? Well Bruce G4WVX
who, as you may know, devotes two evenings a week to helping others
pass the morse test, found out the other day when an invoice from
another club dropped onto his door mat. Bruce had asked a fellow
amateur to take over from him one evening as he was very busy.
Little did he know that the club the amateur belonged to was to ask
for #3.70. After writing to complain Bruce has now received a reply
saying it was all a mistake. I do hope this is very much a one off
; amateur radio clubs are not a business they are there primarily
to provide a meeting place for people with a common interest. If we
start charging for morse over the air you may soon have to pay for
that DX contact!!!
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TECH-EDITOR'S NOTES

Seasonal Greetings to you all, I only hope my present work
commitment does not stop me from having a well earned rest during
the Christmas period. It has been several weeks of late nights that
seem to have made time fly by.

As some of you may already know I have been dragged on to the
diminishing committee, It is unfortunate that as more events are
now being arranged for club nights, the attendance at meetings is
dropping very low.

I arranged with the other clubs involved with the McMichael rally a
meeting this week, which resulted in a commitment between
ourselves, Maidenhead and Chiltern clubs to continue this event.
The main problem of location is still to be completely resolved,
the previous site is still possible despite the closure of the
McMichael company, but the Haymill Centre is being looked at as a
desirable alternative. All clubs will have more to do this year.

I would like to congratulate Dave G4XDU, for the success of the
Special Event station he organised GB0TTT. It was pleasing to see
that although we were running fairly high powers on HF and VHF no
interference problems were encountered. The effect of good
filtering on 2 meters was evident, in being able to run a portable
T.V alongside and also operate on 70 cms. Thanks also to
Peter G4XGD for the loan of his equipment, I was impressed with the
professional finish given to the home -brew equipment.

MERRY XMAS TO YOU ALL FROM DAVE & ANN
G4XOW

ELEVEN TO TEN

After acquiring a CB rig (a Rotel RVC-220) for a silly price I
decided to modify it to ten metres (well what would I want with a
CB rig otherwise?). I had already modified one 11 metre rig by the
CNC method (cheap'n'cheerful) which gave me a usable rig with 4W
out but no repeater shift. It also has the singular disadvantage of
a dial that works backwards! The major reason for choosing that
sort of mod was low cost i.e. nothing. This time I decided to do a
better job - I wasn't so worried about the cost but I did want
repeater shift and a dial that went the right way!

Having seen several add-on boards advertised which work with the
so-called unmodifiable rigs using the Sanyo LC7137 series
synthesizer chips I bought a 10M mod board kit from R.Withers
Communications.

There are several different ways of making these chips work away
from their design frequency. The most popular is to mix the
synthesizer output with an oscillator of the frequency shift
needed. (e.g. 27.9 + 1.7 = 29.6) The problem with this method is
that the rig still tends to work at 27.9! Admittedly sensitivity is
down but with CBers so numerous there are definite problems.

The FBX-RWC mod board uses a new technique - a high speed logic
circuit goes between the VCO and the synthesizer, it subtracts
pulses from the VCO output and 'cons' the synthesizer into
believing that the VCO is at a lower frequency. This technique
takes advantage of the fact that the synthesizer chip doesn't
really measure frequency, it merely squares up the signal and then
counts the number of pulses in a given period of time. Obviously
the VCO feeds the RF circuitry direct, at it's full frequency.


THE HARDWARE

The kit contained the following:-

1 P.C.B.
6 I.C.s
1 Transistor
1 Zener diode
10 Resistors
10 Capacitors
7 A4 Sheets of instructions & diagrams

Which doesn't seem too much work until you a) count the legs and b)
find out that the P.C.B. is double sided and most components need
soldering both sides!
€PE
Ease of construction gets about 5/10. Although the I.C.s are easy
to fit it is necessary to cut a leg off one due to the P.C.B.
design! Most of the resistors and capacitors were longer than the
spaces between the holes, two components have to be soldered
together and tacked under the board, and in one or two places there
are two holes for three wires. Not the most professional of designs
but, for all that, it does the job! A fine tipped, low power
soldering iron is vital as the soldering involved is complicated by
the high packing density. Ideally an iron with a thermostatically
controlled tip should be used.

FITTING

Fortunately the Rotel RVC-220 seems to use the chassis that this
board was designed for and fitting was very easy. The spacing
between the holes in the RWC board is the same as the spacing
between the self-tappers that hold the main P.C.B. in the rig. Two
P.C.B. pillars later and the board was in place.

Wiring up the board is also quite easy one capacitor has to be
removed and 6 wires soldered to the main board near the
synthesizer. In fact the Rotel has a complete set of unused
component holes around the chip so wiring the board up is a doddle.
The only remaining job is to drill a hole and fit a repeater shift
switch before the tuning up can begin.


TUNING UP

About the worst aspect of the instructions is the lack of
information on how to retune your rig. There are about a page and a
half of tips on how to go about it but these are mostly of a very
general nature. I'm not too sure what could be done in the way of
instructions as there are a vast number of models that can be
modified with this board but the kit isn't cheap and tuning the rig
up can be more of a problem than constructing the board (especially
if you spend #5 more on the built board!). In fact the RWC ad
mentions "full fitting instructions".

You may have gathered from the foregoing that I had problems!
Although the rig is now working on 10M I'm still not totally happy
with it. The VCO and all but one of the tuned circuits were easily
retuned. The odd tuned circuit refused to peak at the new frequency
at first but was pulled in by adding a capacitor. Unfortunately the
gain is now low (probably because the Q of that tuned circuit is
low) and the rig only gives 2 Watts out. Guess I'll have to connect
my 25W linear!

73, Mike Brown

RADIO HAYMILL

Slough's own and newest independent radio station got under way,
but was forced to close down after only 12 Hours.

And it came to pass that the Telethon was underway. The hard work
started at about 11 am deciding on the final location of and
erecting the aerials. Once this had been done what does one do with
all the cables? Well, it just so happens that there was this window
and a mallet when one of these items is used to strike the other, a
small hole appears in the wall and hence cables can be passed
through with some ease. ( I wish it was as easy as it sounds ) The
equipment could then be put in place and some checks could be made.
Now, I'm not one to gossip, but someone in our group was trying to
check the SWR when his rig was switched onto SSB the result of
which did not look very good. However, this was overcome
eventually, and the station came under starter's orders.

Things were going well up to about 1.30 am, people having a good
nose at what was going on. Even our friends at St John came along.
( Nobody is sure whether that was business or pleasure ) But all
good things come to an end, and the remaining operators were
starting to suffer the loneliness of the quiet airways. And so it
was that Slough's newest independent radio station folded and was
taken away. The evening was sucessful though, with a little more
than #8 being thrown into our bucket and with sponsorship forms
looking to bring in about #500.

The final figures will be announced as soon as they are known.

I would like to thank everyone who has helped in any way to help
the club in its financial struggle to gain support for those who
really need it.

Here endeth today's lesson!!!!!!!

Lynas G6LYN

BITS'N'PIECES

MISINFORMATION

The RSGB have changed the telephone number of the Databox, their
Prestel compatable information service. It can now be reached on
Potters Bar 52242. Hopefully Dave will have managed to reproduce a
page or two from the Databox for you to see here. Obviously the
information is reproduced courtesy of the RSGB!

DATA & REPEATERS

The U.K.F.M. Group (Western) have had a new type of repeater on the
air since the 5th of February. GB3MT, on RB12, is a RTTY repeater
is located at an I.B.A. transmitter site 15 miles from Manchester.
Any 50 baud RTTY appearing at the input is repeated, providing it
starts with the correct sequence of 3 CR's and GB3MT DE GxXXX
(insert your call)! The repeater group will shortly be adding the
facility of 300 baud ASCII, using V23 tones (1300Hz mark & 2100Hz
space) and are also looking into adding some form of message
storage facility.

I have to applaud the group for the work and effort that they have
put into the project and will look forward to hearing more about
how it works out.

It has to be said though that a) they are rather getting away from
the concept of having repeaters for mobile stations and b) the idea
of a conventional repeater for data is a little passe. There can be
little doubt that some form of packet system is the most efficient
way of transmitting data over an RF link. The much vaunted (but
expensive) AX25 protocol is a start in the right direction and once
in general usage it will be entirely feasible to have a single
channel repeater, or DIGIPEATER.

As the data rate is much higher than either RTTY or even 300 baud
ASCII there are long gaps in between the short bursts of data. Thus
it is possible for the repeater to use the same frequency as the
originator while still leaving gaps for other stations to break
in.

Looking at it logically it would be more sensible to have a new
type of repeater for data. The only reason for full duplex
operation is if there is a requirement to relay speech or other
signals with a high (>50%) duty ratio.

SINCLAIR=RFI?

If a Spectrum can wipe out all R.F. communications when it isn't
even a transmitter, what chance have we got if Uncle Clive
introduces his promised #99 cellular telephone?


Mike G4RAA.


P.S. I wonder if Dave has found out how to print a # sign this
time????

GB0TTT

This issue of Beechlog seems to be full of the Telethon but I am
sure that a few of you may be interested in the whys and wherefores
of a special events callsign.

The issue of the letter of variation to your licence comes from the
RSGB these days, and proved to be easier to get than I thought. It
was necessary to apply at least four weeks before the licence was
required, and in the case of GB0TTT we only just got our
application in in time. The only major requirement for the licence
is that you personally are licenced for the the type of licence you
are applying for. The RSGB cannot guarantee that the GB call you
want is available so alternative ones are requested. Both 2 letter
and 3 letter GB calls are available in GB0, GB2, and GB4. Class 'B'
in 3 letter only GB1, GB6 and GB8. Once issued the licence is valid
for 31 days for use at the specified location only, although
simultaneous operation on any band is allowed. The call-sign will
not be re-issued to another amateur for 18 months but of course we
could use the same at any time by just re-applying.

Generally, the special events station should be open to the public
or be of interest to other radio amateurs. The sending of greeting
messages by non-licenced people are now allowed, not only to UK
licenced stations but to stations in Canada, USA and Falklands.

The RSGB was concerned about the fund raising aspect of GB0TTT.
This is why we were quote 'privately sponsored on the number of
calls made' The Department of Trade will not allow canvassing for
monies, pledges, sponsorships and the like over the air under any
circumstances.

The RSGB proved very helpful throughout the planning of the special
events station, although I did receive two letters of variation to
my licence, two sets of publicity material, and two letters with
the application forms for the licence!

Dave G4XDU/GB0TTT
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May I take this opportunity of wishing you all a very

Happy Christmas

and a Prosperous New Year
Dave G4XDU Editor.....

EVENTS WINTER/SPRING 1986

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16th December.................Film Evening (RSGB+BBRC)

6th January..................Natter Nite

20th January..................Junk Sale

3rd February.................G0DCQ Aerial(mobile) measurements

17th February.................G3VA Pat Hawker

3rd March....................AGM

17th March....................G4XMJ E.N.G.

7th April....................
21st April....................Power Supplies

3rd/4th/5th May..................Spring DX picnic

19th May......................
2nd June.....................
16th June.....................

20th July.....................McMichael '86 (Rally)
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Talks planned but not confirmed: 6mtrs operation, PMR equipment
Community Radio,UOSAT 2,T.V.
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MEMBERSHIP LIST

001 Eileen Chislett G6EIL Md.25720
002 Dave Chislett (Editor) G4XDU Md.25720
003 Tony Alderman G4LQD Fc.3286
004 David Ayers (Chairperson) 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 (Computer Ed) 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
025 Dave Bentley G6LKZ Sl.25101
026 Kevin Hadley G4HDK 0734 731026
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 G6DVC Rslp.72125
043 Bruce Gilson G4WVX Bn.64415
047 Peter Melling G1LHU Sl.29025
048 Mike Gathergood G4KFK 0895 834167
049 B. Mockett G1DSI ********
051 J.Sanders G1LMI Sl.27150
050 T.Kay G4ZTK Bn.4255
052 D.Slatter G6WZC Sl.821862
053 J.Slatter SWL Sl.821862

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Please note if your details are not correct please 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
Publicity Officer Eileen Chislett Tel:Maidenhead 25720

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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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