INDEX AND ACKNOWLEDGEMENTS ISSUE No.12 DECEMBER 1984 MERRY CHRISTMAS AND A HAPPY NEW YEAR. Page 1................Index Page 2................From the Chair Page 3................News & Views Page 5................Homebrew Page 7................BackTrack ................For Sale Page 8................Tech-ed Notes Page 9................Noise Bridge Page 10...............Questionnaire No.1 Page 11...............Questionnaire No.2 Page 12...............Membership List Page 13...............Membership Form (Use this please when paying in January) Editor................Dave Chislett G4XDW Technical Editor......Gerry Thorn G8VNA Printer...............Dave Ayres G6GBC **************************************************************** 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 **************************************************************** FROM THE CHAIR As I write this edition of " from the chair", the club is facing a time of decision and, most probably when you read this copy of Beechlog, the choice will have been made as to whether we move to Haymill School Community Centre or not. I would like to take this opportunity to thank Martin G4WSW for the assistance he gave me at the various meetings we attended at the centre, and also to the rest of the committee for attending a meeting at short notice. Another event that should be taking place at the time of reading this is the Christmas dinner, and I would like to wish you all a very pleasant meal. Greetings also to our friends of the Home Counties T.V. Group who will be joining us for the third time. As Chairman of this club, it is my responsibility to make sure any club events that are organised for the benifit of the members are properly coordinated. It is therefore very disheartening to see three events this year being cancelled through lack of support. I refer to the treasure hunt, club contest and the last foxhunt on which only the Fox G6DRP and myself turned up. Some members say to me that their non-attendance was due to the fact they didn't know about the event. These people are obviously licenced under false pretences as it is a prerequisite of the RAE to be able to read and reading Beechlog is a good way of finding out about club events. (Not so in this edition as no details of next years events have been received. Ed.) Anyway, enough of this divisive talk and on to more cheerful things. The DX picnic was a great success with more people than last year and a good time was had by all, not least Paul G6DVC who thought he had a 70MHz contact in Scotland which turned out to be Mike G4KFK in another tent. I think the resulting laughter could be heard in Slough. I must end by saying that this particular year in the club's history has been very enjoyable for me in spite of some particular low points and I look forward to next year with the expectation of still better things to come. It only remains for Janet and me to wish you all a very Merry Christmas and a Happy New Year. Dave G6LKZ ------------------------------------------------------------------- Just recently I found out why John G4HMG and Diana G4MVV have resigned from their activities in amateur radio locally. They are about to move out west to Zummerzet. Amateur radio in Slough will be the loser, both John and Diana have made a considerable contribution to both the BBRC and the ATV group. I do hope that GB3SN will still be in reach so that the early morning net will survive, I think they may have 145.2 to themselves down there. I think you will all join me when I wish them the very best in the new QTH. I do hope, John and Diana, that you will visit the club should you visit this area in future. ED. NEWS & VIEWS If you are having trouble with the Slough Planning Office in respect of putting up aerials, a snippet of information in the local rag may be of interest. Concerning the proposed Cellular Radio mast in Britwell a planning officer was quoted as saying that if the mast caused interference to radio and T.V. it was the fault of the radio or T.V. set! This of course is what we have been telling them for years. It's funny when big business steps in everyone gets the message? ------------------------------------------------------------------- As I said last issue your scribe is now up on Prestel. For anyone who is interested my mailbox number is 075321896. B.T took their time in getting me onto the Mailbox service. After repeated requests via Prestel itself (it should have been automatic anyway) to get onto the main computer so that I could deposit and receive mail, I decided to use voice and contacted them direct. Their reply was ' It all happens Nationally from Monday Sir!' Pity, I thought, that it could not have been explained on the normal computer I use, which would have saved me lots of phone calls. Or is this how they make that big profit each year! Well it has happened, and the other day I received my first piece of electronic mail. ------------------------------------------------------------------- On the subject of mailboxes. Have any of you listened in to the RTTY mailbox on 145.200 run by G4VRK near Guildford. While tuning around the band I came upon it by accident. I listened for a while and then decided to have a word with G4VRK as to the legality of the system. He assured me all was in order. However, I still felt the leaving of mail for others was against the licencing reg's. A phone call to the RSGB cleared the problem up-- it was illegal. Since that time I've been unable to raise the station by phone. I do hope he has got the message by now. On the same subject, while trying to contact G4VRK another RTTY station came up on top of me repeating 'The quick brown fox....' neither was there a callsign by RTTY or by phone. I think he was complaining about the use of the station but he/she was as illegal as the mailbox: I doubt if he/she thought about that! ------------------------------------------------------------------- FOXHUNTS 1984. The foxhunt season for the club is now over and this year the winning teams were as follows: G6EIL assisted by G8XCK..........April G4WVX............................June G6LKZ............................August G6DRP............................September The DF mug will be engraved with this year's winners and will be on show at the AGM. ------------------------------------------------------------------- NEWS & VIEWS At long last the Haymill school will be opening its doors to local clubs in this area. It may be of interest to note that the first meeting of the users group was attended by Eileen when she was Chairman. By the time this issue comes out you should have had an EGM to decide whether to move the club to the Haymill Centre. I think the local council deserves a cheer for moving the project along so quickly! ------------------------------------------------------------------- A recent article in the "Leader" free newspaper about the club's Open Day, gave quite the best write-up on Amateur Radio I've seen for a long time. The chairman was seen beside the sign on the front door of the club HQ with handie-talkie, the text bore non of the usual embellishment put in by other editors. In a recent article in the "Slough Observer", your scribe was called a CB fanatic, and the club had CB added to its name. All of this was, I expect, added by the editor who, I might add, did not have the courtesy to reply to a letter sent in to complain about the additions. I must say that if the "Slough Observer" is worried about losing readers and advertisements to the free papers then it only has itself to blame. Well done the Leader! ------------------------------------------------------------------- I have received a letter from the owner of Brimmer's Farm, thanking the club for the monies sent. I asked if it would be possible to hold an event in the springtime as well as in the late summer as usual. Although he could not give us the same field because of being laid down to grass he offered no objection. If sufficient people come forward and say that they wish to take part in a springtime event we will arrange a suitable date. Please let me know if YOU wish such an event and don't leave it to others. ------------------------------------------------------------------- In this issue of "BEECHLOG" we have printed two questionnaires. Number one is concerned about this very magazine. We get very little feedback from YOU and although it usually follows that if nothing is said then we must be giving you what you want, it would be good to know your opinions. Although we have asked for material to go into the pages very little ever comes from those not on the committee or involved with the magazine, I sometimes think it's just a mouthpiece for yours truly! (This is true!SPELCHEK) The second questionnaire is about computers. All information will be handled in strict confidence for obvious reasons and there is no need to give a callsign if you don't wish to. Please fill in these and return to Mike and myself and we will try to ensure that the magazine and activities of the club reflect YOUR views. ------------------------------------------------------------------- HOMEBREW - IS IT WORTH IT?...... It was just over a year ago that a project to build a VHF/UHF mobile transceiver came to mind. I had built several transceivers before, both for 2mtrs and 70cms and was currently running a well modified Wood&Douglas 70cms rig in the car. The car was becoming a mess inside with rigs and power amplifiers all over the place, it was also becoming unreliable with constantly being removed at night and installed in the mornings. The final straw came with the converted CB rig for 10mtrs. Something had to be done! A 2mtr Wood & Douglas rig was purchased off Ted. It was of a very early vintage as I was later to find out. The 70cms rig was removed from the car for the last time. The time had come to put them together. If you were at the Open Day this year you would have seen the results of a year's hard work. The rig is now in daily use on both bands and although, as with all good projects they are never really finished, I am pleased with the performance. Only a small intermittent fault and not quite the Japanese audio modulation still remain to be sorted out. Installing two separate rigs into a box small enough to install in the average motor proved quite difficult. The decision was taken early to also include the power amps and also pre-amps to boost the overall performance. The control panel was also to control both bands with just a simple switch to change from one to the other. Although cross band working was thought about it was decided that talking on one band when driving was difficult enough without that added distraction. Consulting the circuit diagrams showed that it would be possible to control the two synthesisers simultaneously, and that a single microphone amp and modulator could be used. When the time came to wire up the 2mtr synthesiser it was discovered that the boards bore no resemblance to the circuits I had. A phone call to Wood&D brought the circuits free and by return of post. At this time depression set in as it seemed that extensive circuitry would be required now to control both synthesisers. A look through some of the data books brought the answer with some analogue CMOS switches. Converting the transmitters was not needed only DC switching i.e. Supplies. The receiver side had been tried before and although the RF sides were separate they combine before the discriminator and so use the same squelch and volume and audio output. DC switching of supplies changed the band. Wiring the whole rig up proved to be quite easy as I had spent some time putting the various boards in the right places. All that is left now is to make up some new small PCB's to tidy up some of the mods that had to take place. Also to tidy up the other small points mentioned earlier. Well, after reading all this, you will possibly be asking, was it worth it? As this is being written there is only one other mobile rig on the market that offers both bands in one box and that costs over #400. The cost to me probably has been around #250; a reasonable saving but most of all the fun of getting it on the air, and using a unique rig that is tailored to my needs has made it very worth while. Dave G4XDW BACKTRACK FINAL As 1973/4 progressed, club membership declined sharply, and several meetings discussed the possibility of winding up the club. Typically, no decision was made! Happily things improved and during 1974/5 the average attendance was noted at 9.76. However, by January 1977, fears were expressed about the size of the club getting out of hand, but "Natural growth and wastage would control numbers" so said the committee. a cull perhaps being the alternative..... In any event the club was threatened by huge rifts in the membership, and a letter of censure was sent to various members. The final paragraph reads "BBRC exists to foster interest in amateur radio, the primary purpose of which is to promote goodwill by communication. Our club belongs to us all; there is no room for splinter groups, cliques or divided loyalties. We have had a moderately successful year. Only by our unselfish devotion to a common objective can we maintain this progress." After this serious situation, the club seemed to return to normal rapidly and in April the committee decided to "...purchase a 7lb box of broken biscuits from Bracknell Market." I am assured they have now been consumed, if indeed they were ever bought, but they may of course be hidden in your Christmas Pudding. Merry Christmas, readers Eileen G6EIL ------------------------------------------------------------------- FOR SALE TR2300 2Mtr Tranceiver complete with case/nicads, battery charger and power supply. 10watt PA and Mobile Mount. #80 Contact Dave G4XDW Sl.21896 SME Pickup arm Series 11 Detachable headshell+ extra headshells #20 Contact Dave G4XDW Sl.21896 DATA Cassettes C15 Brand new 38p each BASF CR02 C94! " " #1.15 each Contact Mike Brown G4RAA ------------------------------------------------------------------- TECH-ED'S NOTES Not much to say this issue as I have been very inactive radio wise. One thing I have been trying is an ASCII transmit-receive programme for the BBC micro which enables all the normal numbers and letters to be sent from the cassette port at 300 baud (using the standard CUTS tones of 1200 and 2400Hz). At first I thought that there would be little activity but that proved not to be the case, most evenings there are several stations transmitting ASCII or even Packet Radio in the all mode section around 144.625 MHz. If anyone has ASCII transceive programmes for their micros let me know and perhaps we can arrange a contact, who knows we may even be able to hold the club net on ASCII. Also in this issue is a questionnaire from which we hope to get some feedback from members on the contents of "BEECHLOG", so please let us know if you feel there should be more technical articles or perhaps they should be of a more general nature on say local events or problems that members have encountered on planning permission or tvi etc. Please let us have your ideas or articles so that we have something to put between the front and back covers! ********************************* * A very Merry Christmas to all * ********************************* Gerry G8VNA =================================================================== NOISE BRIDGE CIRCUIT NOISE BRIDGE This name is used to describe an RF bridge which is energised from a wideband source of noise obtained from a zener diode operating at a low current level. The frequency range of this white noise extends up to 200MHz. The noise source which is followed by a three stage wideband amplifier to raise the noise level to around 100 microvolts enables a receiver to be used as the null indicator. The noise output is applied to a quadrafilar-wound toroid providing two arms of a bridge circuit which has a variable resistor in the third arm to obtain a balance against the aerial in the fourth arm. When the noise across the resistance arm equals the noise across the aerial the bridge is balanced. Co-incident adjustment of the receiver tuning and of the variable resistance is necessary to discover the point of minimum noise, which occurs at the resonant frequency of the aerial. Toroid cores can be obtained in several grades and ferrite suitable for the frequencies of interest should be chosen. Dust-iron cores are also suitable and may be more readily available. The winding may consist of four lengths of 30swg enamelled copper wire twisted together to form one multistrand length: five or six turns are then spaced around the circumference. The four wires are are divided into two pairs and each pair connected in series so that the end of one wire is connected to the beginning of the other. Check that the two series pairs are insulated from each other. Lead lengths from the transformer to the bridge should be kept as short as possible and the layout symmetrical. The variable resistor should be a good quality carbon type with low capacitance and linear track. A scale should be fitted and calibrated by means of an ohmmeter. OPERATION With a receiver connected to the centre point of the secondary winding and a resistor or 50 across the aerial terminals, a noise minimum should be obtained when the variable resistor is set at the value of the test resistor. With an aerial instead of the resistor connected to the socket a noise minimum should be found when the receiver is tuned to the design frequency of the aerial, and should approach a null when the resistor is set to the characteristic impedance of the line. If the frequency is not as expected , the length of the aerial needs adjusting; if the resistor value is not that of the line, the aerial is not matched to the line. The ratio between the impedance and measured resistance gives the VSWR. Gerry G8VNA QUESTIONNAIRE No.1 CALLSIGN: .................. NAME: ........................... DO YOU THINK BEECHLOG A GOOD IDEA: ................ Beechlog is published every three months would you like it more often, or less often. MORE OFTEN [ ] NO CHANGE [ ] LESS OFTEN [ ] DO YOU READ THE FOLLOWING ITEMS: YES NO From the Chair [ ] [ ] News & Views [ ] [ ] Technical Ideas [ ] [ ] Tech-Eds Notes [ ] [ ] If you answered no to any of the above would you like them replaced by something else. Please give ideas for topics. ................................................................... ................................................................... YES NO Do you think the technical items are useful [ ] [ ] Would you like to see more [ ] [ ] Would you like more theory [ ] [ ] More practical [ ] [ ] More construction [ ] [ ] Is the members list useful [ ] [ ] Is the diary of events useful [ ] [ ] Have you contributed anything to Beechlog. [ ] [ ] Have you anything you wish published. [ ] [ ] If yes to the above please outline it below. ................................................................... ................................................................... Please hand this back to Dave G4XDW. Thankyou for taking part. QUESTIONNAIRE No.2 1) Do you own a computer? YES [ ] NO [ ] 2) If yes, what model? ......................................... 3) Do you own or want any of these? OWN WANT Printer [ ] [ ] Monitor [ ] [ ] Disc Drive [ ] [ ] Floppy Tape (Microdrive) [ ] [ ] Modem [ ] [ ] RTTY Terminal [ ] [ ] 4) What programmes do you own or want? RTTY [ ] [ ] Packet Radio [ ] [ ] Morse Tutor [ ] [ ] Morse TX/RX [ ] [ ] ASCII TX/RX [ ] [ ] HF Propagation Predictions [ ] [ ] HF Aerial Design [ ] [ ] VHF Aerial Design [ ] [ ] Transistor Equivalents&Data [ ] [ ] Basicode [ ] [ ] Logbook [ ] [ ] Beacon Data [ ] [ ] Repeater Data [ ] [ ] 5) Have you used any of these Morse aids? Records [ ] Cassettes [ ] Computer [ ] Morse Tutor [ ] Slow Morse Transmissions [ ] Any difficulties with the above? ................................. .................................................................. Please return to Mike G4RAA all details held in strictest confidence. 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 010 John Duel G6CHO GX.84366 011 Dave Lomas G4XOW Lt.Grn.2847 012 Ann Lomas SWL Lt.Grn.2847 015 John Betts G4HMG Iver.651652 016 Diana Betts G4MVV Iver.651652 017 Gerry Thorn (Tech-Ed) G8VNA Wey.52775 018 Caroll Thorn SWL Wey.52775 021 Peter Harman G4XGD Sl.28826 022 David Tanswell G6LAU Iver 652412 024 Brian Page G1BAP Coln.5029 025 Dave Bentley (Chairman) G6LKZ Sl.25101 026 Kevin Hadley G4HDK 0734-731026 027 Graeme Platts G4XOF Sl.78495 028 Ian Rae G8BUE Sl.20757 029 Graham Stewart G6HEJ Fc.5897 030 Richard Ashberry G6RTM Sl.46012 031 Ted Swaby G4XOE Sl.75099 033 Dave Hemmins G6DRP Bn.64436 034 John Williamson G4XJN Sl.24008 035 George Wall G4XPR Fc.5954 037 Dave Clifford G6UFV Bn.64567 038 Paul Robinson (Secretary) G6DVC Rslp.72125 041 Martin Heaver (Committee) G4WSW ******** 042 Ron Howlett G1BSQ 0895-445006 043 Bruce Gilson G4WVX Bn.64415 044 Mike Thomson G6WNU Bn.62328 045 Peter Phelps ***** ******** 046 Janette Phelps ***** ******** 047 Peter Melling SWL** Sl.29025 048 Mike Gathergood G4KFK 0895 834167 049 B. Mockett G1DSI ******** ******************************************************************* 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. ******************************************************************* 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 St John Ambulance Brigade HQ Burlington Road Slough. Secretary: Paul Robinson G6DVC. Telephone. Ruslp72125. ******************************************************************* MEMBERSHIP DATA FILE Membership Renewal 1985. 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] *******************************************************************