Compi by Issue number 14 Phasing receivers Direct conversion receivers have been popular wit the ORP enthusiasts for some time mainly becaus of their simplicity and they appear to work quite we( with one proviso - they suffer from imag interference. Phasing type receivers have no enjoyed quite so much popularity because they ar thought to be complicated to build and sorn people think they are more difficult to design tha filter type receivers, They are, however, muc cheaper than filter type receivers. Tim Walfor G3PCJ has done a lot of work trying to show tha phasing receivers are not difficult to design. One his early efforts was for a phasing receiver/doubl sideband transmitter for 80 metres. He then went on to think about CW (and this includes CCW). If oni these modes are considered most of the problems with design disappear and quite simple circuits can be used. A 40 metre receiver for CW only was described recently in RadCom. If any non-members would like a copy of the notes please ask - there is only one page but it contains ail the details you require. The notes regarding the design in RadCom are not too easy to follow. At least I didn't make much sense of them until I asked Tim for more details which he obligingly provided. If you are happy with a frequency of 734 Hz you can just copy the design as published but this frequency is not too convenient for CCW. In my case 500 Hz was needed and 1 KHz would be needed for the original CCW designs published in QST. I will prepare a set of notes showing how to calculate the various resistor and capacitor values if there is sufficient interest. Briefly the circuit consists of an r.f. ampiff ier followed by two balanced mixers. The local oscillator at the required frequency is fed to the mixers through 45 degree phase shifting circuits, each shifter consisting of just one resistor and one capacitor. The signals from the two mixers are passed through various audio filters1followed by two audio all- ass filters which introduce a lus 45 degree shift in one channel and a minus 45 degre shift in the other at the desired frequency. Th outputs are combined in an op-amp. which provide further filtering before being passed to a small audi amplifer. Three transistors and five small i.c's. ar used. There is no reason why the circuit should no be built for other frequencies provided the r.f phasing circuits are modified so it is quite possibi to build for 6 MHz and then add converters such a those available for the White Rose receiver t operate on other bands. Tim is at present workin on a improved 80 metre design which he hopes t be able to make available as a kit for about E45. Operating frequencies John Stockley has suggested that we continue t use 7.030 MHz but use 14.060 MHz for 20 metres. As it is likely that direct conversion (and perhap phasing) receivers will be popular this will enabl operation on two bands by simply adding a multiplier to the oscillator. Just a suggestion but it looks a sensible one. Notes from the U.S.A. Cliff W6HDO has sent some notes on CCW activity in the States. There is a lowband beacon operating on 179 KHz in California using the callsign MPM. One would expect-a station to have been allocated a frequency of 180 KHz in Europe and, when I listened today, there was one there so it is unlikely that we should hear MPM here unless things are much quieter during the night. MPM transmits continuouslysendingBPSKforfiveminutesfollowed by CCW for five minutes and the CCW has been copied in Hawaii. Cliff also states that QRP CCW is transmitted every night on 3.540 and 7.040 MHz but I am afraid I do not have any definite times at the moment. Clover news Bill Henry has brought me up-to-date with regard to the Clover project which he and Ray Petit are hoping to get on the market. Things are going a been made to the FCC. The Clover patent has been filed though this resulted in a six week delay. Since my last notes a new name has appeared - Summer Clover. Two of these second-generation prototypes have been built and others are on the way. These units are "no-holds-barred" versions and are fairly large measuring 17" x 10" x 3" and, if sold, would be expensive. So a new version using a plug-in board for IBM compatible computers is now under development. As Clover needs a computer to work this seems to be the obvious way to go especially as it will reduce the cost considerably. It is hoped to have this new unit introduced at the Dayton Hamvention at the end of April 1992. Ray Petit's tests of Clover are made on 10,000.100 KHz if you would like to monitor this frequency though I cannot give you any indication of what time to listen. SEPAC I have always been interested in anything out of the ordinary so I assume most of you will also be interested - otherwise, why did you become interested in CCW? Some more notes from Cliff W6HDO relate to SEPAC which is coordinated by Mike Mideke W86EER. This has nothing to do with CCW but I think you may be interested to learn about the project and may like to take part. SEPAC is a small part of the Atlas 1 mission and concerns the part known as F07. SEPAC's electron beam will be modulated by a progression of twenty frequencies between 50 Hz and 7.04 KHz. Each frequency will be used for 100 mSecs. Three beam power levels are to be used between 1.45 KW and 6.2 KW. The whole sequence takes five minutes. During this time Orbiter will have traversed about 21 00 Km in a generally north/ south path pretty well covering North America. Ground stations will listen and everyone hopes they will hear something. To receive the signals an E-field receiver is needed and a simple design has been produced though any broadband VLF receiver can be used. A recorder will be needed to record any signals heard. It is hoped that a complete package consisting of the receiver kit, instructions, demo tape and follow-up mailings will be available in December and will cost $49.95. At least 1000 kits should be available, Everything is a little hazy at the moment and no-one knows what will happen or whether anything will be heard. I did wonder if there is any possibility of hearing anything here in the U.K. and have written to WB6EER for more details. Since writing Cliff tells me that there have been ten Italians who have signed up so someone in Europe is hoping to take part! All I have at present is a two-page news update which I can copy for anyone interested. Mailing list AKOB GOOKX G4DWC NQ6Z DF3CT G3CCH G4FKH OEIATU DG7YFW G3CWl G4GMV OE1 KYB DJ3AM G3EGQ G4HCC OE6VVTD DJ4SB G3FMW G4LRA OK3EW DJ7HS G3GRT G4SYC SIV16FPC DK110 G31RM G4VSO VE3DPB DL2AAX G3JPP G4XOP VE30SE DL2RW G3MBN G4YND W6HDO EA8YU G3RHI G7CBX W7GHM GOFVE G3SBI GWOKZW WUOI GOHIN G3TFV GW3DEX Y23VH GOIKS G3TMQ HB9DDO Y24XO Q01YY G3XHQ K6ARE ZF1 HJ GOMIF G3XVR K9GWT 3A2LF IBM computer program I recently found a Philips computer program for designing phase-locked loops using the 74HC4046. It is public domain so if anyone wants more details please ask. Copper clad board One of the American magazines I see regularly is Electronic Design in which there is a column every issue by a gentleman called Bob Pease. In a recent issue he was saying how useful copper clad board can be. I haven't tried it but he says you can cut the stuff with tin-snips. I much prefer a fretsaw which makes an excellent job and one blade lasts quite a long time - if you don't break it. Boxes can be made and he also uses two pieces of board soldered together as a baseplate and panel. Triangular bits of board are soldered at each end to support the panel. For a prototype I can see this is a good idea but I don't like the look of the finished product. However, one piece of board with the components mounted can fit inside a screening box made of board and makes a very nice module. He uses strips of board glued to the base as power rails and small squares glued on as mounting points. Here I prefer to drill a hole, clear away the copper round it and push a terminal pin through. He uses wire-wrap i.c. holders with the pins bent over for connections. The earth pins are left longer and bent over and soldered to the base. Other components hang in the air. Circuits built this way are claimed to be good and are often better than obtained with the neat p.c.b. final product. 73 Peter