CCW NEWS Issue number 7 Compiled by G3IRM August 1990 Cloverleaf 10. 1 00500 MHz The main Item of news this time Is the successful completion of tests of Clover. This has been fully reported In QSX for July and, If you would like a copy, you will find It listed In the Information section. Ray has sent me a copy of the diagrams for a suitable transceiver for use with CCW or Clover and the following Is an almost complete copy of the notes which accompany the diagrams. These will permit the experienced home builder to assemble a transceiver suitable for CCW and Cloverleaf operation on the bottom end of the 30 meter band. It has been designed for high dynamic range (SL6440C high-level mixers), exceptional I.f. selectivity (9-pole 300 Hz crys- tal filters) and ultra-stable operation (local and b.f. oscillators phase-locked to a standard). It Is kept as simple as possible and the frequency plan makes use of Inexpensive microprocessor clock crystals. It Is also designed with a thought to the future, when Its single-frequency stabilized h.f. oscillator can be replaced with an 18-1 9 MHz frequency synthesizer. It Is recommended that the unit Is built as a set of shielded modules connected by r.f. cables. All signal and oscillator paths have been mat- ched to 50 ohms for easy connection between units making It easy to build and check each unit Independently of all others. The crystal filters are based on the Cohn design. Unlike most I.f. amplifiers this one has no a.g.c. - all the compensation being provided by the Clover t.n.c. The audio output varies from about 30 microvolts to 1 volt. The Input and output filters have a bandwidth of about 1 MHz, a 2db Insertion loss and very steep skirts. Alignment Is simple and requires a 10.5 MHz r.f. signal and an oscilloscope. It Is all described In Ray's notes which come with the diagrams. A 16 MHz oscillator provides a signal required by the optional future frequency synthesizer, the 8 MHz b.f.o. signal and the clock signal required by the Clover t.n.c. Separate switch- able b.f.o. outputs are provided for T/R switching. The 2.1 MHz local oscillator uses the same basic scheme for the oscillator and phase detector but uses a divide by 21 counter to Publicity The RSGB has at last written to me regarding Ray's Cloverleaf article just In time for a revised article to be published In QEX! Some- thing tells me they will not now Include the article In RadCom though It would appear that Pat Hawker may make some mention In his column. A second note from me about CCW was also Included In the July QEX. There Is a paragraph about Colin's keyer chip In Technical Topics In RadCom for August where we got a mention. New Members DJ7HS Ernst Schoedor, Hannover DL2AAX Wolfgang Seebauer, Lagesbuettel DL2NI J6rg Logemann, Lalchlngen DL3YDZ Klaus NaB, Warendorf G3EGQ John GrIffen, Hayle G3.1 PP Ted Price, ShurdIngton OE1 KYB Kurt ArIt. Wien PA3 EZ I U do Tel I j ohann, Katwl j k Y23VH Lutz Bergner, MOhlanger provide the signal for the phase detector. The r.f. output from the high-level mixer should be set to about 10 dbm and be followed by a small linear amplifier. This Is not described In the notes but there are plenty of suitable designs to be found In the amateur magazines. Suitable sources for the components follow. With the notes I send there will be Included a list of suitable sources for the U.K. There are some components which are difficult to find and the first builders will have to carry out a little experimentation with what Is available. However, Ray hopes to have a set of circuit boards and complete kits available In the near future and should be able to supply those parts which cannot be found here. May I ask those of you who would like to join me on this side of the pond to lot me know and I will keep you up-to-date on availability of boards and any now developments. As the next News will be not be for another two months and a lot can happen In that time, those who write can have the latest from me at any time. But before you decide to join In the Clover activity please read the article In OEX for more details. Clover - what is required, The transceiver diagrams available will get you on the first Clover frequency but will not enable you to operate. In addition to the transceiver you will need a stable frequency standard on either 1 or 2 MHz together with an RS232 terminal or a computer running terminal soft- ware. The final Item Is, of course, the Clover t.n.c. Itself which Ray hopes to be able to make available In the States for about $300 which Is comparable with devices for most other modes. I have no further details of this at present but you must remember that there will be Import and value added taxes chargeable In the U.K. and, no doubt, similar taxes will be payable In other countries. Once again I will keep those Interested Informed. Bi-phase,a Shift Keying Stan Wilson AKOB has sent me some Interesting extracts from a newsletter called The Low- Down which caters for those Interested in experimenting with the low band available In the States. From what I can gather the band runs from 160 KHz to 190 KHz and experimenters use very low power. Reading through the sheets It struck me how very much like CCW are the techniques they use. These Include high accuracy oscillators and sample and dump filters. Some of you have commented on the slow speed of 12 wpm used by CCW but think of the speeds used by The LowDown readers - speeds of 1160 baud are mentioned! The system used Is called BPSK or BI-phase Shift Keying and Is 2 method of modulating an r.f. carrier In which the Information to be conveyed to the receiver Is Impressed on the phase of the carrier. There are only two phases allowed - the signal and an 180 degrees out of phase signal which translate Into highs and lows. The main article, written In five parts, Is for a receiver and Its complexity reminds me of the first digital morse decoder I built which used about 70 TTL devices (I did build a mechanical decoder In 1950). My TTL decoder was soon made obsolete when Jon Titus KZ1G produced his design for the first home-built computer and Clive Sinclair produced the ZX80. Jon Is now editor of EDN Magazine and Clive Sinclair Is now Sir Clive and a millionaire. I met Clive, as he was then, In a computer shop In Cambridge where he lives. He was sitting In a corner and asking customers what they thought of his computers. I am afraid I wasn't as truthful as I should have been! But getting back to BPSK; the circuits go on and on and on...... I have Included the sheets In my list If you are Interested In reading them. Another article describes a receiver for WWVB to be used for stabilizing oscillators. As I should be possible to use this design largely as It Is. The next article describes a communicatIons receiver for the low band using 74HC4066 devices as mixer* with the Lf. on 400 KHz. The remaining two articles cover a BPSK beacon exciter and an add-on digital readout for receivers. The writer claims that the readout can t adapted for almost any receiver and uses Intersil 7217 as the main component. Information sheets 31 (4 pages) The "Cloverleaf" Performance- Oriented HF Data Communications System by Ray Petit from QEX July 1 990 32 (1 0 pages) Clover 30 metro transceiver The following are from LowDown are all by Max Carter and are supplied by Stan Wilson: 33 (4 pages) WWVB receiver L I 34 (6 pages) Channelled LowFer communica- tIons receiver 3 5 (21 pages) BPS K receiver 36 (5 pages) A BPSK ASCII LowFer Beacon Exciter 37 (5 pages) Add a digital frequency readout to your receiver Computer programs I have had one or two enquiries regarding computer programs for the more common com- puters (Commodores, SInclairs, Altairs and the like) suitable for use with CCW. So far as I know there Is none In existence. The program will be very similar to the usual CW programs with the one exception that the speed must be synchronized to the standard. The most likely way to do this would be to use the standard to Interrupt the processor. Has anyone tried to write programs on these lines? News from members Although I have had many letters there does not seem to be much building activity at present - well, It Is summer! G4VSO Is still looking for someone to work. Peter Lumb 2 Briarwood Avenue 73Bury St- Edmunds Suffolk IP33 3QF England