. . . 11 I I I.. - . . ... 1. I . .1 1. @ I I COHERENTI.C. @ .."NEWSLETrE Comp by Issue number 17 Publicity Stephan HB9DDO hopes to be able to get so publicity in Switzerland by writing some notes f the SARTG's journal. If there is any response he be prepared to distribute the Newsletter for me Switzerland as weil as our information sheets. Da GOOKO has suggested that I write a note for t RAFARS magazine QRV which I have n completed and sent to the editor. Tests Kurt and Bernhard have continued their tests a John Stockley has also tried to take part. it must my turn soon! Comments I have been thinking about what I said a while ag regarding the poficy I adopted when I first start writing these Newsletters. My aim was to 9 together as much information as possible whic would be useful to those building CCW equipmen As a result I think I gave the impression to many you that CCW was complicated. I have spent a I of time testing as many designs as possible to try t confirm that they work. All this has resulted in th fact that I still have not got on the air myself! Wha I should have done was to concentrate on th simplest possible equipment needed to get on th air with CCW. I started to rectify this mistake las time with the simple 7030 KHz transceiver using th Howes kits.At least one member (Stepha '111320DO) hastaken up this suggestion and ha started buildingone of the kits. Here are a few mor thoughts, some are my own and some are fro letters received, starting with operating frequencies Operating frequencies We seem to have decided that 7030 KHz is the bes frequency. There are three reasons - most of us are in Europe and forty must be the best band - it is the qrp frequency so qrp operators may hear us and become interested - most builders these days are qrp operators and could therefore become builders of CCW equipment The simple 7030 KHz transceiver A day or two after Corn etin the notes on th simple transceiver I realised that it may be possi to simplify It further. Why use the Howes vfo Why not use the receiver vto? Having got the working I don't feel inclined to modify mine perhaps someone else would like to try. When usi the synchronizing circuit given last time I ha noticed a slight rumbling in the background wh the output is monitored on a receiver. This can cured by some additional filtering. I added a 2.2 resistor in series with a 33OnF capacitor from output pins of the CD4066 to 0 volts. The note both transmit and receive now appears to be sta and satisfactory. I have also added a switch in t voltage control line so that the varicap can disconnected from the stabilizer and connected a thmpot set so that the transmit frequency available in either switch position. By changing t switch over the oscillator reverts to a normal without stabilization. The Howes receiver us separate tuning capacitors for the antenna and tuning. I have used a small three-gang vhf tunin capacitor with two sections in parallel for the vfo Each section is about 18pF capacity. This tun the CW end of " metres with some overlap b the single capacitor for the rf covers too wide range. it would be possible to alter the number turns on the coil but I have obtained satisfacto tracking by adding a 3OpF trimmer in series with th 18pF tuner and another 3OpF trimmer across both By adjusting these in turn it is possible to obtai tracking across the band with just one control knob The whole thing can be simplified further if w ignore the phase locked loops and go back to th original design by Woodson and use a crysta oscillator. This can be stabilized with the Bill d Cade circuit. We could use two crystals in the sarn ,oven', one for transmit and the other for receive. The receive crystal on either 7029 or 7031 can have a panel trimrner for fine tuning and a small trimmer will be needed to set the transmit frequency. Bill's oscillator uses half a 74HCU04 so there is the other half available for use with a second crystal. I haven't output is a square wave. There is a sine wave available near the crystal so perhaps this can be used and the buffer amplifiers linearized by the use of feedback for a sine wave output. The standard There is not much we can do to simplify this though the K4EEU unit originally designed could be improved with another of Bill's 'ovens'. The Petit filter If fine tuning is provided in the receiver the original filter in the Woodson articles is all that is needed - Colin's audio synthesizer epid can be added later if desired. Building the filter, which is the most complicated part of CCW, can be made easier as Kurt OE I KYS can supply all three boards as a set and I have a set of his board layouts if you can make your own. The keyer Perhaps the easiest way to make this is to use Colin's epid keyer chip which was specially designed for CCW use. You can always go to the keyboard later. John Stockley G3FMW John has completed his revised (Woodson) filter and finds it more sensitive than the original one he had though otherwise results seem to be similar. He reports that there seems to be a lot of interference in his part of the world (Yorkshire) on 7030 KHz and thinks that once contact has been established it may be an idea to have another frequency available to continue the contact. R.f. synthesizers There was a short article by HB9AJS in Old Man for January 1990 which described a very simple r.f. synthesizer based on the Motorola MC145163. This was translated and reprinted in QEX for January 1991. So far I have not been able to obtain one of the devices nor a data sheet. No-one in the U.K. seems to have heard of it so I am trying to obtain one from the States. The device resembles the MC145151 used in the Cirkit and G4VSO designs and most of the pins seem to correspond. The difference appears to be that in the '151 phase lock loop the n-counter is programmable in binary while the '163 is in bcd making everything so much simpler and, as a bonus, providing a very convenient readout of frequency. There also appears to be a difference in the reference decoder. The '151 uses pins 5,6 and 7 to give a choice of eight division ratios. This may also be so in the 'i 63 but HB9AIS uses just two of the pins to get a ratio of 4096 which is a figure not available on the '151. In the '151 pins 8 and 9 are the outputs from the B phase detector and these are not used In the HB9AlS circuit - they are probably still the B detector outputs but, without a data sheet, I do not know. His design uses pin 4 which in the '1.51 is the A detector output and presumably still Is In the '163. The big difference between the two designs is in the low pass filter. HB9AlS's is a simple first order lag- lead fifter and uses just two resistors (one variable) and a 4.7uF capacitor, the rotor of the potentiometer being connected to the varicaps through another resistor. I have calculated the values for the fifter using the '151 data sheet on the assumption that all Motorola devices will be similar and get roughly the same values as those used by HB9AlS. However, he makes the ratio of the two resistors adjustable by using the potentiometer which he says should be set for a lock-up time of 0.2 to 1 second. This not only saves the op-amp used by Cirkit but all the additional components in the low pass filter. If I am right in my assumptions, it could be worth trying the same simpler low pass filter with the 'i 5 1. I'll report later if I can get hold of the MC145163 data sheet. Clover March QEX carries a two page update by Bill Henry - if you are interested and want a copy please ask. The first Clover product will be PC-Clover as expected and will be known as the PCI-4000 and HAL Communications are hoping to be able to ship the first units on or before July I st this year. Final note I have tried using the MC145151 as suggested above and it works nicely on 7030 with switching to 7031 for receive. However, I am still unable to get anything relating to the MC145163 though Jermyn are making enquiries on my behalf. If anyone knows of a source of data sheets and MC145163 devices I would be pleased to hear. All for now 73 Peter Lumb G31RM 2 Briarwood Avenue Bury St. Edmunds Suffolk IP33 3QF England Please keep me informed of what you are doing and send in any interesting notes which may be of help to us.