CCW NEWS I sstie number 8 Compiled by 631 RM Suggested now system !.-. thQ !ast :ssu@w I had Clovor and SP5ZK neither of which can be described as true CCW arti- cles. This time John G3PGQ has written with a suggestion for what he calls an SSB version of CCW which I have tried to summarise. He first points out that modern transceivers are pro- bablxj, not stable enough for CCW though Bert G3RHI is hoping to prove otherwise. John suggests using a commercial rig and radiating a carrier with a Ireved 1 KHz sideband (upper or lower) derived from an audio tone into the microphone socket. Both signals are received and, as they are exactly 1 KHz apart, they produce a keyed 1 KHz tone from the receiver. This remains regardless of drift at either end. A 50 Hz carrier filter would allow for a little drift but give a good s/n ratio- To help overcome fading the received carrier may be reconditioned by filtering, amplifying and limitina before beina demodulated. Alterna- tively a phase locked loop could lock to the carrier and generate a good quality signal. To remain stable during fades an integrator facility may be included. We could have an add-on I.f./demod unit (In- cluding a narrow filter). The 33 db s/n penalty may be acceptable In view of the suggested 20 db benefit from the basic system. The carrier filter may be a problem but ;@ very low Lf. may be thQ answor. To roducQ bandwidth nQQdod there seems to be no objection To The use of, say, a keyed tone at 1 00 Hz. !f anyone would like to follow the suggestions or have any Ideas or comments on the sugges- tions please contact John Griften, 37 Trelissick Fields, Hayle, Cornwall TR27 6HZ. Finally, here are the possible disadvantages and advantages suggested by John: Disadvantages, QRM on carrier frequency Total fade of carrier If reconditioning technique used Reduction of s,,;n by 3 db if eciual powers are assigned to carrier and Peve C! 4 C!, L Need for radiation of' carrier requiring greater bandwidth Advantages: bility to use standard equipmen-, Use of usb or lsb to avoid ORM October 1990 Useful hint Do you use the two piece plastic cases with anodised front and rear panels which fit into slots in the top and bottom of the boxes? In the U.K. they are known as Veroboxes- Next time you buy one make two new panels out of aluminium sheet or single sided circuit board and use one of these as the rear panel of your box. Then, if you want to use the box again you will have new front and rear panels ready. New members DG7YFI/V J6rg R@back, Harsewinkel EA3FYZ David Gim4@!nez, Barcelona N06Z Bill Liles, Reston OP60UG Edgar Neukirchner, Graz OE6WTD Dieter Trummer, Knittelf eld SM6FPC Peter van Haeringen, Goteborg VF_1 LK/W1 Wim Klyn, East Winthrop Fr,eqijqrvc,-y standardS Ray Petit In hIs notes with Cloverleaf data mentions that Fair Radio Sales, P.O. Box 1 1 05, Lima, Ohio 45802 have 2 MHz oven-stabillsed frequency standards available for $12.95 plus postage. I ordered two and paid by credit card. the cost being 5:18.84. 1 was also charged E6.84 by the post office here In the U.K. for tax and handling. The oscillators seem to be very good though 1 haven't run them for any length of time Thov are in a metal box 100xS0x50 mm htted wit'h an octal valve base on the square end. Also supplied is a complete circuit dia- gram, parts list and pin connections. Fine and extra finG adjustments are provided. Output drives high speed CMOS used In Clover. Clover 1 0 MHz transceiver Here are three more notes: Pin 6 of the SL6440C is the negative supply so it to 0 volts. connect I boucht 25 series crystals and found that the frequencies Nuvere between 0 and 200 Hz IoVV- The first filter I built used 51 0 pf capacitors. The band-ass came out correct but the centre v %,as 8000.300. Reducing the offset frequenc, capacitors to -30 pf put the centre frequency on J 8000.550 without altering the bandpass. Front end cojis - 44 turns 30 swg close wound on Arniden T50-2 or 48 turns _336 sAg on T37-2 if vou ,;,!ant to save space. Frequency standaf d compensation 1 K4EEG frequency standard In 1975 W6NEY wrote this about frequency compensation in relation to the K4EEG "UnIvor- sal Frequency Standard". They have unusually stable oscillators but even these oscillators need temperature compensation to meet the accuracy . requirements of CCW_ A little effort with temperature compensation has made the Standards stable @,vithin or.G _^ycIG at 10 MHz or 10-1 under ordinary conditions. To measure temperature I used an ordinary thermometer attached by tape to the metal box in which the standard was housed. I varied the room temperature frorn about 15 to 26 degrees centigrade by leaving the window open or by placing a reading lamp near the standard. I found it took nearly an hour for the standard to stabilise after a change of room temperature. The metal box obviously has insulating proper- ties as weil as shielding properties. Observations were made by ad lusting a small variable capacitor for oscillator zero beat on WWN/ at 1 0 or i 5 M Hz, and then recording the capacitance l0r, dQgrGGs of the rotator from an arbitrary point-) and the room temperature. I varv the strength of the oscillator signal to match that of WWV bv adjusting the length and placement of an "ant@nna" (about 1 metro long) on the output of the standard. The observations of temperature and relative capacitance were then graphed and the trends were examined to infor the type of compensation changes needed- Each graph Is labled with the capacl- tanco combination used and after a few graphs the needed changes were obvious. Compensation is achieved by changing the temperature compensation coefficient of the total capacitance in series with the crystal while maintaining the total capacitance at the same value. For example, if more capacitance from the variable is needed for zero beat with increasing room temperature. then a decrease in the amount of negative temperature compen- Sation in the total capacitance used is needed. 11 found my local TV parts Store had a supply of NP(D, N1500 anc! N750 ceramic capacitors In Values Of 10 pf and belOW. I suggest purchase ot 4 or 5 of each -available value. -; fie standards are so stable that it is possible !o chart the changes in received frequency of VV\A(It/. In case you didn't know. as propagation conditions change, e.g- the F layer goes up, the recei% - led frequency of WW\/ changes. When the "sing. rhe frequency Is lower due to dopialer effect because. electronically, the !ransmitting station is getting further from you. I have observed chances as large as 0.5x1O-1 and freeze are easilv noticed in the average of -several observations over a few days. ! Can anyone copy me this article from Har- I Radio for February 1974 please. CCW printed circuit boards layouts Kurt OP1KYB has prepared a set of three double sided printed circuit board layout's for the diagrams in the Woodson articles. They are double size so need reducing by 5011/i for actual size. If you are able to mal@e double sided boards copies of the layouts are avaii- able. Remember though that there is the usual problem with board layouts - you have to find I components to fit the hole spacings! Inductance meter Clearing out some old magazines the other day I came across a very simple design for an inductance meter. Provided vou have a digital frequency meter which will @ead up to 1 MHz and accLss to any computer it is well worth making. It consists of an oscillator using an LM31 1 followed by one transistor. it reads from a fraction of a microhenry up to at least 20 H. The article includes a 21 line Basic program which can be adapted for any machine. At least, I re-wrote it for a Casio FX 730- P. I Information sheets 38 (6 pages) CCW circuit board layouts by 01=11 KYB (above) 39 (1 page) All about Henry by WB4DCV from 73 Magazine for November 1988 (above) News from members DJ3CT Bernhard has his set-up now planned and much of the work completed. G3CCH John reDorts slow progress on the receiver for CCW. G3CW1 is looking inro digital signal processing. G3FMW John is building t!!@,o VF30BE Vev- "cards - one 'or a ffien . I I I %@ iG3TFV has completed The VF-30SE keyboard łand divider chain. G3R)-;I,' Anvone able to he.'P Bert ..(,fifth sorne tests? I ' G4LRA Garv novv has onlv his tcvr -o sort out. i - Petel Lunlb 2 Briarwood Avenue -7, n Bury St- ,f C@, Suffolk IP33 -AOF 11 I4n Z. I a n ri