June 2003
Contents
1. 410 224 0681 or email to ray acgsys com NU7Z nu7z aol com has a TWTA that provides 65 W on 13 cm and 55 watts on 3 4 GHz with about 4 to 5 mW drive for sale It uses 24 Vdc switching from standby to operation and runs on 110 Vac Including the book for the power supply Rick is asking US450 shipping VE4MA ve4ma shaw ca has an 8970 NF meter that needs work and is looking for service manual 9HIES is looking for source of finger stock If you know of a source please reply to fbonnici hotmail com ABSIG lrr sbcglobal net is looking fora V4MA feed for 1296 see his report W1ZX ESTATE has for sale Willie s 32 dish 24 ribs feed poles misc hardware and hub Also a Bird 43 Wattmeter and Kenwood TS 870 Contact klrgg aol com or bamank earthlink net TECHNICAL This month we have the first part of a two part article by F5VXM Graham D wanadoo fr on his Zero IF Radiometer appears at the end of this NL The original article was written for the 2003 French VHF UHF conference Graham writes Things have moved on a bit since the original article After feedback from folks I have decided to do a total new PCB concept The new this board currently underway will have switchable inputs for 144 432 and 1296 and will include the necessary helical filters at least one gain stage and the detector with it s support circuitry The output will be a DC voltage directly from the detector at LIMITED CURRENT CAPABILITY to drive a meter Folks will need2. 2300 KE2N 559 569 and switched JT44 9 10 dB 661 and 2350 K6JEY 569 569 and on 12 May at 0000 KJ7F 8 12 dB on JT44 I could not decode Terry at the start as he was several seconds off in time I had a relay fail during my JT44 skeds but found I could manually switch between TX and RX and was able to complete my JT44 skeds NETNEWS DLOAO is a Bavarian Contest Club station operated by DJSRE and should count as an initial ZS6JON Jon johnsygo netactive co za is interested in EME on 70 cm and up N4MW email address is now n4mw msn com NU7Z Condolences to Rick whose father passed away FYSDG is QRV on 70 cm and worked DLOKR on random in May W9ITX worked K5GW during the May SW on 23 cm but heard no one else He has now completed the metal work for two GS23B cavities and needs to send them to get silver plated W7MEM is not QRV on 70 cm at this time KOYW_ worked during the May SW on 23 cm worked N2IQ on CW and heard K2UYH on JT44 W7CI is making progress on 23 cm EME FS5VHX has located a dish mount but needs to dismantle it before he can ship it home KSWXN s move from TX to Alaska is on schedule KL7 K5WXN will hopefully be heard off the moon soon CTIDMK currently is only QRV on 6 cm and 3 cm K4AR blew the center pin out of a Cablewave 1 5 8 connector on his EME array but now has a replacement and should be QRV again soon on 432 GMOONN hopes to be QRV on 70 cm the Ist weekend in July He is also working on a 4 m dish 9H1BN ha
3. Because the temperature being measured is so much higher than any chosen quiet source then the measurement requires a receiver with good linearity over a largeish dynamic range and no AGC action to eliminate gain change errors being introduced d Most if not all amateur sun Y factor result calculators are rather inaccurate or just plain wrong This came as somewhat of a surprise during 2001 2 when Doug VK3UM decided to revisit the subject and construct a new Y factor computer tool I and a group of others contributed to Doug s project with research of existing tools and more fundamentally into the equations needed and their implementation as well as cross checking results from Beta software releases with actual system measurements It soon became clear that many existing implementations were primitive Some discounted or did not allow input of major system parameters most had no or poor documentation For example they demanded input of Solar Flux but gave no hint of which solar flux Some just simply implemented the well known equations wrongly Just about all made no allowance for spectral content in the suns output and for the different bands attempted a straight line approximation if they bothered at all Doug s final effort can be downloaded from http www qsl net sm2cew and as well as Y factor handles moon budget and radiation compliance calculations It has now been tested by a good number of stations worldwide who make c
4. Unfortunately I am currently not QRV during weekends and must rely on skeds on Monday through Thursday only I have finished work on a 23 cm Septum feed and am in preparation for measurements on an Antenna Test Range SM2C EW Peter sm2cew telia com writes On May 4 I completed with K7XQ for initial 152 on 1296 Unfortunately I was not able to spend the time I wanted on EME during the May SW I was on 1296 for an hour on 10 May and worked HB9SV impressive signal G4CCH G3LTF IK3COJ and ZS6AXT On May 11 I just worked DL8OBU and IK2MMB There seemed to be very low activity during the Eur window I have been working on my 1296 feed preamp and TX cable now 1 5 8 Heliax and I think things are a little bit improved I also will be changing the TX line for 432 to 5 8 in the near future W2UHI Frank fblumn pathwaynet com continues to keep the moon warm on 1296 During the May SW he worked DF3RU G4CCH IK2MMB F2TU VE6TA K2UYH WA6PY ZS6AXT HB9YSV He put out a CQ call and was called by K7XQ but could not pull him out of the noise and did not complete Frank has a new transverter and is looking forward to checking it out on the moon See Frank s web site at http www w2uhi com W2UHI s HOME BREW 5 5 m 0 45 F D DISH W4AD Jack jomara erols com in VA FM18ip has worked W5LUA for his initial 3 cm QSO He has a 10 dish and has recently improved his sun noise from 10 dB to 14 5 dB WAOPY Paul pchomins san rr com wa
5. solution I have arrived at is not new revolutionary or breaking much if any new ground Many have been here before and those dedicated to Radio Astronomy have gone much further My approach has been to take a fundamentally sound principle and try to simplify it by exploiting modern technology and specifically new R F chips that have become available in the last couple of years Currently my solution is for 1296 MHz it is rather easy to change for any band by simply changing the three 2 stage helical filters employed to define the band of use In fact it may also be necessary to change slightly one or two stripline inductors and matching sections components experiments to move this design to 432 MHz and are underway The increasing high frequency capability at low cost equation of these new parts means that one can take a much simplified approach to designing and constructing a noise receiver It is now possible for a few tens of dollars even at what have been thought of traditionally as very high frequencies to work with to take the band of interest directly from the antenna element to the detector element and with no need for narrow band signal separation or complex modulation detection that demand messy frequency transformations filtering alignment and strategies to stop these more complex elements degrading the required stability parameters we need KISS keep it simple stupid has got even easier for the solution to t
6. at a later date I chose the tin plate based on availability cost and the fact that this current model is really a test piece so throwing away non working revisions cheap also To achieve sufficient stability mechanical and thermal for the Radiometer to be useful as a radio amateur station measuring tool was also a consideration to push the techniques further and target better resolutions required for a more pure Amateur Radio Astronomy solution probably does demand better housings 2 To use fibreglass PCB material where possible I have little concern for losses other than in the LNA where I used Teflon FR4 material is cheaper and more easily available to than Teflon types 3 To use stripline matching and other techniques where possible 4 To design build each module as a total stand alone unit that means it s own 5v regulators RF in out connectors etc This modular approach allowed some sections to be discarded and redesigned initially and has now provided a kind of building block approach where various sections can could will be used in other projects INTRODUCTION TO THE THE VARIOUS MODULES antenna Gain amp Detector block Gain amp attenuator stage LNA outside at feed Analog to Digital converter microcontroller To be continued Bottom of LNA view where the 2 stage helical filter is the holes to the left of it are for another filter which I have elected not to fit at this time Top view
7. certification of mixed modes Modern modes won t be hampered and the efforts of those who stick with the rough dinosaur type modes can be certificated separately as usual ES8X Tom ES2RJ lt es2rj erau ee gt reports that the ES2WX team is going again this year to KOI8XC island of Kihnu The operating time will be around 25 July to 5 Aug Special attention will be focused on 432 MHz EME on CW and JT44 We will have a better antenna and higher power than last year We also will be QRV on 6 m 2 m and 23 cm JT44 I will let you know when more detailed information is available and would like to arrange skeds for EME via KIRQG SS F6CGJ AT F6KHM IN EWW CONTEST WINDOW REFLECTION F6KSX J Jacques FIEHN reports on the EWW EME Contest The F6KSX EME group was active during the second part on 10 GHz Activity was good only during Saturday evening and no QSOs were made on Sunday We did not heard any US stations All QSOs was made on random and with good reports We worked on 12 Aprill2 at 1845 ISPPE O O 1858 OKIUWA 539 559 1912 DL2LAC O O 1953 F2TU O O 2055 DLOEF O O 2105 G4NNS M O 2113 FIBLL 559 0 2200 IK2RTI O O and 2230 CTIDMK 0 0 for a total of 9 callsigns x 6 DXCC x 100 for 5 400 points Our station is a 3 3 m dish with vertical pol and automatic tracking with FIEHN EME System 50 W TWTA 40 W at horn 0 7 dB NF and 10 GHz transverter We received about 15 6 dB of sun noise and 1 8 dB of moon noise We b
8. make such a Y factor measurement using a typical amateur radio receiving system These are shown in following diagrams along with a quick summary of the methods First Amplifier s Volt Meter Transverter Main Antenna FHecemer The voltmeter is fed from the audio out of a traditional receiver there must be no AGC action in the receiver this is covered in further detail later measurement is made by moving the antenna to the quiet source noting the reading then moving the antenna to the hot source and noting the reading the Y factor is then known remembering of course that 3dB power and 3db Volts are not the same First Amplitier s Volt Meter a ae Ste Transverter Main Antenna Receiver The voltmeter is fed from the audio out of a traditional receiver in this case AGC action is undesirable but if it cannot be switched off then the measurement is still valid Measurement is made by moving the antenna to the quiet source noting the reading on the voltmeter then moving the antenna to the hot source and by use of the step attenuator adjust the signal level until the same reading is reach The Y factor can then be read directly in dB s from the step attenuator EASY Yes but There are many pitfalls in using this somewhat simple concept in practice The first question to be addressed is which sources to use for the cold and hot comparison To some extent these choices are driven by the frequency at which the measur
9. of the 2 stage LNA Input is on the left The line up here is an ATF54143 front end input stage this was chosen because of it s exceptional IP3 performance and easily achieved low noise figure characteristics full active bias is employed it feeds through a 2 stage helical filter to a second stage comprising of an Agilent MGA53543 this second stage was again chosen because of it s IP performance noise figure amp small physical package There is option on this board to add a second filter after the MMIC in this picture you can see it has been jumpered out with a short length of coax The final performance of this LNA is an NF of 0 3 0 35 dB with a total gain of around 30 dB The filter provides an impressive roll off below is a picture of the low side of this shape the high side is close to symmetrical
10. to move around This is the same HPA I used at EA8 LA8LF for 2 years My new 3 8 m solid 0 325 f D dish and VE4MA circular pol feed worked extremely well Yoshiro JA4BLC has kindly sent me some FHX 35LG s and I will make repair to my DJ9BV LNA which had been out of service because of a lack of devices As soon as I complete the repairs I will do some CS G and Sun noise tests N7AM Jack s jackriggs attbiccom May 23 cm operation was cut short I worked K5GW and heard a weak one calling me at the start of the Italian Contest when I got hammered with a lightning bolt that put my tracking system out of service The elevation failed The problem was the RS232 unit at the tower I am now attempting to get things back together here The WX was good for the contest We get very few lightning bolts here The location of the lightning crash was three seconds from the tower so we really got hammered It was the loudest crash I have ever heard in 60 years NN6T Glen glenansue msn com is active on AO40 with a Kenwood TS2000 and a 10 dish He is interested in trying EME and wonders if his system is good enough to hear signals off the moon Definitely He also has a preamp but does not indicate the NF PAOPLY Jan jan kappert comtestnl com is QRV again on 432 but now from his new shack and is looking for skeds During the May SW I worked OE9ERC and KE2N for initials I want to sked KO7N but have lost email contact with Richard I hope all is ok
11. year if not sufficient interest then I ll just post schematics and PCB layouts There is now underway a very comprehensive piece of plotting logging software which I will give away as a EXE running under windows when it is ready In all probability this will also interface to my Ulti track project as well at www rtham com newulti index htm This will allow heading as well as time stamp calibration of the X axis when plotting FINAL This June the International Microwave Symposium www ims2003 org will be hosted by my local IEEE section and be in Philadelphia This is professional gathering but many members are also hams and some EMEers I have arranged for a Ham Social at this year s symposium The reception is scheduled for Sunday June 8th from 7 30 to 9 30 pm in the Conference Center room 307 AB If you are in the area I would like to invite you to attend The social is open to all hams Let me know if you need any assistance The 2004 Trenton EME Conference has received its first official registration from HB9OBBD Although it may seem a little far off it is really not too early to start making plans to attend the conference If you have not done so already please check the conference web site at www qsl net eme2004 HB9CRQ asks everyone to update their initials standing at www hb9q ch I have been in contact with FIEHN We are working on organizing a 3 cm EME contest for sometime next year probably in the summer before the EME conferen
12. 432 AND ABOVE EME NEWS JUNE 2003 VOL 31 6 EDITOR AL KATZ K2UYH ENGINEERING DEPARTMENT THE COLLEGE OF NEW JERSEY PO BOX 7718 EWING NJ 08628 TEL W 609 584 8424 OR H 609 443 3184 FAX 609 631 0177 E MAIL a katz ieee org PROD MAIL BRIAN MULLANEY KB2TIS 609 883 6390 E MAIL mullaney mccc edu NETNEWS EDITOR G4RGK DAVID DIBLEY E MAIL g4rgk hdeng freeserve co uk based on KIRQG s Netnotes EME NETS 14 345 10 AM ET SATURDAY AND SUNDAY AFTER VARO NET ENDS ON SUNDAY NET CONTROL AND SKEDS CORDINATOR JOE KIRQG TEL 207 469 3492 E MAIL kirgg aol com EME DIRECTORY http www dl4eby de DL4EBY DKOTU KLAUS TIEDEMANN TEL 49 30 7955467 E MAIL lt tklaus berlin snafu de gt E MAIL LIST CORD WARREN W2WD wbutler comcast net NL DISTRIBUTION SCOTT KD4LT lt cscott surfsouth com gt TXT OR PDF EME STANDINGS DAN GAUTSCHI HB9CRQ HB9Q E MAIL hb9crg hb9g ch OR SEE HIS WEBPAGE AT www hb9q ch THE NL WEB VERSION IS PRODUCED BY W6 PAOZN AND AVAILABLE AT lt http www nitehawk com rasmit em70cm html gt CONDITIONS May Skeds weekend SW activity was boosted somewhat by the Italian EME Contest Turnout for this contest was not spectacular This newsletter NL missed promoting it Propagation was good with the exception of 70 cm Faraday rotation which was often near 90 degrees and produced poor echoes A May high spot was the appearance FYSDG lt Christian Albrieux cnes fr gt on 70 cm see DLYKR s report and the April N
13. L I am sure Chris will be the source of much 432 activity in the coming months Unfortunately planned June 70 cm activity from YL and LY was canceled see below The ARRL s June VHF Contest is often the source of additional EME activity This year s contest occurs a week after the SW but is at high southern declination Nevertheless it may be fruitful to look for new stations during the contest period ABSIG Lee Irr sbcglobal net picked up a collapsible 12 Luly type military antenna dish at Dayton with about 35 f d He is lookin g for a V4MA feed for 1296 Lee is planning to try portable EME on 23 cm using an SSB solid state 100 W amp and TS2000X DF9CY Christoph cpe df9cy de is getting active on EME again I am still alive but a little quiet radio wise I sold all my VHF UHF gear except my 8 70 cm yagi array and LNAs Recently I purchased a VHF UHF rig IC820H and I will put up a small station for 432 in the future I have experimented with WSJT last year on 6 m with some success Perhaps this is a way to return to 70 cm with a little lower power than I had 10 years ago In the meantime I have a family with my wife Meike and the two children Christoph and Sarah my homepage at lt www df9cy de gt I have some gear for sale DLIEJA Oliver s DLIEJA yahoo de June 70 cm EME dxpedition to YLIA and LY2AAM is cancelled During my final checkout of the 70 cm EME station I had a fatal failure of the power amplifier Because o
14. ce There are very few skeds this month I guess this is a consequence of the universality of email but it is still nice to know what skeds are happening when If you make direct skeds pass them on to KIRQG for posting on the master skeds list Please keep the reports and tech material coming My June EME active will be a bit limited by the Microwave Conference which begins the same weekend as the SW I still expect to be on the moon in June 73 Al K2UYH KEEK KEE KKE ee ee ee ee K E E K EE EK EE EKE E K K K K K K K KK EME SKEDS 7 JUNE Time 432 040 1296 050 1100z ZL1IKA DL1YMK 1900z WBOGGM UT3LL 1930z WBOGGM G3LOR 2100z OZ9AAR KOYW BE IS OS ISIS OS OAS DIS IS OIE SIS FIR IS IS 2S OIE OIE E OI FIC SIS IS IS IS 2S IS IS IS OI KE OIE OI OIC SIS IS IS E IS IS IS K OI OIC KE IS IS K K K K K K K K K K K K K KKK KK ZERO LF RADIOMETER BY F5VHX G8MBI This article is an introduction to an on going project to construct an Amateur Astronomy Radiometer The original idea was to enhance the tools available to me in evaluating a 4 m dish used for Amateur Moonbounce communication on UHF SHE This article is not intended to be an exhaustive scientific study of the subject matter it s purpose is to highlight the difficulties and sources of error in what appears to be a relatively simple thing to do in plain day to day language I have deliberately a not used many traditional and confusing scientific terms names amp concepts and b no
15. de up dates us his 70 cm activity In the EWW Contest March I could only be on for 4 hours on Saturday I worked 34 stations without any initial However I added initials on 12 April with DF9ORJ 775 and KIOLE 776 559 In May despite poor conditions which obviously suffered from the aftermath of an aurora activity seemed to recover The following were worked on 10 May S52CW VK4AFL UA3PTW SP6JLW SKOCC DJ3FI UT3LL JA9BOH OZ6OL YUIEV and DLOAO 777 this is a club call operator indeed DJSRE but at a different site using to my knowledge 4 x FT and 600 W WBOGGM K9SLQ loud F2TU RZ3BA 1 S51ZO KU4F loud as usual G4YTL and DF3RU Heard were K2UYH wrong polarity for EU H pol EA3DXU loud with new PA and OE9ERC On Sunday 11 May I tested my echoes in preparation for the USA window when somebody tuned up below my echoes That station started to call me and I nearly fell off my chair when I heard DLOKR de FYS5DG 559 This QSO understandably made my weekend as initial 778 and DXCC85 Chris was puttin g in stable and very readable sigs I guess this is the second appearance of FY on 432 after FY7YS back in the mid seventies just prior to my start up Chis will give many guys a chance to work South America after PYSZBU s QSY to 23 cm I want to also comment on behalf of Joel W5ZN s views on JT44 that appeared in the last NL They seem acceptable and should settle the discussion about the inclusion of modern modes into the
16. e rather large beamwidths of modest amateur antennas then the tendency is to not resolve the single source that you search for but a sum of the energy within the large beamwidth This also highlights the mostly inadequate pointing accuracy of amateur antenna systems because the noise sources are in general close to or surrounded by other parts of noisy sky the temptation is to peak the noise in the array This might or might not be peaking the noise source It is most likely peaking the best sum available in a larger portion of sky covered by your beamwidth and hence invalidates the measurement if any attempt to reference the measurement to the known object temperature is made 3 The Sun Available for large parts of the day in all locations and offers a considerable hot source with a high Y factor to any chosen quiet source makes the sun an irresistible choice for amateur Y factor measurements The problems are a The effective temperature of the sun at any measured frequency follows the long term trend of the sun spot cycle one absolutely has to know the latest professional data about the state of the sun for any measurement to mean anything on any band this has got much easier with advent of internet near real time data availability b Within the long term trend of the sunspot cycle there are much shorter term deviations these sudden storms and outbursts can cause considerable deviations over seconds minutes or hours c
17. e to constant Whilst one dB step attenuators can be found on the surplus or used market to find fractional dB step models is very hard B USE QUIET SKY TO NOISE SOURCES such as Cygnus Sagg A etc This method requires measurement of much smaller deltas or Y factors Method 1 and Method 2 require stable milli volt meter readings to resolve the small changes to be measured and in addition method 2 requires a fractional dB precision step attenuator At lower bands one has some chance to take these measurements On 144 you can be dealing with a few dB at 432 one is dealing with typically 1 2 or 3 dB on most more modest amateur antennas At 1296 and up one is dealing with fractions of a dB Some people use a hybrid of method 1 amp 2 for these measurements using a 1 dB attenuator step to reduce the linearity agc requirement and then trying to take the final fractions from the meter This is the right moment in the discussion to raise the issue of Bandwidth In small noise temperature change measurements then bandwidth can be your friend Wider bandwidths at detection stages offer the possibility of greater resolution The structure of a modern amateur transceiver is in fact in many areas in conflict with the requirements for making good Y Factor evaluations The modern transceiver is more generally targeted at narrower and narrower bandwidths as this improves efficiency for working with signals it is also targeted at handling la
18. elieve a separate contest for the microwave EME is needed to truly boost turnout on these bands G3LTF Peter s 100633 1656 compuserve com May EME report I was active over the Italian EME Contest weekend but didn t find many Italians on the bands On 432 MHz on 10 May I worked JA6AHB DF3RU JA9BOH K6JEY for initial 373 OZ6OL SP6JLW KU4F S51ZO S5 2CW and on the 11th EA3DXU SKOCC UA3PTW and PAOBAT Condx were good with well defined polarization On 1296 on 10 May I QSO d G4CCH F2TU ZS6AXT OZ60OL DKOZAB SM2CEW DF3RU G3LQR IK2MMB N2IQ IK3COJ SM3AKW and WA6PY and on 11 May LA8LF really good to hear Anders on again HB9Q Dan HB9CRQ hb9crg hb9q ch was QRV on 432 for a few hours during the May SW Conditions seemed to be quite good See my band pages at lt www hb9q ch gt for detailed logs We will be next active on 7 June 1100 1400 and 1900 2400 and 8 June 1215 1400 on 144 432 and 1296 K6JEY Doug dougnhelen moonlink net DMO3wt was activity on 432 for the Italian Contest I QSO d on Saturday of the May SW DK3WG 0 0 G4LTF O O partial SS2CW O and G4YTL 0 0 All three were initials Conditions were fair with deep fades I am redesigning my preamp and should be able to receive better by next month with N6CA preamp better relay system and 1 10 dB loss preamp filter The system is now 4 x 25 el KIFO yagis 1 1 kW PA and a 22 dB NF LNA K7XQ Jeff k7xq elite net CM97qi was QRV on 23 cm
19. ements are to be made For amateur purposes and using amateur budget and size systems the choices are few FOR COLD SOURCES 1 Resistor You can could attach a 50 ohm load to the system and use that as a stable cold ish source reference This load can be switched into the system by a relay this is quite popular at 144 MHz the problems are a Temperature match drift of the load changes noise reference b The different impedance presented by the load and the actual antenna to the first amplifier stage absolutely ensures that gain of that stage will change during switching clearly this is undesirable for accurate measurements c Having an extra relay at masthead to switch the load in and out introduces a degredation to the overall system noise figure 2 Ground The temperature of a non reflective black body object is well known the problems are a Few people can realise sufficient negative elevation to completely fill the array aparture especially with a dish antenna b ground in peoples back yards is neither constant non reflective or of known temperature 3 Galactic Quiet Sky These are areas of the sky largely unpopulated by noise sources the problems are a At lower band frequencies especially 144 the noise temperature of the antenna and hence the system may already exceed that of the quiet sky b The smaller the array the larger the beamwidth the more difficulty in defining where quiet sky is The temptation i
20. f the lack of time we were leaving the next day there was no possibility to fix it and all efforts to find a replacement failed This is a great disappointment It took months to assemble of all the equipment and modify everything for EME use This station was built for traveling and working EME portable Thanks to all who helped with technical advice equipment and organization We will try again soon on 70 cm with 4 x 38 el M2 full azimuth elevation DJ9BV preamp NF 0 4dB tested by DL9KR GS23B PA 1 5 kW and modified FT 847 DLIYMK Michael DL1 YMK aol com JO31qx plans to be active during the June SW on 23 cm and will be particularly looking for ZLIKA Next year he will be moving to a new location in JO33 where he plans to up grade to a 7 5 m dish and now has two TH 347 PAs for use there DL30OCH Bodo DL3OCH t online de is planning to go to Liechtenstein to try some additional 1296 JT44 EME tests see the last NL I want to go on 29 May but am flexible I would consider the 30th 31st of May or Ist until 9th of June if any of these dates would yield more skeds The conditions are not the very best but I allow QSOs with big antenna stations I will use an IC 706 and a transverter made by DJOYW with 100 W output My antenna is a 59 el yagi Later this year I plan to vacation in TK and would like to operate 1296 EME from there and possibly ISO in Sept Another possibility is the T70A club station DL9KR Jan Bruinier t online
21. for the May SW I spent only 1 5 hour on the band on Saturday starting at my high 20 deg moonrise at 2230 I worked HB9SV 579 for initial 21 G4CCH 549 and F2TU 549 Heard were VE6TA K6DV and W2UHI On Sunday I added N2IQ 539 random Initial 22 and KOYW 539 The system is still my 3 1 m dish with 150 W from 2 x 2C39 water cooled PA KJ7F Terry terry velocitus net is interested JT44 skeds on 70 cm I QSO d K2UYH on JT44 during the May SW Initially I could not copy the JT44 My clock was so far out of sync that the timing peak didn t even show up on screen I can t believe that it took me so long to figure out what was wrong K2ZUYH was speaker copy very frustrating I had somehow killed the GPS clock and the time was wandering all over Another lesson learned I just wish that we could get more of the 432 crowd to try out JT44 It can be a lot of fun LASF Anders MILCOM tiscali no is QRV on 1296 again I worked on 11 May during 6 hrs of activity F2TU 559 559 behind trees covered with leaves G4CCH 569 569 OH2DG 569 569 JA6AHB 569 559 and G3LTF 559 569 but did not make it to the NA window I had a bang from my TH 328 HPA The TH 328 HPA is now 35 years old so electrolytic capacitors are at the end of their life I have made repairs to the PSU of the Plisch TH 328 HPA But as it is very heavy I have decided to build a new separate PSU I will put the cavity in a smaller cabinet so the 2 units will be easier
22. his problem WHAT DOES IT LOOK LIKE THIS NOISE RECEIVER I will now describe my solution and the progress so far with some practical results This is not a simple construction article of the here it is build it variety it is a presentation discussion and explanation of the concept the current implementation the pitfalls and failings which will hopefully provide inspiration or a route map for others wishing to go this or a similar way Before I present the electronics content here is some data generated by it to wet the appetite a little with what is possible The plot below was one of the earliest practical results from my Radiometer although primitive by professional yardsticks it clearly demonstrates the usefulness of such a tool in evaluating one s radio site This plot shows very well the challenges that can be faced operating EME at 1296 MHz at low elevations Some of the objects identified are at large distances from the dish for example the object identified as two trees alone are 150 metres away The object stone tower on hill is over 300 metres away and offers only a small dish aperture fill at the 5 5 degrees of elevation that the scan was made at It also shows the difficulties of deciding what is ground tempera ture if you wish to use that as a reference it can be clearly seen that the wall of trees to the west of the dish offers a higher temperature than the shack concrete wall even though
23. my dish into the park position On Sunday we were hit by a cold front so it was impossible to work on the EL drive Thus I lost the second pass of the moon We had very gusty winds and my other solid dish which was standing next to the tower was overturned Fortunately the only damaged was just a rotary wash line Dish is so strong that it was not damaged Saturday conditions were very good and my echoes were coming stronger than I heard them for long time I received many 569 and a few 579 reports This was pretty good for my 200 W The only station I heard and missed was HASSHF It is a pity the activity was not better K2UYH I added of two initials on 432 and had several interesting JT44 QSOs on both 70 and 23 cm On 5 May I ran with VK3FMD on 1296 JT44 after several failed attempts on 432 Charlie has even a smaller system on 23 cm where he runs 100 W to the feed of his 20 4 dBd yagi I received 4 syncs 28 dB from him but he heard nothing from me This was the reverse of our 70 cm results During the SW I worked on 10 May on 432 at 2114 F2TU 559 559 2125 called DLOAO QRZ but had to leave for sked 2130 PAOBAT O O for initial 660 then switched to1296 at 2224 F2TU 56 55 on SSB for a 2 band 2223 DJ9YW 8 11 dB on JT44 excellent signal 2302 HB9SV 579 579 2307 W2UHI 569 569 2312 IK2MMB 569 559 and 2315 partial IK3COJ sent QRZ but then realized the call but he quite on 11 May on 432 at 2230 S53J nil on JT44 sked
24. put The output offers a variable slope voltage I have set it for 20mV Per dB of input change The minimum detection level for the chip is around 70 dBm and the quoted dynamic range is 70 dBm for 3dB output accuracy the second figure quoted is a 65dB dynamic range within 1 dB accuracy at 1 9 gHz various typical graphs and plots are avaialable on the full data sheet available for download at the Analog Devices website Having a cheap simple and apparently reasonably accurate detector it is then necessary to provide some gain ahead of it along with some band filtering as well as some method of extracting the resulting DC output and reading or displaying it Before discussing my choices for those sections and why here is the basic block diagram of my Radiometer design I will work through these one at a time with a quick outline of component choices experiences and final results MAJOR DESIGN DECISIONS To use Surface Mount Components and techniques throughout this is in any event forced upon you as most of these new devices are only available in smt packages it also happens to be my preferred method nowadays It offers greater reproducibility in no tune designs and also allows mostly single sided board occupancy and tracking which is easier to handle on prototyped boards without full plated through holes 1 To house the various stages in tin plate boxes I would prefer to house these in milled aluminium boxes and may do so
25. redible measurements and offers good correlation to those measurements It has been repeatedly blind tested at F5VHX on 1296 MHz and accuracy is within 10 to 15 SFI numbers 2800 MHz SF is the data used 1 Ground can be used as a hot source to reference to quiet sky The problems are the same as those as using it as a quiet source outlined above It is not my purpose to discuss in further details the difficulties and correction strategies for ALL the above choices this would inevitably lead to a detailed long and complex analysis of several entire systems Instead I will summarise the situation in two simple and common choices and highlight the challenges they present to the receiver amp measurement systems only outlined in the diagrams of the standard two methods available A USE QUIET SKY TO SUN This offers a large delta to measure big difference from low temperature to high temperature and so in many ways and on some bands is the only viable measurement that can be made by amateurs Leaving aside the difficulties of the actual calculation and correction factors already discussed the receiver only challenges are Method 1 You need a system linear over the necessary measuring range this can be as little as a few dB on 144 with a modest antenna but as much as 20 dB on 1296 with sizeable dishes Clearly this means that any in built AGC action of the receive system must be switched off entirely it also means that ALL gain stage
26. rger and larger dynamic ranges differential between the smallest usable signal and the largest it can cope with however it often does this is an increasingly less flexible manner Many modern transceivers do not offer the facility of being able to turn off entirely AGC and other actions They also may not be coping with signal level differentiation in a truly linear manner As more and better DSP techniques and components arrive this situation is likely to get better and better from a signal handling perspective which is what they are designed to do but perhaps worse and worse from a noise measurement perspective As DSP moves into the IF and further then we are further and further removed from the opportunity to really know the relationship of what goes in the antenna socket to what comes out of the speaker socket SUMMARY SO FAR For making repeatable and reliable noise temperature Y factor measurements one needs good linearity possibly over several tens of dB of dynamic range with larger gain bandwidths if possible and stable gain over at least tens of minutes time scales with a broad bandwidth detection stage all targeted at offering fractions of a dB measuring capability and readout SOLUTION These requirements have been well understood and well solved in recent history by professional Radio Astronomers It is beyond the scope of this article to explore all the possible solutions I just want to clearly state that the
27. s active on 1296 in May In the Italian Contest I QSO d on 1296 K5GW HB9SV ZS6AXT G3LTF G4CCH W2UHI IK2MMB F2TU KOYW and N2IQ DF3RU got away In an extra sked I QSO d ZL1IKA Now I need only South America for WAC on 1296 My 5760 transverter is almost ready I have to finish the 144 switching circuitry and build an LNA Then I will test performance on the dish but I doubt if my current dish will perform correctly on the 6 cm band Before the SW I forgot to switch off my AZ drive and sent the dish a few turns around the mount The 7 8 Heliax feed line was flattened at one place I made it more round using pliers but my return power went up from 0 to 5 of the full power This is non linear scale so I have to measure it with a network analyzer I suspect that Return Loss went up form 30 dB to about 20 db Probably the best fix will be to cut off the destroyed piece of Heliax and to use two connectors ZS6AXT Ivo zs6axt global co za was active in the Italian Contest On 26 April just after local midnight I worked on 23 cm ZLIKA 549 549 for initial 188 During the Italian contest I started on 13 cm on 10 May and worked JA4BLC F2TU OE9XXI and G3LTF There was not much activity so I QSY d to 23 cm and worked JA6AHB G4CCH F2TU IK3COJ G3LTF DF3RU DKOZAB OZ6OL HB9SV SM3AKW SM2CEW K5GW G3LQR PA3CSG IK2MMB N2IQ WA6PY VE6TA and W2UHI on the horizon Then my EL motor started to play up I had quite a problem to get
28. s installed a Septum feed for 1296 on his dish but lost a 24 actuator in the process The dish was not adequately counter balanced He now needs to balance the dish and repair the drives before he can be QRV FOR SALE DF9CY has two 7213 PAs designed for the aircraft band that can be converted for 144 and 432 MHz operation available Anyone interested should contact Chris at eme df9cy de AFIT has some 10 GHz Qualcomm amplifiers for sale They are high gain over 40 dB and may be driven with less than 100 microwatts from a diode mixer All are tuned up and have SMA connectors for input and output They include a power unit to supply 10 V and 5 V from a 12 V supply or battery The cost is US150 post paid Contact Dale at 603 428 3840 or via Lee AAIYN at http www aalyn com vhf AAILYN can make 10 GHz feedhorns designed for the Primestar offset dishes These horns are bored out to 0 795 and have an SMA or N to circular waveguide transition tig welded to them W3ZQ has a military surplus AM2066 TRC PA for sale This is a 400 600 MHz cavity tuned amplifier with rack cabinet RF Deck and Power Supply included It runs a GL6942 final spare Included It takes between 50 and 150 W of drive at 432 This is a twin of the PA that was used at K3NSS on the 84 dish up until the early 80 s Under an STA from the FCC they consistently got 3 kW output Pick up only as it is heavy Value is around US800 Please contact Ray W3ZC His work phone is
29. s must be linear and not subject to degradation of noise this is very improbable in a modern narrow band receiver In addition you need to increase the integration time in order to have a stable average milli voltmeter reading in most cases this is not w 2601 OG T B43 245 29 743 z 2 n 57 i a n 3 85 3 99 aE 2 1134 28 ay g 127 a 141 Se 155 i a 169 a i 183 g 5 3 1972 z g 2112 g 253 an z as E J 239 E 253 267 3 281 z 295 i 309 3233 ggj 337 TIAN 3513 2l easily achieved either and you end up studying either a blur of numbers on a digital meter really unsuitable for this purpose or a fluctuating needle on a traditional meter You also need a large scale meter with good resolution and because of the large swing with measurement most likely some attenuator or range switching in the milli volt meter itself Such meters of good professional quality can however e found from time to time on the surplus equipment market Method 2 System linearity requirements are easier and AGC actions have less or even no influence the difficulties of integration time and milli volt meter ranging remain The biggest challenge however is locating suitable step attenuator s that are rated at the required frequency and offer the necessary precision within switching steps Once again one is faced with possible match gain changes for each step if the impedance is not very clos
30. s to swing the array until you find the quietist sky possible but in doing so one does not really know if you are peaking the quiet source or nulling the other noise contributions Attenuator FOR HOT SOURCES 1 Resistor surprise This one shows up in both categories the reason for that is that on higher bands the temperature of the load offers a considerable increase over that of quiet sky Even at 144 on a large antenna system it is possible to measure a negative delta between a load and quiet sky The problems are a Exactly the same as those outlined in using the resistor or load as a source for quiet reference 2 Galactic noise sources throughout the sky One can find well documented individual objects and clusters of objects that are known to be hot relative to the general background temperature of the surrounding sky The problems are a The output from these objects is rather low on most amateur bands the traditional choices of Saggitarius A Cygnus etc offer reasonable deltas in reading Y factor referenced to quiet sky at 144 in the 3 to 8 dB range for a typical 4 bay antenna system at 432 the array gain is higher for a given physical size and they offer results in a lower but similar range at 1296 and up you are required to be able to measure Y factors of fractions of a dB to be able to use them b On lower bands especially 144 it may not be possible to find them at all in city or suburban environments c Because of th
31. t included many equations amp calculations these are freely available from many sources I finally present a new solution to an old problem bought within the grasp of amateur constructors by the onward march of R F chip and micro controller technology WHY DO I NEED ONE One traditional tools for making a judgment about the performance of an EME system is by use of a Y factor measurement It is not the purpose of this article to explore all the details of how why amp when to make such measurements but in principal the methodology is to point the receiving system at an area of Quiet Sky with a low noise temperature take a reference reading then move the system to an object area with higher noise temperature ie a hot source By manipulating the delta between the two readings the Y factor one can reach conclusions about overall system performance and by substitution component parts of ones receiver system This process is described adequately in many professional and amateur literature sources together with the math and equations necessary However they generally omit to cover adequately the difficulties in obtaining the measurements and any discussion of the pros and cons within source choices and methodologies for the measuring process Although simple in nature and easily comprehended in practice Y factor evaluation is rather difficult to realise with absolute and repeat accuracy There are two methods that can be used to
32. the shack wall is much closer to the dish itself Obviously reflectivity plays a large part here The wall of trees to my west displays a range of readings depending on season and if they are wet or dry The scales used in this plot are far from either clear or desirable They were concocted before I developed a little more sophisticated PC software to command the radiometer and collect the results the antenna was driven by hand one degree at a time and each point laboriously noted by hand before entering into EXCEL for analysis and plotting As will be seen later I have since largely automated this process although there is much left to do THE ELECTRONICS Although I do have access to decent CAD tools for RF simulation schematic capture and PCB design this project has been undertaken and constructed using not much better than kitchen table tools as far as pcb manufacture and soldering etc is concerned although having access to a good network analyser for my initial experiments and tuning and matching of my gain strip has proved invaluable The heart and the inspiration for this project is a detector chip designed for professional power measurement and control from Analog Devices This chip first appeared during 1999 and I subsequently became involved with it on a semi professional basis in the implimentation of a micro controller based power meter application This AD8313 chip has been designed to translate rf input to a proportional DC out
33. to implement their own drivers This leaves the final DC out available for people to add their own A Ds I will probably do a simplified Micro controller with A D control and A D devices My current one uses too much high density SMT and in circuit programming for software upgrades to be easily managed I ll do a pluggable chip version This concept leaves potential users to provide their own additional gain chain ahead of the instrument but it does add a lot of flexibility as many people wanted to feed transverter chains with 144 IF into something so this setup will allow either direct RX gain chains on the 3 bands or the possibility to use existing setups Obviously the accuracy and especially the drift accuracy and bandwidth control will then be thrown into the users court for the rest of his RX chain ahead of what I design This is the compromise of stability versus flexibility The more knowledgeable users will be able to ensure their chain thermal gain stability and linearity The less knowledgeable users will still have a very usable instrument for good Y factor measurements into the 0 1 perhaps even 0 01 dB areas i e very sufficient for proper EME system evaluations The folks wanting to really launch into Radio Astronomy will have a base to work from but will have to input some effort themselves to get the better stability accuracy bandwidth control If there is enough interest I may make some PC boards available later this
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