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Building an X-band transceiver with a little determination and a radio budget Brian Thorson, AF6NA Vice-President San Bernardino Microwave Society (SBMS)

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Presentation on theme: "Building an X-band transceiver with a little determination and a radio budget Brian Thorson, AF6NA Vice-President San Bernardino Microwave Society (SBMS)"— Presentation transcript:

1 Building an X-band transceiver with a little determination and a radio budget Brian Thorson, AF6NA Vice-President San Bernardino Microwave Society (SBMS)

2 SBMS, founded in 1955, is a non-profit technical organization dedicated to the advancement of communications above 1.0 GHz. Meetings every 1 st Thursday of the month 7:00 PM The American Legion Hall 1024 Main Street Corona, CA

3 SBMS is an ARRL-Affiliated Radio Club. Several SBMS Members have set 10 GHz distance records Many SBMS members have been ARRL 10 GHz and Up Contest Winners SBMS still holds the record for the highest contest score.

4 10 GHz means ten billion cycles per second. A billion is hard enough to comprehend in dollars or other quantities. But at X and other microwave bands, the physics of electromagnetics is a bit different. Hollow tubes are the best transmission lines, and antennas take on unusual shapes. Making a QSO is a very special event.

5 How many people here have operated radios other than FM and repeaters? How many people have operated a contest? How many people installed their own equipment? How many people consider themselves technical? How many people have gone camping? How many people know how to use a soldering iron? How many people have an all-mode VHF/UHF rig? How may in this room have worked all bands?

6 Whats This?

7 33 cm MHz: 23 cm MHz 13 cmS-Band: MHz; MHz 9 cmC-Band: MHz 6 cmC-Band: MHz 3 cmX-Band: GHz <<< K-Band: GHz V-Band: GHz W-Band: GHz* GHz GHz GHz Above 300 GHz *76-77 GHz has been suspended temporarily

8 This could be the next challenge for some of you Hams with some experience but who are looking for a new avenue or thrill in Amateur Radio!

9 Goleta to San Diego on 280 mW at MHz: 300 km (186 mi.)

10 SBMS, founded in 1955, is a non-profit technical organization dedicated to the advancement of communications above 1.0 GHz. Meetings every 1 st Thursday of the month 7:00 PM The American Legion Hall 1024 Main Street Corona, CA.

11 Hey, isnt microwave just line-of-sight communications? NO !!!! How did I work Mt. Potosi in Las Vegas last month from Los Banos, CA, (529 km) shooting over Mt. Whitney, the tallest peak in the contiguous 48 states ???

12 Los Banos to Mt. Potosi – 529 km

13 The 900mi shots to AD6FP, N6CA and KH6WZ required large antenna gains and high power to extend signals beyond the duct and inland another 100+ miles and over 6000' mountains and up the California Central Valley. Coastal ducting is caused by an abrupt change in the moisture and temperature of the atmosphere at the boundary between the relatively cool wet layer of air hugging the ocean and the dry warm air above it. This boundary zone acts like a lens for radio and optical signals which then follow the curvature of the earth for great distances.

14 During the first half of the GHz and Up contest, the North American distance record for terrestrial X-Band contacts was broken and re- broken 5 times. This milestone for ham radio X-Band operations was made possible by a one-man DXpedition by Frank Kelly, WB6CWN/4C2WH in DL34wt. The average contact distance was 1,178km (732mi) and the accumulated score on just two of Franks log pages was over 65k points!

15 XE Baja California, Mexico DL34wt Operation in Mexico is advantageous because there is a long over water path between Southern California and numerous points along the western shores of the Baja Peninsula. This path is host to weather that produces coastal ducting, a principal propagation mode.

16 Frank made 53 10GHz contacts from DL34wt on the first weekend. The NA 10GHz DX record was broken five times, first by W6QIW in DM04am at 1315km (817 mi). Steves record lasted approx. 7 minutes Then N6CA and KH6WZ worked Frank from CM94xm (1320km/820 mi), then CM95qi (1426km/886 mi) and again from DM05ax (1448km/899 mi) Finally, on 8/19/2007 at 0845, AD6FP completed a contact with Frank at CM96wa, a record-breaking distance of 1460km (907.2mi) The 10GHz Frazier beacon was copied in DL34wt at 1286km - a new DX record for 10GHz beacon DX

17 The revised KH6WZ rig, with transverter system on the ground and IF radio placed on the antenna deck. The 30-in. dish is supported with an N6CA folding support structure made with aluminum tubing. This is the DB6NT-based rig before exchanging the 24-inch M/A- COM dish with the new 30-inch offset-feed dish.

18 SBMS, founded in 1955, is a non-profit technical organization dedicated to the advancement of communications above 1.0 GHz. Meetings every 1 st Thursday of the month 7:00 PM The American Legion Hall 1024 Main Street Corona, CA.

19 The X-Band rigs used can be duplicated; typical performance can be built with ham techniques and resources RX performance: 1dB NF, 25dB gain For terrestrial work, there is little improvement below a 2dB system NF due to ground noise (about 150K). No need to spend $300 on an EME preamp! TX performance: 6W to 10W range Antenna: 30-in. plus dish Bigger antennas are better – But are they practical and transportable? Offset feed dishes have higher efficiency, and are becoming more popular. Other dishes (prime-focus) are a low side-lobe design and not designed for efficiency

20 Attend SBMS meetings and get acquainted GOTA – Get On The Air with a 10 GHz Rig Make it rugged enough to withstand a ride in your car / truck, etc. Partner with another experienced and successful operator for the contest Try it before you say it cant be done

21 The next point down range near the tip of Baja is over 1000 miles XE2HWB and XE2HWH in La Paz, Baja, Mexico now have their own 2W 10GHz radios built by WB6CWN The record can definitely be extended on the Northern side

22 Building a radio from available parts is one of the greatest of Ham radio traditions. Microwave amateur radios are not available off the shelf from any manufacturers. This is really one of the most rewarding parts of becoming a microwave ham. No two radios are exactly alike, they all have their own design, shape factor, performance specs, strengths and weaknesses.

23 Most amateurs have a QRP radio, that is, a low-power radio. The Yaesu FT-817 is a great unit and many experienced microwavers prefer it as an IF radio Many people have an old satellite dish they no longer use, such as a Dish Network or DirecTV dish attached to the side of the house

24 SBMS, founded in 1955, is a non-profit technical organization dedicated to the advancement of communications above 1.0 GHz. Meetings every 1 st Thursday of the month 7:00 PM The American Legion Hall 1024 Main Street Corona, CA.

25 If you dont have one, eBay is a good source of used radios. ($300 to $700)

26 Try to find one with the feed assembly in place. That way, you dont have to do so much math to find the focal point. $ FREE !!

27 A transverter is the heart of the system. DB6NT from Kuhne Electronics GMBH 280mW / 1.2 dB NF …About $650 US plus shipping from Germany Down East Microwave (DEMI) 3W/1.5 dB NF ………….. $775

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29 A simple 280 mW radio will make many QSOs (DB6NT based system shown)

30 A high stabilitymaster oscillator will be necessary to tune in SSB signals at X-band. A Rubidium or Rubi and an OCO are shown $ on eBay

31 Getting the transverter, the T/R switch, the cooling fans, (power amp), and everything to switch on when you press the PTT button may take a little creativity and electronic design. I used relays from Radio Shack Solid State Sequencers are available

32 SBMS, founded in 1955, is a non-profit technical organization dedicated to the advancement of communications above 1.0 GHz. Meetings every 1 st Thursday of the month 7:00 PM The American Legion Hall 1024 Main Street Corona, CA.

33 Waveguide is the best transmission line for the microwave bands. WR-90 is the best for GHz. (3/4 copper pipe)

34 Semi-rigid coax, such as UT-141T, is rated for microwave frequencies, but is more lossy than waveguide.

35 Waveguide-to-Coax transitions are used near the Antenna feed point to convert from coax to the waveguide so the microwave power can be applied to the reflector.

36 Feed Horn Assembly T-R Switching Antenna focal point D.C. Supplies

37 Microwaves are a very elusive quantity - losing a dB here and a dB there in a microwave system is very easy to do. Use the best semi-rigid coax and the shortest lengths possible. Avoid getting kinks in the semi-rigid, and dents in the waveguides. Losses on the receive side can seriously affect your minimum discernable signal (MDS).

38 To minimize power losses, microwave frequency components should be located as close to the reflector feed as possible. K6JEY has a great example of this. Doug Millar, PhD., K6JEY

39 Your best time investment will be spent getting high efficiency out of the reflector antenna and feed system. The lowest cost and lowest noise gain you have in your microwave system is your antenna. If you take care to put the feedhorn at the right spot and point the feedhorn correctly, your antenna gain will be maximized and noise minimized. If you just rough it in the antenna will perform poorly. The receive system will be noisy, making it hard to receive weaker signals and expensive microwave Watts will be wasted.

40 Getting the focus and feed angles correct will take a bit of geometry and algebra. Paul Wade, W1GHZ, has done extensive research work into microwave reflector antennas and has published excellent tutorial material on his website: Additional information on offsets and feeds is also helpful.

41 W1GHZ developed a very useful method of finding the focal point with a string. The string is marked with the calculated values of focal length and illumination angle

42 When making measurements on your dish, measure to the edges of the reflective surface, rather than the outside lip of the sheet metal. This will yield better agreement with calculated values.

43 Bisect the offset reflector vertical illumination angle and thats the spot to point at, not the center of the reflector.

44 SBMS, founded in 1955, is a non-profit technical organization dedicated to the advancement of communications above 1.0 GHz. Meetings every 1 st Thursday of the month 7:00 PM The American Legion Hall 1024 Main Street Corona, CA.

45 Assembling and de-bugging a microwave radio is a very time- consuming and gratifying activity…. …. So much so, that some Hams have turned it into a multiple-year project, and some havent finished yet! The Goal: GOTA!

46 A well-built microwave radio is one that works well not only in the lab, but has been ruggedized to take a car ride all weekend and not fall apart en-route. Should be able to arrive at a roving location and be on the air in less than 10 minutes.

47 Steve, W6QIW: Close to the Dish

48 John, KJ6HZ Has all parts on one plate

49 Every year on the last weekend of July (30 JUL 2011) Fairview Park, Costa Mesa, CA EIRP and MDS measurements

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52 SBMS, founded in 1955, is a non-profit technical organization dedicated to the advancement of communications above 1.0 GHz. Meetings every 1 st Thursday of the month 7:00 PM The American Legion Hall 1024 Main Street Corona, CA.


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