Transverters for 24 GHz CW & SSB Steve Kavanagh, VE3SMA & Bob Golden, VE3OIK OVHFA Annual Meeting, Toronto, Oct. 11, 2003 Contents Background VE3SMA Transverter Description VE3OIK Transverter Description Results So Far Demonstration Background
24 GHz local activity on Wide Band FM: VE3SMA (2 rigs) VE3VXO VE3OIK (2 rigs) VE3FHM W2EV (2 rigs) no other nearby US stations Others using borrowed rigs: VE3MNA, VE3EZP, VE3NPB, WB2VUO, etc. VE3EZP is building, VE3VZ has most parts needed Best DX so far: VE3OIK-VE3VXO 74 km Background Narrowband (CW/SSB) on 10 GHz Active in Southern Ontario:
VE3OIK, VE3SMA, VE3FHM Best DX so far in Southern Ontario: 308 km - VE3SMA (EN92fn)-K2AXX(FN12cs) under poor-toaverage conditions VE3OIK has had several 280-290 km QSOs with W8s VE3SMA heard K2UYH in NJ (about 550 km) in August Compare with best of about 175 km on wideband FM under very good conditions (VE3EZP N2JH) Much easier to work >100km on narrowband Background Nearby Activity on 24 GHz Narrowband Rochester Area K2DH, K2AXX, K2EHF, K2LDU/K2LDT, WO2P, N2EZS, WB2BYP, W2DYY They have already worked paths up to about 200 km K2LDU/VE3 broke Canadian 24 GHz DX record, working K2EHF at 134 km from FN14 (near Colborne) Detroit Area
WW8M, NE8I, WA8HGX Eastern Ohio KB8VAO So why not give 24 GHz CW/SSB a try and see if we can work more/better DX ? Background Commercial or Homebrew ? Only one source of commercially built transverter: Kuhne Electronic (DB6NT) Most Rochester & Detroit ops are using these Approx. CDN$675 for basic transverter with 2m IF (200 microwatts output) Add approx. CDN$740 for preamp + power amp to 100 mW (not including antenna relay, 24 GHz bandpass filter and interconnects, not available from Kuhne Electronic) Bob and I both prefer to spend little and homebrew a lot so the obvious choice was to design & build our
own rigs.what little we knew then ! VE3SMA Transverter Many design options were considered Choice driven by availability of two parts W5LUA LO-doubler/mixer board kit obtained from K2DH (described in Microwave Update 97) 10944 MHz LO input, 2304 MHz nominal IF for 24192 MHz RF (calling frequency is 24192.1 MHz) Qualcomm Q0410 PLL synthesizer board thrown out by my former employer VE3SMA Transverter Block Diagram FT-290R 2m Xcvr 145.9 MHz
Doubler 5472 MHz Image Filter 24192.1 MHz Antenna VE3SMA Transverter Qualcomm Synthesizer Q0410 is demonstration board using (now obsolete) Q3036 synthesizer chip Specified for 1-7 mW output at 900-1600 MHz (mine works over about 750-1700 MHz) Requires +/-5V and +12V so had to provide some power supplies to run from +12V only On-board 10 MHz frequency reference oscillator is not very pure
or stable I used an external 12 MHz TCXO module removed from a surplus UHF radio board Added switches to control PLL divider ratios makes a good multi-purpose UHF signal generator Thanks to N6IZW for providing a copy of the manual VE3SMA Transverter LO Quadrupler (1368-5472 MHz) Own design using amplifier MMICs Quite broadband, covers about 5.4-6.1 GHz Lessons learned: Normally well behaved ERA-3 can oscillate when driven non-linear Input and output impedance of 50-ohm MMIC is not 50 ohms when driven non-linear MAR-8 Doubler Microstrip Bandpass Filter
MAR-3 Amplifier ERA-3 Doubler Microstrip Bandpass Filter MGA-64135 Amplifier VE3SMA Transverter LO Doubler (5472 -10944 MHz) Own design using microstrip circuit with MGF1902B GaAsFET Short section of WR-75 waveguide after this doubler to eliminate any 5.472 GHz output Using 13 GHz spectrum analyzer (tnx to VE3TCK) could not detect any spurious
outputs after this doubler/waveguide VE3SMA Transverter 2304 MHz Intermediate Transverter Single connector for Tx & Rx from/to FT-290R 100 mW Tx from FT-290R on low power FT-290R provides DC on coax on transmit for T/R control Single connector for Tx & Rx to/from 24 GHz mixer 1 mW output at 2304 MHz in transmit Unusual features High side LO at 2450 MHz (allowed the use of an available crystal and tiny surplus 2450 MHz ceramic filters in the LO chain) Use of GaAs FET RF switch ICs for T/R switching (thanks to AD6A for providing them !) Modified Down-East transverter a good alternative VE3SMA Transverter
2304 MHz Transverter Block Diagram (MSA-0786) 9dB pad RF To FT-290R DC GaAs SPDT Switch (AS169) T/R Control 40.833 MHz Osc./tripler (2x2N5770)
GaAs SPDT Switch (AS169) To 24 GHz Mixer (MSA-0786) Control voltages to switches and amplifiers 122.5 MHz Amplifier (2N5179) 245 MHz Doubler (2N5179)
450 MHz Doubler (2N5179) Diode Quintupler (2xVE3EZP) 2450 MHz Amplifier ERA-3+ERA-1 VE3SMA Transverter W5LUA LO Doubler/Mixer Uses ATF-36077 PHEMT doubler and HSMS-8202 dual Schottky diode in rat-race mixer About 13 dB conversion loss, in prototype In this transverter this implies Rx noise figure of about 15 dB and Tx output of about 50 microwatts. Al says he has some boards left but hasnt given me a
price. DEMI no longer stocks the HSMS-8202. Coax-to-Waveguide Transition To get from microstrip mixer to waveguide filter Uses .085 semirigid coax soldered to mixer board and to 3/8x3/16 hobby brass tubing waveguide. Performance unknown as no way to measure ! VE3SMA Transverter 24 GHz Bandpass Filter To remove 19.584 GHz image signal & 21.888 GHz LO leakage 2-cavity post filter in 3/8x3/16 hobby brass tubing waveguide Designed using WGFIL program by WA4LPR (described in Microwave Update 89) 4-40 tuning screws though broad wall of waveguide at midpoint of each cavity Centre post .078 dia. .335 .335 End posts .032 dia.
~.33 (inside) VE3SMA Transverter Antennas 1st QSO with 17 dBi horn made from hobby tinplate sheet 1 foot surplus dish with Penny Feed in 3/8x3/16 hobby brass tubing Feed dimensions (thanks to VK3ZQB) Slots 6.2 x 0.6 mm Disk 12.5 mm dia. x .032 brass sheet Got reasonable SWR without any tuning VE3OIK Transverter Some design options were considered To use 23 GHz P-Com surplus modules acquired in Dayton, would have to build a 3456 MHz transverter for the IF. The design chosen was to use a lower IF frequency based on the availability of parts.
Took advantage of using 12 GHz Microwave L.O. bricks that I acquired. VE3OIK Transverter 20 dB pad MAR-6 MMIC 20 dB gain @ 144 MHz 1st RX IF in 220 MHz dB Coax Mixer IF in/out 144 MHz DPDT RF relay SPDT RF relay
to TS-700A 12 * 680 ohm 2 watt resistors, 24w, 56 ohm load +24vdc In TX IF relays +12v TX RF relay +24v TX L.O relay +24v TX/RX 24 ghz Modules +12v TX/RX Switching TX gnd to TS-700A 2nd TX IF out dB
dB Coax Mixer 3 dB pad 2 * 1pf silvermica caps in series W/G BPF 4 pole 24192 MHz 2nd L.O. 364.388 MHz DB6NT LNA Board 3 * NE32584 Fet's 24 dB gain 1st RX IF out 220 MHz 220 MHz Amplifier
20 dB gain Flex w/g W/G HPF SMA Relay 12/24 GHz Doubler NE32584 Fet Coax Mixer W/G BPF 4 pole 24192 MHz DB6NT LNA Board 3 * NE32584 Fet's 24 dB gain Coax to W/G feed 2nd TX IF in
2 Ft Dish BPF 220 MHz 24 GHz Transverter - VE3OIK MAV 11 MMIC -20 VDC IN W/G HPF 12/24 GHz Doubler NE32584 Fet SMA Relay 12 GHz Brick L.O.
12206.124 MHz Toshiba Amplifier 0.5 watt, 36 dB gain Ref. Osc. 96.874 MHz VE3OIK Transverter 144/220 MHz IF Section DPDT RF relay to switch 144 MHz path for the IF rig either in transmit or receive. The receive path contains a 20 dB pad and a MAR-6 MMIC to protect the IF mixer The transmit path contains a resistive dummy load to terminate the transmit power from the IF rig and provide 1mw of transmit power. VE3OIK Transverter 144/220 MHz IF Section, contd The coax mixer is used for transmit and receive.
The Local Oscillator frequency is 364.388 MHz When mixed with 144 MHz it produces a 220 MHz signal for transmit. On receive it allows a 220 MHz signal to be downconverted to 144 MHz. SPDT RF relay selects either the transmit or receive path from the 24 GHz modules. The transmit output is about 200W. VE3OIK Transverter 24192/220 MHz Downconverter The 24 GHz coax mixer is used to convert 24192 MHz signal to 220 MHz RX IF. The L.O. is fed from a 12/24 GHz doubler which takes a 12 GHz signal from a Megamicrowave Brick L.O. It is then doubled to 24 GHz using a NE32584 FET. The HPF after the doubler filters out any products below 24 GHz.
VE3OIK Transverter 24192/220 MHz Downconverter, contd The 4 pole waveguide filter filters out the image frequency. Intermediate posts .125 dia. .42 (inside) .331 .373 .373 .331 Centre post .125 dia. End posts .062 dia. Ahead of the waveguide filter is a DB6NT LNA board bought as a kit containing an etched PCB, 3 *NE32584 FETs, and some brass foil for making the z-wires during construction.
This amplifier has about 25 dB gain and 2 dB noise figure. An SMA relay rated for 18 GHz is used as an antenna relay The loss is slightly higher at 24 GHz but very useable for amateur radio purposes. A small piece of 0.085 semi-rigid cable is used to connect the downconverter module to the RX port on the SMA relay. VE3OIK Transverter 24192/220 MHz Upconverter The IF input to the 24 GHz coax mixer is 220 MHz, which is filtered by a 220 MHz BPF and amplified by a MAV 11 MMIC. The filter chooses the desired IF frequency of 220 MHz from via the first TX mixer in the IF section then amplifies it drive the IF port on the 24 GHz coax mixer. The coax mixer is used to convert 220 MHz Tx signal to 24192 MHz Tx signal. The L.O. is fed from a 12/24 GHz doubler which takes a 12 GHz signal from a Megamicrowave Brick L.O. It is then doubled to 24GHz using a NE32584 FET.
The HPF after the doubler filters out any products below 24 GHz. VE3OIK Transverter 24192/220 MHz Upconverter, contd The 4 pole waveguide filter filters out the image frequency. After the waveguide filter is another DB6NT LNA board. This amplifier has about 25 dB gain. The DB6NT amplifier also drives a 0.5 watt Toshiba commercial amplifier. A small piece of 0.085 semi-rigid cable is used to connect the power amplifier to the TX port on the SMA antenna relay. VE3OIK Transverter 24 GHz Power Amplifier The Toshiba power amplifier was purchased from EBAY for $85 USD. The output power is rated at 0.5 watt.
The frequency range of this commercial amplifier is 23 26 GHz. Ideal for 24192 MHz. The output from the upconverter module is fed to the amplifier input via coax to waveguide transitions. The amplifier output is equipped with a waveguide to coax transition. This is connected to the TX port of the SMA switch with a short piece of 0.085 semi rigid cable. VE3OIK Transverter Coax to Waveguide Feed The SMA TX/RX relay is attached via a SMA barrel connector to a coax to waveguide transition. A length of WR-42 waveguide is used to cut down the losses of the transmission line to feed the dish. A fish hook feed is constructed using a flex piece of waveguide and a small pyramidal horn to feed the 2 FT antenna with an F/D of 0.45. Parabolic Antenna The antenna is a 2 ft. (60 cm) diameter dish with an F/D of 0.45.
Antenna was purchased from Down East Microwave. The waveguide protrudes through the dish via a cut out. VE3OIK Transverter 12 GHz L.O Brick The 12 GHz L.O. brick is a made by MEGAMICROWAVE. These bricks can be found surplus at Ham flea markets. Other names such as California Microwave, Frequency West, Collins work very well. This particular brick has an external reference oscillator connection. Most of the PLL bricks have internal crystals and dont need external crystal reference. The reference oscillator frequency is 96.874 MHz. VE3OIK Transverter 12 GHz L.O Brick, contd This reference frequency locks the brick to 12206.124 MHz. The reference frequency was chosen using trial and
error to come up with a usable choice for the right up/ downconversion IF frequencies. The multiplication factor is shown below: 96.874MHz * 14 * 9 = 12206.124 MHz This means the total multiplication factor is 126. This signal is then fed into a 12/24 GHz doubler to achieve a fundamental L.O. at 24412.248 MHz. Results So Far Lots of time spent by both of us on design, parts scrounging, construction, debugging, etc. ! We have concluded that, compared to the time spent on the homebrew rigs, DB6NT transverters are well worth the money ! But not as educational, or satisfying. Results So Far Initial QSOs July 29/03 VE3SMA-K2LDU 0.6 km & 4 km paths across Niagara River
Frequency calibration was only 15 kHz different from Charlies. Minimal drift (by 24 GHz standards!) and good CW note were noted. Sept. 9/03 VE3OIK-VE3SMA 3 & 10 km paths in Cambridge/Kitchener area VE3OIK at 2.5 mW output (without power amp) Very loud signals Drift stabilized after about 15 minutes warm up Results So Far 2003 10 GHz & Up Contest (24 GHz NB)
VE3OIK (FN14ba) W2DYY (FN12ev) 127 km VE3OIK (FN14ba) N2EZS (FN02xu) 130 km VE3OIK (FN14ba) KB8VAO (FN02xu) 130 km VE3OIK (FN14ba) W2DYY (FN02xu) 130 km VE3SMA (FN14ba) W2DYY (FN02xu) 130 km VE3OIK (EN92ci) KB8VAO (EN91kt) 85 km VE3SMA (EN92lp) KB8VAO (EN91kt) 94 km VE3OIK (EN92fn) KB8VAO (EN91kt) 89 km VE3OIK (EN92fn) VE3SMA (EN92lp) 44 km Whats Next ? VE3SMA needs preamp, power amp and antenna switching between them Graham, VE3FHM, is collecting parts and starting to build a transverter ! An attempt on the VE-to-VE dx record An attempt on the VE-to-W dx record
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