Transverters for 24 GHz CW SSB Steve Kavanagh

Transverters for 24 GHz CW & SSB Steve Kavanagh, VE 3 SMA & Bob Golden, VE 3 OIK OVHFA Annual Meeting, Toronto, Oct. 11, 2003

Contents • • • Background VE 3 SMA Transverter Description VE 3 OIK Transverter Description Results So Far Demonstration

Background • 24 GHz local activity on Wide Band FM: – – – VE 3 SMA (2 rigs) VE 3 VXO VE 3 OIK (2 rigs) VE 3 FHM W 2 EV (2 rigs) – no other nearby US stations Others using borrowed rigs: VE 3 MNA, VE 3 EZP, VE 3 NPB, WB 2 VUO, etc. – VE 3 EZP is building, VE 3 VZ has most parts needed – Best DX so far: VE 3 OIK-VE 3 VXO 74 km

Background • Narrowband (CW/SSB) on 10 GHz – Active in Southern Ontario: • VE 3 OIK, VE 3 SMA, VE 3 FHM – Best DX so far in Southern Ontario: • 308 km - VE 3 SMA (EN 92 fn)-K 2 AXX(FN 12 cs) under poor-toaverage conditions • VE 3 OIK has had several 280 -290 km QSOs with W 8’s • VE 3 SMA heard K 2 UYH in NJ (about 550 km) in August • Compare with best of about 175 km on wideband FM under very good conditions (VE 3 EZP – N 2 JH) – Much easier to work >100 km on narrowband

Background • Nearby Activity on 24 GHz Narrowband – Rochester Area • K 2 DH, K 2 AXX, K 2 EHF, K 2 LDU/K 2 LDT, WO 2 P, N 2 EZS, WB 2 BYP, W 2 DYY • They have already worked paths up to about 200 km • K 2 LDU/VE 3 broke Canadian 24 GHz DX record, working K 2 EHF at 134 km from FN 14 (near Colborne) – Detroit Area • WW 8 M, NE 8 I, WA 8 HGX – Eastern Ohio • KB 8 VAO • 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 (DB 6 NT) • Most Rochester & Detroit ops are using these • Approx. CDN$675 for basic transverter with 2 m IF (200 microwatts output) • Add approx. CDN$740 for preamp + power amp to 100 m. W (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 !

VE 3 SMA Transverter • Many design options were considered • Choice driven by availability of two parts – W 5 LUA LO-doubler/mixer board kit obtained from K 2 DH (described in Microwave Update ’ 97) • 10944 MHz LO input, 2304 MHz nominal IF for 24192 MHz RF (calling frequency is 24192. 1 MHz) – Qualcomm Q 0410 PLL synthesizer board thrown out by my former employer

VE 3 SMA Transverter • Block Diagram FT-290 R 2 m Xcvr 145. 9 MHz 2304 MHz Xvtr 2304. 1 MHz W 5 LUA Doubler Mixer 10944 MHz Qualcomm Q 0410 Synth. x 4 1368 MHz Doubler 5472 MHz Image Filter 24192. 1 MHz Antenna

VE 3 SMA Transverter • Qualcomm Synthesizer – Q 0410 is demonstration board using (now obsolete) Q 3036 synthesizer chip – Specified for 1 -7 m. W output at 900 -1600 MHz (mine works over about 750 -1700 MHz) – Requires +/-5 V and +12 V so had to provide some power supplies to run from +12 V 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 N 6 IZW for providing a copy of the manual

VE 3 SMA 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

VE 3 SMA Transverter • LO Doubler (5472 -10944 MHz) – Own design using microstrip circuit with MGF 1902 B Ga. As. FET – Short section of WR-75 waveguide after this doubler to eliminate any 5. 472 GHz output – Using 13 GHz spectrum analyzer (tnx to VE 3 TCK) could not detect any spurious outputs after this doubler/waveguide

VE 3 SMA Transverter • 2304 MHz Intermediate Transverter – Single connector for Tx & Rx from/to FT-290 R • 100 m. W Tx from FT-290 R on low power • FT-290 R provides DC on coax on transmit for T/R control – Single connector for Tx & Rx to/from 24 GHz mixer • 1 m. W 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 Ga. As FET RF switch ICs for T/R switching (thanks to AD 6 A for providing them !) – Modified Down-East transverter a good alternative

VE 3 SMA Transverter • 2304 MHz Transverter Block Diagram (MSA-0786) 9 d. B pad RF To FT-290 R DC Ga. As SPDT Switch (AS 169) T/R Control 40. 833 MHz Osc. /tripler (2 x 2 N 5770) 9 d. B pad (MGA-86576) (WJ MY 84 -1) Ga. As SPDT Switch (AS 169) Microstrip Bandpass Filter Ga. As SPDT Switch (AS 169) To 24 GHz Mixer (MSA-0786) Control voltages to switches and amplifiers 122. 5 MHz Amplifier (2 N 5179) 245 MHz Doubler (2 N 5179) 450 MHz Doubler (2 N 5179) Diode Quintupler (2 x”VE 3 EZP”) 2450 MHz Amplifier ERA-3+ERA-1

VE 3 SMA Transverter • W 5 LUA LO Doubler/Mixer – Uses ATF-36077 PHEMT doubler and HSMS-8202 dual Schottky diode in rat-race mixer – About 13 d. B conversion loss, in prototype • In this transverter this implies Rx noise figure of about 15 d. B and Tx output of about 50 microwatts. – Al says he has some boards left but hasn’t 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 3/8”x 3/16” hobby brass tubing waveguide. – Performance unknown as no way to measure !

VE 3 SMA Transverter • 24 GHz Bandpass Filter – To remove 19. 584 GHz image signal & 21. 888 GHz LO leakage – 2 -cavity post filter in 3/8”x 3/16” hobby brass tubing waveguide – Designed using WGFIL program by WA 4 LPR (described in Microwave Update ’ 89) – 4 -40 tuning screws though broad wall of waveguide at midpoint of each cavity Centre post. 078” dia. . 335” End posts. 032” dia. ~. 33” (inside)

VE 3 SMA Transverter • Antennas – 1 st QSO with 17 d. Bi horn made from hobby tinplate sheet – 1 foot surplus dish with “Penny Feed” in 3/8”x 3/16” hobby brass tubing • Feed dimensions (thanks to VK 3 ZQB) – Slots 6. 2 x 0. 6 mm – Disk 12. 5 mm dia. x. 032” brass sheet • Got reasonable SWR without any tuning

VE 3 OIK 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.

VE 3 OIK Transverter

VE 3 OIK 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 d. B 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 1 mw of transmit power.

VE 3 OIK Transverter • 144/220 MHz IF Section, cont’d – 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 200 W.

VE 3 OIK 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 NE 32584 FET. – The HPF after the doubler filters out any products below 24 GHz.

VE 3 OIK Transverter • 24192/220 MHz Downconverter, cont’d – The 4 pole waveguide filters out the image frequency. Intermediate posts. 125” dia. . 42” (inside) . 331” . 373” . 331” Centre post. 125” dia. End posts. 062” dia. – Ahead of the waveguide filter is a DB 6 NT LNA board • bought as a kit containing an etched PCB, 3 *NE 32584 FETs, and some brass foil for making the z-wires during construction. • This amplifier has about 25 d. B gain and 2 d. B 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.

VE 3 OIK 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 24 GHz using a NE 32584 FET. – The HPF after the doubler filters out any products below 24 GHz.

VE 3 OIK Transverter • 24192/220 MHz Upconverter, cont’d – The 4 pole waveguide filters out the image frequency. – After the waveguide filter is another DB 6 NT LNA board. – This amplifier has about 25 d. B gain. – The DB 6 NT 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.

VE 3 OIK 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.

VE 3 OIK 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.

VE 3 OIK 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 don’t need external crystal reference. – The reference oscillator frequency is 96. 874 MHz.

VE 3 OIK Transverter • 12 GHz L. O Brick, cont’d – 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. 874 MHz * 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, DB 6 NT transverters are well worth the money ! But not as educational, or satisfying.

Results So Far • Initial QSOs – July 29/03 VE 3 SMA-K 2 LDU 0. 6 km & 4 km paths across Niagara River • Frequency calibration was only 15 k. Hz different from Charlie’s. Minimal drift (by 24 GHz standards!) and good CW note were noted. – Sept. 9/03 VE 3 OIK-VE 3 SMA 3 & 10 km paths in Cambridge/Kitchener area • VE 3 OIK at 2. 5 m. W 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) – – – – – VE 3 OIK (FN 14 ba) – W 2 DYY (FN 12 ev) 127 km VE 3 OIK (FN 14 ba) – N 2 EZS (FN 02 xu) 130 km VE 3 OIK (FN 14 ba) – KB 8 VAO (FN 02 xu) 130 km VE 3 OIK (FN 14 ba) – W 2 DYY (FN 02 xu) 130 km VE 3 SMA (FN 14 ba) – W 2 DYY (FN 02 xu) 130 km VE 3 OIK (EN 92 ci) – KB 8 VAO (EN 91 kt) 85 km VE 3 SMA (EN 92 lp) – KB 8 VAO (EN 91 kt) 94 km VE 3 OIK (EN 92 fn) – KB 8 VAO (EN 91 kt) 89 km VE 3 OIK (EN 92 fn) – VE 3 SMA (EN 92 lp) 44 km

What’s Next ? • VE 3 SMA needs preamp, power amp and antenna switching between them • Graham, VE 3 FHM, 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