1. Transverters for 24 GHz CW & SSB
Steve Kavanagh, VE3SMA
&
Bob Golden, VE3OIK
OVHFA Annual Meeting, Toronto, Oct. 11, 2003

2. Contents Background VE3SMA Transverter Description
VE3OIK Transverter Description
Results So Far
Demonstration

3. 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

4. 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-to-average conditions
VE3OIK has had several km QSOs with W8’s
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

5. 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 ?

6. 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 !

7. 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 MHz RF (calling frequency is MHz)
Qualcomm Q0410 PLL synthesizer board thrown out by my former employer

8. VE3SMA Transverter Block Diagram FT-290R 2m Xcvr 2304 MHz Xvtr W5LUA
145.9
MHz
2304.1
MHz
MHz
FT-290R
2m Xcvr
2304
MHz
Xvtr
W5LUA
Doubler
Mixer
Image
Filter
Antenna
10944 MHz
Qualcomm
Q0410
Synth. x4
Doubler
1368
MHz
5472
MHz

9. VE3SMA Transverter Qualcomm Synthesizer
Q0410 is demonstration board using (now obsolete) Q3036 synthesizer chip
Specified for 1-7 mW output at MHz (mine works over about 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

10. VE3SMA Transverter LO Quadrupler (1368-5472 MHz)
Own design using amplifier MMICs
Quite broadband, covers about 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

11. 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 GHz output
Using 13 GHz spectrum analyzer (tnx to VE3TCK) could not detect any spurious outputs after this doubler/waveguide

12. 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

13. VE3SMA Transverter 2304 MHz Transverter Block Diagram (MSA-0786)
(MGA-86576)
(WJ MY84-1)
To 24 GHz
Mixer
GaAs
SPDT
Switch
(AS169)
GaAs
SPDT
Switch
(AS169)
GaAs
SPDT
Switch
(AS169)
GaAs
SPDT
Switch
(AS169)
9dB
pad
Microstrip
Bandpass
Filter
9dB
pad RF
(MSA-0786)
T/R
Control
Control voltages
to switches and
amplifiers To
FT-290R DC
MHz
Osc./tripler
(2x2N5770)
122.5 MHz
Amplifier
(2N5179)
245 MHz
Doubler
(2N5179)
450 MHz
Doubler
(2N5179)
Diode
Quintupler
(2x”VE3EZP”)
2450 MHz
Amplifier
ERA-3+ERA-1

14. VE3SMA Transverter W5LUA LO Doubler/Mixer Coax-to-Waveguide Transition
Uses ATF 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 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”x3/16” hobby brass tubing waveguide.
Performance unknown as no way to measure !

15. VE3SMA Transverter 24 GHz Bandpass Filter
To remove GHz image signal & GHz LO leakage
2-cavity post filter in 3/8”x3/16” 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
.335”
.335”
Centre post .078” dia.
End posts .032” dia.
~.33” (inside)

16. VE3SMA Transverter Antennas
1st QSO with 17 dBi horn made from hobby tinplate sheet
1 foot surplus dish with “Penny Feed” in 3/8”x3/16” 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

17. 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.

18. VE3OIK Transverter

19. 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.

20. VE3OIK Transverter 144/220 MHz IF Section, cont’d
The coax mixer is used for transmit and receive.
The Local Oscillator frequency is 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.

21. VE3OIK Transverter 24192/220 MHz Downconverter
The 24 GHz coax mixer is used to convert 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.

22. VE3OIK Transverter 24192/220 MHz Downconverter, cont’d
The 4 pole waveguide filter filters out the image frequency.
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 semi-rigid cable is used to connect the downconverter module to the RX port on the SMA relay.
.331”
.373”
.373”
.331”
Intermediate posts .125” dia.
Centre post .125” dia.
.42” (inside)
End posts .062” dia.

23. 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 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.

24. VE3OIK Transverter 24192/220 MHz Upconverter, cont’d
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 semi-rigid cable is used to connect the power amplifier to the TX port on the SMA antenna relay.

25. 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 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.

26. VE3OIK Transverter Coax to Waveguide Feed Parabolic Antenna
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.

27. 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 don’t need external crystal reference.
The reference oscillator frequency is MHz.

28. VE3OIK Transverter 12 GHz L.O Brick, cont’d
This reference frequency locks the brick to 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 = 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 MHz.

29. 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.

30. 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 Charlie’s. 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

31. Results So Far 2003 10 GHz & Up Contest (24 GHz NB)
VE3OIK (FN14ba) – W2DYY (FN12ev) 127 km
VE3OIK (FN14ba) – N2EZS (FN02xu) km
VE3OIK (FN14ba) – KB8VAO (FN02xu) 130 km
VE3OIK (FN14ba) – W2DYY (FN02xu) 130 km
VE3SMA (FN14ba) – W2DYY (FN02xu) 130 km
VE3OIK (EN92ci) – KB8VAO (EN91kt) km
VE3SMA (EN92lp) – KB8VAO (EN91kt) 94 km
VE3OIK (EN92fn) – KB8VAO (EN91kt) km
VE3OIK (EN92fn) – VE3SMA (EN92lp) km

32. What’s 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