How to get on 10G moonbounce with a portable station..... I did it my way! Michael Kohla What are we going to talk about now? Why 10G on a DXpedition?
Preconditions to be met by the equipment How it was realized practically Experience gained during TK-DXpedition Rugged solid state alternative to TWT-power Some construction hints for your own SSPA (pcb, FETs, tuning, power measurement, safety features, results achievable) EME meeting 2013 in rebro Tell me why. The incentive was to activate TK not only on 70 6 cm, but also on 10G No records found of anybody, who tried 10G moonbouncing portable during a DXpedition b4 M&M
Facing a lot of problems: where to get enough (reliable, lightweight) power, what kind of antenna, which feed (circ./lin.), how to test setup? So, just taking another challenge, which is not for the whimps EME meeting 2013 in rebro How could it work?? No chance to use the stressed dish for 10G (6cm is the ultimate limit, aberration from parabolic shape, +/- 3mm !!!) Solid dish would be nicebut heavy Compromise: modest diameter of 1.85 m Only prime focus, although less efficiency Fortec Star dish (Canadian make, deep drawn metal sheets, 6 panels bolted together)
Gain 41.7 dBd @ 1.1 beamwidth EME meeting 2013 in rebro But with two dishes. More space in Knut is neededsolved: space gained by less knickers for op/2nd op two separate rotators are needed Modified another SPID-RAS with magnetic absolute encoders Wired all to fit with existing OE5JFL tracking system Mounted dish on a second tripod EME meeting 2013 in rebro Dish on test range in DL
EME meeting 2013 in rebro The transverter box A new DB6NT-trvtr-based system was built about 6 weeks before departure to TK Using waterproof installation plastic box (cheap, robust) with alu chassis inside, piggy back on dish For EME-power (???) a 2 x poor mans SSPA was integrated, 2 x 22 W ->41.5 W at N-socket 106 MHz OCXO for improved frequency stability Independent sequencer, steering the trvtr, SSPA and IC-910 in shack; only 10 m Aircell7 for IF and a PTT-line to the shack, 13 V/40 A PS underneath the dish EME meeting 2013 in rebro
Trvtr box behind dish EME meeting 2013 in rebro A look inside the box EME meeting 2013 in rebro Feed development: CP septum chapperal EME meeting 2013 in rebro First test of system Test was run on sked with LX1DB from garden
backyard 4 weeks b4 departure At that time it really was not sure, if 10G would be on DXpedition Willi could hear me right away, with YMK on circ., exchanged O / RO.some hope Willi made me measure CS/G with set-up, only got 3.8 dB of 4.9 dB theor. (no imag. rejection filter, only 1 coaxial LNA (0.8dB NF) at feed Moon noise just detectable EME meeting 2013 in rebro Improvement on system Changed to linear round wg chapperal feed (LX1DB make), + 3 dB on linear stations Added wg rejection filter in front of RX (rejection on 6NT sufficient, but not good enough)
Added wg LNA (selected by 6NT, 0.57 [email protected] 23 dB), directly mounted on wg switch, moved coaxial LNA to trvtr box Measured CS/G as 4.7 dB, moon noise 0.7 dB, a repeatable system improvement two weeks b4 departure Had to put matchsticks in my eyes at work EME meeting 2013 in rebro Block schematic Sucoflex 104 wg lna 28V wg switch
coax lna 13.8/28V dc/dc con Sequencer DB6NT RX 106 MHz OCXO lin.hor. feed 1m Aircom plus
40 W SSPA 25 A FET sw 250 mW EME meeting 2013 in rebro PTT DB6NT TX New feed system EME meeting 2013 in rebro
Final test in garden Ran another sked with LX1DB one weekend b4 departure, exchanged O / 539 Could hear OK1KIR perfectly 519 after Willi, missed a completion by seconds only due to a thuja tree in the West Had to optimise counter weight balance for auto-tracking, DRIACS went mad on speed ramp-up Dismantled system for TK-trip. EME meeting 2013 in rebro The 10G system of TK/DL1YMK on site
EME meeting 2013 in rebro Closer up EME meeting 2013 in rebro Even closer EME meeting 2013 in rebro Cablingwhich is which with 5 bands of moonbouncing? EME meeting 2013 in rebro Results on 10G in TK
TK/DL1YMK Log 3 cm Date Time UTC Call TX rprt RX rprt QSO # initial #
25.05.2012 1901 LX1DB O 539 1 1 28.05.2012
1539 PA0EHG O RM 2 2 " 1605
OK1KIR O RO 3 3 " 1655 LX1DB
539 539 4 / " 1711 DL7YC RO
M 5 4 " 1951 F2TU O RO
6 5 " 2046 W5LUA O RM 7
6 " 2103 W7CJO RO M 8 7
EME meeting 2013 in rebro What was learnt The loss in 1.1 m Aircom Plus TX-line incl. N-connectors sums up to -1.2 db, which means abt. 29 W in the feed WG to feed would be much better 1.8 m dia of dish seems to be ultimate minimum on TX rather than on RX (nb: for REAL EME, of course) OCXO is sufficiently stable (as learnt from trial with K5GW) Coaxial systems on frontend are no good with small dishes Mounting trvtr on prime focus dish for portable use is impossible A dish of 2.4m dia would be competitive EME meeting 2013 in rebro
Hints on hb SSPAs During rebro 2012 reported on poor mans SSPA with salvaged FETs Meanwhile built 7 units, including a 50 W unit Learnt a lot about: * tuning procedure with pre-matched FETs, that dont fit qrg-wise * mounting of pcb *power measurement => lots of hope, little knowing EME meeting 2013 in rebro PCB Design by DL2AM, 50 ohm striplines w/o matching elements, onboard Vg control, RT5870 @ 0.5 mm,
available at SA6BUN Ok for FETs FLM0910-x or TIM1011-x Off freq. devices need a lot of re-compensating by flaking (TIM1112-x) Rigid milled alu-box is a MUST (de-heating) PCB for 3-stage amps MUST be glued into box with electr. conductive epoxy (2 comp. Systems prefered), but not everywhere; cure at 120C!!!! Add. M2-screws needed at points of high RFcurrent (flakes weld on there), see picture EME meeting 2013 in rebro Hot spots on PCB Visible : Infrared (after
1 min 50 W out): EME meeting 2013 in rebro Mounting of critical devices use only small 1p Cs, white ceramic, low ESR, high self res. freq. like Temex CHA if use ATC100A-> always coding face-up
remove flux at output striplines use 2 x 0.5 p, side by side to compensate for inductance EME meeting 2013 in rebro Mounting of FETs Make pcb flush with FETs, avoid any additional inductance Use indium-foil for heat transfer, NO silicone grease, Arctic Silber 5 will do Grind base of FET on 400 wet grind paper on a glass plate Use little compound, avoid short
circuits with comp. squeezed up in gap EME meeting 2013 in rebro Reinforcing of PCB tracks Use additional solder on tracks carrying high DC currents Especially, if 17m copper clad is used 3 x SI4425 need a little help for deheating, rated Ids 12 Amps each EME meeting 2013 in rebro Flaking, on and on.
Iterative process, beginning at input, at full expected input power!! Before flaking: maybe 2 W out, PA gets awfully hot, use sufficient heatsink Finally tune for best phase coincidence at hybrids Measure RF power at dump port, by making up a 10 dB attenuator EME meeting 2013 in rebro Beware of RF hazard!! The un-tuned SSPA will irradiate like hell, be good to your eyes, you only have
two At 10G even at 20 W level you will notice a sandcornlike feeling in your eyes, if unprotected Use fly screen on your goggles Unfortunately, doesnt make the guy looking better. EME meeting 2013 in rebro Measuring RF power on 10G Used HP435A with 8481B on 25 W SSPAs and 8481A with cal. Narda 18G 30dB/100W on 50W
PA Using a Narda 30 dB coupler was bad idea Tried 3 differend 8481A heads: got on the same SSPA results from 21 to 25.5 W with Narda attenuator????? EME meeting 2013 in rebro All power heads calibrated 100%.... Where to get those GaAs-FETs from
All my devices were salvaged from those Elisra TV-link amplifiers, still available on vintage markets If you find one: prefer the TIM1112-x ones; the TIM11128 has the same Ptot (60 W) as an TIM1112-15 (!?); 25 W sat. are easily achieved FLM 1112-8 has only Ptot = 42.8 W the FLM will give you the power mentioned in the specs, but not more! A good source for small quantities of FETs is PA3GIE (www.gie-tv.com), a set for a 25 W SSPA will cost @ 770,- (DB6NT 25 W PA is 2900,- ) If you send me a 180 x 90 mm RT5870 / 0.5mm card, I will be happy to make a pcb for you EME meeting 2013 in rebro Tack fr er uppmrksamhet ! ngra frgor ???
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