Presentation on theme: "How to get on 10G moonbounce with a portable station..... Michael Kohla I did it my way! …I did it my way!"— Presentation transcript:
How to get on 10G moonbounce with a portable station..... Michael Kohla I did it my way! …I did it my way!
EME meeting 2013 in Örebro 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 Örebro 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 set- up…? So, just taking another challenge, which is not for the whimps…
EME meeting 2013 in Örebro 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 nice…but 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 ° beamwidth
EME meeting 2013 in Örebro But with two dishes…. More space in Knut is needed…solved: 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 Örebro Dish on test range in DL
EME meeting 2013 in Örebro 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 Örebro 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 Örebro 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, 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 Örebro Block schematic wg lna DB6NT RX 40 W SSPA DB6NT TX coax lna 13.8/28V dc/dc con 28V wg switch Sucoflex MHz OCXO 25 A FET sw 1m Aircom plus Sequencer 250 mW PTT lin.hor. feed
EME meeting 2013 in Örebro New feed system
EME meeting 2013 in Örebro 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 Örebro The 10G system of TK/DL1YMK on site
EME meeting 2013 in Örebro Closer up…
EME meeting 2013 in Örebro Even closer…
EME meeting 2013 in Örebro Cabling…which is which with 5 bands of moonbouncing?
EME meeting 2013 in Örebro Results on 10G in TK TK/DL1YMK Log 3 cm Date Time UTCCallTX rprtRX rprtQSO #initial # LX1DBO PA0EHGORM22 "1605OK1KIRORO33 "1655LX1DB539 4/ "1711DL7YCROM54 "1951F2TUORO65 "2046W5LUAORM76 "2103W7CJOROM87
EME meeting 2013 in Örebro 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 Örebro Hints on hb SSPAs During Örebro 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 Örebro PCB Design by DL2AM, 50 ohm striplines w/o matching elements, onboard –Vg control, 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 120°C!!!! Add. M2-screws needed at points of high RF- current (flakes weld on there…), see picture
EME meeting 2013 in Örebro Hot spots on PCB Visible : Infrared (after 1 min 50 W out):
EME meeting 2013 in Örebro 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 Örebro 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 Örebro Reinforcing of PCB tracks Use additional solder on tracks carrying high DC currents Especially, if 17µm copper clad is used 3 x SI4425 need a little help for de- heating, rated Ids 12 Amps each
EME meeting 2013 in Örebro 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 Örebro 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 sandcorn- like feeling in your eyes, if unprotected Use fly screen on your goggles Unfortunately, doesnt make the guy looking better….
EME meeting 2013 in Örebro 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…????? All power heads calibrated 100%....
EME meeting 2013 in Örebro 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 TIM has the same Ptot (60 W) as an TIM (!?); 25 W sat. are easily achieved FLM 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 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 Örebro Tack för er uppmärksamhet !