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RFguy

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Everything posted by RFguy

  1. I think hot and humid in Mackay and cold and dry at the north pole is a good assumption.
  2. Skippy, there is no practical difference between a 5 and 5X. the old microphone capsule used in the 5- is no longer available, so they called it a 5X with the new capsule. (AFAIK) Mics get full of mouth stuff as years go by and one of the two ports of the mic gets junked up, and the noise cancelling ability of the microphone is reduced.
  3. Relativistic effects and varying density of the earth and gravimetric effects included or disregarded ?
  4. once on the ground, should have re-flared it right ???, lift the nose wheel back up at just the right time to dodge the rock ? :-) ....deadpan.... This is why, the "clean up Australia day" litter cleanup needs to have scope extended to cleaning up all rocks in all fields, and putting white red cones on those that cannot be moved, wherever they are. :-)
  5. rocks are visible lurking in the grass on the bottom left hand side of the photo. looks like a reasonably fair outcome, really, considering less favourable options.
  6. I'd defer to Mark on that for a 2nd opinion. My opinion : You'd want electret unless your intercom is very old, or Mil. I would be buying electret and nothing else. ALL the civilian intercoms I have seen in the last 20 years have been high level for electret mic I have only ever seen dynamic mics in old JetRangers and old Cessnas. Some of those had a 4 pin XLR with power available for the mic preamp for dynamic headset. And I see dynamic in military helicopters in the 1990s.
  7. Much if it is compatibility Dynamic mics have a low level of output, and can be low or high impedance and must reasonably be matched Carbon mics somewhat different. Electret mics are high level output. Dynamic mics (low output) attached into high level inputs (which are designed for electret mics) must have pre-amplifiers in the headset, and so need some ship power or battery. Some NATO stuff I encountered was 2 ohm dynamic (yes, 2 ohm) , really low and needed a transformer and preamp .
  8. I think augmented reality glasses would be a much better solution here. Project the horizon and a whole bunch of stuff into your field of view without disturbing the far field view. They work great on the bike. And in underground work , and in a lecture theatre, and and and. Or, project an image onto the canopy with a Laser vision projector (they don't have lens, direct scanning spot projection ) Or , you could just look at your HSI
  9. All 912xxxx Rotax use fuel return bypass back to tank, dont they, to keep things circulating ?
  10. I agree with the recommendation of the Thomas and Betts ties Be aware : The Bunnings black ones, "UV" are good for 3 months in the sun, no more and most are a lower temp plastic. Most of the black ones, unless rated , with soften around 90 deg C - 110 deg C. and You dont need UV rating inside the cowl unless there is high reflected UV from the on ground tarmac all day . The Nylon clear/milky types are usually good for 150 deg C but check rating and if they are not rated don't use them. Nylons vary from about 50 to 250 deg C glass temperature.
  11. I would never use zip ties in this application. At least no longer than an emergency temporary when you are out in the Tanami Desert. Like 30 days maximum. AND if you do use black zip ties, make sure you buy the ones with the METAL TONGUE. I would suggest NOT use the types with the plastic tongue, about 1 in 10 has a defect in my experience. -glen
  12. @ Arron25 I was thinking ,for that airplane, to fit the quad (or rather, a full wave loop of any convenient shape) (and remember for vertical polarization feed from the side, not the bottom like an HPOL HF quad) , ....the antenna is probably going to be quite close to you (IE where the fuselage is big enough to accommodate the quad) , and as Mark says will get into your headphones, electronics etc. You could screen the cabin area with a wire net, a mesh or copper or ally, or zinc . (or a fabric mesh that is impregnated, or a gal steel wire coarse mesh. (Gal) Zinc is good.
  13. ABSOLUTELY agree with Waraton- fly the circuits in your mind , do radio calls, do every single thing !!! and then fly circuits in your head while driving your car. every single thing including radio calls out loud. I think doing circuits in your head while driving or riding a bikle is good for learning to cope with distractions.
  14. ahh ok. I get the picture. That's how. still not much room to work with for displays, unless one used a projection onto a large screen and chewed up unused panel space next to it. the other size are 3" holes, ? But see less and less of those with EFIS creeping in . BTW I bought an Uavionix AV30. will advise when i get it installed. Also have a SkyEcho. there is another forum topic on that.
  15. Hi Mark yeah there seems to be alot of EFIS integration. Certainly makes panel space easier. 2" and a 1/4 is hard. (60mm square beyond). I see alot of radios have 2 1/4" mount but a box elsehwere. I have Icom 200, 210s Tray types etc various Dittel, Becker etc My current SDRs are 73mm width PCB . wouldnt be a big deal to get them down to 50mm. (lose the fibre interfaces, linux) , although I imagine the CAN bus remote radios are in a little aluminium box 'elsewhere ' ?
  16. Microairs. yeah, send me your dead Microairs. Either for me to fix (fixed price repair, I'll have to figure out what that will be , probably something like $100 + shipping ), or I will buy them dead. What I need is to see a few more than just a couple so far in the flesh. I need to see what the full spread of problems are. And indeed if they are worth carrying on with. I've done a bit of reading, seems to be a couple of systematic design problems . and vulnerabilities that are maybe easily solved. Down the track, MAYBE I will try and re jig my digit
  17. no ground plane, likely to be extremely poor result, and put RF into all your intercoms, electronic instruments, EFIS etc portable radios only work on VHF with a rubber duck because YOU form the other half of the antenna. if you need a emergency portable antenna just attach the other end of a piece of coax to a length of thick wire, 1180mm long, cut the wire in the middle, hang the wire vertical ish, and feed inner conductor of the coax cable to the top half of the cable and the shield to the lower half of the coax.
  18. My Nav yesterday added also, keep a log of, and changing left and right tanks, recalculating time used, time available on each tank with each iteration, amongst all the bumps and mayhem. g
  19. so changing tanks error ? one tank selected and one tank low, intermittent supply during banking manouvers ? High wing. gravity feed...
  20. As discussed elsewhere in this forum , A good road cycling helmet $150- $200 would protect your noggen from banging it on the aircraft body. They are cool (thermal) to wear and comfortable.
  21. Rob Glenn (my CFI) says "Always stack the odds in your favour if there isn't much penalty. "
  22. Aaron, that white radomed antenna will be just fine with 600mm RADIUS of ground plane (of tube or sheet) , or several strips of wide copper or Alluminium tape or thick foil / flashing - four is good each 640mm long, inch to 4 inches wide. from the antenna mounting base. Antennas on these ships are a compromise. It's important to remember that ideal , perfect omni directional radiation patterns can rarely be achieved due to the interaction with the body of the aircraft and flight controls.
  23. Arron25, actually the quad will be good -enough omni- it depends what shape you built them..... The control rods and cabls will be main influence. However with say 600 sides on the quad, it might be just too big in the empenage. The quad needs a bit over 1 wavelength of wire, any closed shape, preferably not a convex. And it also needs a 75 ohm quarter wave matching section. Or a series 68 is ohm resistor in series which would keep the radio happy over the bandwidth at the cost of 50% of efficiency... anyway, that's just one idea if it fits The biggest issue is B
  24. Mark is right. Also remember in a non metal skinned or composite body that control cables and rods will conduct RF and modify the antenna radiation pattern, the metal cables and rods become part of the antenna and will carry RF energy back to the cockpit...
  25. Lyle, A would NOT recommend any sort of loaded Helical whip. Helical whips are very narrow band and the requirement is WIDE band... And with the quarter wavelength of 640mm at lowest frequency, if you put the whip in the middle of the band , say 124 MHz, a 590mm long whip really isnt too long..... There are other options you can build (I can guide you) for any specific airplane or mechanical requirement. Lyle what is the aircraft, and what is the body ? For a non metal body plane- The fin is a good place to put it, keeps it away from the intercom and
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