I would suggest it is either due to doppler shift from the rotating blades or I think more likely acoustic vibrations of the blades modulating the reflected signal, producing side bands. de John G8SEQ

Why? The FT-817 has a BNC on the front panel. Why didn't you just use that for VHF/UHF and leave the SO239 in place? De John G8SEQ

I am. Not doing much radio due to leaking roof! de John G8SEQ

Optical comms. go a lot further back than that - possibly thousands of years with simple beacons, but the Victorians use heliographs which used a tilting mirror operated by a mechanically coupled Mors

Hi Graham, I had a similar problem with publication when I invented an Absorber - an element in a Yagi or similar antenna that has a dummy load at the centre. Originally it was put behind the reflecto

Hi Neil et al, Years ago I did play around with optical comms. I built a thing called a Photon Phone from a magazine article ( PW I think). It amplitude modulated a torch bulb and used a photo diode/t

Robin wrote: "perhaps not the best idea ... pointed upwards it might be OK" What about pilots of aircraft passing over head? Wouldn't you be putting them in danger? de John G8SEQ

OK Colin Tnx. It says 0.4 to 0.8 ( 0.6 typical ) ( V/pp) Amplitude *2 on the data sheet ( and nothing else; no other reference to *2). I probably won't use it anyway. I haven't played with satellite T

Another dumb question: does the 22kHz need to be present all the time or or does it switch with a burst of 22 kHz? de John G8SEQ

Thanks both for that info.. That simplifies matters. I'm intending to run it from a 14 v Li-ion battery ie Vertical Polarization but this doesn't matter as I am able to rotate this LNB in its mount. I

Hi All, Excuse my ignorance, but I am trying to use a Technomate TM-2 Super High Gain UNIVERSAL TWIN LNB as part of a OSCAR-100 Rx but I'm not sure how to wire it up. The spec sheet says it has two lo

Gold (plate) works well as a reflector at infra red. I've seen gold plated aluminium foil, but I've no idea where you would buy it from at economical prices. de John G8SEQ

That's not true! If you move the feed away from the dish, it focusses the energy at a point somwhere beyond the prime focus and infinity. If you move the feed towards the dish, the "focus" becomes an

The maximum rate of climb of an English Electric Lightning was at 78 degrees ( nearly vertical ). If you do the sums not much of the climb is due lift from the wings - its nearly all due to engine thr

Hi Maarten, It looks similar to mine, but it is a long time since I did the repair. Your photo seems to show an X- package in the centre. It might be worth putting a multimeter in diode test function

Hi Maarten, That mixer looks very similar to the one in my old Texscan SA. Have you had the lid off? If you do you will probably find a four diode ring mixer in an X-package. I made one up out of four

I recognise some of those shots. I got some similar ones when I was there. The only sailing I did was on the "Sickonian". I also did some radio in a 6m contest & got an e-mail from a mildly irate Fren

I could imagine a scenario where two Gunn diodes give more power than the sum - one could be acting as an oscillator and the second as an amplifier with perhaps a slightly different bias on it giving

"polo shorts" are no good to me - I haven't got a horse! Unless they are swimming trunks for the other polo game. I guess you mean "shirts", but spell checkers don't high-light those sort of mistakes

Very interesting Murray. Shows how much I'm out of touch with modern electronics. However, after googling how they work, it seems the associated ground plane is doing a lot of the radiating & in a don