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-   -   USB & LSB on HF?? (https://www.pprune.org/tech-log/10746-usb-lsb-hf.html)

Blacksheep 5th January 2002 09:23

fly-boy,

While you're borrowing avionics text books from the tecchies ask them how they pick their frequencies for testing and the effects of the season and sunspots on the ionosphere and thus on the range obtained from the various frequencies.

Gaunty,
Come of it mate, when you had your flying washing line you also had a Radio Operator to wind it in and out for you. And he usually used CW to transmit because morsing worked better with the carrier wave included.

By the way, did you ever use the HF aerial to fly low level back across the North sea after a night of keeping Jerry awake? You know, the old trick of trailing the end in the wave tops and have the rear gunner call out "climb" if the wake became steady and "dive" if it stopped altogether? :)

Back to the subject - when I was hands-on and had to test an HF after fixing it down on the line, I'd get the best frequency from the handy frequency chart kept in the Jeppeson Nav Bag behind the Captain's seat. All the recommended numbers were there and updated to account for the current season and sunspot activities. You didn't know its there? Tut-tut!

And I wouldn't recommend calling Ujang Padang on any frequency at any time. You'll get far more sense from the good old Aussies at Darwin most times. [provided you know the frequency of course <img src="wink.gif" border="0"> ]

**********************************
Through difficulties to the cinema

Tinstaafl 5th January 2002 20:35

Ah... the joys of finding where the f%^& the FISCOM has got to and then hoping like hell one of the 10 faded, handwritten frequencies listed on the equipment matches at least one of the FISCOM frequences.

Provided the list is still legible. In the dark. With turbulence. In some remote corner of the panel. <img src="eek.gif" border="0">

Loc-out 8th January 2002 03:12

Kagamuga

Wouldn't mind getting my hands on one of those Mil HF's if I knew where to get one.

mcdhu 8th January 2002 13:53

Good replies to a fair question! The only thing I would add is that if you are having difficulty getting the BBC World service on HF when far from home, try all 3 SB settings; sometimes, for some inexplicable reason, LSB or AM might work better than USB.
Hey Gaunty, I seem to remember that one of the landing checks on an old radial, sleeve-valve engined aircraft I used to fly went:
'Trailing Aerial....In, Ratchets Selected, Beads Clamped.'
Boy, have things got better!
Cheers
mcdhu

jbc2001 9th January 2002 10:05

Just remember that use of LSB by commercial air transport is illegal in the US! Most modern HF radios also transmit a small "vestigial" carrier with the SSB that simplifies signal demodulation at the receiver.

christian_MD80 9th January 2002 14:20

Propagation forecast charts:

<a href="http://www.stockholmradio.telia.com/aero/" target="_blank">http://www.stockholmradio.telia.com/aero/</a>

<a href="http://www.bernradio.ch/forecast1.htm" target="_blank">http://www.bernradio.ch/forecast1.htm</a>

Rgds

Chris

Self Loading Freight 9th January 2002 16:07

Loc-Out --

There's quite a market in military HF manpacks, but they're expensive. They turn up on eBay (very expensive), on amateur radio sites (not so expensive) or at amateur radio rallies (you can get lucky, but you have to be able to cope with ham rallies. These can sometimes seem like a home for the terminally bewildered let lose at a Harrod's sale).

Have a look at

<a href="http://groups.yahoo.com/group/hfpack" target="_blank">http://groups.yahoo.com/group/hfpack</a>

or

<a href="http://groups.yahoo.com/group/armyradios" target="_blank">http://groups.yahoo.com/group/armyradios</a>

if you're keen. A much cheaper, more effective, easier and more fun alternative is to get a Yaesu FT-817 portable HF/VHF/UHF transceiver -- which in any case uses technology that Yaesu developed for its mil range. Costs £800 in the UK or £600 if you shop around on the Net (Greece recommended -- US prices and no import duty).

I'll get me anorak...

R, G6HVY and bar

radeng 9th January 2002 16:18

It is said in ham radio circles that the use of LSB below 10MHz and USB above comes from an ITU recommendation. I've never found that recommendation......I believe it came about because of the design of the very early (1950's) ham radio SSB equipment.I don't think LSB gets much use in military circles these days.

gaunty 9th January 2002 17:58

Blacksheep and mcdhu

Modesty prohibits me from claiming the height finding methods of WW11 or WT operator enjoyed by my father or the rare privilege of sitting behind an old radial sleeve-valve.

But in Oz from the mid sixites for me up to the early eighties crystal locked raw HF was the mode for most journeys.
You generally only carried those frequencies (3-4)for the area in which you operated as the limitation of the number of channels (10 if I recall) available on your AWA whizbang did not usually allow universal Oz coverage and the sheer expense of getting a crystal cut and fitted (I seem to recall $500 in the days when that would buy a good used car).
I have kept a souvenir FISCOM which was printed in colours that disappeared when viewed at night with the then fashionable red cockpit lights.

I seem to recall once when the dear old DCA issued about 100,000 pads of new Flight Plan forms with the same disappearing colour ink. The first experience when you picked it up after take off to enter your best guess for the next reporting point was a little bewildering.

Plastic funnels and fences, the first you new usually, was when there was a whirring noise from the HF aerial reel as it ran out to its limit then "twang" followed by the backlash. Fishing rod reels have a lot of design features derived from this experience. OR a very short arrival.

The new Codan SSB thingies were a joy, providing endless amusement with "Donald Ducking" by playing with the Clarifier and the King 93 Godzillion frequency synthesised toys miraculous indeed.

And if all that was too hard, there was what they call music from China and Koran reading competitions from Indonesia helping to while away the long nights.

Spodman 14th January 2002 13:07

Great stuff Gaunty.

Sorry to disappoint, but the good ol' boys at Darwin HF have been in Brisbane for a while now, and before that they were in Perth.

Still get people transmitting AM on HF, my FS spies tell me, sounds like an enraged duck from our end. I have no idea what it sounds like when they tell them to change to USB, but it works sometimes.

The squeally-horrible stuff you hear when 2 stations transmit together on VHF is the carriers heterodyning with each other, multiple stations on USB really do sound like people talking over each other, and can be understood. It would a huge improvement to safety if we only used SSB on VHF.

Loc-out 20th January 2002 02:06

Self Loading Freight

Thanks for that. Will investigate further. <img src="smile.gif" border="0">

Golden Rivet 20th January 2002 15:04

slightly off the thread, but does anyone have a list of HF frequencies that can be used for ground testing HF in the UK?

Thanks


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