HF radio and sighting glass

Submitted: Saturday, Dec 29, 2007 at 19:36
ThreadID: 52956 Views:3296 Replies:6 FollowUps:22
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Few years back I took a couple across the Simpson. The old girl insisted on a HF, and I told her she could hire these at the RFDS base in Alice.

The unit came in an old wooden box with a sighting glass and wire antenna to stick up a tree.

At the time I didn't take too much notice on how it worked, but was always entertained by the husband trying to get the unit going in the late afternoon. Or at least their squabbles.

Apart from being attached to the battery for power, anyone know much about these units and how they worked?

Regards

Kim
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Reply By: Member - John (Vic) - Saturday, Dec 29, 2007 at 19:48

Saturday, Dec 29, 2007 at 19:48
Footy!! Footy!! Where are you Footy??

He's the man you need Kim :-))
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Reply By: Member - Fred G (NSW) - Saturday, Dec 29, 2007 at 19:51

Saturday, Dec 29, 2007 at 19:51
Kim, Be honest...How many years back was THAT ????? I used to pedal an old 2 way for school of the outback, but don't ask me how it worked. My sister and I were just glad on the numerous occasions it didn't.
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Follow Up By: Member - Kim M (VIC) - Saturday, Dec 29, 2007 at 20:29

Saturday, Dec 29, 2007 at 20:29
Fred

Your a cheeky buggar!

Hope you and the family had a good one over Christmas.

Regards

Kim
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Follow Up By: Member - Fred G (NSW) - Saturday, Dec 29, 2007 at 20:51

Saturday, Dec 29, 2007 at 20:51
Certainly did mate, all the best for '08 to you and yours.
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Reply By: Mike Harding - Saturday, Dec 29, 2007 at 19:53

Saturday, Dec 29, 2007 at 19:53
I don't know why a sighting glass Kim - the radiation from an HF antenna is very complex and depends upon many factors - the best one could say for a single wire is that the majority of radiation is from the side of the element.

Mike Harding
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Follow Up By: Member - Fred G (NSW) - Saturday, Dec 29, 2007 at 20:00

Saturday, Dec 29, 2007 at 20:00
Mike, could you please say that in OCKER ?????
Hint...sighting glass may have something to do with line of sight...Sound familiar...NextG?????
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Follow Up By: Member - Kim M (VIC) - Saturday, Dec 29, 2007 at 20:04

Saturday, Dec 29, 2007 at 20:04
Gidday Mike

This was like a piece of very light fencing wire. Not an antenna as we know today. They first tested it at Mt Dare around the side where there are a few trees.

Regards

Kim
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Follow Up By: Mike Harding - Saturday, Dec 29, 2007 at 20:16

Saturday, Dec 29, 2007 at 20:16
Hi Kim

We should catch up for a beer again.

Antenna wise: things have not changed much in 100 years - Amateur Radio people do odd things with antennas, my favourite is the "shopping trolley" antenna - I kid you not! :) It's possible to tune almost anything into an HF antenna. Wire fencing is an old trick.

Mike Harding
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Follow Up By: Mike Harding - Saturday, Dec 29, 2007 at 20:18

Saturday, Dec 29, 2007 at 20:18
PS. Fred: the HF frequencies (below 30MHz) do not behave in the same manner as the higher frequencies so no "line of sight"
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Follow Up By: Bonz (Vic) - Saturday, Dec 29, 2007 at 20:48

Saturday, Dec 29, 2007 at 20:48
I would be in on that catchup for a tipple - maybe If I am in town
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Follow Up By: Member - Fred G (NSW) - Saturday, Dec 29, 2007 at 20:49

Saturday, Dec 29, 2007 at 20:49
Mike, ocker pleeeaaasse....., you lost us all somwhere between the mhz & freq. & line of sight & radiation, antennas, ohms and watts, behaviour. Plain ocker mate, pleeeaaaase.We are just plain old ockers mate....LOL...HAHAHA...:))
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Follow Up By: Member - Fred G (NSW) - Saturday, Dec 29, 2007 at 20:56

Saturday, Dec 29, 2007 at 20:56
We'll have to rename BONZ the "MOTH" .....turn up anywhere there's a light on and booze involved.
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Follow Up By: Bonz (Vic) - Saturday, Dec 29, 2007 at 20:57

Saturday, Dec 29, 2007 at 20:57
hahaah Fred you'd think that wouldn't you, the truth is something we shall not delve into here hhahaha
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Follow Up By: Member - Fred G (NSW) - Saturday, Dec 29, 2007 at 21:04

Saturday, Dec 29, 2007 at 21:04
onya mate, have a great 2008 and beyond...
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Follow Up By: Mike Harding - Saturday, Dec 29, 2007 at 21:10

Saturday, Dec 29, 2007 at 21:10
Sounds good to me Bonz - bring your goat.

Fred: the radio thingies go off from the side :)

Mike Harding
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Follow Up By: Bonz (Vic) - Saturday, Dec 29, 2007 at 21:28

Saturday, Dec 29, 2007 at 21:28
Last time I was in a pub with my goat there was a big blue. Everyone wanted to sit next to me, it got on my goat yannow?
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Follow Up By: Member - Fred G (NSW) - Saturday, Dec 29, 2007 at 21:33

Saturday, Dec 29, 2007 at 21:33
Is your goat Billy the Kidd...HAHAHA :))
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Follow Up By: Bonz (Vic) - Saturday, Dec 29, 2007 at 21:34

Saturday, Dec 29, 2007 at 21:34
lol His name is Jason
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Follow Up By: Member - Fred G (NSW) - Saturday, Dec 29, 2007 at 21:41

Saturday, Dec 29, 2007 at 21:41
appologies to Jason. Will "butt" out now.
Happy New Year all. May 2008 bring you all health, wealth and happiness.
Fred & Christine.
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Reply By: Member - Kiwi Kia - Saturday, Dec 29, 2007 at 21:47

Saturday, Dec 29, 2007 at 21:47
I have not seen one but have a thought on a possible answer.
The 'sight glass' could hav been a sextant. If you heard the time signals on the HF and took a sun sight at the same time you could then get a 'fix' on your position with the aid of some tables.
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Reply By: Footloose - Sunday, Dec 30, 2007 at 08:16

Sunday, Dec 30, 2007 at 08:16
Yo Kim. Is this the unit you are referring to ?
http://home.iprimus.com.au/jimshire/6924_mk1.htm

It's a Codan 6924, commonly referred to as a "lunchbox" .
The aerial was usually strung up in a tree , and pointed towards the appropriate spot.

They are still used by some today.
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Follow Up By: Member - Kim M (VIC) - Sunday, Dec 30, 2007 at 15:45

Sunday, Dec 30, 2007 at 15:45
Gidday Footloose

It's a bit hard to tell from the photograph. Looks like a bit of an up market version. The same principle applies however.

Do you know why the sighting glass was needed on top of the unit?

I might add it was effective. They were picking up Alice Springs at Eyre Creek without any problems at all.

Cooper Creek was ok, but the signal was getting a bit weak at Thargomindah.

From memory the "fence wire" antenna was pretty much as you described.

Regards

Kim
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Follow Up By: Footloose - Sunday, Dec 30, 2007 at 15:53

Sunday, Dec 30, 2007 at 15:53
Kim, the aerial was usually oriented (depending on the kind of aerial they used, did it have a cable bit to connect to the set ?) towards where they wanted to talk to. If it was one with the cable, they would have pointed the aerial at right angles.

Depending on time of day, even the later Codan and autotune whip could have problems at Thargo. That Hf stuff is awfully variable, although when doing a Oz crossing 2 years ago I was always in contact with the 737 network at least once a day, even on the Kidson track. A far cry from my Globalstar satphone that I wanted to throw as far as I could from the WA border through to the coast :(((
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Follow Up By: Footloose - Sunday, Dec 30, 2007 at 16:00

Sunday, Dec 30, 2007 at 16:00
Kim I have more lunchbox pix at http://home.iprimus.com.au/jimshire/6924.htm

Just thinking a bit, it might not have been one of these, although I don't know of any others that would qualify. The compass kinda throws me a bit, although it could have been before my time :)))))
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Follow Up By: Member - Kim M (VIC) - Sunday, Dec 30, 2007 at 16:22

Sunday, Dec 30, 2007 at 16:22
Footloose

Thanks for that. While reading your post it just occurred to me the sighting glass is an optical signal tuning device. How dumb of me not to pick that up.

Regards

Kim
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Follow Up By: Footloose - Sunday, Dec 30, 2007 at 16:39

Sunday, Dec 30, 2007 at 16:39
Kim, I should have thought that but I didn't.
See, not so silly after all :)))
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Reply By: Andrew from Vivid Adventures - Sunday, Dec 30, 2007 at 10:33

Sunday, Dec 30, 2007 at 10:33
This is not really an answer to your question Kim, but...

Electric Bug in Adelaide (mobile radio specialists) have an aerial which you can attach to a Codan or Barrett tuning antennae...

It is like a massive (from memory 10m) carbon fibre whip that is in 800mm or so parts that slide into each other like the electric aerial on a car.

Apparently it significantly increases the power transmitted and received.

I can't find it online, but it is interesting... I've not had the chance to give it a try, but will one remote trip or other.

Of course it only works when you're stationary.
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Follow Up By: Footloose - Sunday, Dec 30, 2007 at 14:28

Sunday, Dec 30, 2007 at 14:28
Andrew, lots of people subscribe to the longer is better theory, although many females might disagree.

Be sure that when you test such things that you do a direct comparison ie the standard whip against the longer one. Don't forget to retune between the two.
Also remember that such tests are often highly subjective, unless the receiver has a signal strength meter and you are using a field strength meter with the transmitter.
As long as the vertical whip will still tune as a quarter wave, you should be OK, but its performance might change on the higher frequencies. Try it on whatever frequencies you have rather than just one.
Another factor which comes into play is the capture length ie the longer the tuned aerial, the greater signal strength...sometimes :))
Obviously the standard whip is useable on the move, and won't tend to catch as many branches.

My own tests with longer and shorter whips simply confirm that the shorter ones don't tune as low in frequency as the longer ones, rather than signal strength differences. But my longer whips tend to be much shorter than the one you are talking about.
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