HAM radio

Excellent results, given how little you have done with antennas at your QTH. This highlights how if something seems improbable, give it a try anyway. Unless you encountered marine telephony on LF it's unlikely you have done much with 160m. Yes the wavelength makes ideal antennas rather long but for FT8, all you have to do is make it resonant and give it a try. This will bring new knowledge and experience of propagation below 2 MHz.
You might find some interesting nets to listen to.

There are still the other bands, time of day, season, grey line and so on.
I'm stil in a YouTuibe spiral from links youve posted eralier...


I'll come up for air in a bit :)
 
Many years ago when I was a Screw at a Cat C Training Prison in deepest darkest and at the highest place in rural Suffolk.

It was a requirement to do a set of nights every 10 or so weeks. Being a Screw who the Governors did not really trust, I used to end up staging on the internal fence patrols. This would suit me fine, bimbling around the grounds all night, in the dark, seeing nobody and speaking to nobody, but maintaining a listening watch to my hand held Motorola radio.

One dark but very clear and cold night I was leaning against the 20 foot high external metal fence and my radio started to pick up transmissions from the Police Control Room numerous miles away in the Humberside area. This was bit of a surprise as the establishment radios were basic line of sight types using an antenna on the tallest building in the establishment connected to a mains set with a range of only a few miles from the establishment.

A phone call to the said Police Control Room and repeating some of thier transmissions confirmed that they were transmitting and I was receiving thier transmissions.

I was the only person picking up the Police transmissions, the establishment main base set was not. I had the Orderly Officer stand next to me to confirm the Police transmissions.

Next day the Home Office had some Signals types down to check out the establishment radios and if the transmissions could be picked up during various times of the day. Apparently it was only happening at night.

This went on for the rest of the week, same fence section, different hand set, same Police Control Room.

It was put down to the atmospherics.

Once the weather changed the next week the transmissions ceased.

We regularly used to pick up the radio transmissions from Dutch Trawlers out in the North Sea but that would be heard on all hand held sets and the main base set.

The Cloggie prisoners would say that they were going to be assisted in an escape by the Trawler Crews. I used to remind them that the River Lark at Bury and the brook at Haverhill were very shallow and would not allow the passage of a sea going trawler.
Thanks for the great dit. I enjoyed that. A fence can act as a very large reflector at VHF. Weather conditions over sea can create a phenomenon known as atmospheric refractivity or ducting. This happens where two different masses of air meet but do not merge because of their different characteristics, temperature, moisture etc. An inversion layer is one example. VHF signals that would normally disappear in to space find their way barred by this new layer and are reflected between it and the ground, creating a ducting effect. Then there's Tropospheric ducting caused by weather a few miles up.

ETA -
Tropospheric propagation - Wikipedia
Atmospheric duct - Wikipedia
Anomalous propagation

ETA - Jim Bacon knows a lot about this stuff. He's one of those weather scientists. Funny him being called Bacon and being in to Ham radio. Video: VHF Propagation Presentation by Jim Bacon, G3YLA
VHF/UHF Propagation - Radio Society of Great Britain - Main Site : Radio Society of Great Britain – Main Site
 
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Gentlemen..Ive just been perusing an obscure part of the forum- The New Zealand bit and... was suddenly met with an impending whiff of pipe tobacco smoke. It is a known fact that pipe tobacco smoke is synomynous with....beards.

I have traced it back to this thread.

@endure post the picture again please.


I estimate Max-beard +45 now - which is not too far off actually discovering the meaning of life.

Good work chaps

:)

Learning a hell of a lot
 
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fv1620

Old-Salt

endure

GCM
Gentlemen..Ive just been perusing an obscure part of the forum- The New Zealand bit and... was suddenly met with an impending whiff of pipe tobacco smoke. It is a known fact that pipe tobacco smoke is synomynous with....beards.

I have traced it back to this thread.

@endure post the picture again please.


I estimate Max-beard +45 now - which is not too far off actually discovering the meaning of life.

Good work chaps

:)

Learning a hell of a lot
Something to aim for...

bbbeard.jpg
 
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endure

GCM
I always thought EMF meant Electro-Motive Force.

Anyway, at 14 MHz, I would be compliant, the “safe limit” is about 11 feet, and it’s more like 80ft to the antenna from the shack.

However, plugging in 0.5W and 850MHz for a cellphone, nobody is going to be compliant. The safe limit is 6 inches. Everyone that uses them without external mic/speaker holds them right next to their bonce.
 

endure

GCM
According to the calculator the safe distance from this 1500W transmitter banging out a telegram on 16Mhz is 12.36 metres :rofl:


opal bounty rr.jpg
 
I always thought EMF meant Electro-Motive Force.

Anyway, at 14 MHz, I would be compliant, the “safe limit” is about 11 feet, and it’s more like 80ft to the antenna from the shack.

However, plugging in 0.5W and 850MHz for a cellphone, nobody is going to be compliant. The safe limit is 6 inches. Everyone that uses them without external mic/speaker holds them right next to their bonce.
Exactly. I used to be wary of a few watts next to my head. I'm sure heating effect occurred with older 2G phones. Nokia's internal patch antennas seemed better. RF engineers I knew used to be wary too but then mobile phones proliferated and it was almost impossible to avoid them. We used to keep conversations short but there was always someone who wanted to chat for ages. The SAR figures improved a lot since then but usage has also increased dramatically.
 

endure

GCM
From the antenna surely, unless that lot wasn't properly screened. Does it show where the peak voltages are to be found on the antenna?
That copper pipe running upwards from the main transmitter on the right of the photo is the antenna.

If the picture had been a little bit wider you would see that it led to an antenna selector box (basically a sliding knife switch) and then through an insulator in the deckhead straight to an antenna.

One of the peak voltages is between the top of the transmitter and the antenna selection box as could be seen from the neon bulb taped to the antenna flashing like a pervert every time you keyed up :mrgreen:.

In radio rooms with fluorescent tubes it was fairly common to have the tube light up in sympathy with the key.

The transmitter PA output is a 2kV tank circuit resonant at whatever frequency you're on from 410KHZ to 22MHz.

H&S wasn't much of a thing in those days...
 
That copper pipe running upwards from the main transmitter on the right of the photo is the antenna.

If the picture had been a little bit wider you would see that it led to an antenna selector box (basically a sliding knife switch) and then through an insulator in the deckhead straight to an antenna.

One of the peak voltages is between the top of the transmitter and the antenna selection box as could be seen from the neon bulb taped to the antenna flashing like a pervert every time you keyed up :mrgreen:.

In radio rooms with fluorescent tubes it was fairly common to have the tube light up in sympathy with the key.

The transmitter PA output is a 2kV tank circuit resonant at whatever frequency you're on from 410KHZ to 22MHz.
Was that a coaxial feed with a solid copper core and solid copper jacket?
 

endure

GCM
Was that a coaxial feed with a solid copper core and solid copper jacket?

It was simple copper pipe - the kind that plumbers use. No point in wasting all that copper when skin effect makes it irrelevant.

Here's a pic stolen from the internet with a Marconi radio room. The transmitters in this are less powerful (100 watts main on the left, 25 watts emergency on the right) but you can see that it's just copper pipe leading into the antenna selector switch in the middle and then up through the deckhead.

mrr.jpg
 

endure

GCM
Thanks for the great dit. I enjoyed that. A fence can act as a very large reflector at VHF. Weather conditions over sea can create a phenomenon known as atmospheric refractivity or ducting. This happens where two different masses of air meet but do not merge because of their different characteristics, temperature, moisture etc. An inversion layer is one example. VHF signals that would normally disappear in to space find their way barred by this new layer and are reflected between it and the ground, creating a ducting effect. Then there's Tropospheric ducting caused by weather a few miles up.

ETA -
Tropospheric propagation - Wikipedia
Atmospheric duct - Wikipedia
Anomalous propagation

ETA - Jim Bacon knows a lot about this stuff. He's one of those weather scientists. Funny him being called Bacon and being in to Ham radio. Video: VHF Propagation Presentation by Jim Bacon, G3YLA
VHF/UHF Propagation - Radio Society of Great Britain - Main Site : Radio Society of Great Britain – Main Site

It wasn't unusual to hear Cape Town/ZSC on channel 16/156.8Mhz 600 miles up the West African coast.
 
It wasn't unusual to hear Cape Town/ZSC on channel 16/156.8Mhz 600 miles up the West African coast.
The sound of some European broadcast stations on Band 2 VHF (analogue tuning) was a sign that there might be such conditions but the affected frequencies didn't always extend to the 2 m band, particularly inland.
 

endure

GCM
The sound of some European broadcast stations on Band 2 VHF (analogue tuning) was a sign that there might be such conditions but the affected frequencies didn't always extend to the 2 m band, particularly inland.
On a ship you're travelling on the world's largest ground plane ;-)
 
It was simple copper pipe - the kind that plumbers use. No point in wasting all that copper when skin effect makes it irrelevant.

Here's a pic stolen from the internet with a Marconi radio room. The transmitters in this are less powerful (100 watts main on the left, 25 watts emergency on the right) but you can see that it's just copper pipe leading into the antenna selector switch in the middle and then up through the deckhead.

View attachment 553843
Thats exactly like whats (or what was) used in the Main Comms Room of British warships-banks and banks of those.
 

endure

GCM
Thats exactly like whats (or what was) used in the Main Comms Room of British warships-banks and banks of those.
These too? I used to sail with the civvy version. Much posher in cream rather than drab grey...

r551.jpg
 

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