What about air horns?
I'm thinking, fairly cheap, anyone could use one, no batteries, not affected by water, no fiddly buttons covered in mud etc.
Is there a downside?

The problem (as I see it) with both air horns and whistles is that you can't easily communicate complex messages or have anything approaching a conversation.

VHF vs UHF,

As miles knows I personally use UHF kit underground and VHF above ground when at work.
UHF works better underground, simple way to look at is imagine a 4 foot pole held horizontally and try walking around, you tend to hit things and the pole bounces off walls etc. Now if you take a 2 foot pole and walk around you tend to hit less things and get the pole futher without damage. That is essentially how VHF/UHF works, VHF is great for line of site out in the open.

My two pence anyways.;D

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What about air horns?
I'm thinking, fairly cheap, anyone could use one, no batteries, not affected by water, no fiddly buttons covered in mud etc.
Is there a downside?

The problem (as I see it) with both air horns and whistles is that you can't easily communicate complex messages or have anything approaching a conversation.

Morse? :smartass:

For most underground work you'd only need to learn a few expletives!

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VHF vs UHF,

As miles knows I personally use UHF kit underground and VHF above ground when at work.
UHF works better underground, simple way to look at is imagine a 4 foot pole held horizontally and try walking around, you tend to hit things and the pole bounces off walls etc. Now if you take a 2 foot pole and walk around you tend to hit less things and get the pole futher without damage. That is essentially how VHF/UHF works, VHF is great for line of site out in the open.

My two pence anyways.;D

Let me think.

Antenna...Omnidirectional...Incidence...Reflection...
Wavelength...Time domain....

Lozz.

VHF vs UHF,

As miles knows I personally use UHF kit underground and VHF above ground when at work.
UHF works better underground, simple way to look at is imagine a 4 foot pole held horizontally and try walking around, you tend to hit things and the pole bounces off walls etc. Now if you take a 2 foot pole and walk around you tend to hit less things and get the pole futher without damage. That is essentially how VHF/UHF works, VHF is great for line of site out in the open.

My two pence anyways.;D

Let me think.

Antenna...Omnidirectional...Incidence...Reflection...
Wavelength...Time domain....

Lozz.

I apologise, I should have phrased it better: The Difference between how VHF frequencies like to travel compared to UHF, not antenna use :o
The pole I mention is simple to explain how RF can travel using an analogy.

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Robert has told me our walkitalkies, were cheap but unfortunately came from Maplins.
So my advice is, if anyone is interested get yourself down there and hopefully you may get a bargain.
I noticed on Sunday they were offering discounts between 20-50%. On their stock.

We tried a pair of Binatone 950 walkie-talkies in a slate mine last night. In theory they work line of sight, but actually we found that they performed quite a lot better than that, maintaining a signal for 60m or so, round a few corners. So they could actually be quite useful in shafts.
Big advantage is the price. Secondhand sets (of 2 plus charger) go for £20-£30 on ebay, and sometimes under a tenner if you're lucky.

I borrowed these from work where we use them for student fieldwork. We've found them pretty good for a mile or more out in the open. There the biggest gripe is that the volume control is easily knocked. Walking around with the unit clipped to your belt it's easy to accidentally turn it down too low to hear when you're being called.

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I have two pairs of these:

https://www.pmctelecom.co.uk/two-way-radios/licensed-radios-long-range/mitex-general-uhf-twin-pack-pk2-two-way-radio?gclid=EAIaIQobChMIgLXq-sPw2QIVcjPTCh3mOASnEAQYASABEgKwCfD_BwE#fo_c=1351&fo_k=13e7e555e9ff0ef31a0a011234bcc8d8&fo_s=gplauk 

I bought them about three years ago and are extremely reliable, rugged and waterproof. And you can lock-off the volume control and channel selector. They have voice activation function so are 'hands free' too. They actually work really well underground so I'm not sure why its never occurred to me to bring them. Never needed them I suppose. We can try them out next time I actually make it out on a Thursday night!

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I’ve used those Mitek ones for communicating at motorcycle race events, very useful. They aren’t the best around but they are good value and have a good range and battery life.

You have a new van?

You have a new van?

PM sent 🙂

A group of us did some work in a big shaft last year (90m to the level), with much of the old timbers, pipes and ladders still in there, and we had huge problems communicating beyond 50m depth, even with powerful radios. Beyond 70m it was impossible, which caused some issues when climbing. I don't know exactly what spec they were so can't comment on the power output, but they were given to us by the company, and definitely weren't toys. I think the junk in the shaft was the problem, as it was very large diameter too.

I've often wondered if the tin-can telephone could be 'upgraded', using thin plastic buckets. After all, you have a very tight line to use, and presumably the larger diameter wouldn't affect transmission too much. Trouble is, to avoid splitting the bottom bucket to slip it on the rope, and thereby probably ruining any diaphragm effect, you'd have to abseil down with the bucket already threaded on. Also you'd need some sort of stop to function as the knot, but something like a Shunt or a Basic could be used for that. But if the top-man were able to shout into his bucket, I do think it could work.

What's the problem with a long hose and two funnels?;D

What's the problem with a long hose and two funnels?;D

Yeah. two road cones and some 2" wire armoured pump hose! :lol:

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A group of us did some work in a big shaft last year (90m to the level), with much of the old timbers, pipes and ladders still in there

Sounds like you have the makings of a 'speaking tube' system already in-situ?

Edit: Is there a continuous pipe top to bottom?

In the earlier times, Robert & I set up a winch on the Wellhope shaft.
Previous visitors had used a field telephone, but we decided to use walkie-talkies.
We found that in this particulsr shaft they worked well, when we were attached to the wire, but failed pretty badly when the seat and cable were going up it.
We came to the conclusion that the wire itself was acting like an Ariel, and we thought that if we were to have any other problems using w/t’s underground then a wire could be brought down from above just to help make contact.
We never tried this idea, but it is worth trying.

At Snailbeach, the Shropshire Mining Club had threaded a single wire through the stopes right down to the bottom level.
At the surface you attached a CB radio via a croc clip on the aerial to the wire and underground you pulled out 6" of telescopic aerial and placed it against the wire. It worked fine all the way down.

nice simple solution. They call that "Leaky Feeder" don't they? You can get special cable to do it but I think any cable would work.

If there is already a metal pipe in the shaft (air/rising main etc) it might do it. Usually the antennas on the radios can have the plastic casing pulled off to reveal the metal coil inside.

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I remember being amazed on the 380 fm level in South Crofty there was a guy operating the decline conveyor listening to broadcast radio (BBC) on a small transistor radio. He just had it situated near the power feed cable.
I'm guessing that the armoured sheath was acting as an antenna and picking up the signal at surface.
Mind you, the Four Lanes transmitter is within eyesight, so the field strength at Crofty would be pretty high anyway.

A piece of wet string and a crystal earpiece would get you a signal in Four Lanes :lol:

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If there is already a metal pipe in the shaft (air/rising main etc) it might do it. Usually the antennas on the radios can have the plastic casing pulled off to reveal the metal coil inside.

In those days, CB radios had bare telescopic antennas........