HAM radio

Joshua Slocum

LE
Book Reviewer
I spotted this on flickr, and thought you may all be interested
its very early spark gap stuff, but I am unsure as to what the motor on the right does, it appears to offer a high speed spark pulse

you can blow the image up large to look at the detail, including the notice at top

 
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Numbers stations fascinate me. The messages could be any of:

Gibberish to keep the opposition busy trying to analyze nonsense.
Acknowledgement of earlier message being received.
”Meet Mr Brown at 6pm on Friday, usual place”.
”24D“

24D could be anything from “get out of town this weekend, something else is going down” to “assassinate target D” or just simply “change to crypto book D from next message”

UK used to have a numbers station that TXed from RAF Akrotiri, its signature tune was “The Lincolnshire Poacher”.


I remember the Lincolnshire Poacher, but I preferred finding the Eastern Block stations, they had a much spookier sound to them. With modern technology it's much harder to find those stations now, though they do still exist.
Cadbury's Fudge adverts, "a finger of fudge is just enough...." was based on the same tune. Subversive Snacks.
 
I spotted this on flickr, and thought you may all be interested
its very early spark gap stuff, but I am unsure as to what the motor on the right does, it appears to offer a high speed spark pulse

you can blow the image up large to look at the detail, including the notice at top


I think that this is further on from a crude spark gap. Yes, it could be a motor driven contact oscillator. The number of contacts being spun increases the frequency that can be generated, which would normally be limited by the speed of the motor. The motor must be synchronised to the supply frequency. The two coils are a coupling transformer. The rotary switch might be for adjusting output power. The telegraphy (Morse) key is used to switch the carrier feed to the antenna on and off. I think @endure knows more about this stuff.
 

endure

GCM
I think that this is further on from a crude spark gap. Yes, it could be a motor driven contact oscillator. The number of contacts being spun increases the frequency that can be generated, which would normally be limited by the speed of the motor. The motor must be synchronised to the supply frequency. The two coils are a coupling transformer. The rotary switch might be for adjusting output power. The telegraphy (Morse) key is used to switch the carrier feed to the antenna on and off. I think @endure knows more about this stuff.
Oi! I'm not that old!

There is the Alexanderson alternator which generates VLF.

There's one at Grimeton/SAQ which is still fired up once a year.

My vid seems to have disappeared so here's a different one

 
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Oi! I'm not that old!

There is the Alexanderson alternator which generates VLF.

There's one at Grimeton/SAQ which is still fired up once a year.

My vid seems to have disappeared so here's a different one


17.2 KHz is just a little too low a frequency for most general coverage receivers.

There is an official SAQ receiver kit.

1642372867771.png


Here is the manual with the circuit of the SAQ receiver kit. https://execubic.se/execubic-wp/wp-content/uploads/2021/08/SAQ-receiver-kit-manual.pdf

It costs around £40 plus postage and maybe bank charges. Radioaffären | Grimeton

It will only be useful for the intended purpose a few times a year. I wonder if it can be used to detect sferics?
Radio atmospheric signal - Wikipedia
 
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17.2 KHz is just a little too low a frequency for most general coverage receivers.

There is an official SAQ receiver kit.

View attachment 632048

Here is the manual with the circuit of the SAQ receiver kit. https://execubic.se/execubic-wp/wp-content/uploads/2021/08/SAQ-receiver-kit-manual.pdf

It costs around £40 plus postage and maybe bank charges. Radioaffären | Grimeton
That's a lot more complex than I anticipated. I expected a simple discriminator with tunable coil. I quite like it.
 

itchy300

Old-Salt
Radio silence from Tonga after the volcano/tsunami. Woman from the Red Cross was on the news this morning saying they lost contact with their team Saturday. The undersea cable has been broken, wiping out internet, power grid is down and the ash cloud is preventing satellite Comms. The only contact at the minute is through sporadic HF radio messages but I haven't been any details on who that might be.

Might be worth a listen!
 

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Radio silence from Tonga after the volcano/tsunami. Woman from the Red Cross was on the news this morning saying they lost contact with their team Saturday. The undersea cable has been broken, wiping out internet, power grid is down and the ash cloud is preventing satellite Comms. The only contact at the minute is through sporadic HF radio messages but I haven't been any details on who that might be.

Might be worth a listen!
Found these comments:

1642424956783.png



Most A35 calls seem to be visitors during DXpeditions.
 
Talking of comms and things underwater, I found an update on the Radio New Zealand news website. This confirms that the undersea cable was indeed damaged by the volcanic eruption. The fault is some 37km off of Tonga and requires a ship equipped to repair it. Unfortunately this is 2500km away in Papau New Guinea so it will take a few weeks to effect a repair. The satellite link(s) is (are) limited in capacity compared to the cable normally but ash clouds are still causing problems.

"The Tonga cable connects into Suva in Fiji, and from there to the Southern Cross cable onto New Zealand, Australia and the US."

Short but informative article: Tonga's undersea cable could take weeks to repair
 
Sadly I don’t think we’re done with bad news from Tonga. I saw a graphic on a news site earlier that showed an entire community washed away.
From Radio New Zealand:

Distress signal prompts UN concern after Tonga volcanic eruption​

A distress signal has been detected in an isolated, low-lying group of islands in the Tonga archipelago following Saturday's massive volcanic eruption and tsunami, the United Nations said, prompting particular concern for its inhabitants.
Distress signal prompts UN concern after Tonga volcanic eruption
 
Been playing with my radio a bit, and came to some conclusions regarding controlling it with a Raspberry Pi, which was something I’d wanted to do. Frankly, the Pi‘s not up to being the main computer for that task.

I’ve got a Pi4 8Gb, with 64-bit OS, and running that off an SSD. In other words, about as speedy as I can get with one of those. I like the digital modes in HF, and use wsjt-x with Grid Tracker for an absorbing hour with the rig. But I’ve been noticing a distinct lack of decodes, despite a waterfall that’s lit up to shit on the set.

So I hooked it up to my M1 iMac, and erm, wow. What a difference. It really surprised me, because both the Pi and the Mac are arm64 architecture with 8Gb RAM. Granted the clock speed and number of cores on the Mac are double those of the Pi, but even so, the difference is shocking.

One example is the time taken to compile wsjt-x. On the Pi, there’s really no choice than to compile from source for a recent version, so I compared it with the same operation on the Mac. Literally, a tenth of the time on the M1 vs the Pi to compile it.

Wsjt-x is giving me many more decodes per period, the Mac will cope with “Deep” whereas the Pi really has to be in “Fast” mode, which has predictable results in terms of decodes. I’m wondering what I’ve been missing in the past now, using the Pi to control the rig.

So it looks like the Pi(s) are relegated to other tasks. Time to rebuild my shack around the M1.

I’ll post something on the Pi thread with more info on the Pi, but on this thread, I am a happy bunny!
 
Been playing with my radio a bit, and came to some conclusions regarding controlling it with a Raspberry Pi, which was something I’d wanted to do. Frankly, the Pi‘s not up to being the main computer for that task.

I’ve got a Pi4 8Gb, with 64-bit OS, and running that off an SSD. In other words, about as speedy as I can get with one of those. I like the digital modes in HF, and use wsjt-x with Grid Tracker for an absorbing hour with the rig. But I’ve been noticing a distinct lack of decodes, despite a waterfall that’s lit up to shit on the set.

So I hooked it up to my M1 iMac, and erm, wow. What a difference. It really surprised me, because both the Pi and the Mac are arm64 architecture with 8Gb RAM. Granted the clock speed and number of cores on the Mac are double those of the Pi, but even so, the difference is shocking.

One example is the time taken to compile wsjt-x. On the Pi, there’s really no choice than to compile from source for a recent version, so I compared it with the same operation on the Mac. Literally, a tenth of the time on the M1 vs the Pi to compile it.

Wsjt-x is giving me many more decodes per period, the Mac will cope with “Deep” whereas the Pi really has to be in “Fast” mode, which has predictable results in terms of decodes. I’m wondering what I’ve been missing in the past now, using the Pi to control the rig.

So it looks like the Pi(s) are relegated to other tasks. Time to rebuild my shack around the M1.

I’ll post something on the Pi thread with more info on the Pi, but on this thread, I am a happy bunny!
Have a look at OH8STN on YouTube. He has done the Pi to death and swapped to a Windows Surface Pro 2 (I think) tablet because he needs Windows specific software to do what he wants. He uses a chat mode that works with email, so he can send and receive asynchronously. It also connects wirelessly to his ICOM 705 so fewer cables. For the shack you could use a second hand pc with Win 7 or Win 10 then remove some of the crap and lock it down.
 
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I have a raspberry Pi 3 and am looking at using it as a hot spot for a DMR set up. I am only just qualified, discovered DMR and I am a fan. The problem I have is I am on the edge of a repeater working area. I can hear it but only work to it by going outside the building, the perils of high insulation buildings.

Long story short I have no idea on how to do it. I may just buy myself a commercial hot spot. There is nothing to be gained by building a good outside antenna as I have the house on sale, in fact I have a buyer and I am looking for a new house elsewhere. Lucky for me the buyer is willing to wait, I don't think they will be best impressed if I start messing around with the fabric of the house.
 
Have a look at OH8STN on YouTube. He has done the Pi to death and swapped to a Windows Surface Pro 2 (I think) tablet because he needs Windows specific software to do what he wants. He uses a chat mode that works with email, so he can send and receive asynchronously. It also connects wirelessly to his ICOM 705 so fewer cables. For the shack you could use a second hand pc with Win 7 or Win 10 then remove some of the crap and lock it down.

Thanks, but Windows just not my bag.

I might have a look at the thin client x86_64 boxes and put Linux on it, effectively similar to a Raspberry Pi, but Intel processor. Seems retrograde, to be honest, given the power (as in Watts) advantage of ARM systems. But not the RPi 4, sadly, and an M1 iMac is a bit of overkill. Perhaps an M1 Mac mini.
 
Thanks, but Windows just not my bag.

I might have a look at the thin client x86_64 boxes and put Linux on it, effectively similar to a Raspberry Pi, but Intel processor. Seems retrograde, to be honest, given the power (as in Watts) advantage of ARM systems. But not the RPi 4, sadly, and an M1 iMac is a bit of overkill. Perhaps an M1 Mac mini.
Me neither. It usually gets in the way. It can be tamed but meh. If I was using the chat relay software he uses then maybe. I have seen those thin clients going cheap. A bit more to them than Wyse terminals.
 

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