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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Mon 05, 2018 4:35 am 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 209
Location: Traverse City, MI 49684
Just to reinforce what somebody else said... LW was used for navigation--marine and air. I've got a couple radio direction finder radios. There were LW radio beacons for navigation purposes, transmitting Morse code identifiers. The RDF units have rotating antennas so you can null out the station with the ferrite bar antenna pointing at it and take a bearing. Then you have a line of position and if you have two stations (or other data) you have a position fix. The radios also have MW broadcast band reception because coastal station antennas would be indicated on marine charts. I keep one on my little sailboat, not for navigating, but because it has an FM band for entertainment. Besides, it looks kinda nautical to have an RDF aboard.

Chris Campbell


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Mon 05, 2018 5:06 am 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 209
Location: Traverse City, MI 49684
Geez, I hit "back" before verifying that I had posted this and lost it. Try again, Chris.

Here's a link to a nice article on marine radio service on the Great Lakes:
http://www.imradioha.org/great_lakes.htm

In it there's a link to this page that lists marine LF radio beacons formerly maintained on the Great Lakes:
http://www.imradioha.org/Old_Great_Lakes_LF_Beacons.htm

In 1969 my brother and I set off on our first cruise in our 26' sailboat. We were headed about 20 miles away to exotic Sebawaing, as the crow flies. We took along our father's Zenith Royal 1000 so we could receive SW marine weather forecasts (MAFOR, using numerical codes). The Zenith did not have a LW band but it did have a little bearing indicator so you could use if for RDF on MW stations.

We magnified the adventure by running into a power line when we got there (it had been moved). That was interesting.

Chris Campbell


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Mon 05, 2018 3:30 pm 
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Posts: 135
Wally58 wrote:
http://websdr.ewi.utwente.nl:8901

This link works for me and I have this website bookmarked. Is the browser blocking it somehow? What message are you getting?


The message I get is this:

Quote:
Unable to connect

Firefox can’t establish a connection to the server at websdr.ewi.utwente.nl:8901.

The site could be temporarily unavailable or too busy. Try again in a few moments.
If you are unable to load any pages, check your computer’s network connection.
If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web.


However, I read all the replies here and also read through the other links, plus did some of my own searches.

If I understand correctly... If my radios were in Europe I could get some LW stations without an external antenna (which might explain why I don't have childhood memories of wires between houses and trees). But across the Atlantic I need an external. This makes sense, but I am still puzzled at the enormous leap in antenna size. From the small coil wound over a ferrite rod that is sufficient in Europe, I would need to upgrade to an antenna that might have to be half a mile or even several miles in length, and would also have to be connected to some grounding rods, or ground counterpoise (that act like a capacitor to ground). At first I thought a long antenna could be a long wire in my back yard, but now I've read articles where people talk about wires that stretch for miles deep into the woods or (as I've read in one case) across an entire suburban neighborhood.

To be honest, I'm still trying to to grasp if there's something I'm not clearly understanding and perhaps I am mixing apples and oranges.

Since I live in New York City it is not an option for me. But my house does have a back yard and I have plenty of leftover copper wires, so I can always stretch a wire in my yard and see what I get. I'm just still not clear on the grounding connection. My house has two 8ft grounding rods in the basement. One is connected to the electrical meter ground and the other to plumbing, plus the same meter. Can I just connect connect my radio ground (which is chassis, too) to any one of those rods, or do I need to hammer in a new grounding rod? And in the event I can use the existing rods, do I need to run a separate wire to that rod, or can I just use the ground connection in any AC outlet (which is ultimately connected to those rods)?


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Mon 05, 2018 4:20 pm 
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Adinol wrote:
Since I live in New York City it is not an option for me. But my house does have a back yard and I have plenty of leftover copper wires, so I can always stretch a wire in my yard and see what I get. I'm just still not clear on the grounding connection. My house has two 8ft grounding rods in the basement. One is connected to the electrical meter ground and the other to plumbing, plus the same meter. Can I just connect connect my radio ground (which is chassis, too) to any one of those rods, or do I need to hammer in a new grounding rod? And in the event I can use the existing rods, do I need to run a separate wire to that rod, or can I just use the ground connection in any AC outlet (which is ultimately connected to those rods)?


You never want TWO grounds. All of the ground rods must be connected together as per Electrical Code. That said a connection to one of those ground rods might help a bit bit they are primarily for an AC power ground. Lots of difference between that type of ground and a proper RF ground. Go back and reread what Steve dutch Rabbit said about his ground system he had and or has for his antenna system. Quite Extensive RF Ground system. And quite an extensive Antenna system as well. As to distance receiving for LW or for that matter also plain old AM broadcast radio stations. You need a night to night path for anything beyond Ground Wave distances. When was the last time you heard an AM radio station for more than a few hundred miles from NYC ? Yes the internal antennas do OK for local stations but for any really long distance you need external antennas that are in the Hundreds of Feet in length.
John k9uwa

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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Mon 05, 2018 6:55 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2862
Location: Nr London, England, SS1 3PT
Amplified magnetic loop antennas do well and only need to be say a meter square. Mounted remotely, 40 ft from the house and power fed over coax cable I receive stations noise free from a 100 miles or more. But they wouldn't pick up LW stations at thousands of miles.

Gary


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Mon 05, 2018 8:43 pm 
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k9uwa wrote:
You never want TWO grounds. All of the ground rods must be connected together as per Electrical Code...

You're absolutely right. Now I remember. We had a grounding rod by the water mains. That was disconnected when we upgraded the electrical service and now the service has another grounding rod. So the old one is freed up. I guess it won't cost me anything to connect to it and see what happens.

k9uwa wrote:
Go back and reread what Steve dutch Rabbit said about his ground system he had and or has for his antenna system...

I read his post multiple times and had to Google some of the terminology to understand what he was explaining. The whole thing is still sinking in with me.

But basically. I guess the best I can do where I live is to use the free grounding rod and connect an antenna from the front of my house, crossing the entire roof, continuing into the back yard and hook it up to the tree. That would be around 100 ft of horizontal wire. Perhaps that would improve the reception but it obviously would not be as ideal as some of the solutions I see on the internet. It is just the best I can do where I live.

A project for the spring time.

k9uwa wrote:
Yes the internal antennas do OK for local stations but for any really long distance you need external antennas that are in the Hundreds of Feet in length.

I guess what's still confusing me a bit is that the internal ferrite rod antennas woudl pick up signals across Europe (which could mean 2,000 miles) but to capture the same signal across the Atlantic the antenna must be so much larger.

Radio Fixer wrote:
Amplified magnetic loop antennas do well and only need to be say a meter square...

Good suggestions. I do happen to have a a whole spool of coax cable, so this is definitely something I'd like to experiment with (probably even before I start climbing that tree). I'm sure there are some DIY solutions for those antenna amplifiers that I can find to make the project even more interesting.

Thanks...


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Mon 05, 2018 10:07 pm 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 4527
Location: Near Brandon, Iowa
Adinol wrote:

I guess what's still confusing me a bit is that the internal ferrite rod antennas woudl pick up signals across Europe (which could mean 2,000 miles) but to capture the same signal across the Atlantic the antenna must be so much larger.


I don't know that anyone is asserting that an internal ferrite rod antenna can pick up signals across the full breadth of Europe. That seems rather improbable. At some distance from a transmitter a ferrite rod will become ineffective and an external antenna will be required. Usually this distance is only in the hundreds of miles (at best) for standard broadcast-band stations but is very dependent on the power and antenna design of the transmitter. Some ultra-high-power LW stations may be capable of far exceeding this, but the physical propagation limits are still "baked in". The strength of any radio signal varies according to an inverse square law relationship: if the RF signal power at distance A from a transmitter is 1.0 units, at distance 2A it will be 0.25 units. At distance 4A it will be 0.625 units. And so forth. Or so the free-space relationship goes- EM wave propagation through the atmosphere gives slightly different results; but the above principle is still generally true.

There's an old saying among radio amateurs to the effect that "if you want to receive more signals, put up more metal". Which of course is a gross oversimplification: to receive a specific band of frequencies with the highest efficiency it is necessary to consider physical lengths of the antenna as well as its height above ground and its orientation with respect to the target transmitter. Just randomly stringing up a wire and hoping for the best is unlikely to produce very satisfying results.


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Tue 06, 2018 12:24 am 
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I know that I said:
Quote:
If you were using the radio in its 'home' environment, the little ferrite rod antenna would be perfectly suitable for receiving long wave transmissions right across Europe from one side to the other.


...but I did mean at night time. The beauty of being on the western side of the pond is that when it's dark with you, it's very dark in Europe.

Here in NZ I can hear the low power NDB at Port McQuarie which is about 400km north of Sydney, New South Wales and about 1400miles away after midnight which is about 10pm there.

Have a look at these posts on that 'other' forum....

https://forums.radioreference.com/hf-mw ... night.html

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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Tue 06, 2018 1:56 am 
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Location: Near Brandon, Iowa
majoco wrote:
I know that I said:
Quote:
If you were using the radio in its 'home' environment, the little ferrite rod antenna would be perfectly suitable for receiving long wave transmissions right across Europe from one side to the other.


...but I did mean at night time. The beauty of being on the western side of the pond is that when it's dark with you, it's very dark in Europe.

Here in NZ I can hear the low power NDB at Port McQuarie which is about 400km north of Sydney, New South Wales and about 1400miles away after midnight which is about 10pm there.

Have a look at these posts on that 'other' forum....

https://forums.radioreference.com/hf-mw ... night.html

As the automobile manufacturers say, "Your actual mileage may vary."


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Tue 06, 2018 2:54 am 
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k9uwa wrote:
Go back and reread what Steve dutch Rabbit said about his ground system he had and or has for his antenna system. Quite Extensive RF Ground system. And quite an extensive Antenna system as well. John k9uwa


yes it was and thanks.

...lots of work...lots...

my medium wave (broadcast band AM) and long wave reception was absolutely over the top.

not only was long wave a treat, i could easily and regularly hear the national powerhouse AM/BCB Blowtorches from: Algeria, Spain, Morocco, UK, Norway, Croatia, Libya, Saudia Arabia, Mauritania, Benin, and others.

Saudi Arabia's monster 2 megawatt blowtorch from Duba (1521 kc) used to almost take over Buffalo (1520 kc) when i notched out the 1 khz differential.

steve


Attachments:
Saudi Arabia, BSKSA, 1521 KHz (1).jpg
Saudi Arabia, BSKSA, 1521 KHz (1).jpg [ 43.71 KiB | Viewed 880 times ]
Saudi Arabia, BSKSA, 1521 KHz (2).jpg
Saudi Arabia, BSKSA, 1521 KHz (2).jpg [ 43.29 KiB | Viewed 880 times ]

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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Tue 06, 2018 4:33 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5233
Location: 253 Blanche St. Plymouth, MI USA
" I remember, when I was a boy, how grown men were explaining to me the differences between the bands..."

Well there's the Beatles who are melodic and the Stones who are bluesier and rock harder.... :D
sorry .... had to do it....
Mark Oppat


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Fri 09, 2018 1:18 am 
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I'll try to answer some of the questions that have come up (in no particular order).

1) According to a source that now escapes me, an international treaty from about the early 1920s reserved a large chunk of longwave spectrum for governmental users. In Europe, radio broadcast licenses were awarded mainly to state-chartered public broadcasters. These were often allocated longwave frequencies because of their superb groundwave coverage. In the Americas, privately-owned broadcasters have dominated the airwaves since the dawn of the medium. Consequently, broadcasting was exclusively allocated to mediumwave. Longwave was reserved for aeronautical beacons, maritime traffic, and weather forecasts.

2) The Beverage antenna that Steve describes has a highly unidirectional pattern. It is not a simple random-length wire antenna. This amount of directionality is required to pull in stations from across the ocean while rejecting stations from North America. The internal ferrite bar antenna found in consumer mediumwave and longwave radios has a figure-8 pickup pattern. Additionally, the signal levels that ferrite rod antennas develop are low compared to a large Beverage.

3) The two red components shown a few posts ago are adjustable RF transformers, not antennas.


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Fri 09, 2018 1:43 am 
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Thanks, Alfredo.

Just a quick clarification. I reread my post where I displayed an image of two IF transformers and now that I've reread my own post I can see that I did not make it clear as to which exact part I was referring to, when asking if it was an antenna. I was actually asking about that small part that is between the two IF transformers, because it is a wire that is wound over a metal rod and the wire does not have a closed circuit. But it turns out it is a makeshift capacitor.


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Fri 09, 2018 4:24 am 
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Quote:
But it turns out it is a makeshift capacitor.


No, not a makeshift capacitor at all. Often a very small but adjustable capacitor is required that has a much lower value than is commercially available - you will often see them where neutralisation is required to prevent oscillation - they will be adjusted by removing turns or untwisting the wires until the desired effect is achieved - usually just a 'oncer' in the factory.

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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Fri 09, 2018 2:49 pm 
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majoco wrote:
Often a very small but adjustable capacitor is required that has a much lower value than is commercially available - you will often see them where neutralisation is required to prevent oscillation...


All I can say is, I'm glad I was able to overcome my impulse to straighten it. I had noticed that the whole thing was a bit bent and that the winding seemed cut off. My first thought was that someone had opened up the radio and possibly knocked this small "coil" which bent the core and also caused the wire to snap off. But when I didn't see the "other end" of the damaged "coil" I left it alone.

I can see how I made quite a few wrong assumptions every since I've tackled a recap job on a few of my old radios. One mistake was me straightening out the outermost blades of the tuning cap. Aghr...


This brings me to one conclusion: as simple as a recap job might sound, it ain't the type of job for "confident amateurs" such as myself.

Which brings me to a second conclusion: if buying a radio that's advertised as having been recapped, one should really know who did the work.


Last, but not least: thanks again, all, for all the valuable info you've shared since I've joined this forum.


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Fri 09, 2018 4:09 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2862
Location: Nr London, England, SS1 3PT
Philips used wire strip trimmer capacitors back in the 30's. You may like to see a picture. It is a metal stud inside a ceramic tube. The outer wire can actually be joined up, rewound and soldered to get more capacitance if needed.

Attachment:
12. Wire strip trimmers WEB.jpg
12. Wire strip trimmers WEB.jpg [ 78.47 KiB | Viewed 771 times ]


Gary


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 Post subject: Re: Longwave Band Selector on European Radios
PostPosted: Mar Fri 09, 2018 6:21 pm 
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Thanks for taking the time to post a picture.

This kind of visual reference is very helpful in identifying parts.


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