Topics

16

European Pirates and Private Stations / UID 6875.00kHz AM - 2000 UTC on 14 Aug, 2015

« on: August 14, 2015, 2015 UTC »

Strong noise floor today on 6-7Mhz here in Berlin/GER
Station comes in with S5-S7, but is heavily distorted.
I can hear music, but it's hard to make out any genre. Every now and then moderation becomes audible. Sounds italian. But I may be mistaken.

Couldn't make out any station ID so far.

17

The RF Workbench / Siemens Mechanical Filter (150Hz and 75Hz) on ebay

« on: August 11, 2015, 0908 UTC »

Hey,

For those who are listening to CW and looking for extrem narrow filters. There are some old, big mechanical filters available on ebay.de (Germany) since several weeks. So, in case you have a receiver that comes with 10/100Hz tuning steps, this may be a filter of interest.

I got myself a 100Hz Filter and it's pretty awesome. Bad side: a IF of about 30kHz, which means you've to come up with your own IF Downmixer-Circuit. Used it for testing with my Yaesu VR5000.  Used the 10,7M IF output jack and mixed the signal it down to 30Khz (variable, So I also have an adjustable  BFO).

Look for "Mechanisches Filter Siemens E401"

150Hz Filter
75Hz Filter

Greetings!
~Zazzle

18

QSLs Received / Common and Precious QSL Card available

« on: July 28, 2015, 2319 UTC »

Hey there,

(Please feel free to move this topic in case there's a better place for it. )

About two months a go I asked a friend (designer) to do a QSL Card. He never did. So... screw it. I did it one my own today night. I send cards to those I (still) owe one out tomorrow.

And of course: want one? Send a valid report (with audio if possible. Ask for mail via DM.)

Greetings,
Zazzle

19

European Pirates and Private Stations / UNID on 6956kHz LSB 2030 UTC July 28, 2015

« on: July 28, 2015, 2035 UTC »

Hearing a Station here in north of Germany.
Pretty strong, S7-S8 but terribly distorted. Can't make out whether it's USB or LSB. LSB sounds a bit more like music... which sounds like Rock music. (Oh funny... the station went off air right now while I'm typing this after something the sounded like a moderation).

20

Equipment / 10M Antenna and operation time

« on: July 21, 2015, 1430 UTC »

Hi everyone. This questions regards a possible Antenna for this project.

I need a compact Antenna for the 10M Band. It can't be too complex nor large beacause it's going to be installed on a (pretty) high tower with strong, storm like winds every now and then. I can't, under no circumstance, run experiments up there. Two ideas have formed in my mind and I would love to get your opinions.

Either way, I'm going to install a wooden 3mtr. pole up there. Thick enough to withstand the heavy wind. That pole allows me two possible Antenna configurations:

• A loaded (in the middle) 1/4λ vertical Beam. I'm could to staple the wire to the wooden pole and insert the load coil in the middle in a weather proof box. Question  II want to use the metal platform as the electrical counter part itself. I wonder about... can an electrcal counterpart (Ground) be too big/large/long? Okay, I guess I can test this Antenna on the ground. We have a closes bridge around here. Full metal construction.
• 2) An Inverted-V. I have a lot of good experiences with this type. The platform is also wide enough for this kind of Antenna. Also, I could shorten it with inductors, too.

And there's a completely different question: from what I read in all the propagation charts lately, it seems that the best time for operation on the 10M Band is during daytime. Is there any use in having a Beacon operationg during night time?

Kind regards,
~Zazzle

21

European Pirates and Private Stations / 2 Stations (unknown) on 6745kHz and 6800kHz 20:45UTC

« on: July 10, 2015, 2053 UTC »

Hearing two stations here in N/E Germany,

6750kHz with S9+. Heavy frequency shift (+/- 50kHz) . Playing misc music (can't identify a title, rather gentle tunes in general).  No moderation so far, Station name unknown.
7800kHz with S8-9. Overdriven modulation. Playing Scooter and more well-known 80/90ies tracks. No moderation so far. Station name unknown.

22

HF Beacons / 10237.74Mhz "Common and Precious"

« on: May 20, 2015, 1219 UTC »

Hi there,

Heard in Enschede (NL, Europe) on 10237.74Mhz.
It sends a longer text, including its name "common and precious". The locator says it's located in Germany and that it outputs 1W.

Kind regards,
~Zazzle

23

The RF Workbench / Beacon Project "Common and Precious III" (OFF air, 26510 kHz, 8W)

« on: May 19, 2015, 1132 UTC »

Hi everyone,

So, as a HF addict I need my next drug shoot aka "HF project" . It's going to be a beacon again.

I felt for doing some urban exploring lately which made me visit an old industrial complex not that far away from home. The are several smaller towers on the areal and two big chimneys. I did some climbing. WOA! That would be the perfect location for a Beacon Transmitter. I mean... 80m above the ground and no big city close by. F#ck, yes!

The smaller towers are easy to climb on. The plattform offers many option for installing Antennas. The tower itself is about 50 meters
The chimney is... a challenge to climb on. Exhausting. Getting stuff up there is even more of a challenge. But, my god, what an awesome place for a Beacon. Sadly, there's a metal tube comming from the chimney which is even longer than the platform and may interfer with possible Antennas. Also, it's too risky I think.

So, for reasons of security, accessibility for maintenance and an obstacle free Antenna environment I will go for the smaller tower. The only bad side is: other people might be tempted to climb on it. Less than on the chimney.

I need your opinions now, because I've a hard time making a decision. It's about possible signal propagation and use of Antennas.

Frequency 1 - 10M Band
Pros

• I have an old 5/8λ CB beam at home. It's easy to install and it's also relatively broadbanded. Therefore, the SWR should be not an issue.
• I could also use a 1/2λ inverted V. Each side would be about 2,60m. That's managable.

Cons

• The propagation isn't the best and DX connections are rare.
• There's not really much activity when it comes to pirate radio/beacons.

Frequency 2 - 40M Band
Pros

• Awesome propagaion, also during daytime.
• Many pirate activities just below the offical HAM-Bands

Cons

• A huge antenna is needed. A Dipole is not an option.  I think I could build a KGD. But this sort of antenna has a very small bandwith and the SWR matching is tricy because it's sensitive to the objects around.

I think a good working Antenna in combination with less potential contacts is still better than a bad Antenna with more possible contacts?

Your opinion?

Greetings,
~Zazzle

24

The RF Workbench / Output Filter Issue?

« on: April 19, 2015, 2054 UTC »

Hey,

Jep, it's about the Morse Beacon project. I like to discuss this issue in a different Topic an hope that's okay. If no, please merge the thread with the Beacon topic.

I wonder whether I might face some problems with the Output Filter. It's a 5-Pole PI-Filter. A Low-Pas (cut-off is 11,5Mhz) that also manages the impedance matching between PA Transistor an Output (which is 50R).

I'd build the Filter by using some basics formula and a lookup-table (for the impedance transformation). The Filter didn't work (almost no output signal) well and I started modifying values. The PA stage had been calculated for approx 1,5W. After some modification of the component values I was soon able to obtain 1,8W. I tested other values and eventually made it to about 4W with the PA becomming quite hot. Still, the signal looked fine on the Oscilloscope.

But I became sceptical about the 4W and looped a Antenna Tuner in between Transmitter and Dummy. The signal became heavily distorted after introducing just the slightest amount of reactive load (C and L). I undid the latest modifcations and the filter was now able to withstand reactive loads to a certain degree before the signal became distorted again.

I ran a test with my HAM Transceiver. At a certain point it also started to show a distorted signal when too much reactive load was introduced.

My basic question is: how must a output filter respond to mismatching? I attached some screenshots from the Beacon Transmitter output in different situations.

I wonder whether the Filtert causes problems and doesn't feed the Antenna properly... which would be odd, because the SWR Meter says: 1,5W forward, 0,3W reflected.

Thanks and Greetings,
~Zazzle

25

Equipment / Antennas for Beacons (tricky terrain)

« on: February 12, 2015, 1442 UTC »

Hi everyone!

I have two primary issues that I'd like to address. One regards an actual problem and the second is a theoretical one for an upcomming project.

Actual Problem:
It regards this project.
I put a 1,5W Beacon up on a roof. 10.240MHz. It looks like it doesn't radiate the field properly. Maybe the issue clears itself on it's own today evening when I check the correct lengths for the Dipole. I may have cut 'em too long. But I also suspect other issues with the location in general as well. As you can see on the attached photos, the Transmitter is installed on a roof with lots of metal constructions around. Given the low Frequency I suspect the construction to interfer with my antenna. Actually, my questions are:

• How much may the roof construction interfer with my antenna?
• I suspect that "as high as possible" is the key for the antenna? I also read that a height of 1x wavelenght is perfect for Dipoles?
• Does an Inverted V, say, with a 90° angle help here?
• The Dipoles are constructed as follows: Dipole wire - 1m of Nylon wire as insulator - (conductive) wire/cable until mountpoint on the ground. Should I use a Nylon wire for the entire length for the support?
• I live in a really, really big city but close to the city limits. How much may the city and it's interferences interfer with my signal?
• Should I connect the GROUND from my circuit to the roof construction?

Theoretical issue:
I'm going to build a second Beacon. Around 7MHz this time. I like to install it on an old air field.
Some fact on the air field:

• No building around for at least 300m.
• The ground exist of sand and ist mostly dry during summer.
• Little vegetation. A bit of grass and some random trees.

I think it's save to erect a wooden slat of about 4m as the center support for an Inverted V without no one taking notice of it from far away.

So, my questions are:

• Is there an Antenna type you'd suggest? I'd go for an Inverted V, even if the angle is kinda low.
• Maybe a "KGD" or a Micro Vert works better?
• Does it make sense at all? Is a high mounting point for the Antenna the key and I can spare myself the effort anyway?

Kind regards,
~Zazzle

26

General Radio Discussion / Who wrote...

« on: September 27, 2013, 1223 UTC »

Hi there!

There's this wonderful article on the wiki. Sadly the contact (mail) below doesn't work anymore.

I want to leave that beautiful and empathic soul of a human being a response

Does anyone has a working contact? It's also okay to tell the person in context to contact me - if that way works better.

Yours,
~Zazzle

27

The RF Workbench / Beacon Project "Common and Precious" (OFF air, 10.237,5kHz, 5W)

« on: September 27, 2013, 1222 UTC »

Hi everyone,

Firts of all: I'm not a native speaker of the english tongue. Please bear with me in case I screw up the grammar every now and then.

I toy with RF stuff since my childhood. (I have a passion for RF stuff on shortwave since I was eight. Back then my grand mother gave me her old valve radio as a birthday present and after I hit the SW button one day in the evening I could not let go. For me, SW is the modern way of the 'travel bug'). I've build quite some stuff so far and operate a small "wide range radio thermometer grid" in my area (µC controlled, solar powered, 1W 70cm transmitters. The farest one is 8km).

Now I want to build a CW beacon. Why? First, there is this a certain curiosity on the technical side: tinkering and the question if someone will pick it up, ever. Then there's this romantic side. A CW beacon is some kind of light house in a dark, stormy night. It's there when no one's around, sending it message to whoever may hear it.

So, enough smalltalk. Lets start with some technical stuff

1) The concept:
The whole beacon will be solar powered (by a 20-40W PV panel - overdone for the summertime but will also offer enough charge during winter) and controlled by an AVR controller. It will charge during day and as soon as the sun has set it'll start transmitting a message. The mikrocontroller will monitor the battery and shut down the device to keep itself in operation with 20% of battery capacity remaining as a buffer. The Battery, charge controller, mikrocontroller and transmitter will be mounted inside a water proof box. It's a low budget project because I guess sooner or later someone will find and steal/disassemble or damage it. The problem is that I live in a rather large city near its limits and so far I couldn't find a proper place that would allow to mount such a transmitter high above the ground without being noticed. Therefore I have to make a tradeoff between performance and security.

Picture

2) Location
The main problem is the place where I live. It's a big city. There are no hills around. But there's lot of destructive people that like to damage stuff and there's a lot of background noise. The surrounding land is more or less flat (and used for agiculture purposes). My focus is on three primary locations:

A) Old Airfield

Picture

It's possible to mount the module close to the ground so it won't be visible from some distance. There's an old fence with massive wooden post running across the field. I could mount long wooden slants to them, holding the transmitter an Antenna.

PRO
- No buildings around
- Wide open space
- If installed clever, not visible from the distance
CONS
- The Antenna will only be 2-3m above the ground
- Easy to reach / disassemble / damage

B) Old bridge

Picture

I could install the PV module and transmitter easily in the middle of the bridge and run the antenna wires left and right towards surrounding trees.

PROS
- Transmitter and module easy to hide
- Not easy to reach
CONS
- The construction is made of steel
- The top of the bride is just 3-4m above the ground since its socket is below the ground level.

C) Old depot house roof

Picture

Except of the (thin) antenna wires the whole setup is easy to hide. Climbing into the roof is hard and requires acrobatic stills. Therefore the setup is not prone to be stolen or suffering from damage.

PROS
- Not easy to access
- Antenan wires will be 10-12m above the ground
CONS
- Still in the city, higer building on one side, an open air field on the other side
- The roof construction is made of steel

3) The frequency.
I'm completely not sure about the frequency I want to use. My circuit is cabable of tuning about -/-20kHz around the fundamental crystal ferquency. I have crystals for:

10.00000 MHz
13.25583 MHz
16.48555 MHz

For me it's important to not disturb the HAM bands or any other service like nautic communication and alike. But of course I want my beacon to be noticed. Therefore I'm looking for a frequency that's not prne to cause trouble but is still likely to be scanned frequently.

My favorite is the 10MHz one. Because it's close to the 30m CW band.

4) The Signal.
This is primary about battery lifetime. Like told before, the whole device runs on Solar power and I also want it to operate during winter, even if not all night long. I have to make a decision between the TX-Time (the more often the more possible the beacon will be noticed) and battery lifetime (there is no use in having the transmitter shut down after just one hour of operation).

At the moment the Concept looks like this:

- Every 10 seconds a 1s long dash (to get attention)
- Each 10 Minutes the following message will be transmitted:

"<LOCATOR> SOLAR NIGHT ONLY UBAT 125" (where UBAT 125 means BATTERY VOLTAGE = 12,5V.)

5) Antenna
I think I go for a classic wire dipole. It will be quite long (23 ft. 4.8 inches / 7.1 mtr. per element) but on the other hand it's easy to build and mount. The box holding the transmitter will be mounted in it's middle. Anything I should pay attention to?

6) Operation times
Given that the signal travels way more far during night I forsee from running the transmitter during day. What's your opinion on that?

7) RF-Power.
Currently the Transmitter delivers 1,6W into Z=50R. Is that too much? Since it's CW I guess it's quite a lot. On the other hand, I have some background noises to overcome, the antenna isn't mounted very high and I still want to bridge some distance.

Yours,
~Zazzle