We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations. Always consult with the appropriate authorities if you have questions concerning what is permissable in your locale.

Author Topic: Beacon Project "Common and Precious II" (OFF air, 6.398.5kHz, 30W)  (Read 67048 times)

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Heyho,

Dunno where to start. Just let's say I discovered E-Class amplifiers by "accident" and now  I wanna play with it. But since Class-E is only fun when it comes to "more power" [Tim Taylor] I'm going to build a second "Common and Precious" CW Beacon on 40M with *gsssssp* 25W. Some may render me a bit too bold for doing that. But hey, hey, no risk no fun. And 25W sounds a lot of fun to me. :)

I was doing some engineering work with a resonant SMPS circuit when I started to wonder why it shouldn't be possible to use a pulse driven stage to generate clean HF with a proper resonant circuit on the output. Well, after checking some things with Google I stumbled upon Class-E amplifiers. Oh-yes, baby. Which basically ruined my whooole weekend 'cuz I got absorbed in technical papers and formulas.

Since it's going to be pirate equipment and may be prone to get damaged or busted, I settled with a simple setup. I left more space on the PCB for the output stage because that's what I want to tinker with.

  • The transmitter generates the operating frequency with a simple TTL-based crystal oscillator (which can be pulled a bit).
  • The last TTL-Gate is keyed by an Attiny25 which holds the morse code / identifier that's to be broadcasted.
  • The TTL Block is followed by a high-current FET-Driver.
  • The rest is obvious. A resonant circuit and just to stay clean (which is important to me) a 7-pole Low-Pass.

The whole thing end up in an small aluminium box with an external (15V/3A Notebook) PSU.

I learned from my last setup that having the transmitter high on a pole sucks rocks because I have to tear down the whole setup each time I need to work on it. This time I go with a transmitter that's hidden under the roof. 25W allow me to lose 2-3W on a long RG-58 cable so I can run the cable in a way that makes it impossible to follow easily and to a place where I can hide the transmitter without any risk of it being found by accident.

So far I got myself all the parts needes. Electronis components, wires for the antenna and poles, paint, wood slants and so on.

I think I make this happen around the easter holidays. Hope the weather works in my favor :)

Question: any reasons against f=6.553,5kHz? I wanna keep it simple and a 6.553,6kHz crystal is chep.

Kind regards,
~Zazzle
« Last Edit: July 24, 2018, 2317 UTC by Zazzle »
Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Re: Beacon Project "Common and Precious II" (25W CW, 40M Band)
« Reply #1 on: March 14, 2016, 1347 UTC »
Evenin'

Update. We got a layout!

  • Bottom-Left: C Keyer
  • Left-Top: Oscillator and Keying
  • Top-Middle: FET Driver
  • Middle: PA Stage
  • Right: Impedance Matching tarnsformer and Low-Pass Filter

~Zazzle
Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.

Offline Josh

  • DX Legend
  • ******
  • Posts: 1741
    • View Profile
Re: Beacon Project "Common and Precious II" (25W CW, 40M Band)
« Reply #2 on: March 14, 2016, 1455 UTC »
Neat! It'd be sweet if you could add some telemetry to it, like ambient temp, barometric pressure, working voltage, a cheerful message, etc.

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Re: Beacon Project "Common and Precious II" (25W CW, 40M Band)
« Reply #3 on: May 14, 2016, 1204 UTC »
Hey Josh!

Neat! It'd be sweet if you could add some telemetry to it, like ambient temp, barometric pressure, working voltage, a cheerful message, etc.

I had thoughts about that two years ago when it was in the making. I agree that those features are a nice thing. Temperature, humidity and alike. In the end I forsaw from adding such. The main reason was, that I didn't want to spend much time and money on features for a projekt that's likely to be vandalised and/or stolen/busted.

Another reason against is based on the fact, that the signal may be received with hard fading. Therfore, I like to keep it short and simple, only containing the basics.

Since the project made it almost through 1,5 years without anyone touching it, I might rethink my decision and add at least a temperature value. We'll see .:)

Kind regards,
Zazzle,


Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Re: Beacon Project "Common and Precious II" (25W CW, 40M Band)
« Reply #4 on: May 14, 2016, 1217 UTC »
Hey,

vacation! Hoooray! I found time to etch and populate the PCB. Sadly, I added a Diode reversed which lead to a 5V TTL IC to be fed with 15V. Which it took, of course, not well. But fortuna was on my side and I found a replacement in my spareparts box.

The circuits works and will spend the next 7 days in a metall box in the basement. Burn-in test.

~Zazzle
Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Re: Beacon Project "Common and Precious II" (25W CW, 40M Band)
« Reply #5 on: May 19, 2016, 1207 UTC »
Hey,

the test passed without problems. Froze it almost to death and heated it up to 90C several times. Steady operation. So I'm gonna install it next weekend. As long as the weather stays steady. I'm looking forward to that. :)

Kind Greetings,
Zazzle
Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Re: Beacon Project "Common and Precious II" (25W CW, 40M Band)
« Reply #6 on: May 20, 2016, 0955 UTC »
Heyho,

Board after cleanup.

Did some fun-testing:

- 60W Po, 81% effiency.
- 30W Po (nominal value): 86% effiency.

Kind greetings,
Zazzle.
Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Re: Beacon Project "Common and Precious II" (25W CW, 40M Band)
« Reply #7 on: May 30, 2016, 1137 UTC »
Hey.

Bite my a$$.

Found time, installed the setup. Of course I had, again, issues with the SWR. I've expected such, given the low frquency, low antenna height and metal based roof construction.

But then, just when I was done with the annoying antenna issue, Murphy decided to join and the 15V Notebook PSU, that powers the whole thing, decided to go FUBAR fo no reason. Yeah, thank a lot.

I still got some more at home, but I wasn't rewarded with a working setup yesterday - after all the work I put into.

So, do it again, Sam.

~zazzle
Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.

Offline ulx2

  • Sr. Member
  • ****
  • Posts: 416
    • View Profile
    • My DX blog
Re: Beacon Project "Common and Precious II" (25W CW, 40M Band)
« Reply #8 on: June 11, 2016, 1550 UTC »
Hello Zazzle!

Did you make some tests on frequencies near to 6400 kHz? I have heard slow CW there during short period of time about a month ago. The CW speed has been almost the same as I heard on 10 MHz. I have made recording then, but unfortunately deleted the file and didn't decode it.

73!
Alex.
« Last Edit: June 11, 2016, 1553 UTC by ulx2 »
LOC: Kyiv, Ukraine
RX: Degen DE-1103 portable
ANT1: Two phased external wires (2x10 meters approx.)
ANT2: Long wire (25 meters)
ANT3: Homemade M0AYF wide bandwidth active loop
ACC: Homemade passive preselector, homemade phasing device

http://ulx2.byethost24.com/

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Re: Beacon Project "Common and Precious II" (25W CW, 40M Band)
« Reply #9 on: June 30, 2016, 0643 UTC »
Hey!

Did you make some tests on frequencies near to 6400 kHz? (...)

*Looks at the date of your post and his calendar* Yes! Very likely! If it was in the hours around midnight, it's very possible. :)

Funny thing that you happen to caugh me on those few rare minutes where I had it on air. :)

Greetings,
Zazzle
Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Re: Beacon Project "Common and Precious II" (on air, 6.398.5kHz, 30W)
« Reply #10 on: June 30, 2016, 0700 UTC »
Phew! What a night!

Finally! I found time (and motivation) to install the Beacon and get it on air.

It's operating on 6.398,5kHz.

To be honest, I wasn't that motivated to spend (again) hours over hours on the roof, trying to get the best SWR. Besides the fact, that the PSU died on me when I was almost done, I also spend too many hours with finding the perfect match with the Balun and Antenna length.

I had the setup installed in my garden before. But due to it's length (almost 22m) I had trouble running the wire Dipole high enough without getting it caught in trees. Back then it got already obvious, that adjusting it will be another pain-in-the-you-know-what.

I tried to fool myself by believing it'd go easier on the roof because there's no trees around and I could work with the already installed support poles. Well, it didn't get that better. Maybe I cut the wire some centimetres too short (well, shouldn't have that much of an effect on 40m anyway) or it's just about the plain fact, that the height of 3m is just too low for the frequency. Especially since the ground is highly conductive. You remember... metal construction.

In the end I put the antenna up and down another 7 times. Until I was that annoyed that I settled with a SWR of about 2.5. Not awesome, but f** it. I got 30W so I can waste some. The SWR-Meter says FWD: 55W, REF: 10W. The Chassis where the MOSFET is mounted to stays almost cool. So. Ehh....

What annoyed me like hell (and made the night one I'll be laughing about in a few months) were those people walking around on the ruin yard. Suddenly, I heard people walking and talking in low voices. It's funny how fast a calm mind switched to paranoia mode. They were just some kiddos walking over the yard but after that every loud noise made me freeze. And, believe me, things that hardly make a noise during the day become quite loud during night. Damn, Duct Tape is pretty loud when it's been unwound. Not to mention all the animals moving in the shrubs near the roof on the ground.

Anyway! It's on air. I could already receive it on two WEB-SDRs
  • - Bedfort, England: 05:45 UTC
  • - Twende, Netherlands: 05:75 UTC

Greetings,
Zazzle
« Last Edit: June 30, 2016, 0709 UTC by Zazzle »
Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Re: Beacon Project "Common and Precious II" (on air, 6.398.5kHz, 30W)
« Reply #11 on: June 30, 2016, 0718 UTC »
Hey,

oh, and this is how the TX-Unit looks like. I'm gonna take photos of the whole setup during day another time.

Greetings,
Zazzle
Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.

Offline Josh

  • DX Legend
  • ******
  • Posts: 1741
    • View Profile
Re: Beacon Project "Common and Precious II" (on air, 6.398.5kHz, 30W)
« Reply #12 on: June 30, 2016, 1423 UTC »
Looks nicely executed.

Offline ulx2

  • Sr. Member
  • ****
  • Posts: 416
    • View Profile
    • My DX blog
Re: Beacon Project "Common and Precious II" (on air, 6.398.5kHz, 30W)
« Reply #13 on: July 01, 2016, 0022 UTC »
Hi!

It's amazing, that I have tuned to 6398 kHz at the same moment when you did unannounced test broadcast and received C&P-II even before it's official start  :)

The signal is good here at the moment: SINPO = 44444. However, sometimes Pyongyang makes a splatter from 6400 kHz on local evenings.

73!
LOC: Kyiv, Ukraine
RX: Degen DE-1103 portable
ANT1: Two phased external wires (2x10 meters approx.)
ANT2: Long wire (25 meters)
ANT3: Homemade M0AYF wide bandwidth active loop
ACC: Homemade passive preselector, homemade phasing device

http://ulx2.byethost24.com/

Offline Zazzle

  • Full Member
  • ***
  • Posts: 184
  • Longing for distant places
    • AOL Instant Messenger - Ask+via+PM
    • Yahoo Instant Messenger - Ask+via+PM
    • View Profile
Re: Beacon Project "Common and Precious II" (on air, 6.398.5kHz, 30W)
« Reply #14 on: July 04, 2016, 0955 UTC »
Looks nicely executed.

Thank you! :)
Trans-/Receivers: JRC NRD-525,  ICOM IC-R72,  YAESU VR-5000,  YAESU FT-897D
Antennas: 80M Halfwave Dipole,  40m Inverted-V,  5/8λ Groundplane,  20M Longwire,  misc. UHF/VHF Scanner Antennas.