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Messages - Zazzle

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1
Hey!

Reception might be weak. There's some RF getting out but not much. I guess the Transistor in the PA stage got fried. I did something realllly stupid. The box holding the electronics is mouted on the side of the PV panel. The panel faces south. Soooooo.. the sun past noon starts to shine on the box. There's a big black battery inside and the acrylic cover might have it function as a green house... heating the whole box up... which killed the transistor (which reaches approx 55C with 20C ambient temperature in the box.

Oh well... I'm gonna have to fix that later. So far the box got covered with a white sheet to reflect the sun and keep the battery from being cooked....

All those thing you need to pay attention to.

Btw: since all other Projects went off-air on Monday... I was pretty worried to find it already vandalised... but all is fine. Phew!

~Zazzle

2
C&P-2 is off air today  ???

Yeah... noticed a lack of reception on Monday. Got sceptical when I didn't hear it today again...

Damage issue. Details can be found here...

3
Hi,

so yeah... after all those years the first serious issue. The Antenna got stolen and some wire-cutting done.

Once more the whole issue doesn't really makes sense when it comes to understanding it. The Antenna got removed WITH its short wooden pole. The wooden pole itself was mounted with U-clamps. The Antenna was bolted to the wooden pole with standard screws. So, someone took Antenna + pole. Why the pole as well? All radials got cut clean of. The ground wire as well. The Antenna cable got cut approx half a meter away from the transmitter box.

In addition, the power cable to the socket (in which the PSU was plugged in) got cut. The transmitter itself was left alone.

The whole setup of Cap 2 (self build Dipole) some meters away was left alone and is still OK (went off air as well because the power cable leading to it  was looped through the socket for this beacon).

To make the whole issue even more odd... the cable that runs under the roof (required climb the metal construction for that) got cut as well. Eh...

So what is this about?
- Most likely someone stealing the CB Antenna. (Have fun trying to tune it to the CB-Bands... won't work. :D)
- FCC? No way. They'd taken everything along.
- Someone else wanting to shut down my beacons? Why just (really clean and neat) uninstall the antenna and not break all setups and take the transmitters along?
- Why cutting the cable under the roof (again... I had cut cables at different points three times by now...)

I stick to Occam's razor. The Antenna was of interest. Everything else doesn't make any sense without further information.

Gonna think a bit about what to do now. So far I took all transmitter units along. Doing maintainance and finally fixing the swapped numbers in the morse code of CaP 2 (sends 52W instead of 25W).

Since the whole area might be torn down sooner or later... gets me pondering whether to get it back on air or find another location. Also, might not give away the location through locator again.

Questions over questions.

(But to mention something positive: had a young fox - likely born last year - following me bit with curious looks. Handsome lad. But I better not get started on foxes again or I get counter-posted with kinky lady-fox costumes once more. ;p )

So long...
Zazzle

4
Heyho!

I enjoyed list e ring to the 30m signal. Hope you get the time to get it running but I sure know how life gets in the way of hobbies.

thank you for the motivating words. It's on the todo-list along with some other projects but I'm sure I'll manage sooner or later this year! :)

Greetings,
Zazzle

5
Heyho,

First: yeah... I'm still alive. I just agreed to some RL commitments (more than I could handle due to complications) and that basically killed all my free time in the first half of 2018. Not to myself: be more egoistical...

Seconds:Common and Precious 3 got father and gave birth to... okay... I stop being ridiculous.

The urge to build this beacon came kinda out of nowhere. I always felt for building a entirely solar operated beacon. The urge suddenly hit me hard. Those who follow my projects from the first day might remember that it was an idea that came up every now and then on the way). Anyway. The recent years gave me an good idea about the level of vandalim to expect. Another point is that I now have a source for cheap second hand and/or partly damaged PV module. So a loss doesn't hurt that much.

The frequency close to 'Common and Precious 3' was choosen on purpose. Even with the difference in RF power level (25W VS 2W) it allows a good comparison of the two setups.

It might also happen that I'll loose the location for my beacons during the next months. The city hall published ideas and plans about tearing the areal down, building homes on it.

A documentation with more details/pictures can be found on the Wiki here. (Proof reading/editing anyone? :) )

Open issues...
Opsie #1, I forgot to tune the frequency back to 6.399,500kHz. It's running at 6.399.000 right now. Lucky me that I've build the TX unit with connectors so it's easy to take it home again.

Opsie #2: I've started redoing my Morse-2-Text routines and it took longer than expected. But I wanted to install the beacon on the scheduled weekend. So it's currently sending only 1Hz dashes.

Also... I might change the PV-Module. Chances are I can get my hands on a 170W type for a crate of beer. This provides more resources for operation during winter.

Overall: I'm very happy with this project. It's a good mix of proper engineering and not overdoing it. It also looks beautiful on the roof. Might sounds silly but those who know the beauty of such project might understand. :)

Circuits are about to follow as well.

(Side node: Eww! Whe wiki does a hard re-compression of attachments (pictures), eh? My poor beautiful and crisp pictures.)



Greetings,
Zazzle


6
The RF Workbench / C based Class E RTTY with Crystal pulling
« on: April 10, 2018, 1323 UTC »
Hi,

I prefer to keep it simple, especially with the kind projects I do (which might be busted, stolen or vandalised). Therefore I was looking for a simple (regarding hardware and also software) way to run RTTY. Here's a funny thing I tried and which works like a charm. Lets share that!

Most modern Microcontrollers (AVR, PIC, STM, etc.) come with multiple hardware functions. UART, IC, USB you name it. Also PWM! The awesome things about those hardware functions are, that they run CPU independent and don't consume computing time.
We play with the PWM unit here. Many controllers also provide clock multiplication. This means that a PWM frequency higher than the CPU (master) clock can be archieved. Some fancy controllers even support adjustable PWM and uneven frequencies, which allows to generate a lot of handy frequencies from a fixed source.

Here's where it gets interesting. Since the divider or multiplication is set to a fixed value, the PWM frequency follows the master clock frequency. If the master clock frequency changes, so will the PWM frequency. Hmm! Let's abuse this!

Crystals can be pulled by adding a variable capacitor into its path. Which means it's frequency can be adjusted up to a few kHz. That's done with a mechanical variable capacitor. But it can also be done with electrical variable capacitors (diodes, a VARIAC).

For RTTY we need a frequency shift of a few Hz, i.e. 170. That's doable with a small change of the capacity. The idea is to manipulate the master clock frequency in the pattern of a RTTY-Signal. Software on the controller generates the proper timing for RTTY (Baud speed) by turning an I/O-Pin on and off. The +5V from the I/O-Pin is feed to a VARIAC (Variable Capacitor Diode) which in return pulls the master crystal (frequency). A hardware PWM output generates the carrier frequency. Since the PWM frequency depends on the master frequency, it chances along with it. In respect to the ratio between master- and PWM frequency.

For example:
  • Require PWM duty cycle: 50%
  • An Attiny25 needs at least 4 clock cycles to make the PWM unit run 50% dt in CTC-Mode.
  • We want 4MHz for our beacon.
  • Therefore, we need a 16MHz crystal. That provides us with 4MHz PWM.
  • At 4MHz we need an offset of 170Hz for RTTY. Since the radio is 4 (16MHz Master Clock / 4MHz PWM), we need to adjust the manipulation loop in a way it grants a frequency shift of 4 x 170Hz = 680Hz.


Notes:
First of all: which oscillator pin should be used for this trick depends on the Microcontroller used. Also, whether the frequency (when key'ed) should go up or down. Have some workbench-testing to get known to your controller. Also, don't overdo the pulling. When introducing too much bypass capacity to the internal oscillator it might stop and freeze. Imagine you climbed all up the Kilimandscharo on your Africa vacation - all wasted from carrying also a 100W solar module and Battery - only to learn that you overdid it and your baby stopped working as soon as you're back home. ;p
  • 1) XTAL may 2-8 times larger than desired frequency. Depends on the used Microcontroller. Read about it's H/W PWM unit and features.
  • 2) Is usually the same as C1 (see data sheet of the Microcontroller). It is required to provide minimal capacitive load to the oscillator circuit. Can also be replaced with a mechanical cap to obtain the desired target frequency on one end.
  • 3) Can be either a classical VARIAC or maybe also some standard diode. All diodes have a VARIAC behavior. Which diode can be used depends on the junction capacity and how far it can be adjusted. Tuning voltage is also a factor. Tinker a bit with it and gain some practial experience. Its also possible to  parallel Diodes.

Also: it's important that all rails (+5V logic and others that are used for tuning) are high stable and decoupled properly.

Kind greetings,
Zazzle

7
Hey,

Just you know... this one's still on my desk. Since it's 3 years old it'll get some mods and a new antenna.

Kind Greetings,
Zazzle


8
Update. Same issue as here.

Operating again.

9
*blinks*

I guess I'm slowly waking up from hibernation. It's still cold but not slippery (one the roof) anymore (so far). The new season is about to start and I got some new ideas.

Anyway, seem like someone's playing cat and mouse with me. The Beacon was down for - dunno - 6-9 weeks or so?

Remember that I got problems with a wire gnawed by a rat or so? In retrospective, it's more likely that someone tried to cut it with a blunt knife.

When I was checking for the reason of the deceased operation I found this:
- Out of three pairs of wires exactly the feeding couple was ripped out of the terminal.
- Also, the cable that runs under the roof (!) which I patched last year had one side ripped out of the terminal. I really wonder how someone managed to get under the roof. Except with exhausting climbing actions (which I had to conduct to fix the connection).

I wonder what this is all about. Maybe it's some kids having fun. Or someone's doing this with a rason. I wonder what the reason might be then. In any case, I grew suspicious and very careful. Maybe I'm gonna move everything eventually.

Anway, this one's up again. I wonder what (and when) will be next.

Greetings,
Zazzle.

10
Hi there,

Late in the show here, but aren't class D and E just the cat's nose?

Class D mimics an analog signal by filtering a PWM signal (x-times oversampling equired for quality) though a low pass.
Class E generates a sine signal directly from a rectangular signal that equals the target frequency. Conversion between REC and SINE is done by a CCL filter at resonance.
In the core, yes, in both types convert a "digital" signal to a analog one by filtering.

20 watts! Did you try amplitude modulating it?

I set it to 20W. The shown board is capable of delivering 60W peak carrier from 12V. Likely more with other components. Class E is fairly easy to upscale. About modulation: yes, whatever can supply with with a positive-wing-only-signal works. Some classy monorail amp with the blocking cap on the output removed will do fine. Or some cheap Opamp-Stuff. Or, if you like to stick to "keeping it efficient": some PWM Amp.


Kind geetings,
Zazzle.

11
Heyho,

the beacon is up again.

Also, I might delay other repair works for now. Winter is knocking at the door. The weather was stormy  today and the temperature went up/down all day long. Despite the fact that the weather report forcasted positive degrees... it was wrong and we're below the freezing point now.

When standing on the roof I took notice of some odd white stuff on it. Oh. Patches of frozen water. Actually, I felt for turning and going back home. But given that I had my pockets full of tools and stuff to fix the antenna (and tune it properly again)... I decided to go on. Turned out that the grip on the roof was still okay. But I won't do that again with freezing temperatures. Not worth the risk.

Fixing everything went smooth and - despite my expectation - I managed to finish everything within half and hour and before I started to feel cold. I took the antenna analyzer with me. SWR is 1.07 (with 51.6R feedpoint impedance, X is below 2R).

Also, this night full of small adventures was another one to memorise. Sometimes it happens that the atmosphere and feeling is just right. I always get into this specific deeply content and slightly longing (not in a bad way) mood then.

Just standing in the middle of the roof, the antenna rising into the canopy of stars above like a finger reaching out, sending its message quiet and unnoticed. Hear me. Find me. Love me. Watching the stars, feeing their soothing shine that makes me feel at home and lost at the same. Hearing the wind whispering in the leaves, tempting them to fall. Thoughs wandering, maybe to such silly though and questions like whether there's actually such a thing like werewolfes that run the forest at night. And whether they're really bloodthirsty things or just human being that are scared out of mind while they go to the burden this transistion with each lunar circle anew.

Fun fact: If I was granted to change my form for one night I'd definitely go for a fox on two legs. Kinda were-fox, you know? But a kind one, no one that seeks blood. Big proud ears, all black on the back. A thick, fluffy rusty red winter coat to keep warm. Bright amber eyes and a nose to match those keen eyes. Not to forget those big black paws to walk on, with soft pads on the sole that allow me to feel the soil I walk on.

I love the mood such night-outs get me in. Oh well, or it's my brain being half frozen from being up on the roof. Or me lacking badly of sleep.

In anyway - kind greetings,
~Zazzle (in human shape right now)

12
Hey Chris!

I look forward to hearing this beacon when it is back on the air. Is the 6.398.5kHz beacon on now?

Si, it is. :)

Kind Greetings,
~Zazzle

13
Hey Autovon!

Thanks for your kind words. :)

I enjoyed listening for your beacons at my old QTH.  Hopefully will be able to catch some soon again.  Keep up the good work; we're glad you are doing these projects.

Mind telling me which your old QTH was?

Kind greetings,
~Zazzle

14
Hey,

Offline right now. Storm damage.

We had two heavy storms recently. One managed to break the 5/8 clean in half.

Oh well, hello quick and dirty fix. I know... Copper on Alu isn't the best thing but... eh.. it'll do for a while. Too cold in the dark hours for complicated tasks.

Kind greezings,
~Zazzle

15
Hey,

baaa. I'm slooooow. Finally found the motivation to uninstall the whole beast and take it home. There's some issue with the seperate amplifier. The screws are corroded. Haven't dealt with that so far.

But I've been rebuilding the dipole.
+ Thicker wire
+ Proper BalUn
+ Adjustable LC impedance matching. (10-15R:50R)

Got a new toy. A55 Zoom Antenna Analyzer. So much fun. :)

Greezings,
~Zazzle

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