NDB CAS

Back to an old passion: VLF NDB hunting. But this time, "live".

Right next to a swimming pool I noticed a weird tower with a capacitance hat and typical white and red stripes. Landing airplanes to Torino Caselle (LIMF) airport passing just over it. Online resources and maps locate the CAS NDB right there.


A detail of the capacitance hat. Don't ask me their length.


A more poetic view of the instllation.

FT817 CAT interface, a clarification on the wipeout warning

So far I have noticed very little interest in my keypad. I hope it is not because of the explicit warning about possible radio settings wipeout, but let me clarify things.

The keypad does not send potentially dangerous data. It sends and reads data as ANY OTHER computer software does. The fact that the keypad uses FT817 "proprietary" commands/extensions does not increase the risk of losing soft calibration settings.

Data (or, more generally, "information") may corrupted on the transmission path by external causes and thus be improperly received. This may happen both with my keypad and any other CAT control software.

Since I do not use CAT control programs I do not know if their documentation issues an accurate warning of total wipeout risks.

I prefer to tell the whole story and provide a preventive measure to recover from such an accident.

So, why hesitate?!

Surplus source for CAT cable

Since soldering MiniDin8 connectors is a tough job, I have found out that in the past there were two commercial applications using these cables:

• Sun SPARC and 3/80 keyboards
• Apple Macintosh RS-422
  

According to a websearch ("sun keyboard pinout"), the Sun keyboard cable has two couples of shorted pins. Fortunately they are not vital for the FT817 keypad application: just eradicate them (pick the right ones!). I've done it and it works.

The same website shows a more friendly pinout for the RS-422 cable, that would be ready to use right away.

One problem: how to find these cables?

FT817 keypad - a suggested assembly

This is the first (and last) keypad I made not for personal use. It is on a veroboard/perfboard and takes about 5x5 cm. I have used a 4 way connector for the cable towards the ACC port and 8-way pin headers for the keypad. I prefer this latter solution to my development board that uses 8 independent wires.


This way the keypad sits on top of the circuit, effectively reducing the overall footprint to a bit more than the keypad itself.

For the reset button I installed only two pin headers, if the owner-to-be will feel the need to add one. The LED is wired permanently to the board.

The cable is 1m long, and did not show any communication error during workbench tests.

These pictures are provided as a guideline for you, homebrewers out there.

Please note that I am not available for building a keypad for anyone for less than 100 Euro, shipping included, advance payment. I hope this amount is high enough to encourage you into homebuilding this keypad. If you have troubles locating some parts, see the keypad homepage for some directions.

Inside Terminator's eye

Don't panic. After you've seen the optical receiving system, the transmitter will look horrible.

The plate is a CD-ROM player cover, bent upwards to hold a clothes peg. The transmitting LED is loaded there. The 488 Hz tone is generated with the usual XTAL+divider chain that drives a 2N2222A (the metallic cylindrical "thing").


In the center of the board there is a current generator (TO-220 transistor, the white cube, two red LEDs in place of a zener) with a jumper to provide two drive levels.

No tilt/turn controls were mounted since the path didn't require any precise beaming. Moreover the LED has a wide beam, so a simple tilt screw might be enough. No need for micrometric adjustments.

Terminator's eye

Finally we've made it! Simone and I could arrange a first complete equipment test.

The OPT201 receiver had been boxed (plastic) and prepared with a 31.8mm standard mount for telescopes. The MCW transmitter was simply mounted on a CD player cover (no picture available yet).

Since I could easily provide a circa 200m path, instead of looking for a dark grass field at <0°c, we decided to stay near the warmth of my place. When Simone looked out of the window was about to ask where the transmitter was. Then he said: "Oh, gosh, there it is! It looks like Terminator's eye!" A 10mm red LED looks pretty bright at 200m. I would compare it to a red light on the back of a car (5W@12V).



Simone brought the "antenna": a tripod and a modified half binocular (dia 50mm, F 300mm). Being experienced at looking for stars he pointed it in the right direction in a couple of minutes, then replaced the ocular with the receiver. Given the strength of the signal we tried staying inside and reducing ambient light (produced by a CFL, by the way) to minimize reflections on the window glass.
The 488 Hz tone was extremely strong and steady, effectively masking out any AC line harmonic. The screenshot below shows more than 50dB over background noise (look at the upper part). The screenshot was taken while my daughter was playing with the laptop keyboard and touchpad sitting on her Ikea drawing desk.


Then I recorded few seconds of signal for postprocess. Since the transmitter was square-wave modulated, many other harmonics were visible:


Note how weak even harmonics are, while odd ones are rather strong, in all the available recorded bandwidth.

Since Simone still had some time available we tried aiming at cars and stars (actually planets, Jupiter and Venus), but nothing could be heard.

Next test will be on a longer distance with some modulated information. Either one way in beacon mode or two-way, if a second CW operator is found. The quest for a proper field is open!

FT817 keypad - real memories, not presets

It is still beta-code, but the keypad is now able to remember your favorite frequencies rather than offer you my factory programmed presets.

The ATtiny2313 has 2kB of program memory, 128bytes of RAM for program volatile variables and 128bytes of EEPROM for long term variables.

In the latter memory space, a program can write data that will survive power off of the microcontroller. This means the program can read something and store it for future use.

In the keypad application, the beta code allows to read the currently selected VFO frequency/mode and write it to a long-term memory area. Then with two keystrokes you can QSY back there. Even days or months after the keypad has not been in use.

Freq/mode information take 5 bytes, so we could store up to 128/5 = 25 memories. Since key combinations are limited and managing them "costs" code memory, I will probably implement these sequences:

- # followed by * followed by any other key assigns current freq/mode to that key
- # followed by any key recalls the assigned freq/mode, except for "#*"

So 15 custom memories will be available. Please note that only frequency and mode will be stored, nothing more. Not even the narrow filter setting.

One thing I noticed. In the BCB band (88-108 MHz) where WFM is the only allowed mode, recalling a memory will hang the radio requiring removal of power (not power-off, total unplug even from internal batteries). This is because I first set the mode, then the frequency. Doing viceversa might result in a different frequency if a change from SSB to CW is performed. Should be worth spending some code to set frequency, mode and then frequency again to avoid these situations, shouldn't it?

[that's why it is still beta code...]

FT817 keypad - automatic whistle

Two more functions have been tested:
- up/down scan (mimics microphone up/dn buttons), with stop too
- "quick tune" for automatic antenna tuners

The up/down scan allows you to scan through the band at the normal scan speed. Takes two buttons, and a third if you also want a "stop" control. Otherwise scanning can be halted with a quick PTT press, or a touch on the morse key.

The "quick tune" sets the mode in FM and keys the PTT for 5 seconds (need more? need less? no problem!), then returns to receive in the original mode. With this function you must take care of the output power level and antenna choice (front/rear) in order to preserve your RF finals' health. No more no less how you'd do it by hand. This function can be assigned to a key or, for safety reasons, to a submenu (ie. within presets or mode combinations).

These two functions can be loaded on customized firmware and replace other functions: you still have got 16 keys and 2k limit on the program!

FT817 keypad - the homepage is out

Finally, the keypad has a homepage.

User's Manual and schematic diagram have been published, as well as a side-by-side comparison of similar FT-817 accessories.

The firmware is available on request (see the User's Manual for details).

Keypad - Saturday afternoon fever

For a few days I did not look at the keypad code. Then I realised I could do one more optimization and... Now it fits all 16 QRP presets with mode, mode change, VFO toggle, VOX toggle, power level and meter mode. And direct frequency dial, of course.
Now it does not miss a thing!

FT817 keypad - how it looks

After a lot of monologue about the keypad, here it is! As you can see, it is real.



On the left of the picture you see the simple parallel port programmer. The keypad pictured is not connected to the radio or power supply.

I might shoot a video of the keypad at work...

FT817 Keypad: good and bad news

Hooray!
The GOOD news: I have been able to control power level, meter mode and vox.
The bad news: as expected, all functions don't fit. So mode change had to be dropped (but it has dedicated buttons on the radio).

73!

ATtiny2313, bascom-avr and serialin interrupts

Since I am apparently not able to receive data from the FT817 with an unbuffered input on the ATtiny2313 HW USART, I decided to try the buffered way.

Remembering my assembler courses, I was prepared to deal with interrupts (URXC, "receive complete", on the ATtiny2313) and ISR (interrupt service routine).

So I went on and modified my code:

Enable Interrupts
Enable Urxc
On URXC My_isr

But on compile, bascom-avr complained that:
"Error : 249 Line : xy ISR already defined [My_isr] , in File ..."

What? The answer is in the help file, under "CONFIG SERIALIN", "ASM" paragraph. Basically bascom owns the URXC interrupt, so you need to use ISCHARWAITING to peek into the buffer.

I received Hell

While MCW allows optical communications with simple equipment and doesn't require a computer, it does require two Morse-enabled operators.

In order to be able to involve more people in my (our) optical experiments, I wanted to try to send computer generated data over light. With all those soundcard programs and modes, there must have been a way to do it!

The people on the laser reflector were very helpful and provided a lot of info and encouragement. So I went on, my way.

Rather than implement a linear modulator that would also allow for AM voice (as suggested), I kept my original idea of simply squaring the audio drive and feed it to the LED. Sidebands are not an issue on a optical channel, where you're very likely to be alone.

For testing I recorded three 60" messages, two in RTTY (standard HAM baudot) and one in FeldHell. These were copied to an mp3 pen and played individually in an endless loop.

I built a squarer transmitter chain as follows:

• AFSK (or whatever) source, mp3 pen or computer soundcard
  
• LM386 amplifier at max gain
• NPN switch to drive LED
  

The receiver is general purpose. RTTY got through easily once TX and RX were aimed at eachother, in a dark room (except for laptop TFT backlight) at 1m distance. For FeldHell I needed to lower the software squelch level, but then...


... words started flowing on the screen.
At the end of the second row ("the binary install" words) I tried aiming the receiver somewhere else, simulating path attenuation: the text is still visible and in extreme situations can be reconstructed by the human brain processor.
I had very strong AC hum on the receiver side, that visualizes as slanted upgoing lines, but do not interfere too much with FeldHell.

Thinking of on-the-field experiments, RTTY would provide a constantly lit LED easier for aiming, while FeldHell blinks it causing more interest in occasional onlookers.

FT817 keypad - serial communication quirks

Wondering where the FT817 keypad has gone? Don't worry, I'm working on it every night. All the one-way features have been implemented and tested: direct frequency dial, mode change, VFO toggle and frequency presets. These controls only require to send data to the radio.

What was left instead requires to read two bytes from the radio, modify one or two bits and return them back.

While the software side has been implemented correctly, I didn't seem to be able to read bytes, thus writing back wrong settings to the FT817(ND). Many hours have been spent in visualizing on 8 LEDs (one byte) what was being received, processed and sent.

The most probable cause is to be found in the ATtiny2313 internal RC clock source. I did look for its beat at 8 MHz, but all I could hear was some wideband noise. Even at 4800 baud the tiny2313 is probably too off to read proper data.

I am completing a pre-production prototype with an external XTAL source. It will run at 14.7456 MHz, that gives a 0% error rate according to the uC datasheet. Theoretically it will be possible to increase the serial communication rate up to 38400 baud (FT817 maximum), but perhaps overall reliability would suffer.

If I manage to master these advanced controls, all sorts of customizations will be possible, from key-function remapping to new/different controls. A UK HAM has already asked me to have 60m presets on the keypad. The only limit is the chip program memory: 2kbytes.

FT817 keypad - circuit diagram

Now that the keypad firmware has reached a usable state, here is the schematic diagram I am about to implement.



The development version ran on the internal clock set at 1 MHz, but it was inaccurate enough that serial communication was not possible at 9600 bps. Since reproducibility of this project is a must, I prefer to distribute a code that relies on an external, more accurate, clock source.

Keypad lines are labeled according to the top-most or left-most key of the column/row. You will need to check the pin layout of your keypad in a datasheet or with an ohmmeter (pressing keys until you map the 8 pins). On mine were exactly in the required order C1 to R* from left to right (looking at the keypad as if you were using it).

LED current flows into the chip, and don't forget to connect the resistor to the +5V line.

Pins on the ACC socket (MiniDIN 8 pins) are labeled as shown on the FT-817 manual.

That's all. If you are equipped to program an ATtiny2313 and need the firmware, just drop me a line. If you want a programmed and tested controller chip, do not hesitate to contact me either! mycall at yahoo.com ("mycall" is the first part of this blog URL, also written on the blog name...). If you need a customized keypad firmware with different key mappings or presets, I'm here to help.

FT817 keypad for serious QRP /P contesting

In August 2008, after a productive VHF contest outside at 2700 masl (8800 feet asl), I felt the need to add an external keypad to my FT817 so that some controls would be readily accessible.

After a few months of software and hardware development I am announcing an alpha version of my keypad!

It is based on Atmel's ATtiny2313 microcontroller, uses very few components and does almost everything I wanted it to. Functions have been tailored to what I needed most last August, and the current release does the following:

• direct frequency dial
• mode change
• VFO toggle

To be tested (tonight):

• Presets QSYs to QRP frequencies (16 of them)
  

Still being studied:

• Output power control
• VOX on/off control
• Meter mode control
  

but I am afraid these last will not fit into the 2313 program memory. So a modular approach might be suggested: functions are loaded as needed by the operator depending on the activity type (contesting, SOTA, ragchewing, ...).

Given the 4x4 keypad layout of the top table (see below), key functions are depicted below per each function.

Frequencies are entered with leading zero-padding to 100's of MHz: 007030 for 7030 kHz, 014060 for 14060 kHz, 0035C for 3500 kHz, 028# for 28 MHz, etc etc.
Mode switching is a star "*" followed by another key (see the Modes mapping).
Frequency presets are accessed with pound sign "#" followed by another key (see the Presets mapping).
VFO toggle is a single key press, as well as should be other functions under development (power, vox and meter).

Keypad Layout
1	2	3	A
4	5	6	B
7	8	9	C
*	0	#	D
Main Menu
1	2	3	VFO Toggle
4	5	6	PWR cycle
7	8	9	VOX toggle
to Mode	0	to Presets	Meter mode
Frequency dial
1	2	3	end
4	5	6	end
7	8	9	end
end	0	end	end
Usage:
014060 = 14060 kHz		144305 = 144305 kHz
014# = 14000 kHz		007C = 7000 kHz
Modes
CW	CW	CW	CW
AM	FM	CWR	CW
USB	LSB	CW	CW
CW	CW	CW	CW
Presets
1843 CW	3560 CW	7030 CW	10116 CW
14060 CW	18096 CW	21060 CW	28060 CW
14285 USB	50090 CW	21285 USB	28500 USB
144300 USB	50150 USB	432200 USB	29500 FM

A LED blinks at each keypress. The current consumption is about 10mA and the device can be powered directly from the ACC socket (where the commands are sent).

This keypad is not meant for a home-based station, where some excellent computer programs can do this and a lot more. It is an operator's aid when having fun on the field.

The same code might work with other Yaesu transceivers, like the FT857.

Interested?

The LED, as seen from 250m

I left the LED TX at my parent's, waited for the night to come, then asked them to fire it up and beam it towards me. Currently the TX draws 36mA. This is the view from the farthest window:

And zooming in... the LED signal is there:

The picture was taken with a 2MP cameraphone without any optical zoom. At the naked eye (not fully adjusted to darkness) the beam was a bright red spot. With a tripod it could be possible to keep the maximum intensity in the right direction. Distance: approx 250 metres.

I couldn't try a reception test because the RX circuit is being boxed and adapted for a telescope mount. Fortunately I've met an enthusiastic amateur astronomer that now wants to become famous by breaking the world optical record. Simone might even learn morse code :-)

Meanwhile I'm slowly building a second TX-RX pair, with the TX capable of sending FSK for an RTTY test.

Attiny2313: listen and repeat

It took about two hours, three evenings and twenty re-programmings to get it working. Though, it probably worked even the first time, since the problem was not in the code.

Once I had verified the 4x4 keypad was read correctly and mapped the Getkbd codes, my target was to send the FT817 a "VFO Toggle" command.

With one Printbin combination I could only get the radio to tune 10'101,01 kHz, while it was supposed to change VFO.

As a last resort I reduced the communication speed from 9600 to 4800 baud (on both the chip and the radio!) and it magically started working. I could also program a static VFO retune command. Cool.

Since the code was not changed I can only assume the internal clock is either not suitable for (fast) serial communications or it is way off the declared/programmed value.

My ATtiny2313 said "Hello World" !

Yes! Yes! Yes! What was I doing wrong?

I could initially program a HEX file into the chip, but that code was downloaded from Internet and probably meant for the older AT90S2313. I had rewritten and recompiled the same code with BASCOM-AVR for the ATtiny2313 but somehow I couldn't get the program into the chip: everything completed correctly, I could change fuse settings, but the CODE memory wasn't updated.

So I tried a -e (erase chip) round with avreal32. Reading the uC content resulted in a lot of F's: the chip was blank.

Then I wrote the code back and ... magic! The LED flashed. Remember: the ATtiny2313 (probably) comes pre-programmed to use the internal 8 MHz clock divided down by 8 to 1 MHz, so you don't need any external component.

This is the BASCOM-AVR code. Don't forget to play with GUI settings to set the proper chip.


Config Portb = Output 'set port B as output

Do ' eternal loop
Portb.0 = 1 ' make portB.0 high
Waitms 500 ' wait 500ms
Portb.0 = 0 ' make Portb.0 Low
Waitms 500 'wait 500ms
Loop

Press F7 to compile. Take the .hex file and feed it to avreal32 (see previous post for the command line string).

The circuit? PortB.0 is pin 12 on ATtiny2313. Wire as follows:

• pin 20 to +5V
• pin 10 to ground
• pin 12 to a LED cathode
• LED anode to 270 ohm resistor (or 220, or 330 or 100+100+100 ohm, you got the pointt)
• the other resistor terminal to +5V
  

Ready for the smoke test? :-)

My first Atmel program

I have been able to program an ATtiny2313 with a very simple setup:

• 1 DB25, 3 resistors and one 20-pin socket
• avreal32 Win software
• computer with a parallel port ("LPT")
  

Even the laptop was able to drive the programmer. Although the female lab personnel (AKA wife) said the programmer doesn't look trustworthy, it did the job.

I can both read and write the uC. The "reading" ability is a huge improvement from my serial PIC16F84 write-only programmer, since I can write the chip and then verify what was written on it. This is how I know the chip was programmed with my code.

The commands for my LPT1 and my programmer:
READ: avreal32 +TINY2313 -ap -p1(0x378) -o0 -r a.hex
WRITE: avreal32 +TINY2313 -ap -p1(0x378) -o0 -w -c b.hex

Reading the chip displays:

v1.26rev0 (Aug 7 2008 17:52:48) http://www.ln.ua/~real/avreal
bug-reports, suggestions and so on mail to [censored]
Command: +TINY2313 -ap -p1(0x378) -o0 -r aaa.hex
Power ON
Device connected, TINY2313 detected
Chip not locked
Fuses
OSCCALs = 68 6A
CKDIV = 0
CKOUT = 1
SUT = 2
CKSEL = 4
DWEN = 1
EESAVE = 1
WDTON = 1
BODLEVEL = 7
RSTDISBL = 1
SELFPRGEN = 1
Reading CODE memory
.... done
Reset pin released
Power OFF

Fuse values are displayed in decimal, while the datasheet lists their meaning bitwise.

Unfortunately the success was only partial, since the uC didn't seem to produce any activity out of the programmed code.

Optical system going NLOS

Thanks to the interest of a colleague in my optical experiments, I sped up the work on my MCW light receiver.

Using a 10mm red LED at ca. 30mA and the OPT201 without any lens or post-amplification I could make some spectrograms with Spectrum Laboratory.


First of all I studied the environment: the incandescent bulb produced a clear set of harmonics every 50 Hz, with those at n*100 Hz being stronger ("1"). Then the 520 Hz line is definately the laptop TFT dimmed backlight ("4"), since at full brightness the signal disappears. Notice the result of a mixing between 488 Hz MCW signal and the strongest 100 Hz harmonic ("2"): this certainly occurs at electrical levels, not optical.

Next was a ca. 4.5m LOS test, with the LED light overloading the sensor. Even the cameraphone could see it:


I used my CW memory keyer to send a meaningful message (pre-recorded holiday CQ) at the lowest possible speed, about QRSS0.5 (0.5 seconds per dot).

In total darkness except the laptop screen, the spectrogram looked like this:

A quick test at 15 WPM revealed a perfectly readable signal. The shade effect of a hand obstructing the light beam is surprisingly strong. A wav recording is available, if anybody wants to hear it.

Then I moved the TX further away in another room, for a total of 11.5 metres Non Line Of Sight (NLOS). Only after my eye had adjusted to darkness I could see some weak red reflections on objects in the intermediate room, but the spectrogram was faster:


There it is! My QRSS CQ was on the screen, fortunately not masked by the laptop backlight. Remember the receiver had no focusing lens whatsoever.

I forgot to measure the response of OPT201 with a 3.3 Mohm series feedback resistor. Next test could be 300m LOS still without lens on the receiving side.

Stay tuned! Or better.... watch out! :-)

NiMH constant current charger

I started working on this circuit long ago, and never used it thoroughly.

Given that NiMH cells can be slow-charged at a constant current rate for a given amount of time, I built this circuit. Provided the timed slow-charge condition is verified, you can live without end-of-charge algorithms.

Some charging facts (if I remembered where I read this, I'd credit the author).
A NiMH cell, if charged at C/10, in 10 hours will reach approx. 66% of the fully charged state. You achieve the remaining 33% with 5 more hours. That's where the magic 15 hours come from.

My constant current circuit required a PNP transistor. I picked a BD646 from the junk box in a TO220 package. Since the transistor had to be floating from ground, I needed a way to attach it to the metallic enclosure for thermal dissipation without electrical contact.
Forgot about nylon screws, a search through the electronic junk showed this solution: wrap the transistor in what I believe to be a mica foil and then press it against the heatsink/box.

This is how it looks like:




I recharged a 9.6V pack while watching the temperature and the current. The transistor runs barely warm, while the power resistor heats up considerably.

The pack under charge will increase its voltage, thus effectively reducing the charge current, in a auto-stop fashion. But since this occurred quite early in my charge cycle, I had to increase the input voltage to more than 14V.

One word of caution about the plugging sequence.

Charge start: connect the power supply and then the battery pack
Charge end: disconnect the battery pack and then the power supply

Otherwise the pack will discharge into the power supply. Probably a 1N400x diode on the +Vcc line blocks the process and allows to use a timed AC socket.

The Amateur's Code

I'm copying and pasting this text here for future personal reference. A Good Reading anyway!

The Radio Amateur is

CONSIDERATE...never knowingly operates in such a way as to lessen the pleasure of others.

LOYAL...offers loyalty, encouragement and support to other amateurs, local clubs, and the American Radio Relay League, through which Amateur Radio in the United States is represented nationally and internationally.

PROGRESSIVE...with knowledge abreast of science, a well-built and efficient station and operation above reproach.

FRIENDLY...slow and patient operating when requested; friendly advice and counsel to the beginner; kindly assistance, cooperation and consideration for the interests of others. These are the hallmarks of the amateur spirit.

BALANCED...radio is an avocation, never interfering with duties owed to family, job, school or community.

PATRIOTIC...station and skill always ready for service to country and community.

--The original Amateur's Code was written by Paul M. Segal, W9EEA, in 1928.


[...meanwhile in the lab a constant current NiMH battery pack charger has been completed and tested...]

18 km per liter = 42 miles per gallon

I've read on CNN.com a long article about hypermilers. I've read on WIRED (April 2008) about a fake company that promised electric cars and, to go with them, a Smart Fortwo that scored an eco-friendly 37 mpg (15.7 km/l).

Yesterday I filled the tank on my FIAT Seicento (1100cc unleaded fuel engine) with 31,61 liters. I had driven 575km (357 mi), on highway, countryside (80%) and suburban, with an average 70 km/h (44 mph) speed limit. With some easy math it turns out to be 18,19 km/l (42.78 mpg). Cool!

My urban average is between 14 and 15 km/l (33-35 mpg) driving 20-25 km per day.

Field Day Logging and the Dupe Sheet (on paper)

If you've browsed through my past posts, you probably know I like to do outdoor VHF contesting. Since I usually carry my station on my shoulders (from battery to antenna), there's no way I would take a laptop with me. Therefore all the logging is done on paper, using a homemade logbook.

I have produced and published two PDFs with either A4 or A5 size pages (scroll down my website to HAM Travel section), the latter being much more convenient when there is no chair and table at the operating position.

Each page obviously stores a limited number of contacts so soon the list of worked stations gets out of sight. In the old days without real-time computer logging, how did contesters avoid duplicated QSOs? Here's a tip I have not seen mentioned in the last years: use a dupe sheet!

What is it? The dupe sheet is a separate page where you copy all worked callsigns, sorted by the first suffix letter, after each QSO. If you turn page on the main log, the dupe sheet will stay under your nose for a quick lookup. During the post-contest log typing, the dupe sheet provides a callsign cross-check to minimize bad/quick handwriting errors.

The dupe sheet from my Alpe Adria VHF 2008 Contest.

From the picture you may also spot another field day tip: you need a sure-write mean of writing. Something that works below 0C/32F and upside down (as well as in absence of gravity). While a scalpel or a chisel might do, they're not fast enough for contest logging. A pencil does the job. I also carry a felt-tip marker (OK for low temperatures).

Open project of keypad for FT-817?

I posted this request on the GQRP reflector.

I am looking for an external keypad to match my FT-817 that can be built at home. Has it ever been published on SPRAT?

I've seen a couple of commercial products whose cost is equivalent to setting up my own development station, since I can master both software and hardware programming.

Yesterday I operated 6 hours /P in the Alpe Adria VHF contest and noticed that I'd like to have direct access to, in descending order:
- VFO A/B control
- Power setting
- Direct frequency dial
- Metering control (Pwr, Mod, Alc, Swr)
- VOX on/off
- Operating Mode (but this control has dedicated buttons anyway)

If there is no known open (= free circuit diagram and microprocessor code) design, I will develop my own external keypad and share it.

I received no feedback, so either everyone is on holidays or the world doesn't need an(other) FT817 external keypad.


Update 2008-11-24: the IK1ZYW keypad is now real! See newer blog posts or its homepage.

My QSL for 9A/IK1ZYW, Summer 2008

I had a little more than 50 QSOs from Rab, nevertheless I wanted to design a nice QSL front.



This originates from a digital picture I shot, some work on the computer and printed at the photo shop around the corner. I printed it in 10x13cm format, and will cut the excess bottom band to fall within QSL bureau 9x14cm limits.

The bottom band also carried an experiment: how small can the text be to stay readable (with magnifying glass, if needed)?

Using a pro service for printing is both cheaper (30 eurocents/pic in small quantities) and guarantees a longer lasting product than home printing.

I will honor all QSL requests for my contacts from 9A of July 2008. I am not sending out first.

Some radio-activity from Rab, IOTA EU-136, IOCA CI-096

2008/June/29 to 2008/July/12: 9A/IK1ZYW on Rab Island, Croatia. References IOTA EU-136 and IOCA CI-096.

Equipment:

• 12V 7AH SLA battery
• FT-817 at 5W
  
• homebrew CW paddle and memory keyer
• homebrew switched L tuner
• 12m vertical wire radiator + counterpoises
• pencil on block notes for logging
  

Being on a family holiday rather than a DX-pedition, time and energies for radio were limited. HAMming time was confined at night, after 23 local time, or during afternoon baby naps, when the operator didn't prefer to take a nap as well...

One HAM-dream finally came true: operating from the sea shore. The 24th OQRP Contest and the visit of XYL's friend allowed me for a little outdoor activity in the bushes of Gozinka cove.



Even though a couple of contests were around, 20m and 40m bands were quite dead for a Saturday afternoon. Was the propagation on holidays too?! I didn't feel any salty-water effect/improvement!

I continued the OQRP contest from the apartment terrace, close to downtown Rab. The antenna was ca. 12m of wire held vertical with a 9m fiberglass fishing pole and one counterpoise of ca 8m tied to the metallic terrace fence. With a switched L tuner I could get a proper match from 80 to 10m.


In the OQRP Contest I worked 38 stations in 15 DXCC entities. I worked everyone I could hear, but did not look for non-contest stations to increase the QSO count.

Overall I had more than 50 QSOs in two weeks. Every time I could be on the air I did manage at least a QSO. 30m was the most prolific band during non-contest periods.

A big thank to all the operators I worked, both in and out the contest. I will reply to all QSLs received with a photographic card I'm assembling with the pictures I took on the island.

72!

4m contest: been there, done what?

Last Sunday I managed to take part for a couple of hours in the "70 MHz and Cross-Band Contest 2008" promoted by ARI Roma. I was in a nice place, open towards most of the Italian territory with no band noise and managed just one (local) contact.

Setup was as follows:

• RX IC706MKiiG
• TX homebrew CW 100milliW
• Antenna 4m Moxon
• Antenna 6m car whip

from the parking lot of Santuario di Belmonte, JN35TI at about 700 masl.

Activity was null, even if the band was open with sporadic-E to Greece. I could easily work Adriano I1NAI in 4m cross-mode. At 9UTC I was disappointed nobody was around, the parking lot was going to be filled with a FIAT 500 event (QRM!!), so I headed back home.

Adriano stayed a bit longer on the air, but he did not manage other QSO's either! Were all Italian operators busy with the HF Contest delle Sezioni? Are Italian ops not interested in a new band?

I could produce three short movies with the Samsung SGH-i780 :
http://www.youtube.com/watch?v=HF4A7X7ZtW0 (location summary)
http://www.youtube.com/watch?v=K13WVOsIc14 (receiving SV5FOUR/B)
http://www.youtube.com/watch?v=owjugPODRhg (receiving IZ1DYE/B)

Even if I had had more power I would have not had more contacts, but a small 1-2W PA will follow on the workbench.

Has anybody the QSL info for SV5FOUR/B?

70 MHz activity alert!

Segnalo la mia possibile attività domenica 15 giugno 2008 mattina, in occasione del "70 MHz & cross-band Contest" promosso dalla sezione ARI di Roma. In caso di bel tempo dovrei essere in JN35TI con i miei 100mW e la due elementi Moxon (piu' dipolo in 6m). In caso di maltempo, da casa JN35TC, sul balcone. Per sked o altre info scrivetemi!
!! Per ora posso trasmettere solo in CW; RX all-mode !!

On 15/June/2008 morning I will most probably take part in the "70 MHz & cross-band Contest" organized by ARI Roma. If the weather is good I will be in JN35TI with my 100mW and 2 element Moxon (plus a dipole for 6m). In case of bad weather I will stay at home in JN35TC. Write me for a sked or other info!
!! I can transmit CW only; RX all-mode !!

Primo QSO in 4 metri

Il primo QSO o qualcosa del genere, ieri sera 05/06/2008 a 70304 kHz alle 20UTC circa, cross-mode CW/SSB.

Avevo modificato la configurazione del keyer in IAMBIC-A, e non riuscivo a mandare correttamente i simboli (ah, il buon vecchio tasto verticale!).

Povero IZ1DYE con tutta la confusione che ho fatto! Abbiamo concluso il QSO al telefono, ma i segnali erano presenti.

QRB: 32km. Moxon contro dipolo, 100mW contro qualche decina di W, CW contro SSB.

Qualcun altro vuole tentare il QSO? Anche cross-band. Io trasmetto solo in CW, ma ricevo all-mode in 50 e in 70 (e in 144, 430, HF). Sono penalizzato in direzione 110-140 gradi, a meno di andare di riflessione sulle Alpi. Vi aspetto numerosi!

Grazie Michele!

PS: perche' mi sta passando la voglia di imbarcarmi nella costruzione di un finale RF piu' potente?!

Primo rapporto in 4 metri

Giusto il tempo di programmare il keyer, avvisare Adriano NAI ed ecco il primo rapporto di ascolto del mio trasmettitore in 4 metri. A 35km il segnale e' ottimo.

A causa della pioggia improvvisa alle 22 e' invece saltato il tentativo con DYE.

Promette bene. Ed ho anche in testa l'idea di realizzare un amplificatore per avere un paio di W...

Have you worked/heard IK1ZYW/M?

Have you heard or worked me on June 04, 2008 between 1515 and 1600 UTC on 6m?

Unfortunately the battery of my voice logging system was dead, so I lost the information on the 4 contacts I had. They where 3 HA and 1 SQ9.

I probably recovered the SQ9 call from the cluster, but it lists too many HA's to be sure I picked the right one.

If you can help rebuild my log for that day, please contact me at mycall at yahoo dot com.

Small Wonder Labs SW-30+ - tuning

Time to do the smoke test to my SW30+!

First I powered it up without ICs. At 12V it took 3.45mA. No short circuits, looks good.
I checked the 8V line on each IC socket, and it was there.

Switched it off, added all ICs,switched on. Current went up to 15.4mA, that should also be the SW30+ receive current, perhaps a bit more with an antenna and earphones connected.

Time to tune the VFO. Instead of keying the transmitter into a dummy load, I chose a different way: the local oscillator has to be 7.68 MHz below the 10 MHz band. With some easy math, the LO runs around 2.420-2.450 MHz, that's where I tuned the primary receiver. My VFO was quite high, I had to add C7=100pF and squeeze turns on the VFO coil to obtain a 2.426-2.46 MHz range.

This means ca. 10.106 to 10.140 MHz.

Every time I've tuned 30m here in Italy I've found a strong RTTY station on 10.100 MHz, so better stay away from the lower band limit. This 34 kHz coverage puts me also away from the DX window. Anyway, coil adjustment will allow me to change my mind without soldering.

Next step, once the 4m TX system is finished, will be to tune the transmitter.

70 MHz, and the antenna is up!

Italian HAMs got a new authorization to use small portions of 70 MHz until 31/12/2008. The TX was already completed, now I needed the antenna I never finished.

The Moxon rectangle was chosen. A wooden "H" structure supports the wire. Lowest SWR is around 65 MHz, 2:1 at 70 MHz. On the balcony it looked like this:


Here it is beaming about 30deg. The tower is the background, for the locals, is at CSELT/TiLAB/whateveritiscallednow.

Six meters mobile does work ...

... when propagation helps!

That's the case of yesterday 27/5/2008 with a super ES opening when I could work HA3UU (JN96), 9A3GI (JN95), HA807PL (JN97), YT1VP (JN94) between 1630 and 1700UTC.

I could also hear SV and I7 stations. All those I could hear were working DL and G as well: there were several ES clouds.

This morning I greeted IW1FZV and IZ1ERV in a local QSO, since the band was closed.

The mobile shack - inside.

The mobile shack - outside

PS: all these mobile contacts were done in SSB with 5W.

Operating QRP mobile on 6m

The 2008 sporadic-E Spring season has started, so did I with home>office and office>home 6m QRP mobile activities.

The first attempt was on Friday, May 23 between 1500 and 1545 UTC, on the way back home throughout the banlieue of Torino.

The setup consists of:

• FT817, 5W, SSB
  
• homebrew earphone-microphone adapter
• modified CB antenna to 6m

On 6m a 1m long antenna has a minimal loss compared to a full 1/4lambda vertical. A urban environment does not help, though! The adapter includes up/down tuning buttons, as in the original 817 microphone, and a switch to use an external voice keyer for automatic CQ.

I checked the DX cluster before getting in the car, and there were no spots to/from my area, but the band was open indeed: always try a scan through the (beacon) band before giving up!

A few observations.

• Even last year I had noticed that calling CQ when QRP mobile is not a successful way to achieve some contacts. Search&pounce has proven to be more effective with my setup when the band is open and stations are calling CQ.

• VOX operation is cool, but noise in the car can turn into pain (open windows, horn, ...): better add a flip PTT switch, so your hands are free except when you have to change TX/RX. Moreover I suffer from some kind of VOX apnea...
  

• Paper logging the contact is awfully dangerous especially in the city traffic if you are both the driver and the operator. I do prefer to record the audio with an MP3 player/recorder and then fill in the log, but this requires the audio to be broadcasted in the cabin, so VOX disabled.
  

This June/July 2008 look for me on 6m between 545z and 630z and after 1530z!

Magmount base, cable attenuation

Once I've seen the lossy look of the RG58 coax cable, I did a quick loss measurement with the MFJ-259:

MHz	dB
10	0.6
50	0.8
145	1.4

Given a cable length of 5 meters (I think), this is not the best performing RG58 ever.

Magmount base, one more fix

New problem on the new magmount base: the PL-259 connector.

Moving the coax cable right at the plug sent SWR from 1:1 to infinite. This is a sign either of a short or a broken connection.

Heated the soldering iron and found out two things:

1. it was a short caused by erroneous (criminal?) coax preparation
   
2. the crimp-on section for the coax braid was loose and I could pull the coax out with no effort

I re-peeled the coax and replaced the PL-259. Now it works.

Morale: if you care about your finals, check the plug assembling quality on your new magmount base!

Now I wonder how bulky the pseudo RG58 coax is! Will do some measurements soon.

The SW30+ is here!

23/04 to 02/05: 9 days including a weekend, a national holiday and a stop by the customs. That is how long it took the small packet to come.

I had to pay extra 13 EURO as import duties and postal service theftcosts.

The PCB is really compact. I could fit 4 SW RTXes into the one I had chosen, or all accessories: battery, antenna, key, log.

Building will begin shortly.

First mod will be a better polarity reversal protection, in place of the 1N4001 D13 diode. I will instead use a fuse and a surge-suppressor diode.

Additions to my SW30+

This is a brainstorming reminder, so that I won't forget to add useful modules to my SW30+, when it arrives.

• improved polarity reversal protection (bypass D13)
  
• keyer, using SKC and an additional 78L05
• integrated LED frequency counter (with on/off switch)
  
• integrated LED SWR bridge
  
• integrated antenna tuner (z-match or L-network?)
• output power pot
• vernier reduction tuning pot
  
• trail-friendly box

So, on the front/top panel there will be:

• tuning pot
• RF gain control
• keyer button
• SWR LED
• counter's LED and switch
• power switch

And on the back panel:

• antenna BNC connector
  
• power plug

Location TBD:

• key, probably on the LHS
  
• headphones, probably on the RHS

I keep on dreaming...

Small Wonder Labs SW-30+ - shipped!

According to the "shipping status" page, it started its journey on 23rd April, 2008.

Keeping my fingers crossed...

A (great?) weightsaver for SOTA excursions

I am test driving an SGH-i780 smartphone that weights about 120 grams. It has:

• mobile phone
• internet surfing abilities
  
• embedded GPS
• photocamera 2Mpx
  
• videocamera 320x240
  

The operating system allows running all sorts of applications, including HAM related ones.

In 120g you have at least two devices you would probably carry along: the photocamera (say 150g for ultracompact year 2008 models) and the GPS receiver (that's 100g for my Geko201). You might or might not want to film your activation, that accounts for 400g or more. A light mobile phone is around 90g. Some crazy SOTAers have carried laptops with them, that is at least 1kg... Let's try a comparative table:

Tool	Weight (g)	Weight gain (g)	Cost (EURO)	Saving (EURO)
Mobile phone	90	Assuming i780	30	Assuming i780
GPS	90	with second	130	Costs 400 EURO
Camera	150	battery is 160g.	100
Videocamera	400		160
TOTAL w/o laptop	730	570	420	20
Laptop	1000		300
TOTAL	1730	1570	720	320

As of mid April 2008, this smartphone seems to be both a weight and a cost saver for technologically sick SOTA activators.

Drawbacks found so far:

• it has a non-standard connector for audio in/out, so it cannot be easily used for digital modes with PocketDigi
• the battery does not last very long, and Samsung sells the device with a second battery
  

Let's see how it performs next Sunday if WX allows for an excursion.

VCR Power Supply

While the shack is still a "work in progress", I disassembled a working (electrically) Philips VR301 3-head VCR. It still was a 98% through-hole device, and it shows A LOT of molded inductors.


The power supply caught my attention. It is in a shielded box, relatively compact and has many unmarked output wires. It might work as a bench lab supply, so I checked unloaded voltages.

On one line it has:

• +5.35V
• +13.7V
• -22V
  

On the second line:

• +5.25V
• +10.7V
• +24V
  

I had hoped for a dual +/-5V or +/-9V, but I got instead a nice +24V for driving a varicap diode.

I wonder how much current each line can source. That's for the next experiment. One day...

The shack is building up

New home, new shack!
Here's how it looked like on April 7th, when the laminated flooring was almost complete.

Small Wonder Labs SW-30+

Riding the favorable EUR-USD exchange rate I decided to order a Small Wonder Labs SW-30+ monoband CW RTX. It will come in a couple of months or more, just the time I need for re-arranging the shack-lab after moving!

LED ERP vs. current

While searching for optical RX-TX systems that would carry voice, I stumbled across an article of the only Italian HAM (AFAIK) that has documented optical experiments, I4VIL. He mentions that LED efficiency at some point decreases even if the current flow increases (in Italian).

I managed to replicate his observations using my MCW TX and the simple OPT301 RX, just the detector without the active bandpass filter. I monitored the received signal strength by feeding the detector output to my laptop MIC input. Spectran software did the measurements. The TX was aimed at the ceiling, as well as the OPT301, without any lens.

I monitored the total circuit input current, not the one flowing into the LED. The MCW TX draws about 6 mA @12V in stand-by, so you can figure out how much current really flows into the LED. But at 100mA average when transmitting, 6mA are negligible.


The Y-axis shows dB reading on Spectran for the 488 Hz line, relative to the first dot (17 mA); the X-axis is the total current flowing into the circuit.

It is obvious that the emitted light reaches the maximum power somewhere between 80 and 100 mA. Going further just heats the diode.

Delta ERP is +17 dB. That would be almost 3 S-points in RF terms.

Interesting, isn't it?

HP iPAQ h5450 dead/flat battery

So, you forgot to recharge your iPAQ h5400 PPC handheld for a week and it doesn't power up anymore? Not even if you leave it plugged to the external supply for days?

Might be too late, or not.

First of all, if you read this before your battery has flatten out, go to the HP website ("software and drivers"), download and install firmware upgrades if you've never done it. There is a fix for the flat battery that doesn't get recharged.

If your h5450 has already passed away without upgrades, you need to find another h5450 (h5400 series), do the patching and then recharge your battery on it. Most probably in less than 24h you'll have your h5450 working again.

If you have a h5500 series handheld (h5550 for example), HP has not released the battery charging patch, while it seems to be affected as well (real world experience). Since h5400 and h5500 batteries are the same, let a patched h5400 recharge your battery and you'll be back on track.

Important: always do these chargings with direct connection to the external power supply. Do not use the USB charging feature.

Good luck.

MCW optical TX - first test

Finally, more than a year after the idea of an optical RX-TX system was born, I have been able to send (pseudo)information through modulated light.

Instead of a laser pointer I used a 10mm clear-case hi-bri bulk red LED driven at 10mA average. The 488Hz modulation is obtained from a 4.00 MHz XTAL divided by 8192 with a 4060 CMOS chip, keying is achieved with the reset function of the chip as of this diagram:


The RX was the prototype of the future optical RX on experimenter's board, with an OPT202 sensor, without any post-amplification. Circuit per datasheet, single supply operation. Output fed directly into laptop MIC input. At first attempts I did not modify OPT202 feedback resistor, but then a 3M3 was added in series and the signal output increased while total bandwidth was reduced. No amplification lens was used.

The test was conducted in a lighted/dark room with the receiver next to the laptop screen with retroillumination. The TX was aimed at the ceiling and Spectran software in QRSS3 mode produced the following output:


I could not broadcast the received audio in the room.
I will soon try building bounce using two adjacent windows.
I did not reduce LED drive to test RX sensitivity.
I will try to overdrive the LED to get the max power out (destructive test).
I might then add an external LED drive control.

The overall distance was about 6 metres: TX to ceiling + ceiling to RX. Not a DX record, but a good starting point!