According to the "shipping status" page, it started its journey on 23rd April, 2008.
Keeping my fingers crossed...
28 April 2008
16 April 2008
A (great?) weightsaver for SOTA excursions
I am test driving an SGH-i780 smartphone that weights about 120 grams. It has:
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:
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:
- mobile phone
- internet surfing abilities
- embedded GPS
- photocamera 2Mpx
- videocamera 320x240
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
14 April 2008
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:
I wonder how much current each line can source. That's for the next experiment. One day...
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
- +5.25V
- +10.7V
- +24V
I wonder how much current each line can source. That's for the next experiment. One day...
09 April 2008
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.
Here's how it looked like on April 7th, when the laminated flooring was almost complete.
05 March 2008
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!
21 January 2008
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?
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?
18 January 2008
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.
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.
07 January 2008
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!
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!
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