23 December 2011

So, your expensive piece of technology had a bath?

Picture by Patrick Hoesly.
It happens. Sometimes technology packed expensive electronic equipment (decide to) get in touch with liquid substances. As many online sources will tell, hope is not lost the very moment the two incompatible objects get in touch. I will not reveal any new method, just what I have done.

Let us consider the case of a smartphone (Galaxy S) being dipped in clean drinkable water.

First of all: read the picture on the right.

As soon as the bath is over take the device apart (battery, main body, back cover, memory card, SIM card) and dry it wth towel/napkin. Don't shake it, but turn it around to get the water out of holes such as the earphone and USB sockets. Then let it dry for at least 48 hours. Be patient: you aim to recover your data from the device, don't you? This should be your first target. If your device works afterwards then it is luck or well designed technology. Or a combination of both.
I dried mine in a bowl filled with (uncooked!) rice close to a heat radiator. Temperature should have peaked to more than 40°C, but heat is not a must: leave it longer.

When you are ready plug the battery and keep your fingers crossed. If the device powers up be prepared to extract your data using the standard method.

Additional notes.
Some online resources mention water-sensitive labels all around these expensive mobile devices. I haven't been able to spot them on the external body of the i9000. Anyway do not lie to the customer service if you are going to return it.
If your device allows to use an external memory card, it is probably wise to save your mobile-authored data on it, or take periodic backups. It is more unlikely that a self-contained hole-less memory card becomes damaged with water (anyway let it equally dry).

19 December 2011

UV-3R data cable (homemade)

I had ordered an USB-to-UART TTL adapter to debug the rotary encoder on the Frequency Reader. While it was on the way to my lab, I solved the encoder problem, so the adapter had to be tested somehow.

Around the shack I had found a cable terminated in a 4-way 3.5mm jack, probably from an old digital camera. That is the connector of UV-3R data cable (and external ear/microphone too), so I gave it a chance. Steps were:
  • identify which cable goes to which connector ring
  • draw a map of pin matches between the cable and the adapter
  • test the whole thing (as shown in the picture)
My ugly UV-3R data cable (not for permanent use)
At first there was no communication with the radio. Then I swapped RXD and TXD connections: UV-3R software downloaded radio parameters. Cool. Note that the UV-3R says nothing on the display about the data cable being inserted or ongoing computer communication. If data is uploaded to the radio it will automatically power cycle.

The adapter is based on the CP2102 chip and costs 3 USD (2.3 EUR) shipped from Hong Kong. Both WinXP and Vista 64bit recognized the device (XP grabbed the driver from an online source).

The same adapter can be used to build a data cable for the FT817, or other transceivers that expose a serial port with TTL logic levels instead of RS-232 voltages (ICOMs, ...).

18 December 2011

New frequency formatting for I.F.R.

My development board with the new display
... and new display too.

On the I.F.R. firmware I have modified the way the frequency is displayed when there is no transverter connected or configured. Information on the first line is right aligned, "Hz" symbol expanded and decimal separator dot added to make the frequency value look nicer.

On the picture you can also see a new display I received: orange on black. For operations in a dark environment it is less bright than the white on blue LCD. Last but not least it matches 817's amber display color (not too closely, I know).

05 December 2011

TX-only transverter for 4m - with mixer

The picture shows my TX-only transverter with the diode ring mixer (SBL-1 or ADE-1) component added. The circuit has not grown a lot, but it does indeed work.

The canned oscillator is now terminated in a 1kohm trimmer and feeds the IF port of the mixer. RF from the HF transmitter goes to the LO port. Trimmers will most probably be replaced with fixed resistors.

As a signal generator I used the FT-817 at 24.9 MHz. Listening on a panoramic receiver I could clearly hear LO-HF (20 MHz) and LO+HF (69.8 MHz). The frequency counter on the mixer output picked up the LO-HF difference, which was expected since there is no bandpass filtering afterwards.

I tried swapping HF and LO signals but the result was the same. Signal output decreases if the HF trimmer reduces the mixer drive.

Next step is to build a resonating termination followed by an amplifying buffer. G3XBM circuit calls for a BF199, which is already sitting on the workbench, committed to take part into this project.

01 December 2011

TX-only transverter for 4m

While I have no news about a possible 4m allocation for Italy in the next months, I have started working on my TX-only transverter - a "txverter"? - for HF-to-70 MHz.

The idea behind this project is that the IC706MKiiG receives on 4m, so there is no need for a full transverter, provided the operator accepts to operate split. It is a KISSAL principle: Keep It Short Simple And Lazy :-)

I decided to replicate G3XBM's simple transverter, TX chain only. I will build it manhattan/dead-bug style using an ADE-1 passive DBM mixer.

The picture shows first components placed on the copper clad board:
  • 5V voltage regulator
  • canned oscillator @44.900 MHz
  • HF input attenuator of about 30dB (50, 680, 100 ohms)
Current drain at 12V is about 18mA, all for the voltage regulator and the canned oscillator.

The output of the latter is not a sine wave on a 100 MHz scope&probe, but it swings 0-5V if left floating.

I plan to blog how the circuit grows and how it performs.