AM EXPERIMENTAL BOARD

I had to build something while I don't have everything set around so decided to buy a small kit and build an AM receiver. The kit looked well built and affordable, using a classic design approach, eg somewhere in the 70's with two 455Khz IF and a diode detector.

So, 2 weeks after paypal payment it arrived at the front door (it come from Malaysia, but I think there's resellers in Europe).

The the built process took about an hour done in small bits, I first tested the audio amplifier part and then proceeded without further "delays". Didn't worked (got any station) at first time because I had no power supply (still don't) and was running it from a Nokia mobile phone charger which infected a lot of noise in the power line. Now I'm running it from a 9v battery and a LM7806.
I works, sensitivity is, well, low, but enough for during the nigth get one or 2 stations from Europe.
I might try to add an extra coil, parallel to the coil in the ferrite and connect an long wire aerial for reception improvement.

Here's the marketing photo:
 
What you see is what you get in the kit.

Mine when arrived:

 I bough from the same seller two small 300pF variable capacitors... their allways handie...

...as always in my assemblies the box is something for "one of these days"...

Have a nice week!

North Cork Radio Rally

I'm getting international in therms of radio rallies, after the Moscavide (PT ARVM) one, Leiria (PT ARLA) and Friedrichshafen (DE), now I went to Cork (IR NCRG).

 ...next is Dayton?
 
It was easy to find the spot since I had already explored a little bit of that area in town, arrived at 11H00, the starting time of the event, and everything was already set. Weather was the classical Irish for this time of the year; you guessed, rain in the morning and then some sun.... and then a little more rain, but was mild rain.
There were the usual sellers and the normal boxes full of odds and ends.

Got home this:

 I never learn....why did I asked the price of the rack airband receiver?...oh well, if it works I will probably leave it like this, if it doesn't I got a really nice quality box and a bunch of components.


I met Ed, EI2HEB who is one of the organizers of the event and we ha a little chat. From what I understood there was another foreign visitor from the Netherlands, so, that made this one a truly international event.

Unfortunately I did not took pictures because run out of memory on the phone and could not delete existing images.


Overall was a nice morning and I got some more stuff to play.

Have a nice week!

New method for PCB making...

...At least for me.

I normally don't do much PCB, using the standard method or standard methods, but this time since there was a need to solder an SMD amplifier device it seemed that could be a good idea to do so. Just because I'm out of my normal shack I started to look for alternatives for the normal Iron perchlorate liquid and came up with a new product to dissolve the cooper. The method is explained elsewhere in the net by it's creator.

 Basically it's 50% of Hidrogen Peroxide (oxygenated water sold in pharmacies used as an disinfectant for small cuts on skin,, at least I used wen I was a kid) and 50% of vinegar with some salt to taste! Without the salt it would not work and you must be adding some so the process continues.

Here's the board before being cuted. The device to solder (PGA103+) is near the 1n5711 diode, big hum?

Had to buy an hacksaw for the job:


And now the mix, from time to time the board must be shaken and some salt added.

 The rest of the cooper part was protected with clear tape.

The final result:

 Does it pays of? No, except if you are in an island and really need to make a pcb....
and if you want to know I used normal white wine vinegar. Took me around 45 minutes from start to finish.
Now I still have to solder!

Have a lot of fun!

Restart

 After almost two month after arriving to this Island (Ireland) I decided it's time to restart my soldering activities.
Since I didn't had space to bring my shack with me, when I flew in, I opted to bring just a small container of hard to find components, what I didn't knew is that all electronic component are hard to find here.
After some search I found only one company selling electronics around and for getting things worst is one that nowadays is more focused in ready made stuff, oh well..., they still sell you a resistor, if its on their catalog....but you will pay premium price! I will never complain again on the prices back home!

Anyhow, after the initial shock I managed to buy some stuff need, other will have to be sourced in the Internet and back home.

here's my shack "equipment" so far:

Top row was bough yesterday, a soldering "station", cheap and according to a fellow ham, durable. Got also a spare sponge since the one in the kit is very small. Two pcb's for rapid prototyping and one for more definitive setup, also sourced a cheap knife on a pound shop for making traces on the pcb and to remove insulation from wires.
 Bottom row: On the left, the box of components that come with me on the plane and on the right two minicircuits rf amp in static protection on top of the letter that bring them. An ofter from a nice fellow ham living on the north side of  the island East of this one. By the way, there's no island to West, just a big pond...

I still need a multimeter, probably I'll ask for shipping me from home one of mine's since I have too many multimeter's, well I have too many soldering irons also but they are almost all junk...

Now the idea is to start building a new receiver, first the audio amplifier and rf preamp and then all the circuits in the middle! Easy!

Stay tuned and have a nice week!

EI/CT2GQV

Well, after 2 weeks in Ireland i'm starting to think if it's not better to ask for a local ham license.
For now it's not of much of a use since I still don't have a soldering iron to build a radio and the "Speaky" was to big to bring with me.

While I don't share some solder work here's some images from Cork and Ballincollig (were I am).

As the Irish say: Thanks a million!

New adventure

A new adventure...

Flight went well, sleep almost all of it and was wake up by the cabin voice stating the approach...

Now have to find a soldering iron but still on limited bandwidth to update the blog.

Have fun!

End block for a spectrum analyzer add on.

Is it preferable to have an spectrum analyzer for ocasional rf work or a nice scope and then make a spectrum analyzer add on module?

Well for me, and for now I'm going the path of the spectrum analyzer module add on, since a stand alone spectrum analyzer is far more expensive than any of my radios....you get the point. Some past experiments on a similar module were already made some blog posts ago

 by using the RSI from a AM detector chip, now I'm using another approach with the AD8307 logarithmic amplifier.

On to the schematic:

It's basicaly a "Bitx" 10 Mhz filter terminated in 50 Ohm (I hope, not measured yet)
connected to an AD8307 with about 45 Ohm input (from Analog datasheet)

On the right of the schematic there's an option for a common 10.7 Mhz filter from Murata (did not test this option).

Here's some signal "injection" for a preliminary test:


With the output from the "signal generator" (dip meter) 1 Mhz from the filter center frequency:

Without signal:
 
 And at filter ressonance:


The AD8307 is the SOIC version and after all was not that hard to solder, I removed some cooper from the board and lay'd there the IC, then soldered some wires to the necessary pins:


Will continue this experiments as soon as possible....that may take some time...

Until then, solder what you can... and have a nice week!