Saturday, June 29, 2013


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!

Wednesday, June 19, 2013

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!

Sunday, June 16, 2013

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 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!

Thursday, June 13, 2013

20m band module

20m band module:

Done, but the switching (pin) diodes are standard rectifier 1n4007, it works and for now enough.
I tried to replaced the original schematic varicaps by BB909 type I bought in bulk nice, although specs are a little different in terms of ratio, but not capacity.
The paint job on this BB909 is not their best feature and after scraping the paint a little bit I can see a diode similar to 1n914 and 4148. I suspect it's some re-branding by the manufacturer which is specialized in hard to find components.

30m band is in prep, oscillator crystal already in place but I suspect will take some time to finish this one....

The Speaky with 5 band modules (2 unfinished):

Also finished the antenna tuner with coil connections for the present "Speaky" bands: 40, 20 and 17m. It also tunes 80m if needed on my piece of wire antenna (something that resembles an dipole :).

Have a nice weekend!

Tuesday, June 04, 2013

In the mail

Arrived this:

For another generic power meter. This time I bought in SOIC form instead of standard DIP, it's a fourth of the price.

Meanwhile changed the the VFO coil on the 20m band module, still need to replace the 18.118 MHz crystal for the 18 Mhz one so I can use the lower part of the band. Now starts here:

Stay tuned!