Thursday, November 15, 2018

Maker Space

Wow,  I see that I haven't posted anything for a long time again ... been busy with my job duties. Maybe a little lazy at times.

Some of our microwave activities are captured on the BARS blog site.

However, I have recently discovered a place just around the corner from my house (closer than the closest pub) where I can do most of the mechanical work on my projects. Even some of the electrical. Here is more info about the place.

I am getting trained in using all the metal working equipment (lathe, mill, CNC machines ...). There are many Ham Radio related projects that depend on access to these things. I will try to catch up in publishing and show some of the results here.

In the mean time, you can go to the link posted above and read some details. You can also find a list of other maker spaces there ... maybe you will be as lucky as I was and find a similar place in your backyard?

73 Herbert

Friday, May 19, 2017

Finally Some Radio-Activity!

I have finally returned from a set of business trips. My job currently seems to be slowing down, looks like I will finally have some time for my ham radio hobby.

I have installed my 23cm looper antenna (still on temporary pole, but operational). Hope to set up more antennas before the ARRL VHF contest next month!

We have already attempted to test this antenna with KO0Z (full report here). 

73 Herbert

Sunday, March 12, 2017

Bi-State Amateur Radio Society

New group of HAMs, calling themselves "BARS" (Bi-State Amateur Radio Society), has been founded in the Missouri - Illinois area. You can find some basic info on their blog site.

The BARS have a simple mission - to enjoy our hobby. BARS will support new technologies, such as microwave and optical communications, digital television, even digital modes and packet radio on all frequencies incl. HF, with emphasis on microwaves.


Thursday, December 29, 2016


Hope you scatter joy and happiness wherever you go all 365 days of the upcoming year and get the same in return. Happy New Year to you!

Sunday, July 31, 2016

Boys with Toys 2

My last posting was about using my RIGOL Spectrum Analyzer with frequency range up to 1.5GHz to show characteristic of a 10GHz filter. That little test made me wonder if I can use the same Spectrum Analyzer to display a signal in the 10GHz range on that analyzer. Obviously, I have to mix the signal down below 1.5GHz using a transposing signal from another synthesizer.

I have used my 24GHz transverter with 11.88GHz local oscillator, because that signal is conveniently fed to a connector on the transverter's front panel. The same mixer from my previous test (IF range only 0-150MHz) was used for the first test today:

Yes! It really works! My ELCOM on the left side is programmed to 10.805GHz (+13dBm) and the gray transverter on the right side delivers 11.88GHz (+10 dBm). Difference of these two signals is exactly 1.075GHz which is what we see on the analyzer. What we also see is the signal level below -40dBm. Hmm ...

I have tried to "zoom in" and changed the RBW ratio on my RIGOL from 1MHz to 300kHz. Signal still looks nice and clean, just not too strong:

Can we do something about the attenuation? Of course we can. I tried 3 things:
  • Find better flexible cables
  • Replace flexible cables by Semirigids
  • Use different mixer
Luckily, I have bought good sized bundle of these flexible black cables with SMA connectors cheap on eBay. Maybe I could find some better pieces in that bundle? Tried and ... the signal strength improved +30dB:

Wow! This is almost perfect! Maybe Semirigids will make it even better:

Hmmm, not too much. Only about 2dB. Surprising, really. These black cables are RG-178 which is OK but not as good as semirigid, at least in theory. Whatever ... let's try another mixer:

Nice! Improvement about 8dB! This mixer has IF range 0-2GHz, but it has apparently been exposed to salty water somewhere. I have bought it cheap on eBay. Lets try better one:

No surprise here, less than 2dB below zero. This mixer behaves as expected. Note that I am feeding it LO signal 11.88GHz about +10dBm and the test signal is 10.8GHz about +13dBm. My RIGOL has internal attenuator of 10dB, so the conversion loss in this case is 13 - (10-2) = about 5dB. That is certainly very acceptable!

My next test will be with a Harmonic Mixer (same thing, but the mixer will generate harmonics from a strong base signal to be able to display higher frequencies, such as 24GHz). But that will be the topic for some other day.

73 Herbert

Wednesday, July 13, 2016

Boys with Toys

Even at my age of 55, I still feel like a boy when it comes to my electronic (not to mention radio electronic) toys. Especially if my friends keep encouraging me by sending me links to interesting articles on the Internet. Like the document (tnx OK1DXD) where I found following picture:

Nice ... especially after finding dual mixer (two mixers with integrated LO power divider) on eBay:

The seller stated max frequency 18GHz and max IF frequency 150MHz. Well, I overstepped the IF maximum almost 10x and the mixer still worked, so I hope that RF inputs will accept 24GHz.

Now, what to test? Easy pick. I have found a nice waveguide filter on 10567.5MHz:

So, I have located couple of cables, not really suited for 10GHz but at least with SMA connectors, and connected everything together:

Where to get LO signal from? That was easy too - my favorite ELCOM synthesizer provided +13dBm on the frequency of 11GHz:

So far so good ... but will that thing work? I have turned my RIGOL analyzer on and activated the Tracking Generator - and YES, it worked:

Let's try to zoom in to check how steep the filter is:

Pretty good, actually. The passband is flat and only ~40MHz wide. Looks like good filter for general use. With this mixer, I should be able to re-tune it to 10368MHz easily.

Of course, I need to calibrate the "Y" axis. No idea how much attenuation came from the mixer itself. Some definitely was introduced from the measuring cables ... still work to do on my side. I will also try to use the same principle (different Local Oscillator and maybe different mixer) for 24GHz.

73 Herbert