MIni-project #2: 23cm etc on the IC910.

 The second mini-project of the year is almost complete.

Two things had to happen with the IC-910: 

1) The original reference oscillator needed to be replaced with a high-stability oscillator. This was necessary, because temperature drift cannot keep the IC910 on frequency, especially when operating at high power levels.

I got the new oscillator mounted on the PLL board, and then the adjustment started. Initially I adjusted the output signal while transmitting low power FM on 70cm. Yes using lots of attenuation. I was using my microwave capable spectrum analyzer with a 10MHz GPSDO as reference. The trimmer in the oscillator was a bit fiddly to work with, but I got the initial 70cm frequency adjusted within 150Hz of the set frequency. After some warm up it looked a bit better.

Time to mount the shield for the PLL and the 23cm module. This is a rather easy add-on.

Set the main band to 23cm and test on 1296.000MHz. The frequency was less than 250Hz, and after warm-up it was within about 150Hz.

Now the radio is re-assembled with all the covers, and tomorrow I will make another test of frequencies with the radio fully assembled, and after a good warm-up period.

I do not expect any significant change, but I do need to check, so I know the offset.

Small Update on Solar Power.

My modest system has not had a lot of juice in the deep of winter.

Right now the only radio connected to solar is the IC705, and it is running a few hours every day.

While the days are clearly getting longer here at this time of the year it is still very short days with the sun very low over the horizon. On top of that we have had a lot of cloudy time.

If the day is clouded right now, with the panels available the system is just generating a tiny bit less than the IC705 uses. With full sunshine, and we had a bit of it today, I can run the IC705 for many hours a day. The battery voltage, as I use the radio, keeps the voltage of the LiFePo4 battery at around 12.8 - 13.3V. I consider that acceptable. 

This year I will need to mount more panels when the weather permits, and also get a bigger battery up and running.

With this setup I should be able to run full station activity for about 8 months of the year - except for high power amplifiers. The remaining part of the year I estimate that I will still have to run parts of the activities on mains power. 

One more thing: Before next winter I should make a "backup plan", so I can charge batteries when the price of mains power is lowest. This may be semi-manual, or I may find a way to automate the process using data downloaded from the internet.

Then there is the use of low power monitoring receivers. Yes, I need to build some of them, and we shall see how much I will build before next winter. There are still possibilities with some older receivers that I can put into service for parts of this. I do not have to build everything.

Higher and Higher. Solar Flux.

The solar flux rose again, this time to 228 SFI. This is almost as high as the highest SFI of the previous cycle. That happened on January 7th, 2014, and it reached 237 SFI.

It looks like the trend is still upwards for this cycle, so will we see a higher peak than in cycle 24?

I like to think so, but we shall see.

Solar Flux.

 The sun keeps on giving.

Today's SFI (21cm solar flux) is 212. I think this is the first time in this cycle the SFI has been above 200.

With a few more days of this high flux I would not be surprised to see 6m opening with F2 propagation.

Exciting times!

Mini Project #1.

Before the NanoVNAs became widely available it was tricky to find low cost test equipment for testing SWR or return loss in the low GHz range. 

At the time I did find one possibility: The transverter-store in Ukraine sold some low cost impedance bridge PCBs, so I got myself one.

The PCB bridge circuitry looks like this:

Looking at a Youtube video I found that the PCB has a fault. The bridge has 2 50Ohm resistances, made up by two 50Ohm resistors that should be connected in parallel. On the PCB he tested, and on mine, this is not the case. No connection between 2x two islands on one side of each pair.

Now, this is not difficult to correct. A short piece of wire  mounted at the junctions between the resistor pairs solve this.

A quick test using my NanoVNA 2 showed a shortcoming of the NanoVNA output level (too low), but also gave an indication of the functioning of the bridge.

With a 6dB attenuator as the DUT (Device Under Test) the return loss showed close to 12dB, as it should.

Testing a 10dB attenuator the same way showed that the return loss went down into the noise of the NanoVNA. Close enough to 20dB, so I accept the reading as correct, and that the bridge is working properly.

That is the end of mini project #1 of this year.

Will I use this bridge a lot? Not really, but I did want it to be in working order. It is now going into the test PCB pile as a working unit.

The NanoVNAs that came out after this are much easier yo use, and much more versatile. The cost is not prohibitive, so in the lab I will be using a NanoVNA F (I think is the designation) for frequencies up to 1GHz, and a NanoVNA v2 for up to 4GHz.

The Sun Is at it Again. X2 Flare.

 Some "new" (actually old, but recurring) sunspot groups just rotated into view of Earth.

3 days ago one of them fired a flare of magnitude X1, and minutes ago the sun fired again. This time X2 - well strictly speaking X1.98, but I made the rounding-up. This is bound to create a sudden Ionospheric Disturbance (short wave fade-out) on the day side of Earth, and it will likely las a little less than an hour.

Also the 21cm solar flux is at 184 today. If this continues for several days more I suspect that there is a good possibility of F2 openings on 6m. 

I will be aware and monitor the situation.

Mini Projects for This Year.

I have an idea for an addition to the challenge/wish list for 2023.

In my shack, and in the lab there are a ton of small projects that will improve the ability to make larger projects. 

This could be an extremely simple repair or modification of some existing equipment or a PCB module.

The intention is to make a small blog entry for each of mini projects.

There should be one mini project per month as an average, so 12 of them this year.

Why?

Sometimes I get the impression that I do not doo anything, even when I do. So this is to show me that I do, in actual fact do some stuff, even if not as much as I want to do.

This is, of course in addition to doing a few larger projects.

Last year's large project was making a minimum of 365 QSOs with 5W output, so I suspect this year I will make fewer QSOs, as I have some practical building projects I want to get done.

Let us see how that goes.