2019-11-08

Solar Cycle 25 Is Slowly Coming to Life.

According to an article at Space Weather ( https://www.spaceweather.com ) a few sunspots have appeared since May this year, all deemed to belong to the new cycle. These spots come interspersed with sunspots from the old cycle, a well known phenomenon during a sunspot minimum.

Now, the minimum is expect to last about another year, then we should see more sunspots going towards a maximum. The article says that it is estimated to me 2023, but I consider that a bit optimistic. I think 2024 is more likely, since low activity sunspot cycles tend to last longer, i.e. the build up to the maximum is slower.

Never the less, I am looking forward to more solar activity, so the higher HF bands will awaken from their deep sleep. Mind you, even in the deep sleep of this minimum, 10m is not completely dead. It does not happen daily, but there are sporadic openings from my place in Denmark, mostly to the Southern part of Africa and occasionally South America, in the autumn/winter/spring-time, and, of course, occasional sporadic E all year around, with a large peak in the summer and a smaller one in the winter.

Here is to be a bit (quite a bit) optimistic and hope for DX F2 openings on 6m. I know it is not likely, but let us see what happens.

2019-11-04

Idea: How To Get Stackable Antenna Masts Up and Down.

For a while I have been using stackable (up to 1.5m long) pipes for some of my antennas.

Getting those up and down has been a bit of a pain, needing at least 2 people to get the antennas erected.
I think that I now have an idea for reducing the man power needed:

When lowering antennas (e.g. verticals) for maintenance 2 people will be ideal, but a system with a pulley might work for one person, at leat in calm weather:

- Clamp a 3-4m long support pipe parallel with the mast
- Elevate the mast enough and fasten to the pipe
- Now the lowest of the stack can be removed and the mast be lowered further
- repeat as needed for maintenance
- fix the mast to the support pipe

For elevating the antenna again, use the reverse order.

As I see it, it works a bit like when using a telescopic mast. Not quite but close enough, and maybe  with a bit more work. The main point for me is that the will be no need for a big(ish) team for antenna work.

Right now I cannot see any serious weakness in the idea. If you see one, please tell me in the comment section.

2019-10-30

Microwave Updates, Part 1: QO 100 "Transverter" Project.

I have been traveling  several times lately, and other activities have been taking some of the time I could have used for radio activities. This includes a crashed main computer, the one that I used for my radio shack.
This made me do a bit of reorganization. At the moment my shack is run with a Raspberry Pi 4B.
It is slightly under-powered, but will have to do until I get the harddisk in the old machine changed (quite some disassembly necessary).

Now for some radio news:

I have been collecting a large amount of components and modules for my projects, and I think that I am now more or less ready to do some assembly, and where necessary, modifications. The plan and design may change, if necessary. Following some projects in more detail than before.

Project #1: QO 100 "transverter" - more like an indoor unit with TX converter and interrface sircuit for the outdoor LNB:

Circuitry planned:
Common circuits:
a) Local oscillator module for the TX mixer, and possible oscillator for further RX down conversion:
- AD4351 PCB module, controlled by a small Arduino board.
- Two buffer stages, capable of delivering 1968MHz for transmission, converting 432MHz up to 2400MHz, and 595MHz for converting the RX 1st IF (739MHz) down to 144MHz.

b) Circuit for switching to 2.4GHz transmitter mode, including PTT signal for the outdoor PA unit.

c) 25MHz reference frequency generation:
- 25MHz TCXO
- Switch for possible connection to external GPSDO
- Buffers
- possibly output for external devices using 25MHz as reference frequency

2.4GHzTX system:
b) TX mixer/driver stages, module, indoor unit:
- Passive DBM mixer PCB,
-  SP5189 PCB
- 2400MHz filter PCB
- SP5189 PCB
- second 2400MHz filter PCB
... if necessary for the stability of the amplifier chain,  attenuators can be added between amplifiers and filters, and/or some microwave foam can be added to the inside of the lid for the shielded box.

c) RF2126 module PCB w/heat sink, about 12dB gain, max 1W out. A shielded box may be needed for this.
I will be happy with 300-500mW out of the indoor part, an additional driver (if necessary) and PA should be mounted in a box near the dish feed.

d) Outdoor unit:
- RF2126 module for eliminating cable loss at 2.4GHz
- WiFi "8W" booster module (8 "Chinese Watts" equals 2 - 3W output in real terms), possibly modified for non- antenna output switching.

10GHz RX system:
At the moment a modified PLL LNB with a simple indoor 25MHz reference canned XO is used. The indoor unit and an outdoor system unit are planned:
a) In my indoor unit:
- 25MHz system, see above
- LNB connection with triplexer for DC, LNB IF out, and 25MHz reference to the LNB
- extra IF outputs for the LNB IF output(s)
- Outdoor system with 25MHz reference signal extraction and distribution to the LNB and possible other units, like transverters or other converters.

Construction:
Stage 1:
A main housing has been found, and a fair amount of mechanical work (not my favourite sort of work ;) ) is necessary, mostly drilling holes for connectors in the main housing and in shielded boxes (with shield walls) inside the housing need to be prepared for mounting (internal) connectors and module PCBs.
Further, space for the mechanical work has to be made, some of the tools are present, but a bit more is needed. I will get there

Here is to hoping that it will look,at least, decent when I am finished ;) .

Progress reports and updates with a few pictures will follow.

More projects to follow.






2019-07-11

Building My Own Website.

I do have an extremely simple page on https://qsl.net/oz9qv/
This may grow a bit, but I have just got the domain where the main (detailed) parts should be.
It should also host the contents of this blog.
When it becomes active, it will be at http://oz9qv.dk When I find out how to set it up it will be at
https://oz9qv.dk https://oz9qv.dk

It will take time to get everything in there, but I should get there along the way.

Next: some project planning. and getting all components/modules and tools ready for starting construction.

2019-07-09

10GHz Horn Antennas and Update on the LNB RX Experiment.

I have a number of horn antennas.
I am well aware that horn antennas of these sizes for 10GHz are a compromise. Small size is used, sacrificing gain, as compared to dish antennas.
Today I found a horn antenna calculator , so I can see what I should expect of the different sizes.
The calculations are like this:

- The largest horn (145x115mm): 20dBi (WR75 WG)
- Two slightly smaller horns (120x115mm) 19dBi (WR75 WG)
- Two metallised plastic horns purchased new: 17dBi (WR90 WG). Same as specified by manufacturer
- a tiny horn with a (Gunn or detector?) diode in an integrated waveguide/horn : 10dBi

I should be able to find more horn antennas when I get access to the rest of the storage - if I have brought them home when I moved, that is.
The three larger horns were painted when I got them, so I hope the paint is not too lossy.
For the 3 larger horn antennas I need to make a coax to WR75 transition. The 2 standard 17dBi horns need WR90. It should be possible to use the WG transition from some ancient single polarization LNBs I have, or, in the first instance, maybe use the preamplifier in the LNB as a 10GHz preamplifier. Still, a modification is needed, and the noise figure is expected to be about 1.5dB. Not as good as it could be, but still in the acceptable range.

It looks like I may have to create a 10GHz antenna "test range" in my garden, so I can check the gain figures (efficiency of the antennas and coax-WG transitions). It is a good thing that I now have a set of 17dBi reference horn antennas, so I can get some relatively reliable gain indications. I know, a test field is not ideal in a garden, due to reflections etc, but it is better than nothing. Yes, coax to WG transitions needed there, too.
Initially I expect to use a HB100 as the signal generator, and test, if I can find log detector covering 10GHz. I am trying to make it simple. It may be possible to use an old (low gain) LNB for converting 10GHz and use log detector for a lower frequency. More tests to do.

Finally, a small update of the LNB receive experiment:
I looked up today to see that the direction of the horn is about 60deg. off the heading to the local beacon. Impressive that I still get a signal at 36km.
The beacon is essentially always audible, now and then with some short dips into the noise.

2019-07-06

A Bit of Work to Get a Workshop Up and Running.

The last few days I have worked a bit more in my "out-house" (40 sqm), to get a better organized space. The plan is getting to one section for storage with a small desk, one section with mechanical tools, and a section for other activities.

It is slow work, because there is a lot of stuff to move around, but right now I have done the beginning of the storage space, not yet with the desk space. A lot of stuff has been discarded, and more will come.

There is a fair bit of good quality tools that I inherited from my father when he passed and I took over the house, but it has been out of use for a while. Some of it probably needs maintenance. I will get there eventually.

Right now the corner section with shelves (and space for the desktop plate) is partly done. Some old stuff needs to be moved, so that more of the shelf space can be made ready and orderly. Next should be the workshop getting ready. A slow process, but it is progressing, along with all the other projects.

6m JA "Heard" - and a bit of rain scatter on 10GHz.

I got up late this morning and I could see on the PSK Reporter that I had received several JA stations on 50MHz this morning (50.313). The best signal was about -10dB, so quite good. I might have been able to work that station.
On top of this, I had received a few South Korean stations.
Interesting propagation at the bottom of the solar cycle. Who knows if the same propagation is seen at solar maximum. I am not sure.

In the afternoon some showers passed across the island of Zealand (Sjælland), and two beacon signals were audible. In addition to OZ9GHZ that I seem to hear at all times, OZ7IGY came through with the characteristic rain scatter sound.