I may have mentioned it before, but I intend to use this blog, not just for telling you about ideas etc, but also for me to be able to find old ideas I have had.
Looked through 10GHz websites. Found a teardown of the HB100 Doppler radar module. It turns out that, apart from the expected DRO (oscillator) is a passive balanced diode mixer, much like seen in older LNBs. It looks like a simple modification of the HB100 module - removing the DRO (or maybe just the power for it) - and entering another LO signal, the mixer could be used the other way, too, i.e. a TX mixer.
The modification should involve adding a few SMA connectors (two for RF/LO and another one (maybe SMA, too) for the IF port, and likely cutting a PCB line from the original oscillator.
The idea could be tested by using the module as it is, just entering a low frequency (IF) drive signal and see what comes out on the RX port.
The HB100 module is an interesting device, even for modification or salvaging the very few microwave components it has, the price of the module off eBay is less than $5.
2019-04-29
Microwave Day in Horsens, Denmark.
In the past week end I went to the Microwave Day in Horsens, Denmark, a one-day event of talk and testing of microwave gear.
I did not bring any gear myself, as I decided rather late to go there, and I am just beginning doing something in the microwaves, mostly due to the QO-100 satellite.
About 30 people attended, and most were experienced microwavers, so I took the opportunity to draw a bit on their experience, and see if I could get some new ideas.
There was test equipment to measure small feed horn antennas for dish antennas, and the possibility of measuring power and noise figure on microwave bands up to 10 GHz.
If they repeat this event (next year?) I may have some equipment to have tested.
In the afternoon some groups went out to nearby hills and tested their equipment in the field.
It was good to get to meetings like this, meeting other people who have already made the first (or many more) steps in the field.
Time to start getting some stuff, more than the simple modified satellite LNB for QO-100. I will need some for the home, and some for portable use, going to nearby (or not so nearby) hills ... and the small simple equipment for local tests.
Aditionally there was a show of a - not too expensive - GPSDO which has been used at the oldest, still running VHF/UHF/microwave beacon, OZ7IGY. It can be programmed from very low frequencies, up to 200MHz, and the price is half of what I have seen for comparable devices.
I did not bring any gear myself, as I decided rather late to go there, and I am just beginning doing something in the microwaves, mostly due to the QO-100 satellite.
About 30 people attended, and most were experienced microwavers, so I took the opportunity to draw a bit on their experience, and see if I could get some new ideas.
There was test equipment to measure small feed horn antennas for dish antennas, and the possibility of measuring power and noise figure on microwave bands up to 10 GHz.
If they repeat this event (next year?) I may have some equipment to have tested.
In the afternoon some groups went out to nearby hills and tested their equipment in the field.
It was good to get to meetings like this, meeting other people who have already made the first (or many more) steps in the field.
Time to start getting some stuff, more than the simple modified satellite LNB for QO-100. I will need some for the home, and some for portable use, going to nearby (or not so nearby) hills ... and the small simple equipment for local tests.
Aditionally there was a show of a - not too expensive - GPSDO which has been used at the oldest, still running VHF/UHF/microwave beacon, OZ7IGY. It can be programmed from very low frequencies, up to 200MHz, and the price is half of what I have seen for comparable devices.
2019-04-25
The Last Ingredient Necessary for a 2.4GHz Transverter Has Arrived.
Today I received some Polyimide tape from China. This should make it possible to lower the resonant frequency of Microstrip and Stripline filters, applying the tape to the resonators.
This should increase the dielectric constant of the surroundings of the resonator strips, thereby lowering the velocity factor , effectively electrically lengthening the resonators.
I have seen this tape used in a TV satellite LNB for lowering the band pass filter frequency. My question is how much loss, (i.e. lower Q) this adds to the filter.
I was promised some PTFE (Teflon) tape from a friend (I suspect with lower losses), but we have not yet had time to get it to me. He has some stuff that I can measure, so he wants to come here, and bring the tape.
The coming week end will be quite busy, but after that I should be able to test the tape for losses, and frequency change of the filters I already have.
This should increase the dielectric constant of the surroundings of the resonator strips, thereby lowering the velocity factor , effectively electrically lengthening the resonators.
I have seen this tape used in a TV satellite LNB for lowering the band pass filter frequency. My question is how much loss, (i.e. lower Q) this adds to the filter.
I was promised some PTFE (Teflon) tape from a friend (I suspect with lower losses), but we have not yet had time to get it to me. He has some stuff that I can measure, so he wants to come here, and bring the tape.
The coming week end will be quite busy, but after that I should be able to test the tape for losses, and frequency change of the filters I already have.
The Beginning of the "Summer" Sporadic E Season.
10m and 6m have been buzzing with European activity today, and some yesterday, too.
Also, I saw someone reporting Es on 4m.
The season has started.
This does not, of course, mean that we will have Es every day for the next monts, but it is a nice beginning.
My 10m map for the last 24 hours show (I think) Es-linked F2 propagation to South america and probably to the Middle East. At least 2 stations from the Arabian peninsula were reported here. Hundreds of reports from European stations and places like EA8, etc.
I am now changing my FT8 listening frequencies to 10m and up. Right now it will be 10m, 6m and 2m, even if I only expect tropo signals on 2m the next few weeks.
Busy times ahead, this time with operation on VHF bands and up, plus, of course, my favourite HF band: 10m.
Also, I saw someone reporting Es on 4m.
The season has started.
This does not, of course, mean that we will have Es every day for the next monts, but it is a nice beginning.
My 10m map for the last 24 hours show (I think) Es-linked F2 propagation to South america and probably to the Middle East. At least 2 stations from the Arabian peninsula were reported here. Hundreds of reports from European stations and places like EA8, etc.
I am now changing my FT8 listening frequencies to 10m and up. Right now it will be 10m, 6m and 2m, even if I only expect tropo signals on 2m the next few weeks.
Busy times ahead, this time with operation on VHF bands and up, plus, of course, my favourite HF band: 10m.
2019-04-22
Idea Box: Simple Microwave Transverters.
For transmission to the QO 100 satellite OZ2OE proposes a simple transverter 144 (or 432)MHz to 2400MHz using cheap Chinese amplifier, synthesizer and mixer modules.
I will most probably do it mostly this way, although, while I lack a sufficiently good filter I might ise the RF amplifier/filter part of a MMDS converter as a filter/amplifier, removing the power (and maybe the components from the LO/Mixer part.
Having transmitter capability for 2400MHz, I think that a receive possibility should be added, too. either by using a modified MMDS converter (I still need to change the filter frequency of that one) or some more Chinese modules.
Lately I saw a Croatian microwave website proposing a "poor man's 5.7GHz transverter", also using the cheap Chinese modules. After getting on the satellite, getting fully on 2.4HGZ and 10GHz, I may look into that.
It looks like I will have to learn the mechanical skill of making pipe cap filters before I proceed much further.
I will most probably do it mostly this way, although, while I lack a sufficiently good filter I might ise the RF amplifier/filter part of a MMDS converter as a filter/amplifier, removing the power (and maybe the components from the LO/Mixer part.
Having transmitter capability for 2400MHz, I think that a receive possibility should be added, too. either by using a modified MMDS converter (I still need to change the filter frequency of that one) or some more Chinese modules.
Lately I saw a Croatian microwave website proposing a "poor man's 5.7GHz transverter", also using the cheap Chinese modules. After getting on the satellite, getting fully on 2.4HGZ and 10GHz, I may look into that.
It looks like I will have to learn the mechanical skill of making pipe cap filters before I proceed much further.
2019-04-07
Idea Box: Second Experiment
The most local beacon for me is OZ7IGY, about 30km away.
Now I am curious how little effort it takes to receive it.
The idea is starting to use a PLL LNB without a dish, just the built-in feed horn.
Because the beacon is beyond line-of-sight, the propagation will be tropospheric scatter, so the signals may be too weak to hear, but the experiment should be done. Next step would be a 15-20dBi horn antenna, then a small dish, 30cm or so.
It would be fun, however, if the beacon is audible with just the LNB, even if it is not constantly audible. This may be an opportunity to try the PI4 mode for beacon detection.
Now I am curious how little effort it takes to receive it.
The idea is starting to use a PLL LNB without a dish, just the built-in feed horn.
Because the beacon is beyond line-of-sight, the propagation will be tropospheric scatter, so the signals may be too weak to hear, but the experiment should be done. Next step would be a 15-20dBi horn antenna, then a small dish, 30cm or so.
It would be fun, however, if the beacon is audible with just the LNB, even if it is not constantly audible. This may be an opportunity to try the PI4 mode for beacon detection.
2019-04-06
IC-703 Modification.
For the first time in almost 2 years I have been traveling (more than about 100km from my home) for a bit less than 2 weeks, and I am back now. This was a non-radio-related round trip From my home near Copenhagen through Northern Germany, The Netherlands and Belgium, then to Paris. On the way back via Köln (Cologne). Last year I spent getting rid of a colon cancer, and I am now free of it, just going to control visits every few months.
Today I modified my old IC-703 for receive output/input. Will likely use that TRX for 10m with aux RXs for 10/11/12m propagation monitoring, using the TRX with the 10m PA running about 200 - 250W CW or about 150W FT8. Should work nicely.
Why do a modification like that ?
Well I wanted to be able to add some kind of spectrum/waterfall display, and possibly use the same antenna with several monitor receivers, e.g. beacon watch, FT8 watch etc.
Today I modified my old IC-703 for receive output/input. Will likely use that TRX for 10m with aux RXs for 10/11/12m propagation monitoring, using the TRX with the 10m PA running about 200 - 250W CW or about 150W FT8. Should work nicely.
Why do a modification like that ?
Well I wanted to be able to add some kind of spectrum/waterfall display, and possibly use the same antenna with several monitor receivers, e.g. beacon watch, FT8 watch etc.
I was using a kit purchased for doing the trick on a IC-7300, but decided to try it with this one first.
The mod took a bit of filing off the outward side of the new adapter and filing a bit of the bottom cover, and removing the connector for the external ATU control. The external control is not necessary as long as the built-in tuner works (or is not needed at all).
It now fits nicely into the casing.
System check of the RX shows that it is working nicely in through-mode.
It is likely that the modulation circuit will need an equalizer, because the reports on the modulation are not good enough. Initially, I will check the adjustment of BFO and SSB filters.
Second use for this low power TRX could be driving a transverter to 4m, including RX output for AUX RXs, such as spectrum waterfall.
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