Posts by pe1chl

I had contact with an Aliexpress supplier where I ordered another special type LNB (DRO type with 9GHz LO) and asked if they would be interested in producing a smallish number of special PLL LNB with lower default LO and capability for external reference.

They appear to be interested in that.

As a first proposal I sent the following characteristics:

- PLL type

- receive frequency 10.489-10.500 GHz

- LO frequency 9.244 GHz or 10.049.88 GHz (same ratio as 9.75/10.6) (IF 439 MHz or 1245 MHz)

- optional locking to external frequency reference (sent via the cable) of LO/390 or LO/424.

- 20mm round waveguide with dielectric lens

and provided them with some links to info about QO-100.

Maybe people have other things to add to that?

It would be a little worrying when there is a link to the FleetSatCom pirates...

Before opening of the transponder I was already worried that those pirates might come over to our new satellite.

In fact the army has put a secondary payload on a recently launched spy satellite which has the purpose of locating those pirates.

So when there is more pressure on them, they might choose to find another place to operate and for some of them it could be QO-100.

Let's keep a watchful eye, and maybe we have to consider to do the above as well...

(that payload is an SDR receiver onboard a LEO satellite that uses doppler to locate the sources when flying over them)

This afternoon I saw 6 transmissions at the same time! (one is the beacon)

Quote from DH2VA

Sorry for the confusion.. we planned this for quite some time and got this now arranged with the satellite operator.

The mailbox message transmitted by the beacon was changed this week (yesterday, I think):

L HI de Qatar-OSCAR 100 (DL50AMSAT)

Transponder is open for general use since 2019-02-14.

Enjoy the Narrow Band (NB) and Wide Band (WB transponders.

Follow the guidelines and keep transmiter power below beacon.

For more information visit: http://amsat-dl.org/

QO-100 was brought to you by Es'hailSat, QARS and AMSAT-DL.

Good Luck and Good DX via the first geostationary P4-A satellite

Maybe changes like this could be communicated there? Or is it difficult to quickly change the message?

Amsat-DL published this today on Twitter:

AMSAT-DL‏ @amsatdl

#QO100 #eshail2 this morning we adjusted the NB Transponder gain by -4dB. The main affect will be less (waisted) noise in the passband, practically no impact on S/N for the user. @amsatdl @AmsatUK

Hey I can use it to check the alignment of my yagi! Let's get out the solar eclipse glasses....

Edit: ok this conjunction was within .6 degrees here so well within the beamwidth of my 80cm dish but I did not notice anything on the NB transponder receive.

Maybe when I make a plot of the noise floor over an hour interval.

I checked the alignment standing behind the antenna with solar eclipse glasses and it looks OK (see the silhouette of the mast over the sun but yagi not visible).

Maybe you can use a coaxial relay and a dummy load, where the relay is energized when the transmitter is keyed? Or you could connect the other port to your antenna and use the relay to switch between local QSO and LNB reception, the relay would be energized only on receive via the LNB (using a switch and a circuit to connect it to the TX line).

Interesting! I remember when I started receiving satellite TV that there were also events when the satellite passed through the earth shadow (during the night, of course) and the transponders were switched off.

I have not heard about that recently so apparently there is enough battery capacity now to keep operating.

S59MZ are you sure the oscillator stops working when you inject the external 25 MHz signal?

Check if you maybe see 2 copies of the beacon, one at correct (GPS-stabilized) frequency and the other at the (drifting) crystal frequency.

It could explain your 3dB drop as you may be receiving everything twice.

An isolator is a circulator with a 50hm termination on one of the ports.

It sends the signal from amplifier to antenna, but the reflected energy from the antenna (and other incoming signals) is sent to the termination resistor instead of to the amplifier.

This protects the amplifier from bad SWR, but usually it is done to prevent intermodulation in the amplifier when strong local signals are present.

Yes of course 75 ohm is OK for this too, I have done that in the past to have circular polarization with a crossed yagi.

My planned experiment is to have two circular polarized antennas alongside the LNB and see if that results in proper pointing.

Indeed I also want to avoid shadowing. For QO-100 NB it may not be important (I can afford to lose some signal) but I use the same antenna for TV.

Ok I understand!

I am planning to try with 2 circular patch antennas alongside the LNB so I need a 1:2 splitter which I want to do that way but of course the impedance of the match will be 35 ohms so it will have to be done a bit differently.

Nice to see that your antenna works, maybe I will try that one as well.

LZ1JH can you show how you made the 4-way splitter and impedance matching?

I presume the 4 antennas are ~50ohm impedance so these somehow need to be matched.

DL5RDI FPV (First Person View) is not the same as WLAN. It is the downlinking of video from drones which can e.g. be used while flying the drone. Of course in theory one could use WLAN and digital video for that, but it induces a delay which would make the drone difficult to control. So in this field of use, analog video with FM modulation is still often used. And of course, an amplifier for that does not need linearity. So you should always be careful not to buy FPV equipment when you want it to use for purposes where linearity is required.

W.r.t. the reverse-SMA connectors I am less pessimistic. Usually you need a short pigtail between e.g. a module box and an N connector on the outside housing, and you can order the correct type (from reverse-SMA to normal N) and use it without any adapter. This can also be semirigid.

But of course it is often easy to change the connectors anyway.

Quote from DK0IT OV Troisdorf

here you can see the portable setup for QO100 of the club station DK0IT.

- 2.4m dish, 35 dBi gain

Today I heard a portable station with a 35cm dish. To me, that sounds more portable. But he used 20 watts so your station may run longer on the batteries.

I am recording a capture with gqrx.

I was just considering to use this recording feature in conjunction with a FIFO.

Then receive the capture and tune gqrx using the program I already started.

I can mail you a link to download it...

Well you could try to use digital modes like PSK31 and CW and use them with decoding software like Fldigi.

Then you can make QSO with standard phrases and/or translate what you receive using cut/paste to a translation site.

But usually with such digital modes you can make QSO just with the pre-programmed function keys that send your name and station details.

Welcome on the satellite!

Let's agree to disagree. That seems to be your hobby.

Indeed, but for NB transponder use with a 60-80cm dish that should not be an issue.

We will see, it is an experiment...

A type that has not yet been shown and discussed here on the forum, rather than a new build of a design that already was discussed here.

It is a test version and it should appear on his website soon.