Posts by dm4im
-
-
It also turns out its not a 1.5m dish, but a 2m dish.
You are not going to ever need that amp just for the NB-Transponder
-
I kindly disagree with Martin: if you setup a 1.5m dish you should try to get out the optimum of it. Otherwise it is a waste of
time and material ...I agree. I just wanted to point out, that even with a cumbersome antenna, you will have good results with a dish that diameter. My first antenna was the 4 element yagi pointing into the dish , the 2nd was a linear polarised patch feed without waveguide for the lnb and the one i'm using now is a poty . Learning by doing, improving over time. It is more important to have a clean signal, may it be not so strong. The LEILA triggering signals are for later, and even those are clean, if you overdrive NONE of your gear......
Regards
Martin
P.S. : I don't encourage anyone to trigger LEILA.
-
I will need some attenuation before the upconverter, minimum output on my TS2000 is 5 watt - and the upconverter needs between 1 and 3 watt, output alone should be a max of 200mW, so i need the amplifier, i am counting on being able to turn down the output power directly on the DXpatrol mk4 upconverter using the pwr adj, and in doing that limit the output from the amplifier.
I don't buy that. If that is true, you must convert a max. of 2.8W into heat to have 200mW output. Meaning the upconverter has negative conversion gain (in the range of ~ -10/12dB) . If you have measurement gear for 2.4GHz it is of great interest what really is going on.
Set your TS2000 to a good , strong audio , the audio you like to have when you talk on 2m or shortwave. Do not touch audio settings for the the following measurements. Set TS2000 to minimum available power with it's power potentiometer. Now insert a 20dB attenuator , this should result in 50mW output. Connect your upconverter and measure the output , while you adjust the power adj potentiometer on the dx-patrol board. If you don't get 200mW out, turn pwr adj to it's highest setting , insert about 15 or 13dB instead of 20dB, for ~200-250mW input to the upconverter. Repeat measurements. I'm sure you will reach the maximum output power with less than 250mW input.
Many dx-patrol users say , the vox circuit will not work properly with low input power, but most of them adjust output power of their radios by reducing mic gain and compression. Which i believe is the wrong way.
Regards,
Martin
P.S. : I may be totally wrong.
-
It is always beter to attenuate the INPUT TO THE Upconverter on the radio side , not the output after the upconverter . This will result in a clean signal without nasty sidebands. You should check if that is enough signal strength. If not, you still can kick in the amp. You will need attenuation ahead of the amp, I'm sure.
73
-
Pic 1: Poty in the holder where normally the feedhorn of the original Hirschmann feed is located. The original feedhorn sits snug against the aluminum holder, but because the poty reflector diameter is 100mm, the 3 feed arms prevent it from being placed snug against it. The distance is 3-5cm , i think.
Pic 2: Reveals the reflector size and why you can't push it closer to the focus position.
Pic 3: To compensate for the poty not sitting in the focus, i liftet the 3 feed arms a bit above the dish with bolts and nuts. Observe the left side of the picture where the arms are mounted on ( ABOVE , that is) the surface.I'm pretty sure this still isn't the best position, but my signal is loud enough even on very low power and i can hear pretty well. Before i lifted the feed arms a bit up, the signal was loud, but afterwards I had to lower power by at least 4-6dB. To this date, i do NOT know my output power, maybe 2-3 Watts , minus the attenuation the 8m long cable from the amp to the antenna introduces.
73, Martin
-
Hi,
with a dish that size, the antenna doesn't really matter much unless you plan to run very low power or datv.
I use a 150cm PFA and got very good results even with the 4 element yagi the manufacturer of my upconverter provided as a free gift, pointed in the dish.
With a POTY or Helix in the right spot (focuswise) you need to keep the power low (wich is good when you use dx-patrol, because they tend to overdrive everything)
73, Martin
-
Hi,
if you use 24MHz, you will find the center of the downlink passband on 10489.750-(24*390)= 1129.750 .
If you use 25MHz, you will find the center of the downlink passband on 10489.750-(25*390)= 739.750.
The 24MHz reference lets you receive the DATV transponder on a normal unmodified Sat-RX ; you can receive the beacon and some other individual signals.
The 25MHz reference does not allow that, because sat-RXes do not cover 740MHz.
If you want to receive with a normal 432MHz rx , you use a reference in the range of 25,78xxxMHz
Some even receive directly on 2m band.
If you use a rtl-stick or other sdr device for rx, it is not important, what reference you use, as long as the device can receive the resulting frequency.
Identify the built-in crystal by checking the LO frequency printed on the plastic cover, 9750 means it is 25MHz.
25*390=9750 , but it will also work with 24.xxx or 25.78xxx MHz.
Edit: The description for the lnb from the link you provided says 9.75GHz. Voila'
73, Martin
-
Hello,
This looks like an empty transponder with the beacons switched off. FT8 is still there, so power is available. Make a screenshot of the strong signal on 10489.300. I see no signal on my rx there, so maybe the websdr you are using receives it from a local source. Is it always there? Which websdr have you been using and what time?
73, Martin
-
It's the "<50000000>" versus the '<50000000>'
"<xxxxxxxx>" seems right.
-
-
Bekommt ihr beide die Fehlermeldung: "recvfrom error" wie bwi DG5EM im Terminal zu sehen?
Probiert bitte die modifizierte Version von ZR6TG mit dem grösseren Empfangspuffer.
und berichtet dann.
Laut ZR6TG müsst ihr nur seine Version 0.89 herunterladen, entpacken und die vorhandene oscardata.exe Version 0.87 durch seine ersetzen.
73, Martin
-
Hallo,
ich denke, du hast alles richtig gemacht. Es sind eben keine Bulletins vorhanden.
Gerade kam Bulletin #9 rein, nach geduldigem Warten, siehe rechts unten:
Und nach weiteren Minuten Bulletin #2 und #4 . Einfach mal laufen lassen, warten und die fett gedruckte #Zahl anklicken. Dort sollte ein Bulletin zu lesen sein.
Nach einem Klick auf "Öffne RX Dateien" kannst du prüfen, ob Bulletins empfangen wurden. Der Dateiname ist immer "amsat-", danach eine laufende Nummer gefolgt von ".blt" , z.B. amsat-310.blt . Schaue von Zeit zu Zeit nach, ob welche mit ansteigender Nummerierung vorhanden sind. Die 10 neuesten sollten angezeigt werden.
73, Martin
-
Hi!
I'd like to see a feature to put a connected DATV-Software to the received signal in the "Wideband transponder activity" window.
73, Martin
-
LOL.
Use LSB for the sstv uplink and switch to usb when talking. Now set your tx frequency to 2400,150MHz. Your sstv signal should appear in the digital part of the band, but your voice signal in the SSB part.
73, Martin
-
And what if you want to do DATV?
Take the cable with the 12V OFF and put the cable with the 18V????
Yes, or you rotate the lnb 90° . Or you use a lnb with 2 Ports, one for 14V / SSB , the other one for 18V /DATV . Then, of course you will need 2 power splitters, 2 power supplies etc. But you know that already, don't you?
73, Martin
-
-
You should have taken the photo with the foil removed, for better recognisability. i have this or a similar splitter and there all 3 OUT ports are labeled "power pass", but power only goes to "IN" and never to one of the other "out" ports. If it is the same: There are 3 connectors labeled "out" . Connect your power source 14 or 18V to the one labeled "Power Pass" Check if there is voltage at the port for your lnb , labeled "IN" , but not at the remaining ports labeled "out". If all is good, connect your RX to one of the "out" ports and your 25MHz source to the other labeled "out".
-
Ari,
So the Groundstation provides 25,7xxx MHz for the LNB while you transmit? Did dx-patrol rework their product? That would be good news. Did you verify it or do you think it works like this?
73, Martin
-
The Satellite Experimenters Handbook, 1984, says we are dealing with Faraday Rotation, where linearly polarized signals from a Mode A satellite (AO-7 IS a Mode A sat) slowly rotate when they pass through the ionosphere, most noticable on 29MHz as fading. The polarization now is elliptical. A circular polarized rx-antenna will compensate this, but will not cure all fading , since the the gain pattern of the antenna in the spacecraft constantly changes as it spins.
So, i think it is best to switch from RHCP to LHCP and back while observing the signal.
You may ask why do i care about this? Well, after all it is less an experiment for reception of a Mode A satellite, but more an experiment for diversity receive on 12 & 10m. I will focus on that and put proper reception of AO-7 very low on my to-do list.
But if polarization was known beforehand, I sure had set it correct. Will i ever bother switching from RHCP to LHCP for AO-7, i don't know.
Thanks for reading
73, Martin
