Posts by G8UGD

    My Bison ex-UMTS amplifier, I believe, is run in class AB and typical bias is around 0.7 to 0.9 for each device.

    A point to check, did you update to the official PlutoSDR 0.31 firmware before going for the F5OEO firmware?

    If you can run the Portsdown/Lime_Mini through the amp without shoulders then I would not be blaming the amp as the Pluto would just be acting as another source!


    Adrian

    I believe that the Radeon HD 6450 will help with hardware acceleration for MPEG2, H.264 and VC-1 high definition video formats, so if you are happy with H264 streaming to the Pluto it will be fine.

    My cards do not support H265 hence going down the HDMI box route. The box simulates another display screen and whatever picture and audio is sent to the HDMI port, it encode into H265, (or H264 if you set it for that). So older PC/graphics cards can be used.


    The software interacts between the Pluto firmware from F5OEO and the HDMI encoder and sets the parameters automatically.

    It does not necessarily give the highest definition possible but, I found it to be reliable in both video and audio. There is a drawback in that it does not seem to pass the correct aspect ratio through to Minitioune software, at least in the version I am running.


    Hope it helps


    Adrian

    One issue I and another local person has found with the Pluto when using the USB to Ethernet adaptor is a lock-up of the Pluto which can be caused by any sort of current surge on the system, so look for the ground mod to apply to the Pluto to help remedy this.


    If you run it from the Ethernet adaptor then it needs a separate 5 Volt power source. If you find the Pluto stops responding to the web browser trying to control it, then just try unplugging the USB adaptor from the Pluto give it a second or two and then plug back in, if that clears it then look to do the modification, or figure another way to equalise the power ground with signal ground in the device.


    That issue caused me hours of head scratching.


    I use OBS, with the H265 HDMI encoder to the Pluto via Ethernet adaptor.


    Adrian

    Pete, can you use/build a very simple style diode detector on a 50 Ohm termination to measure volts with a DVM. should be able to give you relative measurements?

    Many listen and wait for new stations.

    Perhaps this is the problem, people only wanting stations in countries they have not heard of for DX. Not wanting to make friends and chat CW or SSB.


    QO-100 is a repeater and once you have a system to gain access you can converse to almost a third of the world. As said on the A71A Wideband beacon "To receive us clearly and we will receive you 9 by 9"?

    There are digital modes, such as RTTY, FT8 and others, slow scan TV, digital voice, spectrum painting,

    The satellite could be used to arrange skeds and/or talkback for the amateur bands from HF to GHz, arranging long range tests etc. It has coverage of approx 100 degrees of the globe which makes it the best repeater we have other then the internet. There was talk of it providing limited broadband access to some parts of the world. It is apparently 1 year old and perhaps the novelty is wearing off.

    I admit I can not converse in CW my skills are lacking in that area, also I need to build back my narrow band setup again.


    Have fun, be safe.


    Adrian

    This has been done once before on the SSB section of the QO-100 band. There was an 144 MHz uplink and downlink transverter (I forget the correct name). Great care needs to be taken both in design and also in time use, if memory serves me correctly it was left on during a contest weekend when 144 MHz signals were getting in and coming out on QO-100 causing confusion.


    To be effective the HF receiver will need to be sensitive, selective and low noise otherwise the noise floor will be lifted in the corresponding segment on QO-100, so constant monitoring or some active feedback of the uplink frequency to reduce gain to minimise this, a sort of AGC.


    One issue is that with HF and band openings/time of day, the signals on CW can come from anywhere in the world and not just from a local country, so unless all radio amateurs were to know about it how would it be managed, what of regulations, do all countries regulatory bodies allow rebroadcast etc.


    How would you stop a couple of hams say in the states, having a CW natter between themselves ending up on the satellite uplink completely unaware of it. It could be done but you need a way of having some form of input protection such as CTCSS or DCS signal used on FM repeaters, 'color' codes etc as used in digital what could you use for a CW signal that would be easy to implement on existing ham gear?


    Perhaps reduce the proposed 20KHz down to just a few KHz to reduce the impact etc. These are all things that could be considered.


    Then again these are all just my musings thinking aloud, I have no influence over other users or Amsat-DL or Quatar. It could be an interesting concept if all minds worked together and it is done correctly, could lead to complete chaos if done wrong. :)


    Adrian

    I did three plates recently, 2 for local hams and one as a spare for myself, this is the one I did as a spare as I have a spare board.


    In case you wonder, I make two index marks when doing any machining, one is a 2mm hole at X=5mm and Y=5mm and a 3mm end mill hole at X=10mm Y=5mm. These to help me when I change from a 2mm drill to 3mm end cutter without a proper tool change setup I loose index, but it seems to work out for me just takes time. I would still like to get feedback from other CNC'ers!


    Hello Peter & Heiner,

    Thanks for the responses, I was wondering about it as there was little news I could find on the subject. I was also wondering to myself if the reduction in bandwidth would also have a corresponding reduction in power consumption of the amateur side of the satellite, I guess it must have some effect when on for 24 hours a day. Also the uplink would not need as much punch to get a signal to the same MER etc. Overall a reduction in required power levels if only minor. Is there any advance notice of the revised band plan out there as I can only guess that software for Minitiouner, Pluto and probably others would need to be revised?


    Anyway doing a good job.


    Adrian

    I have the model that purports to go to 8GHz and as supplied was an absolute pile of crap, When taken to an OP that has the correct gear, at 2.4GHz it was found to be +5dB high at the top end of it's range which is basically around -5dBm


    As you went further down the dBm range I found the error crept higher. The chips on the processor and display board have been scraped to stop one identifying them but I suspect they would be Atmel. Some have reused the detector board at the bottom and done on one of their own processors with A2D on them.


    I did find what I think to be an error on the sampler board where the output resistors were 100 Ohms instead of what I think should be at 10K, the output is basically voltage doubled, with no signal input being around 4.1 Volts going down towards the lower voltage as one puts more signal in.


    I do wonder if a simple diode detector on the output of a 30dB directional coupler would give better results. I have modified mine changing the output resistors and use of a variable pot so that it tracks within 0.5dB from a range of -40input to -10 input at best, not fantastic, but the best I could get. Unless someone can rehash the software in these personnel experience says they are not worth it.


    Sorry if this is not what anyone wants to hear, but just based on my experience.


    Adrian

    I thought the free updates had gone? But I stand corrected as i see there is still a way to do it. I doubt my old 2009 machine would survive such a transition, unless someone with a dell Optiplex 780 can tell me different.


    Thanks for the reminder Heiner.



    Adrian

    I have done an update to the dxf file, I realized that the previous DXF file (in the zip) would not show the actual image I had been using.


    I have done a dxf for a single PA, watch out for the holes (points for the cover) when you buy the PA as a Single you could get either the left, or, right-hand side of the cover and the holes are very different.


    So anyway here is the single PA dxf with an image file in a zip. Un-zip into a folder and then open the dxf from that folder and I hope you will also see the image file. Please let me know if you do. If it works I will then try to amend the original file I uploaded.


    Also, I need some feedback if you use the file as to it's accuracy. I used a picture of the image to determine where the points are for drilling. I drilled 2mm holes for 2.5mm screws. The PA cover can go bigger and I drilled out and used M4 screws for that.


    If anyone has CNC facilities please mill out first on some MDF or other suitable material before you build your PA. Check the accuracy of everything. My machine is not an accurate one and I am getting small errors, not enough to cause me any issues but I do not know if the errors are in the drawing or my machine, I have normal lead-screws and not ball-screws on the mill and therefore have backlash errors I can not correct.




    Many thanks and feedback appreciated to know if it works for others.


    Adrian

    I must admit to preferring some slightly bigger units, but not for receiver side I am not that clever to design boards.


    I built two of these style ID filters for transmit, one is directly out of the SDR unit and another after the pre-drivers just before the main PA, the idea is to reduce any spurs from the SDR or spurs from the pre-driver stages up to about 2 watts.


    On the trace I had approx 0.3/0.4 dB insertion loss and the divisions were 50 MHz per division horizontal and 10dB per division vertical.


    Adrian

    Hello Peter;

    Nice to know, thank you.


    I was just wondering if there will also be a revamped band plan at some point, such as the 1 MS slots moving down to fill the space and more RB slots at the top? I am sure it is already in hand and well thought out.


    Adrian

    Personally I am using the POTY, but I know of two that have just bought what I believe is the DJ7GP design from Passion-Radio, they are not in use yet, but they do have a tuning screw that has not been tweaked by them!

    So I am hoping for them it to be OK. I did not realise there was two versions of the antenna before I saw this post and I was trying to determine the physical difference between the two to check.


    Adrian

    Yesterday I made some not so scientific measurements. I compared Bamatech DJ7GP and PE1CKK POTY 2.4GHz patch antennas. Already known that DJ7GP design is not circular polarized but POTY should be.

    Can I ask why you say the Bamatech is not circular polarized the web text says it is, I am curious as I know a few that have just bought a couple of these????


    Adrian