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  • AC5PS's Avatar
    Thu 10th Jun 2021, 01:02
    Is it just me ?
    1 replies | 126 view(s)
  • F4VRX's Avatar
    Wed 9th Jun 2021, 16:20
    Hi all, just got a Xiegu G90 and planning to run it mobile eventually. Anyone have any recommendations on best antenna (type or brand) to use mobile? PLease bear n mind that this radio has an inbuilt ATU that I would like to take benefit of, but I am not able to mount a screwdriver like the Yeasu ATAS, so some sort of multi-band (whip) is obviously best. Thanks in advance for the good bad & ugly suggestions :-) 73s & stay safe all Malcolm F4VRX
    1 replies | 126 view(s)
  • AC5PS's Avatar
    Tue 1st Jun 2021, 18:28
    AC5PS replied to a thread Real time water fall in Propagation
    One of the images is close, they start at low frequency and increases. Saw one yesterday that moved back and forth before heading up the band.
    5 replies | 441 view(s)
  • brandon lind's Avatar
    Tue 1st Jun 2021, 02:40
    Google "tweeks chirps whistlers chorus", perhaps even go directly to the images section. Do any of those signals look the same as the one you are searching for?
    5 replies | 441 view(s)
  • AC5PS's Avatar
    Sun 30th May 2021, 13:53
    AC5PS replied to a thread Real time water fall in Propagation
    Interesting ! Thanks
    5 replies | 441 view(s)
  • WZ7U's Avatar
    Sun 30th May 2021, 08:30
    WZ7U replied to a thread Real time water fall in Propagation
    Ionosondes perhaps?
    5 replies | 441 view(s)
  • 5B4AJB's Avatar
    Fri 28th May 2021, 12:47
    5B4AJB replied to a thread Real time water fall in Propagation
    Many things can generate this kind of signal. Electronic equipment "warming up" Like you said, the activity of meteorites ionising the atmosphere FRB's (fast radio bursts) from millions of lightyears away Our own aurora(s) possibly even volcanic activity deep within the Earth, the list goes on Yes, they are a fascinating subject, which we still know very little about...
    5 replies | 441 view(s)
  • AC5PS's Avatar
    Fri 28th May 2021, 01:55
    AC5PS started a thread Real time water fall in Propagation
    I got a IC-7300 a few weeks ago and really like it. I have a question about something I have observed on the band scope. I have been receiving HF frequencies for about 30 years, like many of you I have always heard that occasional noise of a chirp/high pitch for a fraction of a second. Now that I have my first real time spectrum display I can see the signal coming moving left to right leaving a tail behind it ! What is causing this noise ? Could it be meteorite’s ?
    5 replies | 441 view(s)
  • brandon lind's Avatar
    Sun 23rd May 2021, 14:19
    Nice video. I tried measuring the SWR of my HT antennas with a VNA but ran into trouble as well. My first attempt was to screw the antenna right on a nanoVNA. Even bringing my hand close to the VNA made significant changes. Then, I tried a ground plane like you mentioned and still had strange results. The shape of the ground plane made the results change so much I assumed there was no way it was a representation of what the HT will see. What would be nice is if someone had a broken HT and gut it and put a coax connector on the bottom with a ferrite bead on the coax so that the common mode currents wouldn't affect the results and the antennas could be evaluated in their natural environment. I think those antennas are roughly tuned with the expectation of a weakly coupled radio case to the hand. It would also be interesting to see the radiation patterns as I believe some of those handheld antennas, particularly the short linear loaded ones, have broader more uniform pattern extending above horizontal such that...
    3 replies | 1234 view(s)
  • paulears's Avatar
    Wed 19th May 2021, 07:54
    30 miles? With any hand held it’s geography. My office to my home is less than one mile. A handheld in my office cannot make it. The same handheld can talk to a ship 5 miles away. Antenna height is key. But - then orientation is vital. Go a few degrees off vertical and they’re useless. I did some tests of portable antennas on you tube. Results were pretty bad. With one person on top of a mountain you might get 30 Miles, but a couple might be more common. Quarter waves are more efficient than helical types too, so any kind of portable really has range based on very random and unknown circumstances.
    3 replies | 1234 view(s)
  • brandon lind's Avatar
    Tue 18th May 2021, 03:40
    brandon lind replied to a thread Battery in The Junk Box
    I didn't know that, thanks!
    2 replies | 461 view(s)
  • 5B4AJB's Avatar
    Mon 17th May 2021, 10:34
    5B4AJB replied to a thread Battery in The Junk Box
    There's a great Wiki article which explains why in the second section. Surely a couple of humble 18650's would make a good replacement for a centre-tapped version?
    2 replies | 461 view(s)
  • brandon lind's Avatar
    Mon 17th May 2021, 03:50
    brandon lind started a thread Battery in The Junk Box
    Anyone else think 9v batteries (maybe even car batteries) should come with a center tap? If they woulda put a center tap on a 9v, i wouldn't need to use one of four op amps on a virtual ground and big tech wouldnt have needed to design single supply chips. My metal detector would only take one battery. Someone in the battery business missed a market there.
    2 replies | 461 view(s)
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