The Admiral

That's a very sensible approach Bishkek, university life demands a lot in all sorts of ways. Good luck with your studies! Well, in a way that doesn't necessarily help. I tend to go through my subs and only stack those where I think there is minimal streaking, although I did use DSS originally. I found that there is quite a variation in sub quality with my Nexstar mount. You can only get out what you put in! Also, I'm not sure how you are using PS, but you ought to be stretching linear data and certainly not JPEGs. In other words, you should be stacking the RAWs. Is that what Sequator does? Photoshop can be successfully used (as can the free GIMP program), although I've not done so. I use Startools, a very powerful program but not expensive. However, you might not like its modus operandum. Ian

Heard about this on the radio this morning. https://www.pbs.org/newshour/science/biggest-explosion-seen-in-universe-came-from-black-hole Absolutely staggering. Sorry if this is old news or in the wrong section! Ian

I think you are giving me more credit than is due! I hadn't actually taken the step to think of the cable as the filter . All (still) interesting! But I still don't have my head around Smith charts - that'll need some serious little grey-cell study. Not sure that I follow the T-piece connections though, I thought when measuring cable properties it connected between the two terminals, but if you are checking out the resonance nature you'd connect just to S11. Need to look up the tutorials again. What I've done so far has all been a bit rushed as time hasn't been plentiful recently. Keep up the good work . Ian

Well I find it interesting! Can't explain it, but it does mess with my mind . That Smith Chart trace is bewildering. But why does the addition of the coax give rise to this? I suppose that 'off-tune' the impedance of the antenna ceases to be purely resistive, and this must interact somehow with the reactive impedance of the co-ax. It might be interesting to see what the response of the co-ax would be on its own, say terminated with a 50Ω resistive load, or shorted, or whatever. I wonder what the natural resonances of the cable would be? I suppose that one should use a passband filter somewhere in the receiver, or ahead of it, to minimize breakthrough from the signals either side of the desired band. Ian

The thing is that in reality one needs a feeder to use an antenna, so any measurements should be on the system as a whole I feel. However, it would be interesting to compare the result with one directly on the antenna, if only to see if I can resolve the origin. It would need climbing into the loft, not the easiest of tasks, but easier than climbing a ladder outside in our present winds . I haven't a clue as to what harmonics a quad resonates at. My current set-up has the antenna in the loft amongst the rafters, a short co-ax goes to the antenna with a couple of loops to form the balun (as per https://www.innovantennas.com/en/baluns-why-do-i-need-one), and terminated in a Type-N connector IIRC. This is connected to a length of co-ax that goes through the ceiling to the room below, where it terminates in another Type-N. The SDR dongle is connected to that via a Type-N to SMA converter cable. Unfortunate but necessary junctions. Do you know what impedance the nanoVNA input is? I assume that the outside of its SMA connector is common and presumably earthed via the USB connection on the computer. Ian Ian

You are right of course, but like a lot of legislation there is no enforcement, but if you are caught for something else then they can charge you with that as well. Even using mobile phones whilst driving is barely enforced, unfortunately. There is also the practical element of how you'd prevent folk listening to airbands, unless all the messages were encrypted. Ian

I agree in a way. You won't find the equivalent of BYEOS for example, if that sort of thing is important to you. I used my X-T1 because that's what I had and was pleasantly surprised by it's Ha response and sharpness (given it doesn't have a low pass filter in front of the sensor). OK, not as good as an astro cam, but usable. For example, see here. Note that I've only done Alt-Az imaging, and as such the exposures have been no more than 30s. But quite a few of them! And that really is where the problem has arisen, because that's an awful lot of files to post process and store. Originally I used DSS but it didn't work with the Fuji X-Trans sensor, so I ended up converting them all to DNG using the free (and speedy) Adobe DNG converter and stacking those. May be the later versions of DSS will work with the Fuji RAF files. I turned to Astroart in the end and is seemed to cope with all the stacking and calibration files. I'm not 100% convinced it isn't using a fudge to calibrate, not being a Bayer sensor. I've also kept an eye on Astro Pixel Processor as initially it didn't work with the Fuji but there were requests for the camera to be included. However it seemed to be a long way down the list of the developer's 'must do's'. At that point Mabula had constructed his own algorithms for calibration and stacking, rather than relying on DCRaw. However, it seems that this has only been done for CR2 and NEFF raw files, all the others will use LibRaw. But as stated here "APP currently does not yet support FUJI X-TRANS camera's, even when converted to DNG, it will not work yet. The goal is to have this supported from APP 1.077." This has been a work in progress since its introduction 2½ years ago, so one can but hope. I think the problem is that the Fuji really isn't seen as an astro camera, and the market for astro is too small to see any developments along the lines of Canon and Nikon. Pity! Ian

I've now had a bit of time to try out my new nanoVNA. Nifty little gubbins isn't it? It took me a little while to get to grips with it. I'm using it with NanoVNAsaver v2.2-1 on my laptop. I tried it on my W7 PC but I don't have a virtual COM driver on that machine. Here's what I got with my LFA-Q quad Yagi. A bit low for the 2m band. It does have tunable elements however, should I care to go up into the loft, but it'll do fine for Graves radar on 143.05MHz. However, over a much wider frequency span there are a large number of other resonances and things don't look quite so rosy : I used a simple choke balun at the antenna feedpoint. How important this will be for receiving I haven't the foggiest. Once again I thank @Macavity for the heads up on this great device. Ian

Wish I could say the same! Well, actually, no I don't 'cos it was fun. Remember, these were the days of Radios Caroline and Atlanta, such role models . "House of the Rising Sun" through a 6V6 audio output valve, IIRC, on medium wave. Range was pretty minimal. Wouldn't have done it these days, far too much big brother about, and of course the wavebands are so much more crowded. Ian

I don't know how long it's been on the stocks, but it must be a huge and expensive undertaking. Our local airfield frequency has changed. Bureaucracy moves slowly! Ian

I must admit this seemed a bit draconian to me, so I had to check it out. Hmm, seems that it is illegal unless you are licensed to do so. Wouldn't have believed it . Ian

You do seem to be well back in the SWL mould! I presume that you are aware that last year there was a shift to 8.33kHz channel separation for aviation use, and allocated frequencies are changed. You might want to check out the current frequencies. Ian

It would, presumably as it's designed for astro. Are there any astro reviews of it around yet? Mind you, it comes at a price and I can't imagine there are many 2nd hand examples around as it's just been launched. Ian

Sorry, I don't understand why a clip-in filter would not be a consideration, that is, assuming you can get dual/triple band as clip filters? Surely, even if you have a 2" filter already, it's going to be cheaper to purchase a clip-in filter than either of the options you suggest. That's not to say an astro camera wouldn't be a useful development for your set-up. If you can stand the financial hit then to my mind it would be the right way to go, rather than another DSLR/Mirrorless. Also, do we know what sort of performance the new Canon mirrorless cameras have for astro (I take it that your camera hasn't been astro modded), and can BYEOS work with it? An astro cam would at least bring a good Ha response to the game. Then again, I do understand the advantages of having a self-contained unit. Not an easy question to answer! Ian

From what I have read the EF mount lenses can be used on the (APS) EF-S bodies, but not the other way around. So it shouldn't be a problem I guess. It just means that the full frame image will be cropped so that the field of view with the APS camera will be the same as a 320mm lens on a full-frame camera. Ian

First question, what filter are you talking about? Astro or conventional photography? For astro, it strikes me you have two choices: find a solution to a large filter on the front, or a clip-in filter. I've no experience of clip-in filters, but can't you simply remove it when you want to do conventional photography? This is the cheapest solution I would have thought, if you can get the filter you need as a clip-in filter. Then again, can you get astro filters in the size you need (72mm)? Plenty of conventional filters of that size though. I can only think that if you want an astro filter on the front, you'll need to somehow use an existing filter ring and insert the astro filter into that. Perhaps a step up ring might give more options re. sizing. The only way you'd be able to use a drop-in filter between the camera and lens with an extension tube is to use a mirrorless camera which has a much shorter lens flange-sensor distance. You can't add an extension between the camera and lens with your DSLR otherwise you'll turn the 200mm lens into a macro lens! Fine if that's what you want to do, but not for astro . My 2d worth anyway. By the way, what do you mean by 'legs'? Ian

I've just ordered one from Amazon . I shall be interested to see how the Innovantennas 3 element LFA-Q quad Yagi in my loft that I use for meteor scatter is behaving. Ian

Hmm, didn't know such a cheap antenna analyser existed! I might investigate purchasing one. I too was a SWL as a lad in short trousers, many centuries ago when proper electronics had valves and HTs that could kill, but could afford very little then. Visiting the field of meteor detection as rekindled a mildly renewed interest. Thanks for the post. Ian

Nik Szymanek has articles in Astronomy Now called Imaging Masterclass. He's just started a series using Affinity Photo, but has covered Gimp and Photoshop in previous series, IIRC. If you can get hold of back copies that may help. Ian

Nice detail and colour. Curious about the diffraction spikes though, any idea where they could have come for. Ian

My point is, if the contents fall into the above category, then you won't be able to take out loss insurance. Or have I missed the point? Ian

But presumably your contract with them is on the understanding that the content is neither covered for damage nor loss? Ian

This is what I take exception to. I can understand them not wanting to insure for damage, but surely a loss is a loss, whatever is in the package. Wanting their cake if you ask me! Ian

Yes I noticed that a few weeks ago when I was thinking of selling a camera lens. In fact, looking at the list of prohibited items it's a wonder they'll ship anything! Some items you could understand, but what's wrong with spectacles or shoes for heavens sake? At the end of the day, surely it comes down to packaging to prevent damage? I have seen somewhere else (not sure where now) the list has been split into separate categories according to whether they're fully insured for transit, limited claims or no claims, and prohibited. That would make more sense to me. Ian

Ian