n6gn
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I think Clint brings up an important point. For a good installation we are trying to optimize dynamic range with the low end limited by propagated noise. This requires protecting the top of ADC level from local strong signals and is location/time/an…
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The problem with that feedback approach is that the loop gain falls to zero at the desired operating point (no OV, ever). There is also the issue that broadband attenuation hurts sensitivity/noise floor everywhere. The ideal solution is location/…
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Although we ran this for a while, the site Greg mentions has been using APRS in recent months instead. This has an advantage that it is out-of-band signalling and persists even if battery system goes below that which keeps the Kiwi and IP link alive…
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And now John has added an S meter option to kiwirecorder. This all keeps getting more fun all the time !!
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Since not only the frequency but the phase of that test signal is known and repeatable, it offers the possibility of building a rather simple vector network analyzer. Either transmission (e.g. S21) or reflection (S11) measurements could be relative…
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1V p-p OV (+4 dBm in 50 ohms) at the ADC - {20 dB (LTC6401 preamp) + 2 (LPF)} = -14 dBm overload, referenced at the SMA connector. This is what I/ve measured and seems consistent across multiple receivers. I haven't measured very many spot frequenc…
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Martin, I also don't want to burden John and am very appreciative not only of all he has done and does but also of how extremely quickly he often responds to a new idea. Having said that, I want to leave him free to be sure he is doing things he wan…
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It may be that the symptom can be described as "no refresh of old data if new data is off screen".
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You sure it's decaying? T=1 hour: (Image)
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I confess, I didn't wait > 15 minutes but effectively it is useless as a means of making low level comparisons. It's a peak detect for signals where the 'low' signal is off screen. I do not find it useful.
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I just reconnected the same kiwi where this was witnessed, with the GPS disconnected. As I'd had it powered off, it promptly loaded v1.277 before I could even re-try the kiwirecorder call. When it finished, I re-ran the command-line call to kiwirec…
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John, Yes, it occurred every time of the many it was tried it which is what prompted the investigation into why the 3rd kiwi didn't work. The only thing that was necessary to change from the non-working condition, which issued a 'string to float&qu…
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Addendum: After trying a few different arrangements, I think I do note one caution: There are pretty big and fast edges present near the board. It seems it may be important to either shield the PS or keep any open high-Z antenna circuits away. If …
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Well maybe "someone can't easily duplicate my RF current Injected measurement" . I can't do it now !! Several weeks ago I measured similar numbers on two different occasions with one of my enclosed kiwis. I no longer know which unit it …
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John, You may be correct that this isn't the coupling mechanism, I haven't proven it to myself that it's not instead, say, a magnetic loop rather than straight IR drop. But it seems to me the important aspect is that I *did* measure a significant d…
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Perhaps you misunderstood me. I am suggesting that simply moving an injection point a cm along the edge of the board or between the SMA ground and the two-wire ground results in a very significant difference in detection level. This isn't about whet…
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The "lumpiness" of your noise floor even prior to the interference suggests to me that you already have an ingress mechanism and are susceptible. Propagated noise doesn't tend to look like that while CM mechanisms often do. Someone famili…
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Yes, DXE sells them in pairs or packs of 10 (US$240). I suppose they are implying what you say, kill CM current in each direction. Protecting only the Kiwi and not the router/computer could be adequate for our use. Fiber is great but it doesn't so…
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For $US50 DX Engineering shipped me a pair of filters and two short cables to allow inserting them in-line. But before actually trying them out, I had to at least take one apart to see what they were. Essentially these are back-back HALO HFJ11-1G46…
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It seems that the present green icon only transfers frequency/mode/zoom. I'd say this probably has the most use in comparing kiwis by modifying the IP in the URL it gives and bringing up another receiver in a different tab. At least that's the onl…
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Until ~6 years ago when a few of us grew a significant base of VHF+ WSPRers, there weren't even 'standard' frequencies above 2m and virtually no activity. As more got on up there and discovered what a great tool WSPR was -contrary to what K1JT had…
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Oh, just realized that the WSPR extension is using the 10m entry for band so assumes that means 28.1246 carrier. 28.1246+.001529 audio comes out as shown. At least it's correct at the 1 Hz level but not right about band or MHz ! There's apparently …
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I use a Bodnar GPSDO as LO for a homebrew transverter . I just verified that it all works, though with a couple of significant issues. In the screen shot below, I'm using one of my switched antenna inputs for the 2m downconverter. I've told the K…
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Thanks. I'll do that.
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Thanks much for doing that John. Perhaps he'll find time for an upgrade. I did remember about the extension name and have had no trouble with a couple of variation I've used (when I couldn't remember what it was called). Also, I was able to guess …
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That's awesome John! You read my mind WRT the min/max values since that then allows two receivers to be set identically for comparison - a really useful arrangement that I use a lot when examining antennas and noise floors. I'm still figuring out wh…
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Here's a photograph in case you just want to see it but don't want to download the pdf (Image)
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From the LTC2248 data sheet, "Connecting SENSE to VCM selects the internal reference and a ±0.5V input range. " which according to the schematic is what R408 does. 20 dB of LTC6401 gain, data sheet again, and 2 dB of LPF loss, an estimate,…
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I thought I'd try measuring them with the same fixturing I used to measure the CM rejection for currents,between the SMA ground and the PS/LAN side. Ordered but: " Part Number: DXE-ISO-PLUS-2 This part is temporarily out of stock, but you can…