KA7U
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Comments
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I could use some help in describing the Wellgood LNA circuit. The two transistors share a ground through the variable resistor RV1 and appear to operate as Class A and I think in a push/pull configuration by virtue of the common ground. The inputs a…
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I've attached a couple photos of the Bias-T builds. Now that these are made I did a google search for DIY printed circuit boards and find the kits are available at very low prices. Shipping times are 30-60 days though.http://aliexpress.com and searc…
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Martin,I did test without the antenna. Both power sources add noise below 25KHz. Both power supplies are reasonably clean above 25KHz. RonKA7U
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Martin,I placed Mr. Smart's Bias-T into service @ http://ka7u.no-ip.org:8074 today. This Bias-T is provided 3.09vdc with the LM317 voltage control circuit. See attached schematic. The LM317 is powered with a 14vdc linear Walwart with the DC input ca…
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Martin,Thank you for bearing me on this quest. I'm a bit compulsive. So I've now tried several balun types with the Hiletgo and while it achieves good gain the noise floor and images are over the top unless it is connected as a shielded magnetic loo…
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Martin,I wound a 7 turn bifilar on a bn-73-202 core and connected yellow to yellow on the antenna, and red to red on the Hiletgo LNA (red and yellow being the wire colors). I'm seeing between 5 and 10dBm gain with the Hiletgo LNA versus the good Wel…
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John,What is your plan? Once you have this time base and precise location information, do you plan to use it to locate transmitters by triangulation of two or more KiwiSDR on the signal, or what is it you are up to? how will this Gallelio system hel…
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Jim,Donnybrook might be more likely. I've made the 2nd Wellgood LNA and another 120CM copper loop. The new one is between 10 and 14dbm down the scale from the 1st one using the 5 watt to a 50 ohm load test. I did test the joints for continuity and …
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Martin,I've kept your Bias T directions for future use. For now I'm using the Bias T that George Smart provided with his Wellgood board, but if I build from scratch I'll fall back to your BN-73-202 cores. I do want to add voltage adjustment to the B…
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Martin,Thank you for this information. Finding balanced pairs of transistors is a good idea. I did order 2 extra transistors for a total of 8. Maybe they will match up with some testing. The low voltage concern is noted. I found that the noise floor…
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Martin,I tested this Hiletgo loop for balance tonight and it is balanced. My test was with RNZI @ 15720KHz so it was skywave and not totally reliable, but the null on either side was deep and the gain off both ends was pretty much equal. So at least…
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It occurred to me to check the relative antenna / LNA sensitivity this afternoon. I connected a 50 ohm load to the transmitter and set it for 5 watt carrier output. Transmitter is 100' from the loop antenna. The loop and Hiletgo amp provided these r…
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Chasing the 60KHz spurs across the band on http://ka7u.no-ip.org:8073 and have installed shielded CAT6 network cables and a Netgear GS308 switch at a network jack. This dropped the 60KHz spurs by over 10dB across the band. The network jack I plugged…
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This photo is the cleaned up version of the loop being discussed. The 1/2" PVC pipe is not glued, relying on compression to hold together. This makes it easy to break down and use portable. The Hiletgo LNA works fine with a 9vdc battery.RonKA7U
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Martin,The references are excellent although probably written with more education on the subject than I possess. Hi Hi Anyway, these articles prompted me to make a crude SNR test across the KiwiSDR band spread. With the LNA disconnected from the an…
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The problems of balance and impedance mismatch might be worth a separate post in this category. I tested the impedance of the shielded loop I've been working with and noticed an interesting set of attributes. The impedance of the loop is higher than…
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Martin,I believe the loop is unbalanced as currently connected. My next iteration will feature a balun to feed the LNA, the center conductor won't be grounded, and I'll check to see if it has a null in the axle directions. My parts from Mouser Elec…
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A note about the split in the shield at the top of the loop antenna shown in the illustration above. The center conductor can be left continuous. It does not seem to make much difference in the antenna if it is connected to the shield or continues a…
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Here is a schematic of the loop. Please forgive my artwork.RonKA7U
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The home brew loop with the Hiletgo amplifier is finally working adequately. So here is the setup that finally put it into respectable service. The idea that a working amplified loop antenna can be made with retail parts for under $50 is now demonst…
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Martin,Now that I've read through the information you provided and even more that Google was listing, I think I'm getting the scope of loop antennas. Hi Hi. The Hiletgo amplifier is actually doing a reasonable job on the home brew shielded magnetic…
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Since JKS organized the antenna and interference related threads to their own section, I found that JKS had posted this link:https://g0luj.blogspot.com/2018/01/reducing-ethernet-interference-by.html Reading that and noticing that my home brew loop …
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These look very nice and reasonable price. The DRM software is Java based but the JAR file is compiled, I think. So the GUI appears to be the only interface. I do find Python code to control these boards at a command level on github, but it doesn't …
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So today I changed the power to the LNA. I found that 9.25vdc and 10.5vdc results in the lowest SNR. At 60KHz 10.5vdc is optimum and at 15MHz 9.25vdc is optimum. 10.5vdc seems to be the good voltage overall if you want good results at VLF. This migh…
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I tested this loop quite a bit for the last two days. It is not on par with W6LVP loop, but it does work better than my miniwhip and other small antennas that I've tried. So on a scale of 1 to 10, with 10 being my 210' top dipole, the W6LVP rates a …
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Seems to work just fine. 19 Jan 2018 00:37:22 UTC | ZCZC CA65 | SECTOR SAN FRANCISCO BNM SF-0015-18 CA-SUISUN BAY 1. SUISUN BAY CHAN LB 30 ( ... 19 Jan 2018 00:38:06 UTC | ZCZC CA64 | SECTOR SAN FRANCISCO BNM SF-0014-18 CA-SUISUN BAY 1. SUI…
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Thanks. I wonder if another computer could link locally to decode DRM as an extension? Another BBG perhaps.
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This is the one I've been using.https://www.amazon.com/gp/product/B00YP823NA/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1 RonKA7U
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https://www.radionz.co.nz/international/listen Shortwave.info isn't keeping up with the schedule changes of RNZI, so it is a good idea to keep track at the above website for current RNZI broadcasts.Ron
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Took another look at RNZI at NH6XO this morning and sure enough, it is still being received there on the RNZI DRM schedules. Must be a pipeline to that KiwiSDR. I have not found another KiwiSDR that consistently receives RNZI this well. Made another…