Sm6Lkm Vlf Receiver Software To Allow
UNESCO World Heritage Site Grimeton Radio (SAQ)A soundcard-based SAQ VLF receiver Johan SM6LKM has made available software to allow you to receive VLF transmissions, such as those by SAQ, using your PC soundcard. The Receiver: I checked several web sites to see what other people are doing and I saw 3 solutions:You only need to connect an active antenna (often called an e-field probe) to the sound card of your PC and to install SAQrx, a software defined VLF receiver by SM6LKM for the VLF band. An Afedri SDR had substantial noise ingress at VLF / LF / MF, when using the same Hello Lasse, Regarding noise ingress over the USB cable, I found that whilst the PERSEUS itself did not suffer much, an Afedri SDR had substantial noise ingress at VLF / LF / MF, when using the. 04:21, skrev Ivan Cholakov.
QRP ProjectsThis solution comes from the Alexander association, the guys that run and maintain the old Grimeton Station. NS8O - 160m CW/SSB transceiver Optimist 80m DSB 1 watt TX - By SM6LKM. Tuna Tin Two Gallery - Sponsored by ElectronicsUSA.com. SM6LKM- Optimist-80 - QRPp DSB transceiver for the 80 meter band (1 Watt P.E.P.) A QRP SSB Transceiver - By: Paul R.
SAQrx R1N-H-IN, This software made by Johan SM6LKM is for VLF reception.It suggest to use a PC or laptop, take the build in sound card, and receive it directly. More information can be found using this link:Downconversion of the standard 455 kHz IF of a traditionnal receiver around 13. The PC then can use a simple SDR programme to process the incoming frequency.
I will verify this by testing.This website Ferroxcube gives good info on material and mu.I went to the website: COIL to calculate the inductance L for a mu of 250 (4B1) or 900 (3B1).I measured the inductance of my creation and it is only is 74mH. Mu value of a few hundred, used for some MHzMnZn so Mangan Zinc, mu value of around one thousand or so, used for some kHzThe datasheets will tell what materials are used.So if no mu is given, get a MnZn rod. What material the rod is made from? I believe this gives a good indication:NiZn so Nickel Zinc. I will sum up the mu value for the different ferrites:4B1: 250, 4B2: 250, 3B1: 900, 3C90: 2300, 3S3: 350, 3F3: 2000So we see quite a difference and we want to go for a rod of 3C90 or 3F3 material, otherwise we wil go for a 3B1 rod, that's also fine.You can also look at it from a material perspective. I found out the following things:Over here in Europe, most ferrite rods are made of only a few ferrite materials,All from Ferroxcube Philips: 4B1 and 3B1.Well, I did some more searching and the list is a bit larger:The permeability mu is the important parameter, the higher the mu, the less windings to make for the same induction L.
I went to the page with the ferrite rods:Here you can buy a rod of 3B1 material and diameter of 8mm: number of turns: 665.B. I looked at the webshop box73.de. I did do around 900 turns, analysis correct, this rod on my picture has mu=250.Clearly not a rod with a mu of 900, 2000 or more.A. Diameter coil former is the same as rod diameter: 10mm, shift =11mm(?), wire diameter=0.25mm, winding pitch:0.26mm.This is good.
After making a small coil and measuring the inductance, I thought hmmm. Get it!Update: Don't get it, it needed 1200 turns, website shows not correct information.After I wrote the words above, I did buy 3 of the 3F3 Rods above. The 3F3 rod on ebay.de (C) only needs 522 turns and is cheap. When you buy a 8mm diameter 3B1 rod, it only needs 665 turns, MnZnC. The 10mm diameter rod i bought has a mu of about 250, 4B1, NiZnB. Diameter: 8mm, number of turns: 522.It will not get much lower, dear readers!A.
This is not what I expected, as the mu = 350 or so. The results are: to get an L of 82mH, number of windings n = 1030. I will test them next week.The week is over and I have tested the 3B1 rod from box73.de. I have bought the 3B1 rods from box73.de. What I learned here, you can not always trust what is written. These rods have a mu of around 250-300.
Pointing the ferrite rod towards Sweden will give you minimum reception, it's a sharp null, the rod needs to be perpendicular to SAQ. Its rechargable, the preamp uses small power, you can listen the whole day outside and recharge it over night. The preamplifier is using a 9V battery to keeps things portable.
I chose Rd high enough not so have a lot of Id as it would draw the 9V battery empty. I chose Rd a few times smaller than Ri, so that the gain is determined mostly by the preamp and not by the sound card. Ri is something that can not be influenced, and Rd can be chosen. Ro of the fet is much higher than the other two, so can be neglected. Ro is the parallel set of 3 'resistors', ro of the fet itself, Rd (2k7-4k7) and Ri of the sound card (assumed 10k). This is basically : Av = -gm x Ro.
The 2 capacitance diodes have a total capacitance of about 1000pF or 1nF. Ci smaller than 30pF is also fine, this is not so critical.A small resistor is series with the gate (gatestopper) is used to avoid oscillation at VHF frequencies.The 4M7 resistor grounds the gate, so that the fet is set also when the coil is disconnected.The resonant circuit is made of the ferrite rod inductance together with 2 capacitance diodes and a fixed capacitor. Crss of smaller than 1pF is recommended. At the beginning I used a fet with a Crss of 6pF and it made the preamp oscillate. This is important as we have a resonant circuit at the input, and Crss gives feedback from the output back to the input.
Therefore fres max = 27 kHz. At 8 or 9V, the capacitance diodes only have a capacitance of 34pF max each, so Cp (8V) total is 68pF + 330pF = 400pF. The actual fres min was a bit lower, so i guess that the capacitance diodes have a capacitance a bit higher than 500pF each at 0V. With an L of 82mH, fres minimum = 15 kHz. I selected 330pF, so a total Cp = 1330pF.
Rd=2k7, measure Ud and change Rs so that Ud = 4.5V +/-1VFET BFW10 or 11 or 2N4416. Pinning below near pictureFET 2N5485 or 86. Tested.preferred.Rd=4k7,Id = 0.5mA,Rs = 1kOhm. Rd=2k7, measure Ud and change Rs so that Ud = 4.5V +/-1V orFET BF987. Rd = 2k2 Ohm and Rs = 220 Ohm orFET 2N3819, Rd=2k7, measure Ud and change Rs so that Ud = 4.5V +/-1V orFET BF410b.
Value from 10k to 100kOhm.OK. Any lineair potentiometer will do. So you don't forget to switch offPotmeter 22k. Rechargable or not.LED Use a bright LED with bias resistor.
Both of them run this SDR software. But.I have two laptops over here, one on Windows 7 and one on Windows 10. SM6LKM states that the software is designed for Windows XP.
Restarting the laptop always solves this issue and then you will get the picture above. This means that our famous microsoft product did hang itself up. When I plug in the cable from the preamp, it looks like this:Even when you do plug in an audio cable, this action is sometimes not recognised. Your audio recording devices look like this:Here you can see that the bottom input is disabled and the middle input shows that the cable is not plugged in. When you do not have any microphone or line input activated, this error occurs. SAQ48k, the following error occurs:This happens on both Windows 7 and Windows 10.This error is related to the program not seing any audio input.
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