hybridfree/eevblog-posts huggingface dataset:
changing an antenna for better nvis - Page 1
Forum section: electronics / rf-microwave

author: p.larner
author_rank: Frequent Contributor
timestamp: October 07, 2023, 03:38:31 am
content: i have this design for an antenna,can it be altered for better nvis but still be kept small?

author: A.Z.
author_rank: Super Contributor
timestamp: October 07, 2023, 07:31:43 am
content: https://q82.uk/g7fekcheck it, if you want NVIS you may probably consider to go for a different antenna, for example an horizontal loop or a doublet at moderate height with respect to Lambdahttps://ftp.unpad.ac.id/orari/library/library-sw-hw/amateur-radio/ant/docs/Introducing%20the%20All-Band%20Doublet.htmhttp://on5au.be/content/a10/wire/abd.html

author: A.Z.
author_rank: Super Contributor
timestamp: October 07, 2023, 10:05:12 am
content: also seehttps://hflink.com/antenna/

author: pdenisowski
author_rank: Super Contributor
timestamp: October 08, 2023, 10:38:42 am
content: I make a few NVIS antenna recommendations / observations in this whitepaperhttps://cdn.rohde-schwarz.com/pws/campaigns/rsa/Rohde-Schwarz_Understanding-NVIS_v1.1.pdfYou can also see the same material presented in webinar formathttps://www.rohde-schwarz.com/us/knowledge-center/videos/understanding-near-vertical-incidence-skywave-nvis-video-detailpage_251220-908736.htmlA lot of what makes an antenna a "NVIS" antenna is being mounted close to the ground, since that tends to increase the takeoff angle. Contrast this to "normal" HF skywave propagation where a lower takeoff angle is more desirable because it (geometrically) increases the maximum achievable distance due to a lower incidence angle with the ionosphere.

author: A.Z.
author_rank: Super Contributor
timestamp: October 08, 2023, 11:24:01 am
content: The point is that the G7FEK was adjusted to allow low angles and improve DX, so asking how to make it NVIS is nonsense, better going for a different antenna

author: pdenisowski
author_rank: Super Contributor
timestamp: October 08, 2023, 01:58:10 pm
content: Quote from: A.Z. on October 08, 2023, 11:24:01 amAgree that the simplest solution is to simply use a different antenna, but there are plenty of antennas that can be adapted to NVIS operation: e.g. a simple dipole mounted lower to the ground or a mobile HF vertical bent to form a half loop.

author: p.larner
author_rank: Frequent Contributor
timestamp: October 10, 2023, 09:09:30 am
content: i dont have room for a dipole pr doublet for 80 and up tho.

author: pdenisowski
author_rank: Super Contributor
timestamp: October 10, 2023, 10:56:37 am
content: Quote from: p.larner on October 10, 2023, 09:09:30 amI feel your painI'm using an attic dipole cut for 20 meters (tunable down to 40) as my only non-portable HF antennahttps://cdn-bio.qrz.com/z/ko4lz/dipole_2015.JPG?p=4e3571063527aab3a29da519b141ae05I'm not an antenna expert, but I think it's going to be hard to have a physically small NVIS antenna on 80m without a tuner (and the compromises that go with that).DX Engineering has an interesting design for an 80m NVIS antennahttps://static.dxengineering.com/pdf/wp-nvis-rev2.pdf
NLJD frequency under 800MHz? - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: September 18, 2017, 10:35:35 pm
content: So looking at the industry, I see that NLJD typically will stimulate between 800 to 4000MHz.Does anyone know why this lower bound of 800MHz was set? The upper bound I understand, I found it rather finicky to pickup the 12GHz harmonic of stuff (slight movement of objects around the room effects the reading), plus there is heavy attenuation. I feel that above four gigahertz you would need to basically setup a empty room or use an anechoic chamber (so its more like a lab tool).I can't find anything on the market that does less then 800MHz. I figure there would be benefits of cost, ease of manufacture, etc.Interference with official bands? Most things wont mix it (is this a frequency when things stop being microwavy)? antenna too big for commercial use (thought it might be hard to make an antenn that does 400, 800 and 1200 MHz? I thought that penetration into objects would be superb, and so would return loss from the emitter being stuck inside of something.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: September 19, 2017, 01:15:24 pm
content: What is NLJD?

author: isecus88
author_rank: Contributor
timestamp: October 09, 2023, 11:06:35 am
content: NLJD stands for Non-linear Junction Detector. It is also called harmonic radar. It emits a fundamental wave signal, receives the 2nd, 3rd or even higher harmonic/combined wave echo signals re-radiated from the target, and detects them. It is a Radar system for target judgment, identification and detection. Compared with general fundamental wave radars that only receive fundamental wave signals, harmonic radars can not only obtain fundamental wave channel information from the target, but also obtain 2nd, 3rd and higher information. Besides, Harmonic radar has better clutter suppression than ordinary radar and has stronger filtering capability.Natural objects generally do not have the ability to re-radiate harmonics, such as mountains, oceans, land, etc., and purely man-made objects such as metal blocks will not produce harmonic radiation. Only the place where two metals combine to produce oxides (MOM) will produce harmonic radiation. Wave radiation, the most representative is the metal oxide and semiconductor PN junction.In view of this characteristic, NLJD can be used to detect various electronic equipment, explosive electronic control devices, eavesdroppers, recording equipment, etc, no matter they are powed on or off. The NLJD equipment are widely used in public security, confidentiality and other fields.Hope now it is much clear.

author: TimFox
author_rank: Super Contributor
timestamp: October 09, 2023, 01:51:07 pm
content: Good technical journals require that the first time an abbreviatable term is used, it is spelled out.Later uses in the article can then use the abbreviation.
CST analytical Curve - Page 1
Forum section: electronics / rf-microwave

author: katto01
author_rank: Newbie
timestamp: October 05, 2023, 12:36:56 pm
content: Hello,I am trying to build in CST a spiral using the analytical curve command. I do not see an option to define the number of point in the curve.Am I missing somehting?Please adviseThank you

author: RoV
author_rank: Regular Contributor
timestamp: October 05, 2023, 09:48:39 pm
content: I think it is automatic, based on settings of "View options" "Shape accuracy" as regards graphic display, and perhaps dependent on mesh setting for simulation.
Monopole Antenna Impedence - Page 1
Forum section: electronics / rf-microwave

author: Cujo
author_rank: Regular Contributor
timestamp: October 04, 2023, 08:14:50 am
content: Would the impedance of a monopole antenna increase linearly with relative permittivity when different adhesive tapes/insulator are applied to the antenna, or should there be a non-liner relationship? Not sure if this is correct becasue its saying that electical tape has the smallest impedence? Should it be the highest?

author: szoftveres
author_rank: Regular Contributor
timestamp: October 04, 2023, 01:28:10 pm
content: Need some context - is this a longwire antenna, or a miniature GHz antenna on a PCB? A longwire antenna wire is usually made of insulated wire but the Er of the insulation is mostly negligible because the thickness vs. wavelength ratio.Antenna impedance is also a function of antenna tuning, which will change as you change the dielectric around it.

author: coppercone2
author_rank: Super Contributor
timestamp: October 05, 2023, 01:01:17 am
content: this is too broad to answeri also don't know what you are asking. the impedance of a electrical tape is dielectric and hard to measurethat graph looks like its relevant to coaxial cable, not antennas. They wrap coax cables in strips like a mummy to make special coaxes. Instead of foam or solid core dielectric. They suck to work with. and that graph makes no sense to me. What the hell is supposed to be on the line between the tape types? Some kinda hybrid tape? like its mutating to turn into electrical tape by quantum chemistry?I assume what they did is model a section of whatever, changed the parameter and then labeled certain points with materials that actually exist commercially.You need the model that was used with the graph. There is an unknown object in a simulator that produces that graph when you change dielectric materials properties in some element of the model. We can't tell you what that might be.
Random microstrip observation - Page 1
Forum section: electronics / rf-microwave

author: KE5FX
author_rank: Super Contributor
timestamp: September 28, 2023, 12:56:55 am
content: If you press #40 AWG insulated copper wire down against an unbroken copper-clad board, you get something resembling a usable 50-ohm transmission line:Calculating or measuring the loss is left as an exercise...

author: ywara
author_rank: Contributor
timestamp: September 30, 2023, 12:30:47 am
content: Any idea what the insulation on your wire is?TNT is telling me that with 40 AWG, 578 microinches of air between a bare copper wire and a ground plane makes a 50 ohm line. I suspect you are using magnet wire with a Dk of ~= 3 for the enamel, but TNT can't simulate circular dielectrics. I see 4 ohms per meter, which is quite lossy, but maybe acceptable for small assemblies.If Dk is in the range of typical plastics, the gap jumps way up if I approximate a circle as a square. What is the diameter you measure with a micrometer? I would guess it is closer to .006 vs. the .0031 diameter of 40 AWG.

author: KE5FX
author_rank: Super Contributor
timestamp: September 30, 2023, 09:49:23 pm
content: Quote from: ywara on September 30, 2023, 12:30:47 amIt'sthis stuff, or P155 inthis chart.0.003 in / 0.079mm nominal diameter; it measures 0.08mm with a caliper (no micrometer on hand).One site claims that the dielectric constant of polyurethane is near 10, but I don't know how believable that is.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 01, 2023, 01:42:57 pm
content: Enamel wire gives quite low Zo in typical setups, yes.https://www.eeweb.com/tools/wire-microstrip-impedance/Consider 0.1mm dia., 0.05mm height, k = 2 (the dielectric will be hybrid between the enamel coating and surrounding air; you'll have to measure c_0 to get a better idea of it), Zo = 60.8Ω.Twisted pair can be quite low, with the gap being consistently small; want to say I've measured below 50 ohms before. Implying flat microstrip could be below 25.Tim

author: rfclown
author_rank: Frequent Contributor
timestamp: October 01, 2023, 03:41:24 pm
content: Once I found that I could use two conductors from standard ribbon cable for 100 ohm differential lines. I was working with 1G Kx Ethernet, and needed to run a few Kx signal pairs on a board to test some things. It seemed from the dimensions of the wire that it would be close to 100 ohms. To see, I soldered a resistor (200 ohms or 50 ohms, forget which) to one end of some line that would be at least half a wavelength, and SMA on the other. With VNA saw that I got the expected circle on the Smith chart around 100 ohms. It ended out that it worked well enough to test what I needed to test so that when we respun our PCB, I had at least verified the circuit.
Narda 8631 Isotropic Field Probe Teardown  - Page 1
Forum section: electronics / rf-microwave

author: Maruku
author_rank: Contributor
timestamp: September 27, 2023, 08:40:36 am
content: Hi,I am trying to understand the methods of measuring fields in TEM/GTEM and I came across some "isotropic" detector designs but not a lot out there.Anyway I got a beaten up Narda 8631 probe and tried to carefully take it apart. What I found on the sphere were three antenna loops with small PCB's that had a capacitor and what I thought was a detector diode. When measured the element it had same resistance from both directions and all three were different resistances.Will post some more photos if anyone is interested but the element photos are what interest me, I have no idea what they areAnyone ever came across this or can explain what it does?

author: Maruku
author_rank: Contributor
timestamp: September 28, 2023, 10:38:37 am
content: Also if someone is interested this is how the field probe antenna section looks like:
From Raw Crystal to Crystal Oscillator - Crystals go to War in 1943 - Page 1
Forum section: electronics / rf-microwave

author: BrianHG
author_rank: Super Contributor
timestamp: September 27, 2023, 06:55:56 pm
content: Man, those crystals are huge. It's also surprising that they even got anything to work.On the shipping container of the raw uncut quarts crystals:"Damage to this vital war material is SABOTAGE. Please handle carefully."

author: Grandchuck
author_rank: Super Contributor
timestamp: September 27, 2023, 08:01:25 pm
content: OSHA would have shut down the factory!

author: BrianHG
author_rank: Super Contributor
timestamp: September 28, 2023, 12:13:33 am
content: See what modern synthetic quarts crystals look like and how they are made today:(Skip to 3 minutes in...)
Design and tuning of 2.5 Ghz, 1/4 wave, monopole "whisker" antenna - Page 1
Forum section: electronics / rf-microwave

author: davethomaspilot
author_rank: Contributor
timestamp: September 22, 2023, 12:46:00 pm
content: I need a simple 2.5 Ghz receive antenna.One end needs to be U.FL, so I bought U.FL to SMA cable and an simply stripped the insulating braid off a RG178 coax. I went for 27 mm, which is shorter than the calculated 2.5 Ghz wavelength, even considering velocity factor. But, I've seen this length several places on line for a 2.4 Ghz--and 2.5 should be shorter still.Reception is adequate, so I could just leave it at that. But, I have a Lite VNA and figured I would figure out what active length was optimal. I found that the length of the shielded part of the coax had a very significant effect on the resulting SWR as measured by VNA. In fact, picking the right overall length of the cable seems to have a bigger impact on SWR than the length of exposed conductor.Does this make sense? If so, does some one have a reference on how to design an antenna like this that includes consideration of the overall (or shielded) length of the cable?(I suspect it needs to be a multiple of wavelength/4)

author: davethomaspilot
author_rank: Contributor
timestamp: September 23, 2023, 01:15:53 pm
content: Gave up on the monopole--I couldn't get measurements on the VNA to make sense or get a reasonable return loss.So I tried doing a dipole by folding back the shield instead of cutting it off. Now everything makes sense and I can get a good SWR/return loss.I'm concluding that the folks doing the online videos that show making the monopole by just stripping the shield off the last 1/4 wavelength (and saying the length of the shielded part doesn't matter) never actually checked them out on a VNA.I'd like to know if someone disagrees---learning as I go.

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: September 24, 2023, 02:01:30 am
content: Do you have a good ground plane for your monopole?

author: davethomaspilot
author_rank: Contributor
timestamp: September 24, 2023, 09:59:52 am
content: In the application, the ground plane is the pcb ground plane.Presumably, the VNA's pcb and metal case provide the counterpoise while testing.If either of those is insufficient for consistent return loss at 2.5 Ghz, that's reason enough to take the extra time to make a dipole instead of the monopole.Thanks
Tunable Loop Antenna for the AM Broadcast Band project - Page 1
Forum section: electronics / rf-microwave

author: jonovid
author_rank: Super Contributor
timestamp: September 08, 2023, 02:38:37 am
content: made this AM Broadcast Band Loop Antenna from an old wooden hula hoop., 30 meters of copper wire & a dual 360pf air variable capacitor unit. it improves the AM receptionbut the shortwave side of it has no been tested as a feed line is yet to be added.but may not work as planned. as my research suggests that this type of loop antenna is not the best design for shortwave reception.the loop is completely held together with wood glue having no metal fasteners used in its upper hoop design.toothpicks was use as fastenering pegs.also has a platform for the radio to sit on and pvc tube in its base so it will set on a tripod standthe 80cm diameter hoop. can sit two meters off the floor if needed.the indoor Loop Antenna can cut through the noise on the AM Broadcast Band even in city reception.interstate radio stations can be heard in between local stations.image had been edited to remove background objects that are not part of the antennaupdate-further fine adjustments to the inductance capacitanceso the tuning range sits with in medium wave & long wave radio band.adding capacitorsshortwave was disappointing beyond 4MHz.

author: jwet
author_rank: Frequent Contributor
timestamp: September 19, 2023, 01:23:18 pm
content: This is nice work! I hope the SW results don't disappoint. As the frequency goes up, tiny parasitics can ruin things. I wonder if using Litz wire could extend the frequency range. Good luck.
Yaesu FTM-3100R alignment mode - Page 1
Forum section: electronics / rf-microwave

author: Rik
author_rank: Newbie
timestamp: September 23, 2023, 11:03:58 am
content: Yaesu FTM-3100RThe service manual says to hold SQ and TXPO keys while turning on radio to enter alignment mode. I have two radios for a ham friend, and neither responds to holding those keys down. Anyone know how to enter alignment mode on the FTM-3100R?Rik RasmussenWA4BAN

author: xrunner
author_rank: Super Contributor
timestamp: September 23, 2023, 11:14:10 am
content: I don't have that particular model, but I've done a lot of service menu alignments on Yaesu radios.The only suggestion I have if those keys are correct, is to actually remove power from it to "turn it off", meaning turn off the power supply or disconnect it, and apply power from the external supply to "turn it on". Some of these radios are not really "off" just because the power button was used. There are still internal circuits still on.So with the radio "on", just remove power (don't use the power button), and same goes for power "on", re-apply power holding those keys down for the service menu.That's all I can offer.

author: Rik
author_rank: Newbie
timestamp: September 24, 2023, 05:58:41 pm
content: I had not paid enough attention to a previous page in the Technical Supplement that explains how to enter a password. This has to be done first, then you can enter the alignment mode. Doing that, it works OK.
Looking for "VEM 290" PA modification for 144 MHz. SP6GZZ et al. - Page 1
Forum section: electronics / rf-microwave

author: Uky
author_rank: Regular Contributor
timestamp: May 29, 2023, 12:47:56 pm
content: Greetings.Looking for a schematic and modification instructions for surplus PA modules using 2 x SML D1028UK transistorsto be modified for 144 MHz use. I have found some pictures and texts on the internet referring to SP4MPB,SP2DMB, SP7DCS, OK1VPZ et al but not the documents that I have seen and mistakingly did not ask forphoto copies from. The PA is marked "VEM 290" and according to the pictures, these can easily be modifiedand most likely, I can do this judging from the pictures but in order to be absolutely sure, it would be niceto have the detailed schematic where the added components can be seen and precisely located.Ulf KylenfallSM6GXV

author: raftronik
author_rank: Contributor
timestamp: June 03, 2023, 01:12:56 pm
content: Hello,maybe here is some infohttps://so3z.com/?page_id=820

author: raftronik
author_rank: Contributor
timestamp: June 07, 2023, 04:27:12 pm
content: I found .pdf file with some info, but it is in Polish, I can send it to you.I could translate to english but it take me long time.

author: oh4mvh
author_rank: Newbie
timestamp: September 17, 2023, 05:23:31 pm
content: hello,if there is more comprehensive .pdf article available somewhere linked on that page above, I would be interested in to get a copy of that .pdf, even if it is in Polish.73 Petri

author: raftronik
author_rank: Contributor
timestamp: September 18, 2023, 07:07:48 pm
content: Hello,Everything I found :https://so3z.com/?page_id=820One link is missing but I've attached it

author: raftronik
author_rank: Contributor
timestamp: September 18, 2023, 07:09:45 pm
content: Second part what I have.
MOVED: Quick comparison Siglent 3032X-R vs Rigol RSA3030N - Page 1
Forum section: electronics / rf-microwave

author: ehoernchen
author_rank: Contributor
timestamp: September 13, 2023, 10:34:50 am
content: This topic has been moved toTest Equipment.https://www.eevblog.com/forum/index.php?topic=391951.0
new SATSAGEN v.0.8.0.0 - Page 1
Forum section: electronics / rf-microwave

author: albfer
author_rank: Contributor
timestamp: September 09, 2023, 04:38:33 pm
content: Hi!SATSAGEN v.0.8.0.0 is ready to download:https://www.albfer.com/satsagen-download-page/#contentHighlights:- Noise Figure and Gain Analyzer- Digital Phosphor Display- Zero Span- USRP B200mini and NI USRP 2920 support- AS7265x spectrometer supportCheersAlberto
A formula for input matching with a source inductor - Page 1
Forum section: electronics / rf-microwave

author: LM21
author_rank: Regular Contributor
timestamp: September 15, 2023, 08:36:07 pm
content: There is way to get a good noise match of a fet with only a source inductor. Does anybody know where I could find a formula and more info about it?

author: RFDx
author_rank: Regular Contributor
timestamp: September 16, 2023, 06:15:46 am
content: John Rogers & Calvin Plett (2003): Radio Frequency Integrated Circuit Design, Artech House, Boston/London.Chapter 6.3.3 (p163): Input Matching of LNAs for Low Noise.

author: radiolistener
author_rank: Super Contributor
timestamp: September 18, 2023, 03:44:25 pm
content: Quote from: RFDx on September 16, 2023, 06:15:46 amRadio Frequency Integrated Circuit Design, Second Edition, John W. M. Rogers Calvin Plett, 2010 ARTECH HOUSEpage 191: 7.3.4 Input Matching of LNAs for Low Noise

author: LM21
author_rank: Regular Contributor
timestamp: September 18, 2023, 05:49:32 pm
content: Thank you both. Now I don't have to visit university Library.

author: LM21
author_rank: Regular Contributor
timestamp: September 18, 2023, 06:04:19 pm
content: At a quick read I see that this book uses ICs as even its name says. Things are different when you cant spread the fet gate, I'll buy a fet or bipolar. (Or I 'll use a low noise RFIC.) Do you know is there enough info here to use ontheself transistors.

author: RFDx
author_rank: Regular Contributor
timestamp: September 18, 2023, 11:54:18 pm
content: Quote from: LM21 on September 18, 2023, 06:04:19 pmYou can use any off the shelf transistor(s) you like. Attached are two simple examples, 2m RF preamps with 50 Ohm I/O. The first preamp with a BFR106 (@5V/25mA) BJT and the second with J309 JFETs in cascode configuration, both not optimized for lowest possible noise.
specs for 11729-60014 LNA HP (benchtop worthy box) - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: August 30, 2023, 01:20:22 am
content: There is alot of them on ebay. Part of some EMC test set. Can't find any specifics on the amp like noise.ANyone know anything? is it good?

author: xmo
author_rank: Regular Contributor
timestamp: August 30, 2023, 04:29:20 pm
content: From PN 11729C-2The baseband signal is further processed through a Low Noise Amplifier (LNA)...The amplifier has approximately 40 dB of gain (coupled into 50 ohms) and a bandwidth of about 10 Hz to 30 MHz. Typical flatness is less than 1 dB and the noise figure is less than 2.0 dB.

author: coppercone2
author_rank: Super Contributor
timestamp: August 31, 2023, 04:30:09 am
content: hmm thats decent
Radio-Wave Battery-Charging for Off-Grid Device? - Page 1
Forum section: electronics / rf-microwave

author: IdahoMan
author_rank: Regular Contributor
timestamp: August 29, 2023, 06:25:18 am
content: Say I want to keep a battery charged for a low-power device (sensor) or higher-powered device that would be used rarely (once a week? month?) in a heavily wooded area where solar-power would not work, just how possible is it to keep a battery charged via common radio (AM/FM/SW/etc.)?Antenna size/type?How can I measure the power an antenna is receiving?Best long-term battery type for such a project?Thank you.

author: jwet
author_rank: Frequent Contributor
timestamp: September 03, 2023, 07:15:46 pm
content: I played with a project like this as a kid in the 60's! It was from a book called 103 Simple Transistor Projects by Tom Kneitel (IIRC). I found the book in a dusty part of my bookshelf and photographed the circuit. Its sort of a crystal set that rectifies and filters what's available. The author says you can get 300 uA at 3v or 1 mA at .8v. I don't remember but this sounds about right, it wasn't much and I lived near a city. I used a very long wire antenna (100') and a ground stake.Thinking today, I might make it kind of lower Q to get the whole AM band basically or perhaps build multiple receivers LC plus a diode tuned to several stations and or'ing them together.Your other question about measuring power, you need a field strength meter or a spectrum analyzer. You could use a reciever if you get clever. Ask a ham operator for some help.I've build a fair amount of remotely powered stuff mostly for Ornithologists. I would try solar first even if you think you're shaded etc. Find a location where there is some sun at some time in the day. Use an energy harvesting chip (LTC/Analog Devices make them). They will take a feeble output and charge a battery. A small gel cell lead acid or a NiMh battery would be best probably. You could also try a supercap but you'll need pretty low leakage. You could have a comparator that watches the battery/cap and sends a burst when it gets enough. I would just sort of be a relaxation oscillator that will do its best. You'd get more message when the weather was good and less otherwise. You might also consider other EH techniques like wind.Another technique is just to use an oversized battery with good storage life and forget charging. Modern alkaline cells have shelf lives of many years especially when loaded very lightly. I've built audio players that play bird calls at sunrise or sunset for an hour or so. They use a 12v 35AHr lead acid (mini car battery) that lasts about a year of playing for an hour a day.I googled RF Energy Harvesting and got this link.https://www.eetimes.com/powering-the-future-wirelessly-with-rf-energy-harvesting/#:~:text=RF%20energy%20harvesting%20is%20the,current%20(DC)%20power%20source.Below is circuit from my childhood- post your results and enjoy!
Smith chart? To the load or to generator question. - Page 1
Forum section: electronics / rf-microwave

author: mr ed
author_rank: Regular Contributor
timestamp: September 03, 2023, 02:07:53 am
content: I am taking it upon myself to learn something on microwaves so this is a Smith chart question by a newby..I intend to design a frequency multiplier using just diodes. As I understand it two back to back diodes can work as a freq tripler (the 2nd harmonic is somewhat suppressed).I can work the matching net from the diodes to the generator input using the 1/ 4 wavelength trick and a short z matching line in series. What to do for the output side? Do I consider the diodes as a new generator at 3x freq and work to the load? Or from the load impendance to the generators? There should be a 180 degree error if I get this wrong, I think.The circuit would be a series of microstrips...50 ohm in, 1/4 match, short z match to 2 diodes , z match at 3x freq , 1/4 match at 3x and 50 ohm out

author: szoftveres
author_rank: Regular Contributor
timestamp: September 03, 2023, 05:53:52 am
content: Diode has varying characteristics based on the operating point (i.e. how hard it's being driven, ambient temps, etc..).In practice, the driving signal is plenty, there's no concern about snr or too low signal levels - you just need good filtering in order to get rid of all unwanted components.it's quite unusual to make a perfect matching network for a simple diode multiplier, as it doesn't provide any practical benefit, and severely restricts the operating conditions of the multiplier to a very certain input signal level.

author: geggi1
author_rank: Frequent Contributor
timestamp: September 03, 2023, 06:53:57 am
content: Google Charles Wenzel for his publications on 3x and 5x multipliers.

author: mr ed
author_rank: Regular Contributor
timestamp: September 03, 2023, 10:43:05 am
content: The diode operating point chosen is 0 to 10dbm where the dv/di curves are quite straight so the pure resistance is known. Typical capacitance and package inductance are given but not locked down per diode so yes, it's a bit of an unknown. Some diodes have smith charts that wander around by frequency. I assume the output diode impendance is figured at 3x freq but my question is still how to do a z match on the output?
Where to get a Yaesu FT-100D repaired - Page 1
Forum section: electronics / rf-microwave

author: W4TMJ-Tom
author_rank: Newbie
timestamp: August 10, 2023, 07:04:59 pm
content: I purchased the transceiver new when it first came out. Shortly thereafter the VHF & UHF RF outputs failed. This is a known problem related to the VHF/UHF output device. After repair by Yaesu it failed again. Now Yaesu cannot repair it because the original output device is no longer available. I understand, however, that there is another compatible device available & inexpensive. I do not have the tools to make the repair so I'm looking for someone that can do this for me. All suggestions welcome.

author: geggi1
author_rank: Frequent Contributor
timestamp: August 28, 2023, 04:11:02 am
content: https://www.radcomms.net/FT100D_repair.html
Sonnet rectangle drawing - Page 1
Forum section: electronics / rf-microwave

author: prutser
author_rank: Regular Contributor
timestamp: August 15, 2023, 11:15:53 am
content: I started to use Sonnet lite. I am trying to find out how specify length and with of a rectangle when drawing a geometry. The only way I can find out is dragging a rectangle withthe mouse and looking at the dimensions in the status bar. I cannot believe that's the only way to specify rectangle dimensions.I check the help file, but also couldn't find a clear answer.Anyone here who know how to do this ?

author: RFDx
author_rank: Regular Contributor
timestamp: August 16, 2023, 03:26:31 am
content: Quote from: prutser on August 15, 2023, 11:15:53 amToolbox/Rectangle. A dialog box opens where you can input the dimensions you need.

author: prutser
author_rank: Regular Contributor
timestamp: August 18, 2023, 08:04:49 am
content: Thanks for the reply. I am using Sonnet Lite v18, but unfortunately it does not seem to have the toolbox

author: BigBoss
author_rank: Regular Contributor
timestamp: August 19, 2023, 07:48:07 am
content: Quote from: prutser on August 18, 2023, 08:04:49 amThe new User Interface of Sonnet 18 is different. Look at left bottom, yo'll see a coordinate entry window. type your dimensions (relative, absolute or polar ) and draw your
RF-Tight Waterproof Enclosure? - Page 1
Forum section: electronics / rf-microwave

author: clansd99
author_rank: Contributor
timestamp: August 15, 2023, 11:43:56 pm
content: Hi all,I am looking to source a few thousand RF-tight waterpoof enclosures for a University project.The board will be ~45x30mm with two SMA connectors. Any suggestions regarding a potential supplier for the enclosures?-Chris

author: jpanhalt
author_rank: Super Contributor
timestamp: August 15, 2023, 11:59:22 pm
content: Here's a company that specializes in RF enclosures:https://lmbheeger.com/I have used the "drawn steel" version that can be easily soldered water tight.

author: Gribo
author_rank: Frequent Contributor
timestamp: August 16, 2023, 07:37:21 pm
content: There are few vendors that make such enclosures:Bopla, Hammond, few others. Some offer customizations of the panels.
New TinyPFA Phase Frequency Analyzer - Page 1
Forum section: electronics / rf-microwave

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: August 05, 2023, 07:30:20 am
content: For those who need to set their counter, signal generator, rubidium standard, etc, using an off air standard, the TinyPFA is useful.The new PFA is starting to ship, but for those with a TinyVNA-H4 they can load the PFA firmware as it is the same hardware! Something for free. You can switch back to using the 'H4 as a VNA by re-loading VNA firmware.Details:https://www.tinydevices.org/wiki/pmwiki.php?n=TinyPFA.HomepageIn Europe the TinyPFA can be obtained fromhttps://eleshop.eu/tinypfa-phase-frequency-analyzer.htmland soon fromhttps://www.mirfield-electronics.co.uk/Both the above are official "Tiny" suppliers.SJ
[SOLVED] LiteVNA client/saver for Linux? - Page 1
Forum section: electronics / rf-microwave

author: szoftveres
author_rank: Regular Contributor
timestamp: August 05, 2023, 02:31:16 am
content: NanoVNA worked really well with the web clienthttps://cho45.stfuawsc.com/NanoVNA/however LiteVNA doesn't seem to be able to connect - the client recognizes the USB port but unable to connect.I've also tried the "official" linux NanoVNAsaver, which failed to start and gave a Segmentation Faulthttps://drive.google.com/drive/folders/10lU5xnwmHDnPX98z21ky09N8nb_cEOk4Does anyone have a working solution?

author: rteodor
author_rank: Frequent Contributor
timestamp: August 05, 2023, 03:20:31 am
content: Isnn't the python client fromhttps://github.com/NanoVNA-Saver/nanovna-saver/releases/working ?I had to modify a line of code to make it work:Code:--- NanoVNASaver/Hardware/VNA.original.py2022-04-01 17:51:11.000000000 +0300+++ NanoVNASaver/Hardware/VNA.py2022-06-19 12:40:02.514619396 +0300@@ -111,7 +111,8 @@continueif line == command: # suppress echocontinue- if line.startswith("ch>"):+ #if line.startswith("ch>"):+ if (-1 != line.find ("ch>")):logger.debug("Needed retries: %s", retries)breakyield line

author: szoftveres
author_rank: Regular Contributor
timestamp: August 05, 2023, 04:05:09 am
content: Thanks, thishttps://github.com/NanoVNA-Saver/nanovna-saver/releases/download/v0.6.2/NanoVNASaver.linux_modern.zipseems to be working, with no modifications.
Issue with matching network design using LTspice and SmithV4.1 - Page 1
Forum section: electronics / rf-microwave

author: YoungRF555
author_rank: Newbie
timestamp: August 01, 2023, 03:42:59 pm
content: Forgive me if I am overexplaining my issue I am very new to match design.I am trying to match a highly inductive load and am restricted to L (Source-Cshunt-Cseries-Load) or InvL (Source-Cseries-Cshunt-Load) networks. I can make these networks easily with smithV4.1 but when I model them in LTspice I get wildly different results (off by ~60+j200 at most) . I am modeling the networks two ways and the error persists. The first is modeling the network to have the expected load and tuning to have the Zin get as close to 50+j0 as possible. The second way is modeling the load as 50ohm and tuning the Zin to as close to the complex conjugate of the load. I have tried rebuilding the networks on SmithV4.1 and LTspice many times as well as triple checking the AC analysis on LTspice. I can "tune" the network to show the Zin that I want buy my values are off by factor of 10 or 100. I have also simulated many matches in the past (L and InvL with mix of LC) and have had much better luck in getting a closer match initially. I am aware of the error that would occur solely due to the inaccuracy n mouse movements in SmithV4.1 but I feel the margin of error I'm receiving for these only capacitive matches is something more than that.Any help or guidance in this matter would be greatly appreciated. If there is a more efficient or robust way to simulate matching networks please let me know.EDIT0: .asc of the match is now attachedEDIT1: Solution was to use a resistor in series with reactive component to make complex impendence spice does not like complex values for resistors.

author: RFDx
author_rank: Regular Contributor
timestamp: August 02, 2023, 07:33:18 am
content: How about showing where the problem is instead of describing it.

author: Hamelec
author_rank: Regular Contributor
timestamp: August 02, 2023, 03:10:17 pm
content: if you only have a highly inductive load without resistive part there is nothing to match to 50R except the losses of the L..

author: iMo
author_rank: Super Contributor
timestamp: August 02, 2023, 03:24:33 pm
content: Quote from: Hamelec on August 02, 2023, 03:10:17 pmThe losses in L are caused by the "resistive" part there in XL.As recommended above, we communicate via schematics, or .asc files when talking stuff in the LTspice.

author: YoungRF555
author_rank: Newbie
timestamp: August 03, 2023, 01:07:26 pm
content: Apologies I meant to attach my files. Thanks for the heads up

author: YoungRF555
author_rank: Newbie
timestamp: August 03, 2023, 02:12:28 pm
content: .asc is posted now my apologies

author: RoV
author_rank: Regular Contributor
timestamp: August 03, 2023, 08:18:25 pm
content: LTSpice doesn't like a complex value for resistance. Strangely it doesn't complain, but if you use (in your example) R=2.2 ohm in series with L=610 nH (X~=52 ohm @ 13.56 MHz), you get close to 50 ohm at the source.

author: YoungRF555
author_rank: Newbie
timestamp: August 04, 2023, 01:17:32 pm
content: That was exactly the issue, many thanks
Sony ICF-SW55 adjustements - Page 1
Forum section: electronics / rf-microwave

author: nikitasius
author_rank: Regular Contributor
timestamp: August 03, 2023, 08:44:40 am
content: Hi folks!Recently i paid for me pretty nice vintage radio Sony ICF-SW55 s/n 944295 and i had it w/ good price. Well, it's "working". Some caps are pissed everywhere, maybe few nearly passed away but the PCB is in a pretty good state.Actually i'm building a list to buy new caps & some ceramics (wanna pass w/ scope & check ripple on power line).The main question is this that in original docs: big pdf page 24gdriveor small pdf page 24 alsogdriveit says "tune AM 4155 WIDE and go on TP47 to pickup60MHz", while in docs TP47 have 6.275MHz and i measures (even w/ dying caps) 6.27408MHz . So i can't get in.. or thats due bad caps i have correctly indicated freq or there are typos in official docs.Also all PCB's testing points have ref frequency on it (just the freq w/o tolerance +-).If someone know, please share w/ me your ideas or, maybe correct documentation. This is whole folder btw,gdrive.Attachements:screenshot from official docs clearly says 60Mhzphoto w/ green ground and red tp47collage of schema from docs & schema from adjustement pagefreq from my scope which show 6.27408MHzP.S. always wanted to have a SW radio. When i was kid a had one.. it was long time ago..

author: Hamelec
author_rank: Regular Contributor
timestamp: August 03, 2023, 09:22:05 am
content: IC8 Pin6 = TP47 is the frequency of the Xtal Oscillator with 6.275MHz.Your Oscilloscope Probe will detune the oscillator - put 10kR or so in front of your tip to adjust CT6 for the correct frequency.

author: nikitasius
author_rank: Regular Contributor
timestamp: August 03, 2023, 10:08:51 am
content: Quote from: Hamelec on August 03, 2023, 09:22:05 amthanks! But the issue is that official docs asking to pickup 60MHz

author: Hamelec
author_rank: Regular Contributor
timestamp: August 03, 2023, 08:30:48 pm
content: you should have a look to your linked schematic page 27, than you can see whats going on.

author: Hamelec
author_rank: Regular Contributor
timestamp: August 04, 2023, 08:50:50 am
content: the test points are mixed up:TP47 on the PCB is TP48 in the schematic..
AX.25 for APRS with FSK Modulation - Page 1
Forum section: electronics / rf-microwave

author: kml183
author_rank: Contributor
timestamp: August 01, 2023, 08:03:08 pm
content: Hi there!I am working on some code for a little packet modem that you can interface with over UART/I2C that will support the AX.25 specification. I am using a FSK modulator over RF for my physical layer (si466x G(FSK) chip).Is it likely that my transmissions would be picked up by a station that relays information to a site likehttps://aprs.fi?What baud rates are reasonable for APRS?

author: ftg
author_rank: Frequent Contributor
timestamp: August 02, 2023, 07:58:30 am
content: For 2m amateur band it is 1200baud Bell 202 and essentially nothing else when it comes to pure packet APRS.Many DMR radios can also send their position along the network, but that is a pure data packet over DMR, even if it eventually shows up on APRS.fi.There is also 70cm LoRa APRS that uses LoRa for sending the APRS packets.But +90% of all APRS traffic is 1200baud Bell 202 AFSK.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: August 02, 2023, 08:21:50 am
content: Listen on 144.8000 and see if you can hear traffic. You could start with decoding... that would prove most of your implementation including checksums etc.Have fun! This project is a bit of a rite of passage... go for it!

author: nixfu
author_rank: Unknown
timestamp: August 02, 2023, 12:45:47 pm
content: > 144.8000Its 144. 390 in North America.
Combinining snp files into a single snp - Page 1
Forum section: electronics / rf-microwave

author: jmonette
author_rank: Contributor
timestamp: July 27, 2023, 01:07:31 pm
content: I only have access to a 4 port VNA and have a 5(or more) port device. I was wondering how can one export several s2p/s4p files to combine it in a sNp (N=number of ports). I understand the math behind it, I was wondering if their is any utility that can do it quickly.Right now, I do it using ADS, it takes time and, most irritating, requires ADS! Since I work a lot with Wolfram Mathematica, I tough coding a script to do it but I can't believe I'm the first one with that issue. Do you have any quicker solutions? Thanks!

author: hendorog
author_rank: Super Contributor
timestamp: July 27, 2023, 06:38:01 pm
content: Possibly:https://scikit-rf.readthedocs.io/en/latest/tutorials/Networks.html

author: jmonette
author_rank: Contributor
timestamp: July 31, 2023, 03:45:37 pm
content: Thanks, I wasn't aware of that library! I'll give it a go!
TETRA:BURST (TETRA vulnerabilities) - Page 1
Forum section: electronics / rf-microwave

author: madires
author_rank: Super Contributor
timestamp: July 24, 2023, 08:14:00 pm
content: Media:Researchers Find ‘Backdoor’ in Encrypted Police and Military Radios (https://www.vice.com/en/article/4a3n3j/backdoor-in-police-radios-tetra-burst)The researchers:TETRA:BURST (https://tetraburst.com/)

author: Faranight
author_rank: Unknown
timestamp: July 25, 2023, 07:37:26 am
content: Yep, this is why you never accept shady cryptographic systems that are under NDA's.If you ever see such a system, take it as a red flag and walk away from it (or better even, run away from it).

author: Marco
author_rank: Super Contributor
timestamp: July 25, 2023, 11:00:02 am
content: EU lapdog attitude comes back to haunt them.

author: 3apw
author_rank: Contributor
timestamp: July 25, 2023, 11:38:53 am
content: TEA1 is the weakest air interface encryption algorithm in TETRA and mostly for commercial users.Not sure that TEA1 is used in real critical TETRA networks like BDBOS, Airwaves or similar ...

author: jc101
author_rank: Frequent Contributor
timestamp: July 25, 2023, 09:06:14 pm
content: Airwave uses TEA2, from memory. It's been a long time since I was involved in integrating it when first installed. It should have been replaced by the ESN in 2019, now not expected until 2026.

author: 3apw
author_rank: Contributor
timestamp: July 26, 2023, 03:39:13 am
content: Quote from: jc101 on July 25, 2023, 09:06:14 pmYour memory works well.Both biggest critical communication TETRA networks Airwaves (UK) and BDBOS (Germany) use TEA2 (never TEA1).Plus the next security mechanisms:mutual authenticationnational E2E encryptionAccording my information SFPG (Security and Fraud Prevention Group) of TETRAMoU (TCCA) did not never declare the case of the opening of the information communication channel in these TETRA networks.
Amateur On Air Entertainment - Page 1
Forum section: electronics / rf-microwave

author: jonovid
author_rank: Super Contributor
timestamp: July 13, 2023, 08:24:25 pm
content: are Amateurs supposed to post their own entertainment content over the air?I have been watchingIan VK3QLtelevision on youtube.its the most entertaining amateur radio/television I have seen for years.home video sharing over the air.with and music intro's video splash pages over a UHF VK3 Amateur repeater.when is this a broadcast? or running a radio/television program?now VK2 is also getting into this.this beats just swapping call signs. and the stuffy communicate only.

author: xrunner
author_rank: Super Contributor
timestamp: July 13, 2023, 08:57:57 pm
content: Speaking of US regulations ...You can't transmit music, so that is clearly out.You are supposed to be exchanging "communications" with specific amateur stations by call sign identifying every ten minutes. You can't simply broadcast amusing material to unnamed stations or anyone with a receiver, even if you identify.However, to another ham station, the material you talk about (barring the music) might be OK. Could be a gray area worth a discussion.

author: radiolistener
author_rank: Super Contributor
timestamp: July 14, 2023, 11:48:53 pm
content: Quote from: xrunner on July 13, 2023, 08:57:57 pmThis is if you're transmitting with your official callsign, but some radio amateurs with official callsign working also on a radio-pirate bands as a free radio amateurs and broadcast music and other things...

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: July 20, 2023, 10:52:25 am
content: Transmitted on VK3RTV. Every Tuesday night at 8pm.
Help with Part Identification - Page 1
Forum section: electronics / rf-microwave

author: Venturi962
author_rank: Regular Contributor
timestamp: July 19, 2023, 07:08:06 pm
content: Hello All,Trying to find datasheets for these two parts on a 2.4 GHz hobby radio control link. One is a switch marked '2244 5430' and another seems to be an LNA marked '5JZ3' or 'SJZ3'. Google didn't find anything obvious but the pinout seems to align with some SkyWorks parts. Photos attached. Many thanks.Edit:Switch seems to follow this pinout: SKY13348-374LFLNA seems to follow this pinout: SKY65971-11

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: July 22, 2023, 03:25:04 pm
content: The “2244” part could be a mixer, there is a pi attenuator on the track leading off to the left.SH