hybridfree/eevblog-posts huggingface dataset:
Measuring phase noise lower than the spectrum analyzer's own noise - Page 1
Forum section: electronics / rf-microwave

author: M0HZH
author_rank: Regular Contributor
timestamp: December 08, 2020, 12:33:11 pm
content: Trying to understand RF signal generator performance better with the ultimate purpose of doing receiver performance measurements (two-tone, RMDR, BDR, etc). At the moment I'm looking to measure / check signal generator phase noise and the problem I'm facing (partly limited by the equipment I have available) is that the spectrum analyzer's own noise masks the signal generator's phase noise.For example, my best spectrum analyzer's phase noise is -80dBc @ 10kHz offset (Rigol DSA815-TG) while the best signal generator's phase noise is -143dBc @ 10kHz offset (Rohde & Schwarz SMPD); the difference is quite significant.I know there are a few methods to go around this and I'm mostly tempted by using a crystal notch and amplifier, does anyone have more experience doing this and would be willing to share some recommendations ?

author: RoGeorge
author_rank: Super Contributor
timestamp: December 08, 2020, 12:51:15 pm
content: See if any of the links listed along the pages of this project are of any help:https://www.eevblog.com/forum/metrology/phase-noise-measurement/

author: cncjerry
author_rank: Unknown
timestamp: December 26, 2020, 04:46:25 am
content: I'm assuming you looked at my thread and the links I added. Crystal notch is not needed.You use a reference and phase lock it to the DUT or just shift the DUT 90 with a 1/4 wave length of coax. Using a Double Balanced Mixer with a 90 degree phase shift in either the DUT or the reference will reduce the fundamental. Low pass filtering will reduce the harmonics. Stepped amplification starting at +20dB increasing to +50dB will put you above the spectrum analyzer noise floor when using a +7dBm or high DUT signal. You will then be able to plot the remaining noise on a baseband FFT analyzer like an HP 3561a, 3562A, etc. Maybe a sound card with 384K sampling that will get you past 100k (offset from carrier). there are a couple of proponents of this method over the one I chose of using an FPGA with a high speed 14bit DAC. the advantage of the method I chose was the dual channel sampling allowed the author to reduce the noise substantially pushing the noise floor down to -180 or so. The author's FPGA method extends from 0hz to 350Khz.Jerry
Looking for FM audio RF transmitter module for 863-865MHz - Page 1
Forum section: electronics / rf-microwave

author: Fixup
author_rank: Contributor
timestamp: December 21, 2020, 12:05:25 am
content: Hi,Does anyone have some suggestions for a module or relatively simple "one chip type" FM transmitter that can be used for 863-865MHz?I have done some searching but have not found any good solution. Many FM transmitter circuits and stereo encoders seem to be obsolete or not found at dealers like Digikey etc.Alternative 2 would be to find some kind of stereo MPX encoder and also a suitable FM transmitter which frequency could be changed for channel selection.Alternative 3 would be using discrete parts...Would be thankful for some hint in the right direction

author: fmkit
author_rank: Contributor
timestamp: December 23, 2020, 08:34:35 am
content: for me it was easiest to upconvert using IAM-81008 mixer and SAW resonator osc.receiver and tx SAW osc. should differ (I used 427.2 and 433.9MHz) otherwise audio will be distorted

author: Teledog
author_rank: Regular Contributor
timestamp: December 23, 2020, 04:14:00 pm
content: Low buck one chip?How about a VCO? (ie: Z-comm)Watch for your favorite frequency band on eBay (search VCO MHz)- they pop up here & there, sometimes dirt cheap, other times stupid $$$$..Easy to use for FM - couple signal in via a cap to your frequency bias..not terribly stable though.. lots of phase noise, etc..but one chip!G'luck!

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 24, 2020, 11:26:59 pm
content: Is there a freq who is possible? Maybe you looking for some Audio Headphone Transmitter who work in that Area.
Low Cost 26 GHz  Rf Signal Generator (synthesized) Gigatronics 1026  vs HP...  ? - Page 1
Forum section: electronics / rf-microwave

author: rickells
author_rank: Regular Contributor
timestamp: December 25, 2020, 07:23:54 pm
content: -- I am wondering if there might be any recommendations about 26 GHz Signal Generators ??I am looking for a working, affordable 26 GHz Signal Generator in the 1.5K $ range.There is a Gigatronics 1026 26.5 GHz synthesized Signal Generator currently on eBay,seemingly much more affordable than a working HP 8340b.***It has included, a 26GHz Frequency Counter + Power Meter in the same box,.... so the 1026 seems like a better buy ??*** The specs suggest the Gigatronics 1026 has a lower noise output compared to the HP 8340b, which seems fine for basic experimenting at 26GHz ?The Gigatronics 1026 is shown tested and working with photos:https://www.ebay.com/itm/Gigatronics-1026-Synthesized-26-GHz-Signal-Generator-f-Counter-Power-Meter/154257335414?epid=1000617353&hash=item23ea742476:g:T3cAAOSwbI9eKQz9-- Does anyone have any experience with the Gigatronics 1026 ??thanks,

author: rickells
author_rank: Regular Contributor
timestamp: December 26, 2020, 10:43:46 pm
content: Is it true that the Gigatronics 1026 26GHz Signal Generator has lower noise than the HP 8340b 26GHz signal Generator ?Are there fewer harmonics in the Gigatronics 1026 as well ?Has anyone tested this with the units side by side ?thank you,

author: rickells
author_rank: Regular Contributor
timestamp: December 28, 2020, 03:57:33 am
content: Someone stated that there is a "trick to obtaining sub-Hz resolution" on a Gigatronics 1026.-- No idea if there is any truth to that ?How would one modify this particular synthesized Rf signal generator to get from 1MHz steps to sub-Hz resolution ?If so, one would think that a teardown/retrofit example would have been posted to YouTube or other Blog ?Anyone have any experience doing such a mod ??

author: rickells
author_rank: Regular Contributor
timestamp: December 28, 2020, 04:01:00 am
content: Looking into the HP 8340b,More expensive, seemingly better specs....Why do the YIG's die ??
3D printed shielding - Page 1
Forum section: electronics / rf-microwave

author: cncjerry
author_rank: Unknown
timestamp: December 23, 2020, 10:00:58 pm
content: Has anyone experience with conductive filament like Proto-pasta CDP11705 Composite Conductive PLA? Any others?This would be used to make cases for equipment that would normally be RF shielded within a metal case, mostly to shield from external RF ambient noise.Thanks.Jerry

author: wraper
author_rank: Unknown
timestamp: December 23, 2020, 10:12:34 pm
content: I would not use PLA in any device at all. It's glass transition temperature is only 60oC. Conductive spray/paint makes much more sense.https://www.mgchemicals.com/products/conductive-paint/conductive-acrylic-paints/copper-conductive-paint/Also you will destroy printer nozzle in no time with such filaments.

author: PeteH
author_rank: Unknown
timestamp: December 23, 2020, 10:12:53 pm
content: Does seem to be too conductive... Probably would help but certainly wouldn't be close to a full metal shield.
How / Why do Ferrite Choke filters work? - Page 1
Forum section: electronics / rf-microwave

author: vinlove
author_rank: Frequent Contributor
timestamp: December 10, 2020, 02:13:23 pm
content: Hi AllJust had a great success of reducing / getting rid of RFI and hum from the Samsung plasma TV in the house on my MW and HF bands reception by adding some 20 of small ferrite chokes.2x packs of 20 ferrite chokes costed me about 30 Euros total.Please refer to the separate thread on the topic.But my question is, how does Ferrite Choke filters work?They seem really effective on RFI and hum problem solution for MW HF radios.What does the material Ferrite do?Are there any other material which do the same thing as the Ferrite?

author: Grandchuck
author_rank: Super Contributor
timestamp: December 10, 2020, 02:41:02 pm
content: https://resources.altium.com/p/how-do-ferrite-beads-work-and-how-do-you-choose-right-one#:~:text=When%20a%20ferrite%20bead%20choke%20is%20placed%20on,such%20as%20that%20from%20a%20switched-mode%20power%20supply.

author: vinlove
author_rank: Frequent Contributor
timestamp: December 10, 2020, 04:06:30 pm
content: Great presentation and info on the topic.Thanks for the link.

author: jfitzgerald
author_rank: Newbie
timestamp: December 22, 2020, 08:39:46 pm
content: Chuck Councilman has an excellent article on the subject. Seehttp://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf
Learning mm-waves - Page 1
Forum section: electronics / rf-microwave

author: trollphilosophy
author_rank: Newbie
timestamp: December 19, 2020, 08:35:12 am
content: Does anybody know the best way to learn about millimeter wave electronics ? It is a new topic compared with microwaves so I was wondering if there are any resources you have found useful on this field.

author: coppercone2
author_rank: Super Contributor
timestamp: December 19, 2020, 08:45:36 am
content: alot of money unless you are interested in theory onlythe only hobby project I can think of that might be cheap is one of those MMwave car radar chips, and thats only 70GHz.

author: bob91343
author_rank: Super Contributor
timestamp: December 19, 2020, 08:49:17 pm
content: It depends on what you want to learn, and at what depth. Ohm's law prevails at all frequencies so the main things are, what components and what structure to use. Plus, are there techniques at these frequencies that are pertinent due to short wave lengths?

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 20, 2020, 05:47:29 am
content: 1mm is 300GHz. if you dont mind to become homeless and keep tapping your neighboor's electricity, then carry on...

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 20, 2020, 10:22:55 pm
content: Search for Nude O Scope.
How to simulate multi-port net with different frequency point in ADS?  - Page 1
Forum section: electronics / rf-microwave

author: mrf245
author_rank: Regular Contributor
timestamp: January 04, 2021, 06:39:11 am
content: Hello, I plan to design a multi-port RF net (a power combiner), they have different frequency input range in different ports, and one combine output port. For example, in port 1 2 3, input frequency is 300,400,500MHz, 1w power, and output RF power to 50-ohm system.I would like to know voltage and current value in components which are on my net. To design the net, ADS software simulation is easy to operate for me, and I can make AC scan to know all ports response, but in this method they have the same frequency at the same time, it’s not what I desired. If I like to set some constant frequency and power to drive every port, how to set simulation?Thank you

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: January 05, 2021, 03:31:13 pm
content: I'd look at something like harmonic balance.However, superposition tells us that we can just add together the contributions of each of the inputs, provided (and this is probably the key) you are not load-modulating your source.

author: mrf245
author_rank: Regular Contributor
timestamp: January 07, 2021, 08:04:22 am
content: Quote from: TheUnnamedNewbie on January 05, 2021, 03:31:13 pmSome friends also told me to use HB simulation, but the don't tell me how to set. In HB simulation, I checked help file and no found guide.
LNA QPL9065 - Page 1
Forum section: electronics / rf-microwave

author: tchiwam
author_rank: Regular Contributor
timestamp: December 15, 2020, 08:45:38 pm
content: Hello there,I will need a good (wide ish band) LNA, and I am trying to design a few. Goal is from 0.6 to about 3GHz. I've added my take on the QPL9065 here :https://github.com/tchiwam/LNAPower supply was discussed in another forum, since it was my 1st shot on Kicad, this is my 2nd. Feel free to comment and roast away.You should be able to find all pdf plots and gerbers too in the folders.All done with Kicad, and the drawings are on Github.

author: yl3akb
author_rank: Regular Contributor
timestamp: December 17, 2020, 09:08:51 am
content: Those SMA connector pads seem to be too wide for that PCB material. Judging by eye those pads are ~5mm long and ~1mm wide which translates to Z < 15 Ohms and Length of > 30deg at 3 GHz and that would cause quite a mismatch at those frequencies. I would look for connectors with thinner center pins and pads.

author: tchiwam
author_rank: Regular Contributor
timestamp: December 18, 2020, 01:33:05 am
content: Thanks, I will look at this.
Use a 90° Adapter? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 14, 2020, 02:27:32 pm
content: HiCan I use a 90° N to N Adapter for the Antenna or better use that:https://www.delock.de/produkte/1674_Adapter/89601/merkmale.html?My Antenna Port is behind the Mounting Point.Thanks

author: bob91343
author_rank: Super Contributor
timestamp: December 14, 2020, 06:06:52 pm
content: It's not clear what you are wanting to do. If this adapter is going to support the weight of an antenna, I would question its mechanical integrity.

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 14, 2020, 07:33:34 pm
content: No signal wise. Maybe there is enough space to fit a cable there directly.Sometime Chinese produce stuff and dont think how it should get together.

author: coppercone2
author_rank: Super Contributor
timestamp: December 15, 2020, 01:17:53 pm
content: what you should do it hook it up to a VSWR setup and wiggle it around and see what happens

author: radiolistener
author_rank: Super Contributor
timestamp: December 15, 2020, 01:50:35 pm
content: Quote from: Lord of nothing on December 14, 2020, 02:27:32 pmI don't recommend you to use Г adapters for portable radio. Because portable radio is designed to use metal chassis as a counterpoise. It expects straight antenna position. If you use Г adapter it may lead to bad VSWR and output amplifier may be burned out. So, there is a risk to damage your radio if you use TX with antenna connected through Г adapter.

author: coppercone2
author_rank: Super Contributor
timestamp: December 15, 2020, 09:58:14 pm
content: is this also true for plastic body radios? it can use the PCB ground plane also right?

author: HB9EVI
author_rank: Frequent Contributor
timestamp: December 15, 2020, 10:18:45 pm
content: normally those plastic radios consist from a metal chassis underneath; capacitive coupling to the human body is enough as rf counterpoise. So far I don't see a reason why someone would like to send with horizontal polarisation with a FM handheldnormally a radios' finals should not burn about a too high SWR; most modern radios radically turn down the output power if impedance mismatched

author: DaJMasta
author_rank: Super Contributor
timestamp: December 16, 2020, 01:27:30 am
content: Would a short bit of semirigid coax do the job? Unless it has to support a load physically, it would probably give you a very flexible and compact option.

author: radiolistener
author_rank: Super Contributor
timestamp: December 16, 2020, 03:42:19 am
content: Quote from: coppercone2 on December 15, 2020, 09:58:14 pmplastic body radio also have metal chasis inside and large ground polygon on the PCB. They are used as antenna counterpoise.

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 17, 2020, 07:07:16 pm
content: Its a 2,4Ghz Wifi Antenna and a USB Dongle.
DEI GPR-20 manual needed, - Page 1
Forum section: electronics / rf-microwave

author: CaptDon
author_rank: Super Contributor
timestamp: December 12, 2020, 11:16:54 pm
content: Greetings, I bought a Defense Electronics Inc. General Purpose Radiomodel GPR-20 from an Ebay seller. A couple of minor repairs and itseems to mostly work. The peak center response of the spectral displayoutput seems way out of whack with the rest of the radio and the C.W.function seems to be amiss. The signal meter pins on the high side andno recovered signal. I would mainly be looking for a manual with schematicor even just a readable schematic. This thing may be dinosaur technologyas it seems to work from negative 16vdc which usually indicated mostlyall PNP transistors. Thanks for any help/leads!! DEI/Vitro made somereally nice stuff, I nice owned one of the 1037 units with spectral display!!!Wish I still had it!!! Sold it to a friend and his multitude of cats destroyedit!!
Does anyone have acess to the Hytera CPS? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 04, 2020, 05:36:16 pm
content: HiDoes anyone have access to the Hytera CPS for the PD5 Series?I goes a used Hytera BD505LFand need to set some settings for the Digital settings and also for the Encryption.Maybe someone have access to that?Thanks!
CST Microwave Studio 3d modeler size limits - Page 1
Forum section: electronics / rf-microwave

author: MrOmnos
author_rank: Frequent Contributor
timestamp: August 07, 2017, 07:37:51 am
content: I am trying to design a vivaldi antenna in CST microwave studio. I am trying to do draw an analytical curve with equations u(t)= t, v(t)= s*exp(r*t), w(t)= 0. Parameters are as follows s= 1mm, r = 1.1 and Parameter range (max) = 52.5mm. But I am getting an error that 'Body size is outside dynamic range of 3D modeler' . 5 cm is too big for the 3 modeler? What's the problem?

author: tec5c
author_rank: Frequent Contributor
timestamp: August 10, 2017, 12:41:04 am
content: Quote from: MrOmnos on August 07, 2017, 07:37:51 amWhat is t equal to?

author: erre208
author_rank: Newbie
timestamp: December 02, 2020, 05:04:57 pm
content: Quote from: MrOmnos on August 07, 2017, 07:37:51 amI have the same error, what was the solution please

author: Andrey_irk
author_rank: Regular Contributor
timestamp: December 08, 2020, 06:28:51 am
content: I suppose it will go away if you decrease the quality of the model i.e. get rid of the small features or use less points. It gives you the error because it cannot create an appropriate mesh and that is because there are small features (relative to the size of the whole model) that it fails to approximate.You can check if I'm right if you go to the mesh view and try to create it.
Help with 4NEC2 design - Page 1
Forum section: electronics / rf-microwave

author: A.Z.
author_rank: Super Contributor
timestamp: December 01, 2020, 05:01:37 pm
content: Hello folks, while waiting to go on and build the real antenna, I'm spending some time running4NEC2simulations, but not being a NEC expert, I started wondering if I made some mistake with my antenna model; the file is the followingCode:CM ================================================CM Linear Loaded Horizontal Delta-Loop antenna (RX)CM ================================================CESY hgt=9 ' height from groundSY arm=3.4 ' arm endpoint distanceSY dpt=1 ' height of triangleSY slp=0.65 ' feddpoint height difference (from front wire)SY rad=0.0005 ' 3-conductor cable wires radiusSY spc=0.00105 ' 3-conductor cable wires spacingSY tst=14.175 ' test frequency' first triangle (feedpoint - open at ends)GW 1 50 0 -dpt hgt -arm 0 hgt+slp radGW 2 50 0 -dpt hgt arm 0 hgt+slp radGW 3 50 -arm 0 hgt+slp -spc 0 hgt+slp radGW 4 50 arm 0 hgt+slp spc 0 hgt+slp rad' vertical connections #1 (far ends)GW 5 5 -spc 0 hgt+slp -spc 0 (hgt+slp)-spc radGW 6 5 spc 0 hgt+slp spc 0 (hgt+slp)-spc rad' second triangle (open at center)GW 7 50 -spc -dpt hgt-spc -arm 0 (hgt+slp)-spc radGW 8 50 spc -dpt hgt-spc arm 0 (hgt+slp)-spc radGW 9 50 -arm 0 (hgt+slp)-spc -spc 0 (hgt+slp)-spc radGW 10 50 spc 0 (hgt+slp)-spc arm 0 (hgt+slp)-spc rad' vertical connections #2 (center ends)GW 11 5 -spc -dpt hgt-spc -spc -dpt hgt-(2*spc) radGW 12 5 spc -dpt hgt-spc spc -dpt hgt-(2*spc) rad' third triangle (closing the loop)GW 13 50 -spc -dpt hgt-(2*spc) -arm 0 (hgt+slp)-(2*spc) radGW 14 50 spc -dpt hgt-(2*spc) arm 0 (hgt+slp)-(2*spc) radGW 15 50 -arm 0 (hgt+slp)-(2*spc) 0 0 (hgt+slp)-(2*spc) radGW 16 50 arm 0 (hgt+slp)-(2*spc) 0 0 (hgt+slp)-(2*spc) rad' groundGE -1GN 2 0 0 0 13 0.005' short wire junctionsLD 5 5 0 0 58000000LD 5 6 0 0 58000000LD 5 11 0 0 58000000LD 5 12 0 0 58000000' uncomment to add a 580 Ohm loading resistor to front wire' like the one used with T2FD/T3FD antennas, notice that the' resistor will alter the radiation pattern'LD 0 15 50 50 580 0' feedpointEKEX 0 1 1 0 1. 0 0'EX 0 2 1 0 1. 0 0' initial frequencyFR 0 0 0 0 tst 0ENin short, the antenna is a "linear loaded" horizontal (ok almost) loop which I plan to use with my SDR, if you want to better see its structure, change the "spc" symbol to (e.g.) 0.5, that will allow you to see how the wires of the 3-conductor cable forming the loop are connected; in the model I only loaded the cable junctions, but I'm not sure it it's correct so I'm here asking for help from someone more knowledgeable than me; also, would someone be so kind to suggest me the best feeding method ? The loop will be used only for reception (mainly on MW/SW), so SWR isn't all that important, but I'd like trying to squeeze out every bit of signal I can, so suggestions will be welcomejust in case, the wire interconnections are like these (spacing increased to show the details)and here's the radiation pattern on the 20m band
RF device affects power rail ? - Page 1
Forum section: electronics / rf-microwave

author: liviux
author_rank: Contributor
timestamp: November 30, 2020, 11:49:19 am
content: Hello, I am in a dillema.There are 2 small boards:1'st board: has an RF device transmitting telemetry at apx 14dBm (powered from 5v from 2nd board)2nd board: has 5v Reg(step down), 3.3v LDO, MCU, and a video section (powered from 5v and 3.3v).My problem is that the video section gets affected by some sort of RF noise.The question is... what solution should I try to mitigate this RF injection in the video section?the 2nd board has decoupling caps 0.1uF and regulators have recomended caps.Thank you !
Hot Iron newsletter for homebrewers (it's free) - Page 1
Forum section: electronics / rf-microwave

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: November 30, 2020, 10:22:58 am
content: A quick note for radio tinkerers about a free homebrew/technical/experimenter email newsletter you should all get.Example of its contents page is pictured here:https://dailyantenna.blogspot.com/2019/09/introducing-hot-iron-free-homebrew.htmlTo subscribe send an email. Details here:https://walfords.wordpress.com/ordering-design-support/
Have 1000-1500$USD to spend on a UHF/VHF HAM radio setup what to buy? - Page 1
Forum section: electronics / rf-microwave

author: Beamin
author_rank: Super Contributor
timestamp: November 13, 2020, 04:50:57 am
content: I cashed in my bitcoins (I found a trezor I thought I lost)Live in baltimore city apt building, What should I buy for my 1st radio with a general class lic?I have a power supply so looking for a mobile 12v or 120v unitneed SWR meterantenna; omni directional that will sit on 4th floor roof fire escape50 ohm coax f connectors etc.Looking to do 2m 1.25m and 70cm bands (do they make triband radios?)Want a base/mobile unit with handheld mic as I have had no luck with cheap chinese baofung hand helds.What do you guys run? What kind of wattage should I look for? The interface will also have to be easy to use/see as Im legally blind.I was going to do HF but thats too hard in the city so vhf uhf it is.Are there decent chinese radios or should I stick to icom/japanesse brands etc ? When I buy something I want it to last and be the last peice of equipment I buy.Should I look into digital modes? Im just going to use this for talking on and not hooking up to a computer.This is the most knowledgeable place I know to ask these questions.Also Im willing to trade a tek 3365 scope for equipment.Thanks Beamin

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 28, 2020, 11:47:56 pm
content: Depends on what the usual habits of the Hams in your area are. Some places have repeaters that are predominantly on one band or the other. 220 is weird because it is mostly US, so equipment is more limited.Find the biggest Ham radio club in your area and read their website. Look at the repeater frequencies and their activities. They may also have classified section for used equipment.You can get a good 2 meter rig for perhaps $100 (I bought some for $10) and look into making an antenna. It is not hard to make a 1/2 wave dipole out of stainless rod. Or buy one. If you can attach it to metal fire escape, you can probably use a mobile whip antenna with a base that normally would attach to a car top carrier, like on a typical minivan. Really good antenna, really cheap. Antenna unscrews from the mount easily.You only need a few watts for repeater stuff.Chinese stuff is generally poor quality, has terrible harmonics.Buying a radio is a lot like buying a car, The original owner takes the big monetary hit. If you buy something used, you can usually sell it and not take a big loss. This is helpful when you are starting and do not know what you will desire in the near future. This is not meant as a slight to a new ham, I change my mind about equipment all the time. Best to be flexible and gives you something to be interested in once Hamfests open up again.About HF.....Many city bound Hams use balcony antennas like Magnetic Loops. I have one I made myself and it works VERY well, even indoors.
BK1198 radio IC (and Digitech AR1458) - Page 1
Forum section: electronics / rf-microwave

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: November 17, 2020, 09:42:28 am
content: Jaycar sell a little portable radio for under $20 covering AM & FM.But it can be made to cover some shortwave bands.It uses the BK1198 chip. Interestingly they publish the circuit of that radio on their website.And have a datasheet on that chip (which they also sell).Thought I'd put together a page detailing my reviews and experiments so far.https://vk3ye.com/projects/projbk1198.htmAlso note the comments on one of the videos - there will be a very interesting multiband receiver project in the January Silicon Chip.

author: Kerlin
author_rank: Regular Contributor
timestamp: November 28, 2020, 10:39:41 pm
content: Kmart have one for $9.00.I suspect it uses the same chip as its thinner than I would expect, that tuning control doesn't look like a variable cap and it works of two AAA batteries.https://www.kmart.com.au/product/pocket-am-fm-radio/764845You really should have taken those surplus things I offered you for free.I sold the two RF test sets, an IFR1200S (with spec an) and a Marconi 2955 on VKham, sold in two minutes flat.I took one spare chassis of each to the recyclers, and the coils and the wide spaced HV caps went in the bin.I would have held them until after the virus problem caused by our dopey state Premier.I highly recommend you read the book "Radio Girl". Its about where everything that is radio in Australia today came from. Endorsed by dick Smith on the front cover.
Are DOCSIS spectrum analyzer the same as RF spectrum Analyzers? - Page 1
Forum section: electronics / rf-microwave

author: Dan44
author_rank: Newbie
timestamp: December 22, 2020, 09:50:27 am
content: Hey, I've been trying to learn more about RF & RF equipment. I was wondering if DOCSIS cable meters (like the kind the comcast guy might come to your house with), for example Trilithic 860 DSP is the same in a raw sense as a benchtop spectrum analyzer (albeit less functionality & accuracy).

author: Bicurico
author_rank: Super Contributor
timestamp: December 22, 2020, 10:56:51 am
content: While both measure the RF spectrum, a spectrum analyzer will normally support higher frequency range and configurable RBW/VBW, while a TV/CATV/SAT field meter will normally have no spectrum display or a simplified spectrum with fixed RBW/VBW (better ones allow for simple switching of these modes - "fast spectrum" vs "slow spectrum").This does not mean field meter is bad: it is actually more suited, spectrum-wise, to visualize the transponders than a regular spectrum analyzer, plus they come with support to power amplifiers, switches and LNB's.I would NOT recommend to get a TV/CATV/SAT field meter with spectrum analyzer capabilites as a cheap replacement for a spectrum analyzer, when you do want to do spectrum analisys.Also, the accuracy of a field meter's spectrum is normally lower than the accuracy of a spectrum analyzer (which may cost a whole lot money).Regards,Vitor
attenuators? - Page 1
Forum section: electronics / rf-microwave

author: steele
author_rank: Newbie
timestamp: November 07, 2020, 04:10:19 pm
content: Does anyone understand what we are trying to be taught here?Something about attenuators? I Think I lost a few brain cells trying to watch this..https://youtu.be/ncXFx-MLZcY

author: Grandchuck
author_rank: Super Contributor
timestamp: November 07, 2020, 04:25:38 pm
content: I think the presenter is saying that placing an attenuator in line to avoid over driving an amplifier is going to hurt the receive signal.

author: MF-jockey
author_rank: Regular Contributor
timestamp: November 25, 2020, 10:06:07 pm
content: I can't watch the video, got message: This video is private.

author: Mark19960
author_rank: Regular Contributor
timestamp: November 25, 2020, 11:02:35 pm
content: You are not missing anything.The video is made by the same bloke that has been featured here on the forum probably a half a dozen times now in the snake oil section.I saw it before it was made private and it was a disaster of a video. I am sure that's why it was made private.It's more of the same cringy CB radio myths, gaslighting, and pseudoscientific nonsense that's not worth anyones' time.At the time I was on a train in England that was mostly empty and I was bored out of my bloody mind so I gave it a watch.The alcohol free policy on the train was unfortunate. Could have used a drink after that one.He was injecting RF into a variable Bird RF sampler (I think a 427x series) via the sample output and using a CB radio S meter to calibrate it.No attenuator was used. He referred to the RF sampler as an attenuator throughout the video. He likely doesn't know the difference.All the while holding up some illegible ebay sticker shop calibration paperwork talking about being NIST certified or some rubbish whilst using *a cb radio* to calibrate a piece of equipment and seemed to imply that a CB radio S meter is a standard by which to calibrate things.Not surprised it was taken down. It was 5 or so minutes of CRINGE.I can point you at the blokes' channel .... but it's full of cringe. Save yourself.
Possible antenna problem - Page 1
Forum section: electronics / rf-microwave

author: veedub565
author_rank: Frequent Contributor
timestamp: November 16, 2020, 04:58:15 pm
content: Hi, I'm a bit confused by a strange problem I'm having. Hoping it might seem a bit more obvious to someone more experienced.My 2m rig measures 12W forward power and 1.00 vswr into a 50ohm load. When I connect my antenna I only measure 0.9W forward power and 1.06 vswr.A few days ago I was measuring 12w forward power with the antenna connected. So I don't understand now what has happened. And I don't understand how the vswr can stay roughly the same, but the power is so much lower.Rig = Yaesu FT-480RAntenna = Diamond X50Coax = RG213 (8m length)BenM7SCYOh and I used adhesive lined heatshrink on the antenna connector (N type) so as to weatherproof it.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: November 16, 2020, 05:17:33 pm
content: how do you measure the swr?

author: fourfathom
author_rank: Super Contributor
timestamp: November 16, 2020, 05:36:59 pm
content: Quote from: HB9EVI on November 16, 2020, 05:17:33 pmYes. Some SWR meters won't give reasonable readings with very low power, and if you have an antenna or cable problem your transmitter is probably backing off on the power to protect the output transistors.

author: veedub565
author_rank: Frequent Contributor
timestamp: November 16, 2020, 05:55:50 pm
content: I'm using a R&S NAS-Z5 insertion unit to measure forward/reflected power and VSWR

author: HB9EVI
author_rank: Frequent Contributor
timestamp: November 16, 2020, 06:21:09 pm
content: very likely you have either a cable or an antenna problem, so the transceiver lowers the output because of the mismatch, so you're measuring garbage.in such cases you don't get far with an swr meter; if you don't have one of the widespread vnas, I'd recommend you to check the cable with the tdr methodcheck the antenna for eventual leaks

author: veedub565
author_rank: Frequent Contributor
timestamp: November 16, 2020, 06:47:28 pm
content: Thanks, I'll get and investigate the antenna. Water getting in is the only thing I can think of.

author: veedub565
author_rank: Frequent Contributor
timestamp: November 16, 2020, 07:59:48 pm
content: I'm still getting a signal out by the way. My friend I talk to regularly still gives me an S8 report, although slightly down on the usual S9+

author: veedub565
author_rank: Frequent Contributor
timestamp: November 16, 2020, 08:30:43 pm
content: Fixed it, its the cheap N to PL259 adapter I'm using on the insertion meter.Thats what you get for buying cheap adapters and connectors.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: November 17, 2020, 10:06:12 am
content: yea, that's little surprising; the best setup/antenna is worth nothing if you have such a crap in the installationglad that you found it!
Pluto SDR - unknown accessory - Page 1
Forum section: electronics / rf-microwave

author: todorp
author_rank: Regular Contributor
timestamp: November 15, 2020, 12:03:45 pm
content: Hi all, the other day I received a Pluto SDR ordered from Mouser. In the package there were 2 antennas, a SMA cable and the gizmo shown in the photos in attachment.The gizmo has what seems a usb 2 connector on one end.Does anyone have an idea what this might be and what it is used for?Thanks,Tod

author: Fraser
author_rank: Super Contributor
timestamp: November 15, 2020, 12:53:26 pm
content: That looks like a standard USB ‘A’ female to Micro USB adapter. As such it is passive and just adapts the connector type.

author: Fraser
author_rank: Super Contributor
timestamp: November 15, 2020, 12:59:15 pm
content: It looks to be an OTG adapter for mass storage support.....https://wiki.analog.com/university/tools/pluto/usb_otg_host_function_supporthttps://wiki.analog.com/university/tools/pluto/hacking/hardware#connectorsFraser

author: HB9EVI
author_rank: Frequent Contributor
timestamp: November 15, 2020, 04:27:27 pm
content: that's an OTG adapter for the case you want to run an USB-Ethernet adapter with a normal USB A-plug, but it's better to watch out directly for one with a micro USB
Fourier Transform of BFSK - Page 1
Forum section: electronics / rf-microwave

author: Ralphy007
author_rank: Contributor
timestamp: November 12, 2020, 04:38:44 pm
content: If y1(t) has the f1 frequency and y2(t) has the f2 frequency, in a BFSK system, then does the Fourier Transform (FT) of y1(t)+y2(t) equal :FT ( y1(t) + y2(t) ) = FT ( y1(t) ) + FT ( y2(t) )

author: Kalvin
author_rank: Super Contributor
timestamp: November 13, 2020, 11:22:43 am
content: Yes. because FT is a linear operation.https://class.ece.uw.edu/235dl/EE235/Project/lesson16/lesson16.html

author: radiogeek381
author_rank: Regular Contributor
timestamp: November 13, 2020, 11:00:52 pm
content: The wikipedia page is more authoritative and detailed than I can do here:https://en.wikipedia.org/wiki/Frequency-shift_keyingbut as a simple outline:If we're talking a real FSK system, then the actual time function is not y1(t) + y2(t).If it was, then your assertion would be right: as Kalvin says, the Fourier transform is linear.But BFSK is a little more complicated than that.Assume a string of bits x(n) sent over time, where we give each bit T seconds.We'll use fd = f2 - f1 to simplify the notation.In the simplest case the output signal isy(t) = sin(( 2 * pi * (f1 + x(n) * fd)) * t)where n = int(t / T)The Fourier transform of this function is decidedlynottwo spikes in the frequency domain. Switching between the two frequencies in this case is done in "zero time" so there is power between the two spikes -- nature doesn't like sudden changes. (In fact, except in special cases, the power is very very broadband.)Good FSK schemes change that x(n) * fd term to something likeh( x(n) ) * fdwhere h() spreads the pulse out a bit, think of it as smoothing the rising and falling edges. Properly chosen, the h() function can band limit the energy to minimize the channel width for a given data rate. (See for instance "gaussian ask" in the wikipedia article.).Typically the spectrum for a "clean" FSK signal will look like two peaks with skirts.For some example pictures of FSK signals, see for examplehttps://www.sigidwiki.com/wiki/Radio_Teletype_(RTTY)
Rg174, rg316, etc - Page 1
Forum section: electronics / rf-microwave

author: cncjerry
author_rank: Unknown
timestamp: November 12, 2020, 08:27:00 am
content: When I bought a nanovna for the heck of it, it came with two short sections of black cable, about 2.8mm in diameter. It seemed a little larger than rg174 but I didn't have any 174 at hand. It was also pretty flexible. I usually use rg316 for short test leads or hardline for internal connections. I'M wondering if there are new rg174/316 type super flex cables with better shielding and maybe silicone outer material? I would like something with better or at least the same db loss per 100ft @10Mhz like 316 but more flexible, also 50ohm.ThanksJerry

author: HB9EVI
author_rank: Frequent Contributor
timestamp: November 12, 2020, 12:30:48 pm
content: I got 2 cables with blue coat with my NanoVNA; I guess it's a RG316 type cable.if shielding is crucial, I'd go with semi-rigid like the RG402; to my knowledge there isn't anything new in the diameter section of about 3mm with better shielding and higher flexibility than RG174/RG316

author: cncjerry
author_rank: Unknown
timestamp: November 12, 2020, 04:55:22 pm
content: The black cable that came with the nano is very flexible, for all I know it is just twin lead, but it seems fatter and according to my other devices, it is just as good as 316. I have to find some 174, I thought I had a roll to compare it with.thanks

author: thinkfat
author_rank: Unknown
timestamp: November 12, 2020, 07:05:18 pm
content: Semirigid as test leads is not a good idea. You damage it each time you bend it.
Use of 12V Ac Power Supply in Ham Radio? - Page 1
Forum section: electronics / rf-microwave

author: vinlove
author_rank: Frequent Contributor
timestamp: November 05, 2020, 01:05:53 pm
content: Can it be any use in ham radio?I found this 12V AC 1.5A PSU but cannot see any use for it.Any one?

author: Stray Electron
author_rank: Super Contributor
timestamp: November 05, 2020, 01:09:08 pm
content: Use it to make an octopus component checker. Those can be amazingly useful to identify components that appear to a meter to be good but that have partial shorts or other bizarre problems.

author: vinlove
author_rank: Frequent Contributor
timestamp: November 05, 2020, 01:34:41 pm
content: Yes, it looks a very useful device. Thanks for your info.

author: vinlove
author_rank: Frequent Contributor
timestamp: November 05, 2020, 03:13:58 pm
content: Surely, there must have been more needs / uses for these 12V AC Power Supplies, so they had been manufactured?

author: ledtester
author_rank: Super Contributor
timestamp: November 05, 2020, 03:25:33 pm
content: Quote from: vinlove on November 05, 2020, 01:34:41 pmAn AC power supply is a simple and convenient way to apply a time-varying voltage to the component under test.https://www.jammarcade.net/simple-component-tester-a-k-a-octopus-curve-tracer/

author: Ian.M
author_rank: Super Contributor
timestamp: November 05, 2020, 03:36:17 pm
content: Also, if fed to a pair of opposite polarity half wave rectifiers and reservoir capacitors, you can get both positive and negative DC rails, which is very convenient for powering many analog circuits, especially ones using OPAMPs.Nowadays one could use a DC-DC converter for the negative rail, but EMI can be a major concern, and also the rail will come up after the positive rail which may cause problems for some ICs that have strict power sequencing requirements.

author: vinlove
author_rank: Frequent Contributor
timestamp: November 05, 2020, 04:02:08 pm
content: Great info. Thanks.The octopus component checker device looks very useful.

author: TheBay
author_rank: Unknown
timestamp: November 05, 2020, 04:17:36 pm
content: They are incredibly useful, most Hameg Analogue scopes have one built in.
RFsim99 download URL - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: May 20, 2017, 09:12:44 pm
content: This seems like a good site to download what is essentially abandonware. But RFSim99 is an extremely useful program.."RFSim99 is afreelinear S-parameter based circuit simulator offering schematic capture, simulation, 1 port and 2 port S-parameter display and file support, tolerance analysis, stability circles, and much more.]Very easy to use and convenient.Calculate air inductance, PCB square inductance an capacitance, filters, couplers, attenuators, splitters, transmission line, match, etc. Calculator embedded."I am pretty sure that this site is where I downloaded it first several years ago.http://www.sandiego.edu/~ekim/It seems to be mentioned on other sites as the best place to get it.. examplehttps://appdb.winehq.org/objectManager.php?sClass=application&iId=8195

author: G0HZU
author_rank: Super Contributor
timestamp: May 21, 2017, 07:57:13 pm
content: It might be worth comparing MD5 checksums against the installer version.eg I have V1.05 here and I think I have had this for many years.The MD5 for my installer file isEE112A4756D097C6958A7971647884CCThis was taken from an old backup CDROM I burned back in 2001.

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: May 21, 2017, 11:48:35 pm
content: It looks like the setup program for RFsim99 won't work any more on 64-bit Windows (it didn't on my Win7 Pro laptop). Some searching led me to this:https://www.reactos.org/forum/viewtopic.php?t=10988It seems like it's only the installer's 'setup.exe' that won't work, the actual installation will proceed just fine once a 32-bit installer is provided. The link above gives some notes on how to do this (I followed the 'InstallShield 3 shortcut' method).

author: rwlroc
author_rank: Newbie
timestamp: November 03, 2020, 04:10:12 pm
content: Hmm, I was not able to get the 'InstallShield 3 shortcut' method to work. Anyone else have an luck installing RFSIM99 on Windows10?Rich

author: radiolistener
author_rank: Super Contributor
timestamp: November 03, 2020, 10:16:58 pm
content: you can install it on win xp and then copy folder to higher version of windows

author: fedgE_
author_rank: Newbie
timestamp: November 03, 2020, 11:28:40 pm
content: RFSim99 has been my go-to for quite some years, but occasionally I stumbled upon weird compatibility issues with Win10, bugs and issues that unfortunately will never be fixed.As replacement tools, I can strongly recommend SimSmith and QUCS, as they are active and are packed with features!Furthermore, the authors and contributors to SimSmith have published a lot of tutorials, examples and use-cases.SimSmith:http://www.ae6ty.com/Smith_Charts.htmlandhttps://www.w0qe.com/SimSmith.htmlQUCS:http://qucs.sourceforge.net/screenshots.htmlBR
EMC question - Page 1
Forum section: electronics / rf-microwave

author: stoyanoff
author_rank: Contributor
timestamp: October 31, 2020, 07:43:36 pm
content: Greetings! If I have a high frequency module integrated in my product like bluethoot or GSM and it has all neccessary certificates(made in EU/US) do I need to double check the EMI using 5th harmonic of it`s frequency or I can just measure in proper range for the rest of the electronics(which is significantly lower and the equipment is cheaper!)?Thanks!

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 31, 2020, 08:01:53 pm
content: Quote from: stoyanoff on October 31, 2020, 07:43:36 pmIn another thread a member encountered certified AC to DC modules which were causing trouble with EMC. It may pay to ascertain the emissions of the equipment yourself.
at times the image is reversed from right to left. - Page 1
Forum section: electronics / rf-microwave

author: jean françois
author_rank: Contributor
timestamp: October 10, 2020, 03:20:38 pm
content: hello,by moment the image is reversed the right becomes the left, very complicated to read.have you ever encountered this problem?in which direction to look?thank you,best 73s,Jean françois

author: fordem
author_rank: Regular Contributor
timestamp: October 13, 2020, 05:56:07 pm
content: What is the image on? And for what it's worth some folks have very little trouble reading "mirror image" text.

author: jean françois
author_rank: Contributor
timestamp: October 28, 2020, 07:33:24 am
content: Hello,Really sorry, this is an R&S CMU300,it's completely randomthanks, Jean François
Anyone try the Alinco DR-735T VHF/UHF Transceivers DR-735T - Page 1
Forum section: electronics / rf-microwave

author: Beamin
author_rank: Super Contributor
timestamp: November 13, 2020, 05:30:53 am
content: Saw this radio online :Transceiver, DR-735, Mobile, FM, 144/440 MHz, 8-Color LED Display, Hand Mic, Eachhttps://www.dxengineering.com/parts/alo-dr-735t?seid=dxese1&gclid=CjwKCAiA17P9BRB2EiwAMvwNyAu-be9dE86Ubiw_XZHcXfxIyKFStzlWoHCJrfo_TmwIr0-Ue0YpMRoC65YQAvD_BwEAnyone tried this radio ?Looks pretty goood quality with easy to see screen and price is cheap.
sealectro coaxial to PCB cable right angle adapter? (direct solder) - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: October 20, 2020, 06:20:36 am
content: I am looking for a adapter like this one, but not SMB, one that you directly use to mate a coaxial cable to a circuit board. I have 3 of them, they just say sealectro on them, without a part number. I can't seem to find them on the website. The idea is they do not have any dielectric in them, other then the coaxial base. So you take a piece of coaxial cable, strip it so there is a little bit of center conductor protruding (3mm), then solder it to the adapter, which is already soldered to the board, then you solder the little lid on.I know it exists because here it is.

author: mag_therm
author_rank: Frequent Contributor
timestamp: October 20, 2020, 12:48:23 pm
content: Search "sealectro" on Surplus Sales of Nebraska.There is one I saw that looks a bit like the vertical version of the one you need

author: coppercone2
author_rank: Super Contributor
timestamp: October 20, 2020, 05:26:59 pm
content: I found some similar stuff on google searching for terminations, but the nebraska website does not appear to have that. nothing gold plated and nice looking like thatvery interesting website, it is likely to burglarize me in the futureits practically like 'hey someone took all your money and left these little metal hexagons as a calling card'. like the riddler
160kHz from 10MHz - Page 1
Forum section: electronics / rf-microwave

author: Clemgill
author_rank: Contributor
timestamp: October 20, 2020, 03:11:45 pm
content: Hi,I need to derive a stable 160kHz signal from a 10MHz reference OCXO.Stubborn fact is that 160 does not divide 10 000... but it does divide 20 000 (160 * 125 = 20 000)Question :Is it preferable (noise wise) to double the 10MHz to 20Mhz and then dividing by 125,Or to start by dividing 10Mz by 125 (= 80kHz) and then double 80kHz to 160kHz ?Thanks,Gilles.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: October 20, 2020, 03:21:42 pm
content: personally, I'd do it with a SI5351C which can be fed with 10MHz, but it requires at least a small uC which uploads the register parametersphase noise wise, I'd be better to double 10MHz, which can be done with simple diodes, and then divide down to 160kHz.