hybridfree/eevblog-posts huggingface dataset:
Pre-wound HF Tx Baluns - Page 1
Forum section: electronics / rf-microwave

author: hagster
author_rank: Frequent Contributor
timestamp: July 31, 2019, 12:48:16 pm
content: Is there anywhere that sells pre-wound baluns for 1.8 to 30MHz. I need something that can cope with 10 or more Watts, without being overly large. Round about 1:4 ratio is needed.Usual suspects for this sort of stuff like coilcraft, murata and minicircuits come come up blankI can find lots of small low power RF devices that max out at 250mW and lots of audio and power supply types that top out at 100KHzish. Seems like most people wind there own when needed, but I would prefer something with a little more quality control.Thanks in advance

author: Kalvin
author_rank: Super Contributor
timestamp: August 01, 2019, 07:25:50 am
content: Google using these words: ham radio HF balun MFJ 4:1You will get hits for MFJ baluns, but they are inexpensive and quite popular and readily available from various sellers. If you want to have a balun without an enclosure, just buy one with an enclosure and remove the balun.There are lots of baluns available at eBay as well.

author: hagster
author_rank: Frequent Contributor
timestamp: August 01, 2019, 11:03:38 am
content: Thanks for the advice.I was really after something both smaller (10W rather than 1KW), and with some proper data sheets and hopefully S2P files also.I can wind and test my own, but it's an extra step in the build process that I would like to avoid. I would need to document the build and test process to assure repeatability.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: August 01, 2019, 03:53:54 pm
content: Common practice on a RF PA are pig nose ferrites like the BN-43-7051 from Fairrite; primary winding is usually done with a brass tube while the secondary is a enameled copper wire;I'm not sure anymore if a BN-43-2402 would be sufficent for 10W, otherwise the one mentioned above is going to do it just fine.

author: hagster
author_rank: Frequent Contributor
timestamp: August 01, 2019, 04:45:50 pm
content: Thanks HB9' those look just the trick.Never heard the name Pig nose before, but it makes sense. I have seen them called binocular ferrites also.
VHF Multiband WFM Receiver - Page 1
Forum section: electronics / rf-microwave

author: TurtleForGaming
author_rank: Newbie
timestamp: July 27, 2019, 12:54:30 pm
content: So I'm into ham radio (will get a license very soon) and meteo sats reception. Some may know that there is the NOAA sattelites that broadcast an apt signal down two earth. The signal is a 38 kHz wide fm signal. They broadcast on 137.1 MHz / 137.62 MHz and 137.9125 MHz accounting for the error in the doppler shifft calculation I will round out the bandwidth to 40kHz. It would also need to be able to tune into the 145.8MHz frequency (For the ISS SSTV events). So I'm looking for an IC that I could tune into a specific frequency with the required bandwidth (that I could adjust too).I've looked a bit and found the NiceRF SA868 but unfortunatly it hasn't a big enough bandwitdh.Anyone of you can recomand me an IC / Module that meet the specifications ?

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 30, 2019, 05:14:15 pm
content: Why not an SDR?

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 30, 2019, 06:44:58 pm
content: Quote from: Lord of nothing on July 30, 2019, 05:14:15 pmThat +1, Read more here:https://www.rtl-sdr.com/?s=noaa
Maximum LO input to an ADE-6 mixer? - Page 1
Forum section: electronics / rf-microwave

author: Chris Wilson
author_rank: Super Contributor
timestamp: July 19, 2019, 03:13:30 pm
content: I want to input 10MHz from a Trimble Thunderbolt GPS disciplined oscillator which is +12.5dBm into 50 Ohms to the LO input of a Mini Circuits ADE-6 mixer. the sheet seems to suggest LO input max is +7dBm. Do I need to attenuate or will it be OK with the higher level? Thankshttps://www.minicircuits.com/pdfs/ADE-6+.pdf

author: DaJMasta
author_rank: Super Contributor
timestamp: July 19, 2019, 05:47:49 pm
content: Take a look at the performance charts, they all chart data from +10dBm LO inputs, and they specify the maximum combined RF power to be 50mW (+17dBm), so provided that your other input isn't too high, it should be able to handle it. The VSWR of the LO goes up consistently with higher input levels, so depending on the output driver of your GPSDO, you could run into some unhappiness there.I'd probably use a small attenuator to be sure, but I think your configuration would likely work.

author: Chris Wilson
author_rank: Super Contributor
timestamp: July 25, 2019, 03:43:07 pm
content: Thanks very much for the reply, I am using a small attenuation and all works fine much appreciated.
Ferrite material in Magnetron RFI filter - Page 1
Forum section: electronics / rf-microwave

author: paulc
author_rank: Contributor
timestamp: July 01, 2019, 04:41:02 am
content: I want to use it in the GHz. range.What type of ferrite it is?Can someone attach characteristics or datasheets ?Thanls.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 01, 2019, 05:16:01 am
content: Absolutely no way to tell.I would select #61 or the like. But what anyone actually uses, who knows.Tim

author: Gyro
author_rank: Super Contributor
timestamp: July 02, 2019, 12:20:19 pm
content: It might be that the ferrite is not be handling particularly high frequencies, it looks like a wideband filter. From the look of the diagram, only the first part of the close wound section has the ferrite core (the lowest frequency), followed by a section of close wound air cored, followed finally by a section of space wound air cored - probably the actual GHz region. Even the long straight sections of wire from the coil to the filament connections might be part of the highest frequency filtering (?)

author: paulc
author_rank: Contributor
timestamp: July 24, 2019, 10:17:33 am
content: Hi Tim,you probably meant FairRite material #61. This is what they write:"A high frequency NiZn ferrite developed for a range of inductive applications up to 25 MHz. This material is also used in EMI applications for suppression of noise frequencies above 200 MHz"So you are probably right.Thanks.

author: paulc
author_rank: Contributor
timestamp: July 24, 2019, 10:20:39 am
content: Hi,The drawing is just for reference.Actually I found inside magnetrons filters that are made of two wound sectiond with a ferrite cylinder inside each.Thanks.
80m loft antennaHi  - Page 1
Forum section: electronics / rf-microwave

author: m3vuv
author_rank: Super Contributor
timestamp: July 22, 2019, 11:10:17 am
content: Hi all,i want to get on 3.775mhz for a local net,the issue is i live in a flat so antennas are an issue,has anyone ever used 2x 80m mobile whips with a dipole center?,if so was it worth the effort?,the best ive got was an swr of about 3 to 1,would a balun help or manual atu?cheers m3vuv.

author: radiolistener
author_rank: Super Contributor
timestamp: July 22, 2019, 01:20:02 pm
content: if you're needs antenna for receiver, you can use Mini Whip antenna. Just place it as far as possible from the building and it will works good.For transmitter it's much harder to get good antenna when you living in a flat.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: July 23, 2019, 06:59:00 am
content: You'll be well down with that setup but should still make contacts.Ideally you'd use some form of impedance transformation network near the feedpoint of the antenna.
Frequency division - Page 1
Forum section: electronics / rf-microwave

author: arildj78
author_rank: Regular Contributor
timestamp: July 15, 2019, 08:20:45 am
content: I’m designing my first voltage controlled oscillator (VCO) and are planning to use the 74HCT163 to do frequency division. I need to divide by 57 and have a question about the data sheet.https://assets.nexperia.com/documents/data-sheet/74HC_HCT163.pdfThe example circuit is showing a modulo-11 with a NAND from the output to the reset. Why are they not presetting with five and counting up. Then using the carry to do another load? That way you are not using any extra circuitry?I’m clearly missing something but what? Since they are not showing this topology for a divide by 11, the preset must be meant for something else, but what?

author: capt bullshot
author_rank: Super Contributor
timestamp: July 15, 2019, 09:38:36 am
content: The application example shows the advantage of having a synchronous reset input. Using the TC to load the counter would require an inverter anyway.It doesn't show how to build a divide by 57, IMO indeed presetting the counter by using the (inverted) TC output of the second stage appears the best way to achieve this.

author: arildj78
author_rank: Regular Contributor
timestamp: July 15, 2019, 04:03:12 pm
content: Will the load preset behave as a synchronous operation similar to the reset or will it be an asynchronous operation?If the data pins are all set to zero, what will be the difference between the load preset and the reset pin?
Help me identify this surface mount SM-A connector - Page 1
Forum section: electronics / rf-microwave

author: GreyArea
author_rank: Contributor
timestamp: July 12, 2019, 10:38:46 am
content: Hello, some heavy handed person has broken the SM-A connector at the other end of this surface mount connector, can you help me identify it please.It is the flylead with attached connector (shown) that I need to replace, not the actual surface mount component on the board.TIA!

author: chris_leyson
author_rank: Super Contributor
timestamp: July 12, 2019, 12:38:23 pm
content: Looks more like an MCX or MMCX or similar connector

author: eb4fbz
author_rank: Regular Contributor
timestamp: July 12, 2019, 03:45:27 pm
content: MMCX

author: GreyArea
author_rank: Contributor
timestamp: July 15, 2019, 02:06:43 pm
content: Thank you both.
[ASK] Shield braiding coverage percentage at coaxial cable ? - Page 1
Forum section: electronics / rf-microwave

author: BravoV
author_rank: Super Contributor
timestamp: July 11, 2019, 08:43:15 am
content: At below attached photos, a stripped cable at the outer jacket only, from the manufacturer's datasheet stated that this cable has 70% shield coverage, its Leoni brand btw.At the photo its obvious that the outer fine braid wires do not have complete coverage as woven braids still have gaps/holes (1st pic), but underneath it, there is another layer of extra aluminium foil that completely wrapped the cable with an overlapping section (3rd pic).Why is this not count as 100% shield coverage instead of just 70% ? Isn't that the whole center core wires are fully shielded/isolated ?A RF noob here, appreciate any explanation or insight, TIA.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 11, 2019, 09:46:21 am
content: Well, because it's foil, not braid, I would suppose...Foil should count nicely at high frequencies, but not so well at low frequencies, where the braid will matter (and where the coverage will matter as well). That may be visible in the exact shape of the attenuation(freq) curve. Also, if that's aluminum foil then there's the matter of poor connection between any given patch of braid, and the foil surface, which will tend to allow more leakage than otherwise.Tim

author: EVS
author_rank: Contributor
timestamp: July 11, 2019, 12:53:55 pm
content: Foil screens are most effective at higher frequencies as they provide 100% coverage. However as they are quite thin and brittle they are not good for low frequency and/or dynamic use.A combination of foil and braid will provide the best screening over a wide range of frequencies."Habia Cable. Shielding. Comparison of shielding methods"

author: BravoV
author_rank: Super Contributor
timestamp: July 12, 2019, 08:54:38 am
content: Thanks for the replies, I guess it just work on HF, nothing serious actually as it will be used only for GPS antenna for my GPSDO, there is no low freq. component that needed to be protected right ?Just curious, about the low freq, at what range approximately that these 70% coverage will affect the LF signal significantly ?

author: radiolistener
author_rank: Super Contributor
timestamp: July 12, 2019, 05:42:41 pm
content: Quote from: BravoV on July 12, 2019, 08:54:38 amabout 1-5 MHz and below
Measuring Freq. from MFJ 8100 - Page 1
Forum section: electronics / rf-microwave

author: vinlove
author_rank: Frequent Contributor
timestamp: July 12, 2019, 09:46:43 am
content: I have this old MFJ 8100 regenerative SW radio.Could I use my FY6800 or DSO to measure freq it is receiving?If yes, which point in the set should I measure and how?
Sourcing 455kHz ceramic filters - Page 1
Forum section: electronics / rf-microwave

author: arildj78
author_rank: Regular Contributor
timestamp: July 08, 2019, 09:48:43 am
content: I'm designing my first receiver and are planning to use an IF of 455kHz. There are a lot of nice reference designs out there but so far I'm stuck on one key component. It seems like ceramic filters of 455kHz is the way to go, but where can I buy them?Of course there is quite a few on ebay, but where should I buy from to be sure that they can be sourced in the future as well? I searched digikey, but all the 455kHz ceramic filters are obsolete and not for new designs. Are there any good alternatives?

author: fcb
author_rank: Super Contributor
timestamp: July 08, 2019, 10:26:09 am
content: There is more than enough NOS 455KHz filters in the world to see out the human race.I binned a few trays of TOKO 455KHz's a year or two back along with a couple of bags full of 10.7MHz parts. If you want to enter production then RoHS compliant NOS might be difficult.

author: CJay
author_rank: Super Contributor
timestamp: July 08, 2019, 11:14:48 am
content: You threw them away?Wow...If you feel like throwing more stuff away please let me know, I'm sure I could split it up and give it away to other radio hobbyists.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 08, 2019, 12:11:33 pm
content: If you are in the US (can't see the flag on my cellphone), here's a source of ceramic filters...http://www.bgmicro.com/ACS1957.aspx

author: rf-messkopf
author_rank: Regular Contributor
timestamp: July 08, 2019, 12:37:10 pm
content: Murata has discontinued their the kHz-range of ceramic filters:https://www.murata.com/en-eu/products/filter/cerafil/eol.But there are companies which still make them. For examplehttps://www.novitronic.ch/fm/2/Short%20Form%20-%20Ceramic%20Filters%20%28AM%20IF%20Applications%29%20.pdfhttp://www.aelcrystals.co.uk/DocumentHandler/60684I'm sure there will be more.

author: fcb
author_rank: Super Contributor
timestamp: July 08, 2019, 05:16:35 pm
content: Quote from: CJay on July 08, 2019, 11:14:48 amI might still have a bag of 10.7 filters lurking in stores. Defo got some tubes of old (non-RoHS) RF IC's parts (SA605's ring a bell) kicking about from old product runs. I'll do some digging when I get a few mins.G1YWC

author: arildj78
author_rank: Regular Contributor
timestamp: July 08, 2019, 11:04:46 pm
content: Thanks for your reply. I have now ordered ceramic filters from ebay.

author: CJay
author_rank: Super Contributor
timestamp: July 09, 2019, 11:32:00 am
content: Quote from: fcb on July 08, 2019, 05:16:35 pmI'm pretty sure I can make use of some of them and also share them out. PM if you find stuff?
HFSS port 'Port1' does not have a valid reference plane above or below it. - Page 1
Forum section: electronics / rf-microwave

author: promach
author_rank: Frequent Contributor
timestamp: July 06, 2019, 03:17:11 am
content: How to get rid of the following errors :Quote

author: promach
author_rank: Frequent Contributor
timestamp: July 06, 2019, 07:23:03 am
content: I have managed to solved all the simulation issues, and make the simulation converged, but the s-parameter magnitude and phase results make the layout looks like not a marchand balun. Why ?Note that the via is not visible at the end of each strip for ports 2 and 3. I am still trying to make the via visibleplanar marchand balunmagnitude plotphase plot

author: promach
author_rank: Frequent Contributor
timestamp: July 06, 2019, 10:05:33 am
content: I have now added the via correctly and the two vias are visible now.However, the magnitude and plot simulation results remain unchanged. Why ?

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: July 07, 2019, 11:43:04 am
content: First thing with HFSS would be: check the port field distribution. This will tell you if what HFSS excites is actually what you want it to excite. (I'm not that familiar with lumped ports so I don't know how that changes things).Then: Show some more info. How is your design made? What am I looking at? How did you define your materials? What are your boundary conditions? Are you solving with PECs or actual materials? Perhaps look at field distributions to see if you can spot an error (eg, if you see E-field buildup at your vias, you know your vias aren't actually working)

author: promach
author_rank: Frequent Contributor
timestamp: July 07, 2019, 12:31:11 pm
content: I am just trying to replicateNew Design Formulas for Impedance-Transforming 3-dB Marchand BalunsQuoteHow do I do this field distribution analysis in HFSS 3d Layout ?Note:I have attached the entire project file (I am using Ansys Electronics Suite 2018.2) here

author: promach
author_rank: Frequent Contributor
timestamp: July 08, 2019, 01:47:11 pm
content: I have changed the via material to copper , but the waveform results still do not look good at all.The following are the S22 and S33 waveforms.
Is it feasible to manually draw from scratch a 2-layer PCB inside HFSS  - Page 1
Forum section: electronics / rf-microwave

author: promach
author_rank: Frequent Contributor
timestamp: July 04, 2019, 02:11:20 am
content: I am trying to replicatea new planar marchand balunIs it feasible to manually draw from scratch a 2-layer PCB inside HFSS ?Or should I use external PCB drawing tool such as Kicad or Altium, then import the PCB layout into HFSS instead ?Which method is easier to work with ?

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: July 07, 2019, 11:45:45 am
content: Yes. I have done this in the past, many colleagues of mine do it to. Is it a pain? Yes. But if you want fast, parametric simulation, it is a pain you will have to endure.I actually used 3D mechanical cad packages a few times because there are ways to import a parametric STL into hfss and preserve parametric things. The problem with drawing in packages like Altium or KiCAD is that they do not have tools to design the way you would want to. You want constraints like 'distance between traces', 'length of trace', etc, and these packages are not made with such constraints in mind.
Converting CB ATU to Ham ATU - Page 1
Forum section: electronics / rf-microwave

author: vinlove
author_rank: Frequent Contributor
timestamp: July 05, 2019, 05:53:52 am
content: I am thinking of getting back to HF operating after a few years of absence. Problem is I have sold off all my Ham gears.Looking at eBay, these days there are not many good old used ham gears anymore. Maybe Ham is a dying hobby?I bought a couple of CB ATUs (26Mhz - 27Mhz) very cheap thinking I will convert them to HF ATU (to cover maybe from 7Mhz - 28Mhz).Would it be possible? What would be best approach for the project? If it is not good idea, then I would still use them for SWR / Power meter, because the metering covers from 1.5Mhz to 40Mhz.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: July 05, 2019, 08:23:35 am
content: no, I don't think it's possible to just modify them for such a wide band from 7 to 28MHz; You'll get them working for 10m but not for the longer band; neither the L nor the C will match those frequencies and the impedances.You could salvage them,if you have several ones and build a complete new device with the components; could be worth the work if you can harvest high quality silver mica caps for example; but I wouldn't count finding those in cheap CB tuners.

author: vinlove
author_rank: Frequent Contributor
timestamp: July 05, 2019, 09:47:40 am
content: I thought I could wind a coil withe tapping points, and connect it to the CB tuner in L match configuration?I saw in youtube that L match ATU is very simple to make with the tapping coil and variable capacitor.But I am not exactly aware of where to connect the coil to in the CB ATU. Was just an idea.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: July 05, 2019, 12:40:17 pm
content: The tuner settings (L / C ratios and positions) depend on the impedance to match, tapping an L is always a compromise which affects the Q; it's preferable to use multiple L switched in series according to need.If you want a L-formed tuner, you have to make the position of C switchable - C before L if Zin<Zouz, C after L if Zin>Zout

author: vinlove
author_rank: Frequent Contributor
timestamp: July 05, 2019, 12:47:30 pm
content: This guy makes it look easy.
4 port Wilkinson combiner / splitter question - Page 1
Forum section: electronics / rf-microwave

author: Chris Wilson
author_rank: Super Contributor
timestamp: July 02, 2019, 10:49:27 am
content: I am sad to say my maths are far below the required to work out inductance and capacitance values for a 4 port Wilkinson combiner based on this YouTube video linked below. I successfully made a 3 port one using this on line calculator (below), but despite intense Googling I cannot find one for a 4 port version. I need to make one for four 50 Ohm port impedances in and out on 137.5 kHz (LF). A big ask but if someone has bit of spare time the figures for the needed caps and inductances would be GREATLY appreciated, some Paypal money is not a problem! I will be using a star format resistor network, and I know these need to be Zo (50 Ohms) each.This is the video on multi port Wilkinsons:This is the on line 3 port calculator:https://leleivre.com/rf_wilkinson.htmlThanks for any help!

author: ThomasDK
author_rank: Regular Contributor
timestamp: July 02, 2019, 03:00:56 pm
content: Have a look at:https://www.microwaves101.com/encyclopedias/n-way-wilkinson-splittersThe 'arms' needs a Z of sqrt(N) x Z0.You want 4 ports, so 3 arms:Z=sqrt(3)×50 = 86.6RCalculate L and C to have this reactance at your frequency of choice.At 137.5kHz:L= Z / (2 x pi x F) = 86.6 / (2 x pi x 137.5k) = 100μHC = 1 / (2 x pi x F x Z) = 1 / (2 x pi x 137.5k x 86.6) = 13.4nF

author: Chris Wilson
author_rank: Super Contributor
timestamp: July 02, 2019, 07:21:56 pm
content: Quote from: ThomasDK on July 02, 2019, 03:00:56 pmPerfect, even I can follow this and I managed to duplicate your results using an on line reactance calculator, many thanks Thomas and much appreciated!
Looking for schema/infos for a LCT SHX 20 045 oscillator pcb - Page 1
Forum section: electronics / rf-microwave

author: markus_jlrb
author_rank: Regular Contributor
timestamp: June 30, 2019, 11:18:51 am
content: Dear Forum,I'm searching for info's concerning a frequency generation devicelabeled LCT SHX 10100 N°510.The printed label content on the part is:Source SHX 510334428 2.4.84SHX 10100 N°51078. VELIZY VILLACOUBLAYThis part is generating 10 or 15 Gc LO Signal.The oscillator pcb that is not working, generatesa signal for a booster with a bpf in front with 415Mccenter frequency. The booster output is feeded intothe first multiplier (6x) generating 2.5Gc that is againfeeded into a second multiplier (4x or 6x corresponding)to 10 or 15Gc - but I'm having no possibility to measure thefrequency.Have attached some pics and waiting for some info'sfrom the community.First pic. show the demounted part with both multipliersbelow the enclosure.the second and third pic. shows the osc. pcb with thesemiconductors on it. The red circles marks the positionof ten TO-39 transistors placed at botom side of the pcb.These transistors switch varactors to the LC circuitry totune the frequency.Many thanks in advanceMarkus
How do you call the U.FL, I-PEX, MHF, IPEX, IPAX, IPX, AMC, UMCC RF connectors? - Page 1
Forum section: electronics / rf-microwave

author: RoGeorge
author_rank: Super Contributor
timestamp: June 27, 2019, 11:30:49 pm
content: 3-4 sizes of diameters and heights, called different across different manufacturers, yet standardized in dimension.How do you call them?https://en.wikipedia.org/wiki/Hirose_U.FLhttps://duckduckgo.com/?q=ufl+ipx+ipex+mhf&iax=images&ia=images

author: RoGeorge
author_rank: Super Contributor
timestamp: June 29, 2019, 08:17:17 am
content: It's this kind of connectors:http://i68.tinypic.com/bg8q4k.jpgLATER EDIT:Strange thing, the topic showed me no updates, so I thought nobody voted, posted this message to bump up the poll, vote myself, then seen there were already 9 other votes.Got it, U.FLThank you.
Common-base configuration for 12-200kHz front-end - Page 1
Forum section: electronics / rf-microwave

author: floobydust
author_rank: Super Contributor
timestamp: June 28, 2019, 07:41:20 pm
content: Thoughts on using common-base configuration for the front-end for 12-200kHz? I'm trying some different lightning detector designs this summer.For AM radio loopstick antennas, they are in a transformer configuration I think to keep the tuning capacitance requirement low. One winding is tuned, the other goes to the front-end.Manufacturers are always running that into a common-emitter amp, but here it's common base and I thought why two windings needed at all, just run the tank into a CE.I also think there's a few mistakes in this circuit, the emitter resistor ends up shorted by the antenna winding and 100uF is huge for the base capacitor.I found the circuit onStormwise.comJim Pedersen 12kHz & 220kHz Lightning Chaser Rev 1.0 schematicThey sell VLF antennas 30kHz-4MHz. Picture links are broken and no way to email the site owner and let them know.

author: hamster_nz
author_rank: Super Contributor
timestamp: June 28, 2019, 10:45:02 pm
content: If mentally redrawn so that the inductors are on the base of the transistor, and the RC network is a filter off to the side, it sort of makes sense, so might work.Might have to print it out and solve on paper. Looks to be a fun wee problem....
1.5Ghz, GPS, conformal coating - Page 1
Forum section: electronics / rf-microwave

author: GigaJoe
author_rank: Frequent Contributor
timestamp: June 25, 2019, 04:04:19 pm
content: Hello,Below are basic active patch GPS antenna, back cover metal shield removed, it didn't work well, so i removed the shield on the back, it was heavy amount of flux on a coax soldering joint, when I cleaned, it start working. Now i re-do antenna with a ground plane, stand etc ....Question: ! ( it important )If I coat that back by conformal urethane coating (https://www.mgchemicals.com/products/conformal-coatings/4223-polyurethane-conformal-coating)Will it mess up the signal pass on the board, basically ruined the circuit or degraded it ? or it will perfectly OK?Actually, the same question for WI-FI equipment, someone ask me to make it better water resistance, so I wonder if coating will work, or it will destroy the board ...UPD: I Look at this:http://www.techni-tool.com/site/ARTICLE_LIBRARY/Chemtronics%20-%20Conformal%20Coatings%20Guide.pdfhttps://www.mgchemicals.com/downloads/comparison-tables/Conformal%20Coating%20Comparison%20Chart.pdfnone defined some RF parameters, so i'm still puzzling ..

author: eb4fbz
author_rank: Regular Contributor
timestamp: June 26, 2019, 12:23:35 pm
content: You will ruin the transmission lines impedance, as they will no longer have air as dielectric on top.

author: clockspectrum
author_rank: Contributor
timestamp: June 26, 2019, 02:25:41 pm
content: You will need to model the additional material added to the top of the PCB to see the response. You can do this in something like ADS. This is one of the reason it is common to see solder mask removed in sections of transmission lines. It looks like you have a number of transmission lines that you need to consider the impacts for in addition to the antenna elements.
RF Engineering Masters courses - Page 1
Forum section: electronics / rf-microwave

author: jr1990
author_rank: Newbie
timestamp: June 19, 2019, 07:22:51 am
content: Hello all,I've recently started working for a big defence company who are willing to send me on a Masters course and it would be most appropriate for me to find a course which focusses on RF/Wireless communications.I have a first class Honours degree in Electronic Systems Engineering from the University of Portsmouth.Wondering if anyone would recommend any courses which can be taken via distance learning or have minimal "on-site" training. Doesn't necessarily need to be a masters, I just want to learn as much as I can about everything RF engineering related!Thanks in advance!

author: BigMark
author_rank: Contributor
timestamp: June 25, 2019, 09:56:17 pm
content: University of Surrey do bespoke courses. Couple of colleagues did the same course and found the it to good. The price of each module is high, but works out similar to doing the course full time. Also allows you to continue working,https://www.surrey.ac.uk/department-electrical-electronic-engineering/short-courses/msc-electronic-engineering-short-courses
Reducing the inductance of a variometer? - Page 1
Forum section: electronics / rf-microwave

author: Chris Wilson
author_rank: Super Contributor
timestamp: June 22, 2019, 04:12:10 pm
content: I have an ex Russian military variometer (actually I am told it's really a goliometer...), that I use in series with an LF loading coil. It's remote tunable with a geared motor drive. On MF I do not need the main loading coil to resonate the antenna, just the variometer, BUT, it has to be set to its very minimum inductance and the weather etcetera sometimes means even on minimum inductance there's too much. I don't want to try and butcher it, is there any trickery, even if there's a bit of loss, to reduce its inductance a bit and put the sweet spot within its normal adjustment range please? Thanks!

author: bob91343
author_rank: Super Contributor
timestamp: June 22, 2019, 05:07:14 pm
content: The best solution I can think of is to put a large inductance in parallel with it. Careful selection of the value of that inductance can result in the effect you desire.How much do you want to change it? If the answer is, say, 10%, then put an inductance in parallel that is about 10 times the inductance of your unit. The formula is the same as that for parallel resistances.The main thing is to avoid an inductance that is either nonlinear (that is, with a ferrous core) and to avoid interaction of the magnetic fields. They will add uncertainty to your measurement.

author: duak
author_rank: Super Contributor
timestamp: June 22, 2019, 05:38:53 pm
content: I've never played with one so I don't know if this would be physically possible, but could you add one or two fixed coils counter wound and then wired in series with the existing fixed coil? The inductance of a coil is a function of the number of the number of turns squared so even a few counter turns would make a big difference. Note that the counter coils have to be within the existing magnetic circuit. If all else fails, you might be able to make the electrical connections to taps part way down the coils ie., on the fourth turn rather than the fifth. You can't short turns out without affecting the Q but as long as the end is open, you should be OKIf the frequencies of interest are in a relatively narrow band, you could put a capacitor in series. However, the cap will resonate with the inductance at some frequency and upset your matching network.BTW, the way I understand it is that the basic variable inductor is called a variometer and if it is used to measure an angle, it's a goniometer. When I was a kid I ran across goniometer used as a comedic device in Mad magazine. It sounds funny to my ears, but I found later that they really existed.
Jet Jurgensmeyer KE0UWZ talks Last Man Standing & Ham Radio - Page 1
Forum section: electronics / rf-microwave

author: haydenph
author_rank: Contributor
timestamp: June 20, 2019, 09:57:24 am
content: Jet Jurgensmeyer is perhaps best known for his role on the TV show Last Man Standing and has recently passed his license for his ham radio ticket. Jet's callsign is KE0UWZ and he was kind enough to sit down with me for an interview about the show, his music and amateur radio. A great ambassador for AR that will hopefully inspire more his age.
144 MHz considered to be occupied for aeronautical radio at WRC proposal - Page 1
Forum section: electronics / rf-microwave

author: babysitter
author_rank: Frequent Contributor
timestamp: June 13, 2019, 07:14:37 pm
content: France included the 144 MHz ham radio band into a proposal to check feasibility of extending the spectrum for aeronautical purposes, some ham radio media and IARU region 1 report.https://www.iaru-r1.org/index.php/88-news/1864-wrc-23-agenda-itemsPlease don't immediately shitstorm the french ministry overseeing spectrum use or WRC, humble letters may be benficial when more info leaks out.73Hendi

author: HB9EVI
author_rank: Frequent Contributor
timestamp: June 13, 2019, 08:06:46 pm
content: already read it on other places... who knows what went into them; it's shocking but little surprising...I'm seriously reconsidering to join the national hamradio league again; it really seems we are going to need them for the future; on the other side they're unfortunatelly often occupied by themselves and sleep when action would be needed...

author: coppercone2
author_rank: Super Contributor
timestamp: June 16, 2019, 02:17:36 am
content: burglary in process

author: David Hess
author_rank: Super Contributor
timestamp: June 16, 2019, 07:02:54 pm
content: Will this be like when they took most of the 220 MHz band and gave it to UPS who promptly abandoned it?

author: kakabouras
author_rank: Newbie
timestamp: June 17, 2019, 05:54:54 pm
content: Apparently a French company that is heavily involved in aeronautical electronics(Thales Group) initiated all this.Keep in mind that the 2m band is GLOBALLY assigned as a primary use for the radio amateur service and think of the benefits. No special licensing depending on geographical region for the official user
ALT-512 and the controversy - Page 1
Forum section: electronics / rf-microwave

author: HB9EVI
author_rank: Frequent Contributor
timestamp: June 16, 2019, 06:34:26 pm
content: hi thereI'd like to push a discussion about the ALT-512 ham radio transceiverhttps://www.aerial-51.com/alt-512/we had an engaged discussion or maybe more a controversy about the technical parameters on qrpforum.de. In the end operators of forum closed down the threads leaving many unanswered questions since they want to sell that device and not hear critics about the esoteric manner of the creators claims.we were talking about the narrow specs 'optimal' operation condition like the voltage of 12,6V, which if not respected seems to cause a decline in carrier suppression of about 3dB - in the range +/- -65dBc.Another claim of the creator was the usage of 0,01% tolerance caps to reach the devices' outstanding performance, which nobody of us could find e.g. a Mouser. Otherwise mentioned were narrow tolerances of 1,2mV in certain circuits of the device without pointing where and why.Our inquiries for further information like block schematics or circuit details remained unanswered pointing out of being 'incredible afraid' from chinese counterfeits.Why to point out all these fancy details without the intention of backing it with facts everybody can verify. When reading those things it more remembered me some hifi voodoo article than a portable ham radio transceiver.
Affordable 5Ghz Antenna? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: June 25, 2019, 02:11:40 pm
content: HiI need outdoor a Directional 5Ghz Antenna. The "Branded" one should cost 300€ (exclude).Can someone recommend a Company who produce directional 5Ghz antenna?I would use: Zyxel WAC6303D-S put then under the Rooftop and feed 2 Antenna for Mimo outside.I also would stay with some Delock Antenna Cable for the connection.Hopefully the AP Support 1W Power for the 5Ghz Channels sure - the Gain from the Antenna.There is one problem...I draw it in Google Earth so its quite accurate.Green + Orange HouseYellow is the Bus Station and Light Blue the Tram Station who is a view Meter above the Ground.So I never was on our Roof to know exactly if we see over the Building but the are not realy in the way.So could I get a good connection on the Tram station? If yes can someone recommend a good Mimo Wifi Antenna?Thanks

author: frogg
author_rank: Regular Contributor
timestamp: July 01, 2019, 12:18:55 pm
content: Can you use a cheap pcb microstrip feed into a horn?

author: Psi
author_rank: Super Contributor
timestamp: July 01, 2019, 12:21:41 pm
content: There are lots of guides online for building helical 5.8ghz directional antennas for FPV video links.You could easily adapt one of those guides for 5.0ghz

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 01, 2019, 01:54:32 pm
content: I ordered an Cheap Delock Antenna.

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 01, 2019, 07:55:36 pm
content: https://www.delock.de/produkte/1468_Antennen/88806/merkmale.htmlSo I should choose the Channel 140 (5,70 GHz)for the "max" Performance?

author: hagster
author_rank: Frequent Contributor
timestamp: July 01, 2019, 09:03:12 pm
content: Any S11 better than 10dB is good. In terms of tx or rx signal level the difference between all these measurements is tiny. Google "mismatch loss calculator" and try a few return loss values. Very little to be gained by going further.
VNA Cal Kit Manager - Page 1
Forum section: electronics / rf-microwave

author: sixtimesseven
author_rank: Frequent Contributor
timestamp: June 10, 2019, 02:14:50 pm
content: I'm having a hard time getting the .ckm file with the Cal Kit Manager 2.1 right.http://www.vnahelp.com/products.htmlThe standard definitions tab is pretty self explanatory. But what do I do on the Class Assignment Tab? I have not found much documentation apart from what is on Kirkbys page.Could someone share a .ckm file, preferably only one connector type (female) SOLT?

author: hendorog
author_rank: Super Contributor
timestamp: June 11, 2019, 12:39:27 am
content: Just load up one of the samples, on mine if you select File Open then all of the HP cal kit definitions are there.Load one of them up and it should be clearThe contents of the Class Assignments tab changes according to the VNA you have.Have attached one of the sample files.

author: sixtimesseven
author_rank: Frequent Contributor
timestamp: June 11, 2019, 12:39:28 pm
content: Quote from: hendorog on June 11, 2019, 12:39:27 amThank you, I did not see that! That should solve it.

author: sixtimesseven
author_rank: Frequent Contributor
timestamp: June 11, 2019, 08:47:42 pm
content: Well, new problem:It seems CKM2 is unable to load some comma seperated values on to the HP8753D.If I for example specify the open as:C0 = -17,5C1 = - 2000C2 = 140C3 = -7,5Offset delay = 33,356Offset Loss = 2,2And I load this to the 8753 and then modify the kit I see the following:C0 = 5C1 = - 2000C2 = 140C3 = 5Offset delay = 356Offset Loss = 2,2 (This one is loaded correctly???)So it will ignore everything before the comma for most values. There seems to be no option to input other seperators or the (n, mu, m) prefixes into the CKM2 as well so I have no idea. Is it just a bug?I also tried to save it to floppy disk but apparantly the HP8753D cannot read .ck files.

author: hendorog
author_rank: Super Contributor
timestamp: June 11, 2019, 08:55:31 pm
content: Have you tried using a decimal (.) instead of a comma (,)If CKM2 can't handle that then you will probably need to change your PC to use decimal places instead of commas in Control Panel.Then the app should work and it should also send values the 8753 can handle.

author: sixtimesseven
author_rank: Frequent Contributor
timestamp: June 12, 2019, 06:51:26 am
content: Yup, that solved it.Control Panel\Clock and Region -> Change date, time or number formats -> Additional Settings -> Decimal Symbol -> Change from "," to "."Thank you hendorog!And dam you Windows

author: Tony_G
author_rank: Super Contributor
timestamp: June 12, 2019, 03:41:37 pm
content: As an aside, this is actually pretty common where apps aren't written with globalization in mind. Typically the dev calls some formatting API/Method and doesn't fix the number formatting to the required locale to get the correct output for the file. If they don't do that then these libs will just use whatever locale is set in windows.If you're interested in the information on how to do this it is available here forWin32and.NET Framework.TonyG
New Signalhound 6GHz Vector Signal Gen :- VSG60A - Page 1
Forum section: electronics / rf-microwave

author: hendorog
author_rank: Super Contributor
timestamp: June 18, 2019, 04:38:40 am
content: Looks nice.50MHz - 6GHz and 40MHz bandwidth, low phase noise.https://signalhound.com/support/forums/topic/product-announcement-new-6-ghz-vector-signal-generator-coming-in-q4-2019/

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: June 18, 2019, 06:31:40 am
content: Too bad it has such low modulation bandwidth. I can see it useful for WiFi and BLE work etc, but it seems a bit narrow band for other stuff.Looks cool though, though the price will be the end-decider of that.Makes me wonder if they could sell a box to act as a interface for the software. Kinda like some of the high-end AWGs (M8100 series) of keysight come in a AXI chassis with a embedded computer built in. Though then again, what is stopping people from just buying an intel NUC or similar and using that....
RF textile for wearable applications - Page 1
Forum section: electronics / rf-microwave

author: Bud
author_rank: Super Contributor
timestamp: May 31, 2019, 12:08:21 am
content: We soon be shopping for impedance controlled T-shirts and sockshttps://www.mwrf.com/materials/breathable-e-textile-proven-rf-wearable-apps

author: Bud
author_rank: Super Contributor
timestamp: June 12, 2019, 02:20:46 am
content: Plot thickens...QuoteSoworkingFlux capacitor T-shirts are coming to your local Walmart store.https://www.electronicdesign.com/power/charge-storing-threads-turn-fabric-supercapacitor
Collins 51S-1 Power Transformer Primary Resistance - Page 1
Forum section: electronics / rf-microwave

author: fuzzoli
author_rank: Regular Contributor
timestamp: June 09, 2019, 10:47:06 pm
content: Hi all,I'm starting a repair on a Collins 51S-1 receiver that's failing the dim bulb test. Each of the two primary windings on the power transformer measures only 8. Does that sound right? It seems a bit low, especially since they are connected in parallel for a result of only 4@110V mains.EDIT: So it looks like all is good from the dim bulb results. All tubes tested good. I guess I was just being overly cautious before turning it on. Now onto the next issue.Thanks,-Frank

author: Geatnows
author_rank: Newbie
timestamp: June 11, 2019, 06:52:00 am
content: Get more knowledge. I like it. Thank you for giving advice.
Choosing the right SMD size - Page 1
Forum section: electronics / rf-microwave

author: Nikos A.
author_rank: Regular Contributor
timestamp: June 09, 2019, 12:50:24 pm
content: Hi everyone,I am wondering whether or not there is any guide of selection of the right SMD size for RF applications.I know that the bigger the size the highest the paracitic capacitance of the component.. So, select components as small as possible.. correct?Furthermore, when is calculated the impedance of a transmission line i.g. microstrip, is taken into account the trace width. I suppose that components should be sized as close as possible to trace width in order to keep impedance matched.. Is it correct this statement?Is there any other factor while selecting components size? Is should be first calculated the RF trace width and then choose the appropriate size of components?Thanks in advance

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 09, 2019, 04:21:40 pm
content: Yeah, more or less.Obviously, you'll be limited by other constraints when applicable: for example, an 0402 isn't going to handle more than 50V, or 62mW, say. At higher power, you'll need to use bigger parts.So, what you're asking about, has to be just the default component size, and exceptions may be necessary.Yes, component size (width in terms of Zo over GND plane, length in terms of electrical TL length) matters; these properties (Zo, length) may or may not matter, but they can be compared with the frequencies and impedances of interest and a decision made that way.Tim

author: Nikos A.
author_rank: Regular Contributor
timestamp: June 10, 2019, 06:40:41 am
content: Yes, the electrical characteristics is a second consideration and can obviously change the size.That's great thanks Tim!!Nick
ARRL VHF contest - anyone else on the air? - Page 1
Forum section: electronics / rf-microwave

author: TheSteve
author_rank: Unknown
timestamp: June 08, 2019, 07:33:59 pm
content: I'm all setup in the backyard for the VHF contest, sadly there are no openings on 6 meters in my area(CN89) at this time.Using a buddipole configured as a 3 element beam and broke out the fanciest antenna analyzer I could find, radio is an Icom IC-7000.VE7FM
Math Notation Question re Planar Microwave Engineering by Lee - Page 1
Forum section: electronics / rf-microwave

author: 0culus
author_rank: Super Contributor
timestamp: June 05, 2019, 04:39:08 am
content: I was hoping someone could explain the notation that first appears section 2.5, Equation (9). He is talking about (avoiding) summing an infinite series, but the notation he uses here doesn't look like anything I've ever seen before...and I have a math degree.It appears to be a recursive definition. I've reproduced the equation here for those that may not have the book:$$Z_{\text{in}} = Z + [(1/Y) || Z_{\text{in}}]$$Thanks!

author: bob91343
author_rank: Super Contributor
timestamp: June 05, 2019, 06:09:06 am
content: I don't know either, but the double lines have been used in electronics to signify parallel connection. So when you write them you mean the usual parallel connection formula, product divided by sum.

author: rf-messkopf
author_rank: Regular Contributor
timestamp: June 05, 2019, 11:48:55 am
content: Yes, that's correct. By definition, for two complex impedances \$Z_1\$ and \$Z_2\$,$$Z_1||Z_2=\frac{1}{1/Z_1+1/Z_2}.$$

author: 0culus
author_rank: Super Contributor
timestamp: June 06, 2019, 12:59:47 am
content: Awesome, that makes sense. Thanks!!
ESP32 LNA and PA - Page 1
Forum section: electronics / rf-microwave

author: petergriffin56
author_rank: Contributor
timestamp: June 11, 2019, 05:33:25 pm
content: Hello,I would like to add an LNA and a amplifier to my esp32. As opposed to other radio chips I've worked with, this on has only one RF IN/OUT port. I'm thinking of adding an RF switch that I would toggle whenever I am transmitting, and leave switched to the LNA the rest of the time.I am unsure where to place the RF switch (the image should clarify).What do you guys think ?

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: June 12, 2019, 08:48:49 am
content: I'm gonna ignore potential protocol issues here, because I know little about the ESP32 (I don't even know what it uses? Wifi? BLE?)The long answer is that it depends. You can, sometimes, make it work with just one switch. You want two switches both for isolation (otherwise you might be making an oscillator) and because there is a good probability that your PA can blow up the first stage of your LNA.If you go to distributed elements, you could, perhaps, make a wilkinson power combiner/splitter work, but that would result in 3 dB loss. So I would just go for an RF switch on both ends.

author: rfengg
author_rank: Regular Contributor
timestamp: June 12, 2019, 09:17:32 am
content: IMO, both the options you have shown are not the best options. Are you familiar with the PIN diode based T/R switch?See link :https://electronics.stackexchange.com/questions/166579/pin-diode-t-r-switch-for-use-with-rf-power-amplifier

author: OwO
author_rank: Super Contributor
timestamp: June 12, 2019, 09:58:24 am
content: Both of those will not work, you MUST have switches on both sides. What power level are we talking? If this is 2W or less then go with a MMIC switch like the MXD8625C, it will make your life much easier than messing with PIN diodes. MXD8625C is a drop in placement for the common BGS12PL6 RF switch but with better isolation and insertion loss.