hybridfree/eevblog-posts huggingface dataset:
foundation licence holder + 2.4 ghz / 13cm band. - Page 1
Forum section: electronics / rf-microwave

author: m3vuv
author_rank: Super Contributor
timestamp: March 25, 2021, 09:03:14 am
content: just a quick question,ive ordered a 4 watt amp for wifi 2.4 ghz,just wonder if i can use this legaly in the uk with my foundation licence?,ive lookes on the rsgb site but still none the wiser!,cheers m3vuv.

author: srce
author_rank: Regular Contributor
timestamp: March 25, 2021, 11:30:09 am
content: Table A for foundation licenses doesn't contain 2.4GHz band, as far as I can see:https://www.ofcom.org.uk/__data/assets/pdf_file/0027/62991/amateur-terms.pdfUnlicensed device limits are on page 42, here, I think:https://www.ofcom.org.uk/__data/assets/pdf_file/0028/84970/ir-2030.pdfLooks like 'no' to me, but I'm no expert. Better get studying for the intermediate license

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 25, 2021, 08:07:45 pm
content: I also think it's a no. The 2.4GHz band is outside of the scope of the foundation licenses.Just out of curiosity, do you have any neighbors? They may not like the idea either.

author: bd139
author_rank: Super Contributor
timestamp: March 25, 2021, 09:13:13 pm
content: It’s a definite no for foundation. Seehttps://www.ofcom.org.uk/__data/assets/pdf_file/0027/62991/amateur-terms.pdfAlso 13cm is secondary use only for intermediate and full. That means you aren’t allowed to interfere with other services so you have to tread really carefully. Power limit is 50 on intermediate and 400 on full. Also due to the directional nature of antennas around that space it’s your ERP you need to consider so it’s not difficult to have 20dBi gain on top of your TX output.Ergo don’t go near it unless you have measurement equipment and a detailed band plan and allocation and know where to find the info you need and know what you’re doing before. I know enough to know not to go near it (yet)
Yaesu FP-9 old style powersupply connectors. - Page 1
Forum section: electronics / rf-microwave

author: DC1MC
author_rank: Super Contributor
timestamp: March 24, 2021, 12:22:26 pm
content: Hello old hams, does anybody remember what kind of "cigarette lighter " type connectors were used on the old Yaesu FP power supply, from the socket side it looks like a coaxial plug with ca. 12mm outside diameter and 4-5mm center nipple.Is it still available somewhere ?Many thanks,DC1MC
Can I use the RF generator in R&S CMU200 as a vector signal generator ?  - Page 1
Forum section: electronics / rf-microwave

author: electronic_guy
author_rank: Regular Contributor
timestamp: March 23, 2021, 09:40:26 am
content: Hi,Is it possible to use CMU200 RF generator as a vector signal generator ? How different the CMU200 compared to true vector signal generator like R&S SMIQ ?

author: xmo
author_rank: Regular Contributor
timestamp: March 23, 2021, 07:22:09 pm
content: You can if you have option B17:"The CMU-B17 option allows access to analog I/Q and IF signals in both communication directions (uplink and downlink)"
Naive question: Caller initiated LTE data connection - Page 1
Forum section: electronics / rf-microwave

author: DC1MC
author_rank: Super Contributor
timestamp: March 22, 2021, 01:14:15 pm
content: So to make it short: a cheap mobile data provider does not allow the LTE connection to stay on without traffic, and reconnecting is a pain.I was wondering if I can just set the (some) LTE module to just stay registered to the cell and when a call/SMS is detected to activate the (PPP) data connection. Any ideas/actual implementation case, hints and so on are welcome.Cheers,DC1MC
RF preamp BJT replacement - Page 1
Forum section: electronics / rf-microwave

author: A.Z.
author_rank: Super Contributor
timestamp: March 19, 2021, 02:12:34 pm
content: Hello all, I was thinking to try building this RF preamphttps://www.okdxf.eu/files/preamp_r60.pdfthe design is from W7IUV and the first version dates back to 1998, now the problem is that the 2N5109 used in the schematic (see page #5 in the PDF) has become hard to find and, sincerely, I'm not going to try chinese clones; so I started seeking for equivalents and found the NTE278 which is available and, judging from the datasheet, may be a drop-in replacementhttps://www.nteinc.com/specs/200to299/pdf/nte278.pdfhttps://www.digikey.com/en/products/detail/nte-electronics-inc/NTE278/11647036and here's the question; do you think the NTE278 may fit or is there some other BJT which may better match the original 2N5109 characteristics ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 19, 2021, 03:59:55 pm
content: Shrug, 2N3866 is still made by Central (and/or others? I see a bunch in stock at Newark by Solid State). Not seeing a lot of 2N5109s though.Actually, those NTEs are surprisingly cheap, I thought most of their stuff was boutique priced. Interesting.Otherwise, I mean if 2N2219 is good enough, it really doesn't matter much... this is short wave we're talking, it doesn't take anything fancy. Probably a low-Vce(sat) type would do, of similar ratings, and if one can be found in SOT-89 or SOT-223 for power. (Downside is, most are rated a few amperes -- too big junction, too much capacitance.) Would be fun to find a MOSFET of similar ratings, but about the closest you're going to find is 2N7002, and it's a bit of a pig for this, even if it could handle the power (nevermind what noise it might have).Noise, as far as I know, basically comes down to selection. Some parts are better than others, and some types are better than others (or more likely to have good parts in them). YMMV. If modern RF types are off the list (e.g. for reasons given in the doc) then you're basically stuck sorting them yourself, or buying old parts. The modern alternative is a much larger scope of substitution: just plug everything into an SDR or whatever, with a good enough ADC to do the same but even better. The DSP to run that, probably takes less power than a single 2N5109 anyway...Tim

author: A.Z.
author_rank: Super Contributor
timestamp: March 19, 2021, 04:58:41 pm
content: Hi Tim, thanks for the reply; as for the use of 2N5109 or 2N2219, probably either one will work, although I'm trying to stay with the original, at this point I think that the only way would be to pick some NTE278 and try ...To tell the whole tale, I found that preamp while looking at this loop ideahttp://www.w1aex.com/loop/loop.htmland the author was pretty impressed by the preamp performances, plus some friends told me that they tried it and that on the top bands (160 to 40) it plays VERY well, so after finding the schematic, I thought I may try putting it together and giving it a spin, I think that at this point I may just try and seeThank you again
Miniature DCF77 receivers in radio controlled watches - Page 1
Forum section: electronics / rf-microwave

author: galvanix
author_rank: Contributor
timestamp: March 24, 2021, 09:19:36 am
content: Hi,I've got a radio controlled Casio watch that can synchronize itself to the LF time signals transmitted from DCF77 in Frankfurt, MSF in GB and other transmitters in Japan and the one in China.I've always wondered what receiver topology Casio's ASIC uses to get the tiny LF signal to a usable level and decode it?I know that there is a tiny ferrite rod antenna in these watches, but that alone isn't sufficient to get a usable signal level.Do these ASICs use programmable capacitor banks to create the LC resonant circuit with the ferrite rod antenna? Do they use the antenna as part of an LC resonant circuit at all?If anyone knows I'd love to hear how it's done so compactly.I've tried many times to build my own DCF77 receiver and it's certainly possible with lots of gain and the right capacitance value, however it has always been rather finicky to get it to work properly without going into oscillation due to high gain and positive feedback.Thanks!

author: Gyro
author_rank: Super Contributor
timestamp: March 24, 2021, 11:54:04 am
content: My neighbour has one. It has a (maybe two) plastic link in the metal bracelet, near the watch, so I think it is using the bracelet as an antenna in some way.

author: galvanix
author_rank: Contributor
timestamp: March 24, 2021, 12:40:44 pm
content: Quote from: Gyro on March 24, 2021, 11:54:04 amI don't think the bracelet is necessary for the reception of LF signals. The one I've got has a resin (plastic) band and case, the only metal part is the watch back.

author: Andie
author_rank: Contributor
timestamp: March 24, 2021, 12:56:56 pm
content: Quote from: galvanix on March 24, 2021, 12:40:44 pmQuite a while ago I owned such a watch (from Junghans, if I remember correctly). The bracelet was made from a leather-like material and this bracelet incorporated an antenna made from a stack of very thin metal sheets, carrying a coil.
Reciever frontend/buffer/IF amplifier. - Page 1
Forum section: electronics / rf-microwave

author: geggi1
author_rank: Frequent Contributor
timestamp: March 10, 2021, 12:36:06 pm
content: Im working on a design for a reciever from 10khz up to about 173Mhz. It will be a module based conversion unit with an IF of 45Mhz. There will be several conversion stages with variable frequency in a way that will give continues reception form 10khz and up. The vfo will be a SI5153 because this will give me the required number of VFO/LO and IF frequencies.Because of the large bandwidth i need a very wideband amplifier in the stages in front of the mixer. Mixer will be a DBM that will handle square wave form the SI5153.

author: David Hess
author_rank: Super Contributor
timestamp: March 14, 2021, 02:17:38 am
content: At HF and lower frequencies, an RF amplifier before the first mixer usually does more harm than good because the noise levels are so high, so it just reduces the dynamic range.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: March 14, 2021, 11:10:21 am
content: The trend is to use a switchable “strong” preamp on the lower HF frequencies, although it is unlikely to be useful below about 10 MHz. A separate, higher gain, low noise preamp is generally employed on higher HF and VHF frequencies.One such strong signal handling HF preamp is this one:https://www.qsl.net/g4aon/pdfs/aonrx_pre.pdf

author: A.Z.
author_rank: Super Contributor
timestamp: March 18, 2021, 03:09:54 pm
content: Quote from: Solder_Junkie on March 14, 2021, 11:10:21 amThe original design is from W7IUV and dates back to (at least) 2009, pity the W7IUV website isn't online, but the original schematic and the (important) notes can be found herehttps://www.okdxf.eu/files/preamp_r60.pdfthe gain is about 18dB with an IIP3 of 21dBm and an OIP3 of 39dBm, so it may fit pretty well; also and since we're at it, that preamp seems to work well with RX loop antennas too, at least judging from what's reported herehttp://www.w1aex.com/loop/loop.html
What is this RF connector on my HP power sensor 8485D ? See pictures - Page 1
Forum section: electronics / rf-microwave

author: electronic_guy
author_rank: Regular Contributor
timestamp: March 14, 2021, 07:00:44 am
content: Hi,I have a 8485D power sensor. I need to know it's connector type.

author: TheSteve
author_rank: Unknown
timestamp: March 14, 2021, 07:27:03 am
content: That would be a 3.5mm (male) connector.Technically it can be mated with SMA - but be careful not to damage it with lesser quality connectors.

author: electronic_guy
author_rank: Regular Contributor
timestamp: March 14, 2021, 11:16:34 am
content: Thank you. @TheSteveI think it's better to use a 3.5mm jack for this right? I read that the SMA is prone to damage and in turn damage the 3.5mm connector too.

author: mankan
author_rank: Regular Contributor
timestamp: March 14, 2021, 12:24:07 pm
content: I would use a high quality SMA female/female adapter or a SMA male/female aka connector saver and have it semi-permanently installed.

author: ogden
author_rank: Super Contributor
timestamp: March 14, 2021, 01:25:17 pm
content: Quote from: mankan on March 14, 2021, 12:24:07 pmFor everyday engineering work better option is low loss cable, with S21 measurement on hand.

author: Tony_G
author_rank: Super Contributor
timestamp: March 18, 2021, 01:52:30 am
content: I bought a bunch of 3.5mm connectors from MiniCircuits.com to do exactly what Mankan was suggesting - I just leave them connected to my 3.5mm gear, torqued correctly, and then just use SMA cables. When they wear out I'll just replace them. That said, Ogden's point on the cable is certainly a good way as well.
HP 8753C Zero Span vs. CW Time Sweep - Page 1
Forum section: electronics / rf-microwave

author: BrumsiSol
author_rank: Newbie
timestamp: March 15, 2021, 09:01:28 am
content: Hello together,for my master's thesis I need to make some time measurements with a HP8753C. To do so I have 2 options:1. CW Time Sweep2. Zero SpanFor both modes I would expect to see one sine period if I set the Sweep Time to 20 ms. The 1st option (CW Time Sweep) meets my expectations but the Zero Span mode doesn't:Option 1:" alt="" class="bbc_img" />Option 2:" alt="" class="bbc_img" />Settings:For both options I have the same settings:- Carrier Frequency: 1 GHz- Modulation Frequency: 50 Hz- RBW = 3 kHz- Number of Sweep Points = 11- Sweep Time 0.02sObservation:As this didn't make sense to me, I startet a test series where i adapted those parameters. What I saw was that the number of displayed sine waves stays the same for adjustment of RBW and Number of Sweep Points in CW Time Sweep (makes sense to me), but they change in Zero Span (doesn't make sense to me).So the question is how the zero span mode is working here and what is the difference to the CW time sweep.

author: radiogeek381
author_rank: Regular Contributor
timestamp: March 16, 2021, 10:52:33 pm
content: What is it that you are trying to measure? (That is, what is the thing, and what "measurement" do you intend to make?)
video on hairpin filter with some interesting techniques - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: March 15, 2021, 01:47:43 am
content: This video was by Charles Grassin.H uses OpenEMS to design the filters and a cheap directional coupler to evaluate the filters. (one could also use a nanovna2)He then used a homemade probe and an arduino technique to sense and visualize the RF leakage from the circuit. Wow. Very slick.
Piggyback RF PCB onto exiting board - Page 1
Forum section: electronics / rf-microwave

author: beandigital
author_rank: Contributor
timestamp: March 16, 2021, 09:27:37 pm
content: I have a board that was routed incorrectly. The input is a 4G FPD LINK iii signal that needs to be 50R. What I want to do is create a temp solution by creating a new PCB to attach onto the top of the existing board. But what concerns me is how to mate the two boards together. The existing board has a DS90Ub960 chip. I would need to attach the new board to the RIN pins of that chip. Does anyone have any tips on how to do this and maintain good signal integrity? Thanks

author: cdev
author_rank: Super Contributor
timestamp: March 18, 2021, 04:20:33 am
content: a coaxial cable interconnect, soldered on, might be good for a one off project. and more robust than some pins or plugs.
Motorola P1225 hand held just beeps on xmit - Page 1
Forum section: electronics / rf-microwave

author: videobruce
author_rank: Frequent Contributor
timestamp: March 18, 2021, 02:04:17 pm
content: Out of the blue, when I try to xmit on this older (probably early 90's) Moto P1225 hand held, all I get are a flashing red & audible beeps. I initially thought it was a antenna issue (high swr), but not so, it does in on it's one rubber duck antenna. I'm figuring the CPU xmit section is messed up somehow.I have the Service Manual on this, but I don't see ant 'reset' function. I removed the battery pack for a few minutes, but no change. I have it sitting in it's charger, power off, connected to a outdoor VHF antenna (tuned), it's rarely used.Receive is Ok.Any ideas?

author: TheSteve
author_rank: Unknown
timestamp: March 19, 2021, 07:27:07 am
content: Are you sure TX is enabled on that channel?There is no simple reset, the radio is programmed via PC software.

author: videobruce
author_rank: Frequent Contributor
timestamp: March 19, 2021, 12:58:16 pm
content: Long story short, it turned out it was the battery pack. I didn't remember this goes in to some 'weird' state when the pack is very low, it receives ok, but when you go to xmit, it 'flakes out' (for lack of a better term.The behavior was more like a component issue, causing the behavior which is why I was looking at the problem that way. It was a older pack, recharging it wouldn't of help since when I put it in the charging stand, it showed charged within minutes instead of a couple of hours.
75 ohm noise source - Page 1
Forum section: electronics / rf-microwave

author: hs5424
author_rank: Newbie
timestamp: March 11, 2021, 09:58:50 pm
content: I am considering building an RF noise generator as my commercial one has caused me nothing but trouble over the years. As I am in the TV trade I am only interested in constructing a unit with an o/p impedance of 75 ohms. 5 mhz to 2Ghz will suffice. Any suggestions appreciated.
the relation between the frequency and the anechoic chamber ? - Page 1
Forum section: electronics / rf-microwave

author: harrysmith
author_rank: Contributor
timestamp: March 11, 2021, 07:35:12 pm
content: Hellowhat is the relation between frequency and anechoic chamber. or it is just one of the tool which reports the frequency ?I would appreciate your expertise.Thank you.

author: tszaboo
author_rank: Super Contributor
timestamp: March 11, 2021, 10:10:01 pm
content: I dont even know where to begin...
Power connector - Page 1
Forum section: electronics / rf-microwave

author: srce
author_rank: Regular Contributor
timestamp: March 09, 2021, 10:42:54 am
content: What's the name of this type of power connector? And what's the best way to connect to it?

author: Gyro
author_rank: Super Contributor
timestamp: March 09, 2021, 10:50:24 am
content: It's not a connector, it's a feedthrough capacitor, used for RF isolation going through a shielded enclosure. You can get either solder-in types or threaded bush+nut. Yours is clearly the latter, with a solder tag fitted. You normally just solder to them.

author: srce
author_rank: Regular Contributor
timestamp: March 09, 2021, 02:27:08 pm
content: Ok, thanks. I had just been soldering them, but was wondering if there was a better way.

author: radiolistener
author_rank: Super Contributor
timestamp: March 09, 2021, 04:02:37 pm
content: Quote from: srce on March 09, 2021, 10:42:54 amThis is feed-through capacitor. It is used to remove RF noise from power supply line. Most of all it is 1 nF.It looks like Chinese LNA in the shielded box. In such case the center pin is "+" and the shell pin is "-".Here is schematic of my LNA in the same shell:
NFC Reader Choice? - Page 1
Forum section: electronics / rf-microwave

author: willemb
author_rank: Newbie
timestamp: March 11, 2021, 08:18:11 pm
content: I'm starting a new project converting our 125kHz RFID readers to 13.56Mhz. This will be a basic external reader with additional microcontroller onboard for delivery of RS232 messages. It will be prone to some metal and water and will be potted in epoxy. I've been experimenting with the ST25R3916 from ST with good results but have also looked at the NXP CLRC663. I was hoping there would be some opinions, one way or another, as to which platform they would go with if they were going to start from scratch?
More Than a waterfall- Best way to receive & decode Digital Modes on a Receiver - Page 1
Forum section: electronics / rf-microwave

author: jonovid
author_rank: Super Contributor
timestamp: March 09, 2021, 02:52:39 am
content: if I have a DIY receiverthere was a time when any DIY radio receiver or shortwave radio had is modes of AM FM CW or SSBbut now amateur radio has digital modes.what is the best way to receive amateur radio digital modes without the Internet?best way to receive digital modes on a radio receiver & a laptop or tablet to decode it.so I see text or get sound clips or see slow scan images, not just a waterfall.what is the best open source software? digital mode browser or waterfall with decoders.what is the best way to hook up a radio receiverfor receiving digital modes. dial up internet speeds . adding bandwidth to any radio receiver output.why not just use the Internet? then have us asking a question why have a radio receiver in the first place?its amateur radio, not amateur internet. IMOhere are some of the digital modes that any DIY radio receiver must have IMO.https://www.sigidwiki.com/wiki/Category:Amateur_Radio

author: radiolistener
author_rank: Super Contributor
timestamp: March 09, 2021, 03:09:05 am
content: It depends on what modulation type you're want to receive.Most of all DIGI modes are supported in popular software likeWSJT-XorJTDX.There is no need internet to receive DIGI modes.But you're needs to synchronize your PC clock very precisely, because DIGI modes are depends on a current time.Internet is used just to share all your received messages with other users world wide. But you can disable such option. Also internet is used to synchronize your PC clock.If you enable option to share your received messages, other users can see all stations which you received for a specific time periodon the map. They can find it by your callsign. With help of this map you can see wave propagation all around the entire Earth on different bands in realtimeIf you're talking not about DIGI modes for ham radio, but about digital broadcasting like DRM, you can useDream DRMdecoder. Note you're needs to install some libraries separately for Dream, due to their license limitations.With Dream decoder you can decode DRM audio broadcasting on a short waves.
CMU200 et SPAN de l'analyseur de spectre - Page 1
Forum section: electronics / rf-microwave

author: jean françois
author_rank: Contributor
timestamp: March 07, 2021, 09:02:44 am
content: Hello,I am offered a CMU200, R & S measurement benchcan a user of this device provide me with some information regarding the spectrum analyzer "SPAN"is the "ZERO SPAN" function possible?Is the "FULL SPAN" 100khz at 2.7ghz possible?I ask the question because I have an E4406A (it's not really a real A S), but the SPAN function only allows 10mhz.the seller is coming on Tuesday,thank you in advance for your answers.jean françois

author: Qw3rtzuiop
author_rank: Frequent Contributor
timestamp: March 07, 2021, 01:33:59 pm
content: Quote from: jean françois on March 07, 2021, 09:02:44 amYes both things are possible BUT the min frequency is 10 MHz not 100 kHz.https://www.rohde-schwarz.com/file/CMU200_dat-sw_en.pdf

author: jean françois
author_rank: Contributor
timestamp: March 07, 2021, 01:51:12 pm
content: Hello,thank you for your information,ok 10mhz to 2700mhz and zero span is perfect.thanks again,Jean Francois.
typical cheap walkli talki antenna covering? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: March 06, 2021, 08:54:27 pm
content: I want to fix one of my walki talkies, the rubber on top of the antenna spring totally disintegrated. It is a old motorolla one.It looked to be glued into the plastic, on one of them it just cracked off so I glued it back on with loctite prism and sensitizer and it seems to be holding OK, but the other one it disintegrated like the andromeda strain.Are these antennas tuned for the covering?I don't want to invest too much time into studying this because the walki talki is old and worth about 15$ only, it is a candidate for things to throw out, also I think the quiescent current is a little high so it has frequent battery changes (i keep it with the flashlights and power banks for 'emergencies', but it is not a high priority because I have 2 more walki talkies and 2 of those tiny new dewalt ones that clip on your belt).Does it need to be ESD safe plastic also? The easy option seems like to cut a piece of PEX pipe, since its on hand. I have some glue I can use but not much else can be spared. I can buy a ESD safe plastic spray because I wanted to use it on my 3d printer printers (it would sweeten the deal if I could make a replacement), but I would need to be sure it sticks to the plastic I want, or be suggested a paint stick sensitizer, if it exists.
Anybody Know What This Part Is? - Page 1
Forum section: electronics / rf-microwave

author: Bitstream
author_rank: Contributor
timestamp: March 12, 2021, 02:16:45 am
content: Anybody know what this part is? It's from the CPU board in an AEL ATTR-2193 receiver. I can't find any info about it anywhere. The only thing that comes up for "Augut are DIP sockets.

author: JDubU
author_rank: Frequent Contributor
timestamp: March 12, 2021, 02:54:43 am
content: It appears to be a fiber optic transmitter driver.There is a reference to it here:https://books.google.com/books?id=KJX7pT5QLtcC&pg=PA20&lpg=PA20&dq=698-021EG1&source=bl&ots=AL1R8wWAB5&sig=ACfU3U2kl8FzJWjCXt2qdUkkRIwEBCZomQ&hl=en&sa=X&ved=2ahUKEwi07ezl36nvAhXRrZ4KHfy8AqcQ6AEwAHoECAEQAw

author: radiolistener
author_rank: Super Contributor
timestamp: March 12, 2021, 03:01:10 am
content: fiber optic receiver module 10 MHz bandwidth

author: Bitstream
author_rank: Contributor
timestamp: March 12, 2021, 03:37:30 am
content: Wow -that was fast. I had been searching around for over an hour and couldn't find anything. -Thanks !!
LimeSDR - strong harmonics - Page 1
Forum section: electronics / rf-microwave

author: arno
author_rank: Contributor
timestamp: March 08, 2021, 05:24:35 pm
content: Dear all,I found that my LimeSDR produces a high amount of odd harmonics. The third ones are around 12 dB below the first, independent of frequency and output power. All even harmonics are less than 60 dB or even better. I am measuring using my Siglent SSA3021x and I am pretty sure the input is not saturated.Any suggestion is appreciated.Thanks in advance!Arno

author: 9aplus
author_rank: Regular Contributor
timestamp: March 09, 2021, 12:56:47 pm
content: Which SW you are using?

author: arno
author_rank: Contributor
timestamp: March 09, 2021, 03:34:52 pm
content: Hi,this happens with LimeSuite and GNU Radio. I found this video , it seems to be normal behaviour. Maybe I am hunting a ghost, again.Thanks for your responseArno

author: 9aplus
author_rank: Regular Contributor
timestamp: March 09, 2021, 05:32:23 pm
content: Under Win 10 you can test with SDR Console v 3.n.n on the same frequency.On Linux try with Sdr Angel.Try to keep updated your Lime firmware and drivers.That problem is usual on HF because of specific way of generating.
About advantest R3267 of RF microwave cross device - Page 1
Forum section: electronics / rf-microwave

author: ZY.Huang
author_rank: Newbie
timestamp: March 05, 2021, 09:06:50 am
content: Hi, everyone:Does anyone know the specific parameters and models of the RF microwave cross device in the attached picture?Its silk screen mark is 2i, a ceramic cross device, SMT86
Is possible to use a Vector Signal Generator as a normal RF signal generator ?  - Page 1
Forum section: electronics / rf-microwave

author: electronic_guy
author_rank: Regular Contributor
timestamp: March 04, 2021, 05:29:24 pm
content: Hi,What is the main difference between a normal signal generator ( 9kHz to 3 GHz) and a vector siganl generator (9 kHz to 3 GHz) ?Can I use vector signal generator just like a normal signal generator ?

author: Qw3rtzuiop
author_rank: Frequent Contributor
timestamp: March 04, 2021, 05:33:15 pm
content: Yes. A vector signal generator just allows you to do all kinds of modulations that a normal signal generator cant.

author: electronic_guy
author_rank: Regular Contributor
timestamp: March 05, 2021, 05:55:48 am
content: @Qw3rtzuiop Thank you!
How to choose a DC blocking capacitor for R&S CMU200 ? - Page 1
Forum section: electronics / rf-microwave

author: electronic_guy
author_rank: Regular Contributor
timestamp: February 28, 2021, 08:29:17 am
content: Hi,I have bought a CMU200, how do I choose a DC blocking RF connector so I can use the equipment safe?I searched DC block connectors on electronic stores online.But the terms used in the datasheet are still introductory to me. What is the significance of the insertion loss and return loss when it comes to choosing DC block connector for a particular spectrum analyzer?for example, I have attached the datasheet of two DC block connectors I'm interested.

author: xmo
author_rank: Regular Contributor
timestamp: February 28, 2021, 04:32:19 pm
content: What sort of measurements are you planning on that you expect to expose the instrument to DC?The CMU has a high power I/o connector where you can conduct initial measurements with minimal risk.The posted DC blocks have SMA connectors. Are you planning on adapting the CMU front panel connectors down to SMA and using SMA test cables exclusively?The required adapter(s) might be a bigger source of mis-match than the DC block.If some of your work will involve test cables with N connectors, it would make more sense to get a type N DC block and only adapt down to SMA as needed.

author: electronic_guy
author_rank: Regular Contributor
timestamp: March 01, 2021, 03:17:11 pm
content: Hi,I'm not planned on which measurements that I will have to go through. I thought the DC blocker will allow me a wide range of experiments without having to buy each according to experiment type. But I'm thinking of buying this as a general measure of safety for the spectrum analyzer. And you're correct the CMU can withstand considerable power. And the one I have does not come with the B95 and B96 options. So the RF inputs have some power tolerance, up to about 50W. But I'm concerned with the chances I will put the front end under accident power input while measuring. maybe a malfunction in signal generators, since I'm using surplus instruments I assume there could be some possibility as such.Actually, I did not plan on selecting the SMA connector based on my requirement. This is what I could find in the online store that matched the frequency band of CMU. I did not know that there is a bigger mismatch when the connectors are chosen cross series. I will try to find an N type of DC blocking connector.
Icom R71E not setting up correctly-RAM board issue?? - Page 1
Forum section: electronics / rf-microwave

author: BarneyRubble
author_rank: Newbie
timestamp: February 26, 2021, 12:28:06 pm
content: Duplicate post, sorry! I will remove the other later when I get home again. Thx.Hi folks,,,, first post on here, here goes!I have an Icom R71e Rx, doing crazy things. Can anyone please help by looking at this video I put on the 'tubeand see if it looks like the battery has failed on the logic board? I have been told so, but the few vids I have seen are showing things a little different to this, and mostly show the IC745/751 Trx too. Note the display segment brightness as well. Anyone give me some pointers please? I note where I can get a better replacement board from, but are there other issues that can be spotted in my short clip? The RF gain misbehaves in this video, it reaches a certain point and a relay clicks in or out? I can maybe add more if it helps, any specific checks I can do? The battery on the RAM board is measuring in situ at only 0.4v or less. . Please ignore the filthy external appearance, I got it like that! And that's another job........cheers'n'beers folks!
Beitan GPS modules, rs232, 1pps, etc - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: February 26, 2021, 11:57:05 am
content: Beitan, a Chinese company is now selling some RS232 (DB-9) enabled GPSs. I am wondering if they connect PPS to the DB-9 and if so, how its wired.If the PPS is connected like the old GARMIN receivers that would be great for older computers with a real serial port, with a fast serial port interrupt.
FSK radio - continuous wave diagnosis (SX1262) - Page 1
Forum section: electronics / rf-microwave

author: kamtar
author_rank: Regular Contributor
timestamp: February 24, 2021, 07:10:20 pm
content: Hello,I'm looking for advice on where I should look to solve this issue.I have a board with SX1262 and when I switch it to CW I get this on SDR (attachment)I have ruled out FW issue with testing it on evaluation board where I can see nice CW as I would expect.Somebody with a deeper understanding of these radio ICs who could give me some idea what could cause something like that?

author: radiolistener
author_rank: Super Contributor
timestamp: February 24, 2021, 07:17:33 pm
content: most of all this is just not CW mode. Maybe you didn't switch it to CW mode properly or something like that.
receive antennas - Page 1
Forum section: electronics / rf-microwave

author: A.Z.
author_rank: Super Contributor
timestamp: February 27, 2021, 12:25:31 pm
content: I was seeking for some infos about horizontal loops, when I stumbled upon this linkhttps://www.w8ji.com/receiving.htmand I believe he's still right nowadays; a good TX antenna IS NOT automatically a good RX one, he clearly explains why, and I agree, what's your take ?

author: tautech
author_rank: Super Contributor
timestamp: March 04, 2021, 08:00:55 am
content: Google: antenna reciprocity

author: yl3akb
author_rank: Regular Contributor
timestamp: March 04, 2021, 10:53:56 am
content: Why not? Reciprocity only talks about signal transmitted between TX and RX antenna and vice versa, but not about additional signals such as noise received by RX antenna or in other words, signal-to-noise ratio.Here is example. Imagine we have ground station (GS) with high gain parabolic antenna directed towards satellite with cold sky background. Satellite has simple dipole antenna. Let's look at the two cases:1. In the case of satellite transmitting with dipole and GS receiving with high gain antenna, noise at GS would be very small due to narrow beam directed towards cold sky and small sidelobes towards warm earth.2. If antennas are exchanged (satellite now transmits with parabolic antenna and GS receives with dipole), now GS receives much higher noise due to large part of the dipole pattern directed towards the warm earth.In the both cases the received signal strength would be the same (antenna reciprocity), but SNR would be much worse in second case ("good tx antenna IS NOT automatcally a good rx one").

author: A.Z.
author_rank: Super Contributor
timestamp: March 04, 2021, 11:12:54 am
content: Quote from: yl3akb on March 04, 2021, 10:53:56 amRight so

author: ejeffrey
author_rank: Super Contributor
timestamp: March 04, 2021, 05:51:10 pm
content: Yes. Antenna reciprocity is a thing, but the features we care about with Tx and Rx are different.Another example is mismatch/loss. At low system power Tx antenna loss or mismatch just means that you need a bit more gain from your PA to compensate. If you primarily constrained by regulatory power limits this might not be a big deal. On the receive side loss directly degrades overall noise figure. In a high power transmitter, loss and mismatch cause heating and stress the PA which is a completely different effect than the RX antenna has to deal with. In another parameter regime where the ambient EM noise is far above thermal a lossy antenna will be fine since it attenuates the signal and noise the same amount and the noise contribution of the antenna itself is negligible.Some practical antennas are also non-reciprocal. AM ferrite coil antennas can be relatively efficient Rx antennas considering their deep sub-wavelength size due to the high permeability. If you use them for Tx at significant power the ferrite will saturate, the permeability will drop and its efficiency will suffer substantially.Reciprocity is an important concept and tool, but you need to understand what it actually says.
FM Broadcast Pre-emphasis ?  - Page 1
Forum section: electronics / rf-microwave

author: Gregory
author_rank: Regular Contributor
timestamp: February 20, 2021, 11:25:52 am
content: Hello guys,I'm designing a little Stereo FM baseband processor and I have some doubts about it.In FM broadcast a pre-emphasis filter is used before the frequency modulator, to improve the SNR. From a mathematical perspective, with the pre-emphasis filter, the modulator becomes a hybrid FM/PM modulator. (FM for lower frequencies and PM for higher frequencies).This makes sense and seems right for mono signals.For stereo signals, we need to DSB modulate the stereo image L - R with a 19khz/38khz sub-carrier.I'm seen a lot of block diagrams on the internet where the pre-emphasis is applied in the L and R signals at the input of this scheme, before the stereo processing.But this does not make sense for me.It sounds much more right to apply the pre-emphasis after all the processing, just before the FM modulator.This would guarantee the hybrid FM/PM for all the 53khz baseband stereo signal and would not need two pre-emphasis filters.Also, for the mono part of the signal (0 - 15khz) it would work exactly equal a mono only modulator.

author: szoftveres
author_rank: Regular Contributor
timestamp: February 23, 2021, 05:14:48 am
content: Successful stereo demultiplexing and good separation is only achievable if the group delay is constant, which is the case if there's no pre- and de-emphasis applied on the MPX signal, or the pre-and de-emphasis cause theexact samephase shift. Any slight difference between the phase shift of the pre-and de-emphasis would ruin the separation, had the phase shift was introduced before the stereo decoding in the receiver. FM stereo was conceived in the early 1960s in the days of vacuum tubes, cheap carbon-composition resistors and paper capacitors.Had the pre-emphasis been applied on the FM MPX signal, the de-emphasis RC network would need to be made of ultra precision components and the radios would have been much more expensive to manufacture. Hence it was decided that pre- and de-emphasis would only be applied on the separated audio channels, where the poor quality and cheap RC filters didn't cause any harm.
LMH6321 as a coax cable driver for active antenna? - Page 1
Forum section: electronics / rf-microwave

author: Co6aka
author_rank: Unknown
timestamp: February 21, 2021, 05:59:52 am
content: Has anyone played with the LMH6321 as a HF-range coax cable driver? I'm wondering about its IP2, IP3, NF, etc -- wondering if it'd make a decent "output stage" for low-input-Z loop amps and high-input-Z whip amps.
Splitter/combiner input impedance - Page 1
Forum section: electronics / rf-microwave

author: Miti
author_rank: Super Contributor
timestamp: February 16, 2021, 02:15:06 pm
content: I was playing with a Mini Circuits splitter/ combiner model ZESC-2-11 and Nano VNA V2 Plus4. Port 1 of the Nano VNA is connected to port S of the splitter, the two output ports are terminated with Mini Circuits 50 Ohm terminators. The input impedance seen by the Nano is nowhere close to 50 Ohm within the specified range of 10 - 2000MHz for the splitter.Am I doing something wrong? What's the expected input impedance? Is the splitter bad or my method is incorrect, or the Nano VNA is crappy?Cheers,MitiEdit: I redid the experiment after a fresh calibration and it does get close to 50 Ohm at the high end of the band. However, at the low end is almost like DC. Picture attached.

author: radiolistener
author_rank: Super Contributor
timestamp: February 16, 2021, 02:57:42 pm
content: At 2 GHz your NanoVNA shows RL=28.87 dB, this is about VSWR=1.075.According to theZESC-2-11 datasheet, at 2 GHz it should have VSWR=1.11.And at 10 MHz it should be about VSWR=1.99.At a glance all looks okay and within specification (1.075 < 1.11).What is wrong?Quote from: Miti on February 16, 2021, 02:15:06 pmI don't see exact input impedance specification in the datasheet, but it has VSWR specification 1.99 at 10 MHz.So, for 10 MHz we can expect impedance within range 25.12 - 99.5 Ohm.As I can see, at 10 MHz there is RL about 10 dB, this is VSWR=1.925.According to the Smith chart it's about 25.97 Ohm.This is also within datasheet specification (1.925 < 1.99).As we can see, your splitter input impedance is about 25.97 Ohm @ 10 MHz and 46.5 Ohm @ 2 GHz.And this is well corresponds with a splitter specification from the datasheet.So, both - NanoVNA and splitter works as expected

author: Miti
author_rank: Super Contributor
timestamp: February 16, 2021, 03:30:59 pm
content: I don't say is anything wrong, actually I'm asking if there is anything wrong. In my noob-ness I was expecting something closer to 50 Ohm within the entire range.I see there are charts to calculate VSWR from RL but how do you know the impedance range that would give you that VSWR?Maybe this should be in the beginners section but it is about RF...

author: richard.cs
author_rank: Super Contributor
timestamp: February 16, 2021, 04:48:04 pm
content: The device is within it's mediocre spec at 10 MHz, still an OK match for many applications. The 46 Ohms is "good enough" for the vast majority of RF applications.There are a whole range of impedances that would give a particular VSWR value because impedance is a two-dimensional quantity (it has real and imaginary parts) whereas VSWR is a a simple scaler. Even if you know the impedance is purely resistive, or otherwise only care about the magnitude there are still two values that can give a particular VSWR.VSWR is a rather crude metric really, it was created because it's easy to measure with simple tools, but doesn't carry all the information that the complex impedance or the reflection coefficients do.
DDS AD9910 Arduino Shield-Any good for FM/General Receiver alignment? - Page 1
Forum section: electronics / rf-microwave

author: djsb
author_rank: Super Contributor
timestamp: February 26, 2021, 11:25:11 am
content: I'd to hear the opinions/reviews of this DDS signal generator before I buy onehttps://tinyurl.com/a3jpnpt8Is there something better out there than this? Maybe something smaller or with better noise performance and a cleaner spectral output? The same or a wider frequency range would be good.I just want to use it for FM receiver alignment and I need something with an FM sweep facility and an accurate attenuator. The one above is good because it can be developed further and the Arduino helps with understanding how it all works. I'd like to hear what other people think. Thank you.David.
Old car radio buttons - Page 1
Forum section: electronics / rf-microwave

author: jmurphy
author_rank: Contributor
timestamp: February 12, 2021, 05:59:22 pm
content: Is there a name for the switch used in old car radio channel preset buttons? The ones where there is a group of buttons but the selection is mutually exclusive. Can you still buy these types of switches?

author: themadhippy
author_rank: Super Contributor
timestamp: February 12, 2021, 06:58:36 pm
content: Do you mean this sort of thing?http://www.farnell.com/datasheets/104875.pdf

author: bdunham7
author_rank: Super Contributor
timestamp: February 12, 2021, 07:07:46 pm
content: Are you actually working on an old Hudson radio, or is this just an example of what you think you are looking for? Those old radio preset buttons were not switches at all, but rather mechanical devices that would move the mechanical tuning apparatus to the preset location.

author: jmurphy
author_rank: Contributor
timestamp: February 12, 2021, 08:09:20 pm
content: I'm not working on a Hudson radio. I just want that type of mechanical switch where only 1 button can be pressed at the same time.

author: ralphrmartin
author_rank: Frequent Contributor
timestamp: February 13, 2021, 04:29:39 pm
content: This quite probably doesn't help, but software guys refer to them (well, their on screen equivalents) asRadio Buttons (where in a given bank only one can be selected at any one time)as opposed toCheck Boxes (where each one can independently be on or off).This is very weak evidence of a lack of a "better / proper name" which the software guys might have used if there was one in common usage.

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2021, 04:36:01 pm
content: Quote from: jmurphy on February 12, 2021, 08:09:20 pmGeneric term would be 'interlocking pushbutton switches'. themadhippy gave you one example above, you can find others by searching. You typically have to build them up yourself in the configuration you want. Some better examples of where these are used would be old bench DMMs and pushbutton blenders--those are actual switches.
Any repair experience with R&S SMY01 generator.  - Page 1
Forum section: electronics / rf-microwave

author: prutser
author_rank: Regular Contributor
timestamp: February 09, 2021, 05:05:26 pm
content: I bought a defective R&S SMY01 signal generator. I wonder if there are some people out here having experience with this generator.RF level drops after being powered on for a while. And when executing the level preset calibration, it shows error 15 (Also when the RF level is not yet dropped)Since today it also started to indicate error 1 (10 MHz loop out of lock), spectrum analyzer still shows a clean output signal. I would expect more phase not when it is not locked.Any suggestions are welcome.

author: prutser
author_rank: Regular Contributor
timestamp: February 13, 2021, 03:52:16 pm
content: Well I have to answer my own question. The 10MHz lock error was just as stupid as accidentally pushing the button to select an external ref. It does no have an error code which mentions"no ext. ref present" but just indicates 10Mhz ref unlocked.The other issue is fixed as well, which was a problem in the amplifier chain.
ICOM IC-751A receiver alignment - Page 1
Forum section: electronics / rf-microwave

author: Galen
author_rank: Regular Contributor
timestamp: February 07, 2021, 03:32:50 am
content: Dear all, got a IC-751A recently, try to do alignment for its receiver. The service manual says 'set IC-751A at 14.0000MHz, USB mode, signal generator input 0.3uV to antenna port'. question is, the signal should be a AM modulated? or just carrier only?I applied carrier only, and adjust the RF/IF transfomers to get the noise level high. Then, it's sensitivity looks OK when try to receive HF broadcast. Is this alignment method correct?Any advice is highly appreciated.

author: Galen
author_rank: Regular Contributor
timestamp: February 11, 2021, 09:23:53 pm
content: looks like no people try to align the ICOM HF rig? Or didn't consider the details of the alignment?

author: DeepLink
author_rank: Regular Contributor
timestamp: February 12, 2021, 06:37:18 am
content: I would think it is just the carrier, as you first select USB
Some basic calculations from s parameters - Page 1
Forum section: electronics / rf-microwave

author: Cyberduke
author_rank: Contributor
timestamp: February 23, 2021, 03:00:46 pm
content: Hi everyone, this is suppose to be simple, but I am somehow not getting the right answers.Imagine you have the s Parameters, send power and Z0 of a 2 port network, and want to calculate the current flowing into the first port, and voltage over the second. Here is what I have:Power going into the port is Pin = ptx(1-|s11|^2)Z11 = Z0((1+s11)/(1-s11))lastly the current I = sqrt(Pin/|Z11|)and for the voltagePrx = |s21|^2 PtxU = sqrt(Prx*Z0)When I am doing the calculations, the answers that I am getting it most definitely very wrong, but I am not sure where. I am sure someone would point out something I did wrong quick! thanks

author: radiolistener
author_rank: Super Contributor
timestamp: February 23, 2021, 05:07:01 pm
content: Quote from: Cyberduke on February 23, 2021, 03:00:46 pmUrx = sqrt(Prx * Zrx)where:Prx is a power on the loadUrx is RMS voltage on the loadZrx is a load impedance (and it may not be equals to Z0 of port2 on your network analyzer)Note, each port (network analyzer and network) has it's own Z and they can be differentCan you provide calculation example, because it's unclear what do you mean when you talking about wrong answer.

author: radiolistener
author_rank: Super Contributor
timestamp: February 23, 2021, 05:41:48 pm
content: can you please provide calculation example? (with numbers)Because it's unclear what you're talking about.For example:Zrx = 50 OhmPtx = 10 W|s21| = 0.31623Prx = |s21|^2 * Ptx = 0.31623^2 * 10 = 0.1 * 10 = 1 WUrx = sqrt(Prx * Zrx) = sqrt(1 * 50) = 7.071 VrmsNote: |s21| depends on Zrx.

author: Cyberduke
author_rank: Contributor
timestamp: February 23, 2021, 05:58:47 pm
content: Hi, thank you for the replies, I figured it out.As embarrassing as it is, the Maths was fine, the issue was in the code that did the calculation.For interest sake, the second example that you showed is exactly right and what I meant.