hybridfree/eevblog-posts huggingface dataset:
Unusual BNC connector identification - Page 1
Forum section: electronics / rf-microwave

author: svirot
author_rank: Newbie
timestamp: December 27, 2017, 04:27:17 pm
content: Hello,Apologies if this is not in the right section ; please feel free to move the topic.The BNC plug shown in the pictures below is quite unusual as it is made of two connector pieces. One 3mm diameter one that crimps onto a 1.8mm coax cable (both the core and the shield are attached) and one standard BNC plug with a gland at the back that receives the 3mm connector.The big advantage of this solution is that the terminated cable can be fed through small 3.5mm holes where usual BNC connectors would been to be cut/re-crimped.This very plug has been pulled off a cable and I'd like to find a replacement but can't identify the manufacturer. Unfortunately, there is no name or logo on the metalwork.Please let me know if you know where to find such a plug or if you know the name of this arrangement.Thank you very much in advance for your help.

author: stj
author_rank: Super Contributor
timestamp: December 29, 2017, 06:19:58 pm
content: i think that's 2 different things.a compact plug - that i think i'v seen inside something before - maybe a scope.and a bnc adapter.
RFM69HW-433 and Linx Technologies ANT-433-SP - radio module gets killed - Page 1
Forum section: electronics / rf-microwave

author: miduchp
author_rank: Contributor
timestamp: December 24, 2017, 09:14:25 am
content: Hello everyone,I'm quite a newbie regarding RF designs. I've recently started to experiment with RFM69HW-433 modules to put them together with my Atmega based sensors. In order to have compact design, I've started to experimeth with Linx Technologies sourface mount antennashttps://www.linxtechnologies.com/wp/wp-content/uploads/ant-433-sp.pdfI've prepared following adapter, in order to experiment with radios using prototype boards.The problem is my radios are getting killed. After a short time, there radios staring to have short circuit. It was not happening whem I was using antenna of 1/4 wavelength done from piece of wire.Should I have some matching circuit for antenna ? Is there any way to tune it without spectrum analyzer ?Could you be so kind to give me any clue / materials to read so I could fix this issue ?Regards,Piotr

author: Gribo
author_rank: Frequent Contributor
timestamp: December 27, 2017, 01:52:35 pm
content: The ANT433 is DC coupled to ground. Make sure your module has a DC blocking capacitor. Also, you might want to add a matching network, as the antenna might not be exactly 50 Ohm on your board.
4G Cellular Bands - Page 1
Forum section: electronics / rf-microwave

author: madhu.wesly01
author_rank: Regular Contributor
timestamp: December 25, 2017, 08:23:07 pm
content: Hi,I am Madhuwesly from India. In India the 4G services are being offered with the bands: B3, B40, B5 mainly. Please consider a 4G module that supports few number of 4G bands but among them only one band (B3) is being matched with India supported 4G bands. Generally telecom providers offering their services with more than one band.Will the module work good for voice and data communication even if it supports only a single Band?Please note when I call to a telecom operator it is told that there will not be any problem for communication even if a module supports a single Band.Thanks & regards,

author: DC1MC
author_rank: Super Contributor
timestamp: December 25, 2017, 10:54:28 pm
content: Quote from: madhu.wesly01 on December 25, 2017, 08:23:07 pmIf where you're using the module there is good signal in the supported band and the towers are not crowded, then the module will work OK, and you'll never know or care on which band it is.On the other side, if some band becomes overcrowded, and the provider has towers on multiple bands in the area, your connection may be bumped between different bands, depending of the available capacity.Depending on your data contract, the module may even "roam" between different providers (of course on different bands) in mode that is transparent to you.Of course, if your module only supports one band, the connection quality will degrade or even be dropped.I work on mobile communications with LTE modules, and I've never seen a single-band general purpose (voice+data) LTE module, only some obscure M2M special modules, working on a reserved band where there is no possibility of congestion. The LTE module manufacturers usually licenses all bands for a region, for example India, because having different versions accepted by the regulatory authorities is a pain in behind.Is that a licensing issue for costs optimization, or how did got a single-band LTE module ?DC1MC

author: madhu.wesly01
author_rank: Regular Contributor
timestamp: December 26, 2017, 02:12:12 pm
content: Actually, the 4G LTE module supports three bands B3, B7, B20.But in India the B7 and B20 bands are not used(not licensed), all the telecom providers offer 4G services based on any two or three bands among B3, B40, B5, and B41 bands. One advantage is B3 band is being used by many telecom providers along with either B40 or B5 bands.Will the module work in India??

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 27, 2017, 12:49:39 pm
content: You can look on the Webpages from the different Company like Sierra Wireless and look into there Datasheet.
Genuine or Fake Nagoya NA-771 - Page 1
Forum section: electronics / rf-microwave

author: CJay
author_rank: Super Contributor
timestamp: December 18, 2017, 08:09:28 pm
content: I've just received one of these:https://www.amazon.co.uk/gp/product/B00MGGL9DI/ref=od_aui_detailpages00?ie=UTF8&psc=1At first glance it looks genuine but reading the Nagoya site, it raises a couple of alarm bells, one the packaging is almsot but not quite like the genuine one, rough back, rounded bottom corners but not quite rounded enough and a few other things.Seems I broke my own rule and bought without reading the reviews.So, is there enough in my observations to say 'fake' and if so, how the hell does one report a fake to Amazon?

author: cdev
author_rank: Super Contributor
timestamp: December 18, 2017, 08:24:06 pm
content: You likely could take photos and send them to them and get their feedback.. also, how does it work, is there any way you can test the SWR too- I would worry about that.

author: HoracioDos
author_rank: Frequent Contributor
timestamp: December 21, 2017, 05:46:07 pm
content: How to identify the genuine and fake antennahttp://www.nagoya.com.tw/s/2/news-31478/?latest-updated?How-to-identify-the-genuine-and-fake-antenna.html

author: DaJMasta
author_rank: Super Contributor
timestamp: December 23, 2017, 06:25:11 am
content: One telling feature is that the seller is Nagoya. While not a guarantee as Amazon probably doesn't curate the names closely, if there was a fake seller using their name, they could probably get amazon to stop that seller from selling products under their name. All of the other products from the seller seem to be Nagoya branded as well.

author: CJay
author_rank: Super Contributor
timestamp: December 23, 2017, 05:55:59 pm
content: It sort of ticks the boxes for being a fake, the rounded corners on the package aren't as rounded as they look on the Nagoya website, the printing of the QR code isn't great, the back of the pack is rough and not smooth like the front but the text on the antenna looks very close.It seems to work quite well, I have nothing to measure how well it's matched or where it's resident but I can borrow a VNA and find out.I'm figuring the next time I buy one I'll not buy Nagoya as they're just too difficult to avoid fakes.

author: stj
author_rank: Super Contributor
timestamp: December 23, 2017, 08:19:40 pm
content: Nagoya changed the connectors to a shorter bullet shape some time back.like this:http://www.409shop.com/409shop_product.php?id=101888409shop is my go-to for radio stuff.
Which L-section do I use when matching a BJT? - Page 1
Forum section: electronics / rf-microwave

author: ezalys
author_rank: Frequent Contributor
timestamp: December 21, 2017, 03:05:53 am
content: Suppose I've settled on using a simple two-element matching network when matching the input to the base and again on the output to collector of a BJT amplifier for use at microwave frequencies (> 800 MHz), match to 50 ohms on input and output, for wide bandwidth performance (well, as wide as possible given an L-section).How do I pick whether I should use a shunt-L series-C or series-L shunt-C matching network?It seems like whether the shunt element is closer to or further from the impedance to be matched is dependent upon the impedance to be matched, but I still have the freedom to pick if it should be shunt-L series-C or the converse. What generally goes into this choice?It seems as if the Q is not influenced between the choice of series-C/shunt-L vs series-L/shunt-C, as the Q for both are identical.I am, additionally, aware that one L-section will have a low-pass characteristic, and the other a high-pass characteristic. This would seem less important to me as the device will only match over a narrow range of frequencies given that the matching network is only a single section. I’m more curious about things that don’t involve how matched the thing looks. If I have a certain input impedance, matching network, and load impedance, I know how to write down and plot the power delivered to the load. It’s just that the matching network will surely have impacts on harmonic generation, stability, bias network design, and noise. I’m more curious about these things.

author: rfeecs
author_rank: Frequent Contributor
timestamp: December 21, 2017, 04:06:31 am
content: This may help:http://highfreqelec.summittechmedia.com/Mar06/HFE0306_Rhea.pdfhttp://venividiwiki.ee.virginia.edu/mediawiki/images/c/c2/Basic_Matching_II.pdfRefer to figure 4 of part 1.
Need to id this RF component  - Page 1
Forum section: electronics / rf-microwave

author: Yavin101
author_rank: Newbie
timestamp: December 19, 2017, 11:26:17 pm
content: I'm a newbie to electronics and found this Sma component. best i can figure its some type if signal coupler. any information would be great in my self-learning endevours

author: vk6zgo
author_rank: Super Contributor
timestamp: December 20, 2017, 12:10:23 am
content: Detector probe.Built a bit like a directional coupler, but only one direction is detected.Depending upon the circuitry in the top box, it may output the modulation, or just a dc level.

author: ConKbot
author_rank: Super Contributor
timestamp: December 20, 2017, 11:33:18 pm
content: Yep, agreed, it looks like a directional coupler with a detector tacked on. The two transmission lines are coupled, the one on the top will have a 50 ohm termination at one end, and the detector on the other. Estimate the length of coupled TX line, and it should be a quarter wavelength, after allowing for a 60-70 percent velocity of propagation in the coax.I.e. (c*0.7) /( 4*length) = center frequency of operation. For an estimate. If you have a rf signal generator of the right frequency that can do a pulse, (an AM radio with sufficient depth of modulation and low frequency response may work) you could measure the time constant of the detector, and get an idea on if you can use it for power monitoring or AM demod also.
Ebay Bandpass Filter? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 18, 2017, 09:29:32 am
content: I found this Guy who sell Bandpass Filter and other Stuff:https://www.ebay.de/sch/iseeabluewhale/m.html?_nkw=&_armrs=1&_ipg=&_from=&_sop=15&rt=nc&LH_PrefLoc=2I need an Filter to get AIS and other Freq.I see he offer an Filter + LNA for 1090 perfect to have an all in one to track AC onboard an AC.Can someone here say anything about the Quality?
Thoughts on my custom transmitter circuit - Page 1
Forum section: electronics / rf-microwave

author: Gip-Gip
author_rank: Contributor
timestamp: December 22, 2017, 02:30:36 pm
content: I made another AM radio circuit and I'd like someone's opinion on it. It's quite a simple design, and looks like it would work, but as you could probably guess by now, I'm more-or-less a beginnerSchematic/PCB in attachments as always, waiting to hear someone's opinion
Can an antique radio be used to pick up digital modes on HF - Page 1
Forum section: electronics / rf-microwave

author: jcrubin
author_rank: Frequent Contributor
timestamp: December 11, 2017, 01:11:26 pm
content: This started off as a simple photo that was posted to a group when I was working with my National 173 boat anchor. The question became apparent. Can this 70 year old radio be use to effectively receive digital communications over HF for FLDIGI and other software?

author: German_EE
author_rank: Super Contributor
timestamp: December 16, 2017, 08:54:52 am
content: In theory, yes, it will work. Your only problem will be drift (if any) as the software should be able to decode the data through all the background noise and propagation present on HF.Oh, one other thing:Catapvltam habeo. Nisi pecvniam omnem mihi dabris, ad capvt tvvm saxvm immane mittam.

author: jcrubin
author_rank: Frequent Contributor
timestamp: December 18, 2017, 01:25:10 pm
content: Here is the second half [the conclusion] of the project.

author: jcrubin
author_rank: Frequent Contributor
timestamp: December 28, 2017, 03:37:14 am
content: Schade... Ich hab doch kein geld aber noch viele steine da hoim.... du darfs eine gratis wenn du sie mochtest...... u. fur die andere leute....The software does adjust for drift and some noise correction, but only for the locked frequency highlighted. something exists in the radio that when the bfo is upwards it drifts up and downwards drifts down, im sure with time i could find the culprit.MFGJ
13 pin acc socket on Icom Transceivers. - Page 1
Forum section: electronics / rf-microwave

author: CJay
author_rank: Super Contributor
timestamp: December 16, 2017, 09:39:29 am
content: I seem to remember the 13 pin connector on the back of Icom transceivers were used on various video cameras and also the Atari ST, I used to order them a lot but for the life of me I cannot remember what they were called, does anyone know a 'proper' name for them so I can order some from a reputable supplier?

author: German_EE
author_rank: Super Contributor
timestamp: December 16, 2017, 05:33:16 pm
content: Assuming you mean the circular plugs and sockets these are DIN connectors, try Mouser and Digikey first or maybe Farnell and RS as you are in the UK.
FM I.F. alignment using a spectrum analyzer questions. - Page 1
Forum section: electronics / rf-microwave

author: xwarp
author_rank: Frequent Contributor
timestamp: December 12, 2017, 03:18:00 pm
content: In regards to aligning the I.F. cans on a typical FM 88Mhz-108Mhz receiver, I have read multiple places that it seems a tracking generator is a must if using a spectrum analyzer.Why is this?Why wouldn't a sweep generator set to sweeping the unit's I.F. work if the spectrum analyzer's center frequency set to the unit's I.F.?

author: Richard Head
author_rank: Frequent Contributor
timestamp: December 13, 2017, 03:24:28 pm
content: Because you are trying to measure the IF amp response at frequencies around the IF and not at exactly the IF frequency. The TG by definition tracks the S.A. receive freq and the pair slowly sweep across the IF freq measuring its response.

author: donmr
author_rank: Regular Contributor
timestamp: December 13, 2017, 07:10:27 pm
content: A conventional spectrum analyzer is a receiver that sweeps across the frequency range. If your generator also sweeps but is not synchronized you won't see much.In some cases it can work. If on side sweeps much slower (several x) then you may see usable results. Also real time spectrum analyzers can do more.For a really crude TG/SA you can sweep a generator and look at the output with a scope triggered from the generator.

author: CJay
author_rank: Super Contributor
timestamp: December 13, 2017, 07:56:23 pm
content: A spectrum analyser seems somewhat overkill for an FM receiver.However,

author: xwarp
author_rank: Frequent Contributor
timestamp: December 15, 2017, 12:37:33 am
content: Thanks for the replies.I've got scopes, which I am much more proficient in using. I also have a couple spectrum analyzers that I'm not so much proficient in using.

author: albert22
author_rank: Regular Contributor
timestamp: December 15, 2017, 01:11:18 pm
content: You can use a spectrum analyzer that has a peak hold function.That will plot the freq response even with just noise as the input.
Gigatronics 80301a 10MHz to 18GHz power sensor doesn't work... let's teardown! - Page 1
Forum section: electronics / rf-microwave

author: DaJMasta
author_rank: Super Contributor
timestamp: April 29, 2017, 09:23:34 pm
content: Bought a cheap power sensor on a gamble in untested condition, the gamble didn't work. Naturally, I tried every noninvasive option to see if I could get a response, then I cracked it open. Amazed at how little was inside, I probed around the sensor with a known-good input and got no response... so I took the teardown a step further and got all the way down to disassembling the detector. Enjoy the pics:The PCB has almost nothing on it. A cheap eeprom, two resistors, and a bypass cap. On the underside there's a thermistor with some heatsink compound for temperature compensation. Nicely machined housing though, next to no chance of a failure due to a lose wire because everything is sturdily held down.But can we go deeper.Yes, we can. The detector is nestled in a heavily shielded, well machined, block of a shield. Suprisingly, it's not potted, but instead uses a split ring to hold on a cylindrical metal shield around it. Forgive the lack of a macro lens, but here's where the magic, and presumably the cost, is all happening:Despite the blurriness, you can sort of see the top bond wire looks different, and I think this is the failure with the whole unit, as there was absolutely no output and it's the only visible damage (though it took several looks through a jeweler's loupe to verify that it was actually broken).I don't have any of the equipment or expertise to replace the bond wire, but I'm thinking of trying a hack with a strand from thin stranded wire that's pretinned, maybe with a tiny bit of solder paste on the pads trying to be bonded, and then rely on conducted heat from heating the top of the wire to make it join. There's no chance such a hack would be in calibration or would make a useful power sensor in the end, but it would be cool to get some output.

author: khach
author_rank: Contributor
timestamp: December 13, 2017, 11:01:47 am
content: Would it be possible readout and share EEPROM dump?

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 13, 2017, 11:23:52 am
content: Quote from: khach on December 13, 2017, 11:01:47 amMost likely it will be calibration data for this specific sensor, so not of much use.Re. the bond wire: It could have just given up because the sensor was destroyed/shorted, in which case putting it back together will not do a lot for you.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 13, 2017, 01:27:30 pm
content: I would try to put in touch the broken bond wire under a microscope, then apply a very thin film of conductive paint (Ag based) to keep the bond wire in place.

author: khach
author_rank: Contributor
timestamp: December 14, 2017, 11:34:28 am
content: Quote from: PA0PBZ on December 13, 2017, 11:23:52 amYes, eeprom contain calibration table, sensor serial number, sensor typ etc. But I am obtained few Gigatronics sensor with completely cleared eeprom. So I will try to restore eeprom for my sensors and recalibrate myself.
Testing an antenna change over relay question - Page 1
Forum section: electronics / rf-microwave

author: Chris Wilson
author_rank: Super Contributor
timestamp: December 13, 2017, 02:04:40 pm
content: I have a big Russian co-axial antenna change over relay based box (home made) that is supposed to direct the antenna to either a TX running a kilowatt on 136kHz or to my Kenwood TS-590 used as a receiver, connecting the aerial to the RX antenna socket. it worked fine for weeks, then something *VERY* nasty happened. It got 1kW of RF up the RX antenna socket, and needless to say the results aren't pretty...I want to test this thing in a safe way. if i put say a 24V Xmas tree light bulb across the RX antenna socket of my relay box would it blow if the relay misfired or whatever and sent the RF to the receiver socket of the box? The box has an internal boost board to give the relay 24V from a 12V input, I am wondering if it's iffy and the relay failed to change state. Thanks.
AIM4170 antenna analyser - view remotely on a Smartphone??? - Page 1
Forum section: electronics / rf-microwave

author: Chris Wilson
author_rank: Super Contributor
timestamp: December 12, 2017, 10:31:52 am
content: I have read about using a Windows based tablet to view the AIM4170 outdoors. but what about having the AIM4170 indoors at the end of a LF antenna co-ax and using an Android smartphone to view the PC screen remotely whilst I fiddle with the matching coil's variometer outside? As you can probably tell, a smartphone is new to me, so apologies if it's a dumb question, I am a Luddite with such devices! I would have no need to actually control the AIM, just watch the sweep. Thanks!

author: CJay
author_rank: Super Contributor
timestamp: December 12, 2017, 12:01:58 pm
content: I don't see why not, there's a Remote Desktop client for Android and I'm sure there will be a VNC client or similar too if the PC is Linux.What may be an issue is the size of the screen but I'll leave that for you to decide.

author: Chris Wilson
author_rank: Super Contributor
timestamp: December 13, 2017, 11:59:51 am
content: Quote from: CJay on December 12, 2017, 12:01:58 pmI found a free app called AccessToGo by Ericom that seems like it will do as i require. I will check it out this week. Many thanks for the reply, this app seems to have much better reviews than the Microsoft RD client for Android phones. I suspect all will be fiddly on such a small scree and a tablet would make things more manageable, but I have a phone and don't have a tablet....

author: CJay
author_rank: Super Contributor
timestamp: December 13, 2017, 12:19:58 pm
content: I'd definitely check out the RDP app from MS first, I've found it works well enough that I could do server maintenance from a beach in Cornwall on a smart phone, but YMMV, if the Ericom one works then go for it.

author: Chris Wilson
author_rank: Super Contributor
timestamp: December 13, 2017, 12:26:07 pm
content: Quote from: CJay on December 13, 2017, 12:19:58 pmOK, will do I guess these apps are easy enough to UNinstall as well as to INstall? (New to the world of Smartphones as you can tell....)

author: CJay
author_rank: Super Contributor
timestamp: December 13, 2017, 12:59:59 pm
content: Absolutely, in Play Store just select My Apps and scroll down the list, tap the app you're interested in and it should give you the option to Open or Uninstall.
Transceiver for time of flight measurement - Page 1
Forum section: electronics / rf-microwave

author: Nogtail
author_rank: Regular Contributor
timestamp: December 12, 2017, 01:29:48 pm
content: I'd like to be able to measure the distance to a transceiver using time of flight. I can't use light or ultrasound, so it looks like I'm stuck with RF.I've got a couple of ideas of how to do this:Send a sine wave which the transceiver transmits back on a different frequency. The phase difference between the transmitted and received signal can then be compared to determine the distance.Send a pulse/number of pulses and start a timer. The transceiver echos this back, and the time difference is used to calculate the distance.Regardless of which option I choose, I need to have a transceiver module that can rebroadcast the signal in a way that doesn't interfere with the original transmission, and with minimal (or at least consistent) delay.I've never practiced the black arts, so I haven't got a clue where to start or what to look for. Are there any particular types of transmitters, reference designs or search terms that might help me?Thanks.

author: fcb
author_rank: Super Contributor
timestamp: December 12, 2017, 02:10:41 pm
content: As you aren't versed in the black arts, then you probably need the dumbest SAW-based radio modules available, but I'm not sure that these exist anymore? Certainly a little scoot about the web shows the usual suspects (LPRS, Radiometrix, RF Solutions, etc..) don't have the capacity to send audio as an analogue signal.You might find some cheap analogue 'video sender' modules from China will be a better bet.If you've got a round-robin setup, you might be able to find a basic digital radio based on a SAW filter - then just keep inverting the same data pulse and sending it round the loop, then measure the frequency.

author: Kalvin
author_rank: Super Contributor
timestamp: December 12, 2017, 03:37:22 pm
content: What is your distance/range and how much it may cost?Solution 1:- GPS module with a microcontroller transmitting the location data using those cheap RT/TX-modules- Receiver connected to a PC or microcontroller- Works outside and over long range- Accuracy few metersSolution 2:- UWB radio + beacon- Works indoors and even outside up to 100m- Accuracy around 10cm or something like that-https://www.decawave.com/
More Icom IC-745 repair video - Page 1
Forum section: electronics / rf-microwave

author: Radio Tech
author_rank: Frequent Contributor
timestamp: December 11, 2017, 02:04:39 am
content: It's IC-745 week. We have a stack of Icom's to repair.The first one has a loose VFO knob that is causing erratic receive and no tx/rx on 24 through 29 MHz.Here is a thread we are discussing programming of the original memory board.https://www.eevblog.com/forum/rf-microwave/programming-volatile-memory-boards-in-older-icom-rigs/In this thread on my site I am posting software and files along with pictures of the ram board and other 45 repair.http://gokarters.com/smf/index.php?topic=2766.0

author: xrunner
author_rank: Super Contributor
timestamp: December 11, 2017, 02:12:22 am
content: Oh goody more repair videos - thanks!

author: Radio Tech
author_rank: Frequent Contributor
timestamp: December 11, 2017, 02:35:37 am
content: Quote from: xrunner on December 11, 2017, 02:12:22 amThanks, hope you enjoy it.
do traveling wave tubes work with a pulse? - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: December 10, 2017, 03:25:47 pm
content: So I see typically a TWT has a saturation point (gain).Will it transmit a pulse with greater power? I know magnetrons can.

author: 4CX35000
author_rank: Regular Contributor
timestamp: December 10, 2017, 10:34:40 pm
content: Quote from: CopperCone on December 10, 2017, 03:25:47 pmPulsing is forcing the device into the saturated region of the amplifier. Done to make the amplifier more efficient in sync periods on TV signals. In the sync period there is no video (Vision) signal, so the amplifier can be run in the non-linear region, but under normal video period is opposite is the case, were the video needs to be amplified in a highly linear region of the amplifier. It is a power saving measure.Personally I have never seen it done on TWT's, but on high powered UHF Klystrons running 15KW upwards to 40KW were amplifier efficiency can be around 30% for a typical high power amplifier running in linear region for TV. Pulsing pushed that figure up by a few percent.
Quick repair of a classic Johnson Valiant CW / AM transmitter - Page 1
Forum section: electronics / rf-microwave

author: Radio Tech
author_rank: Frequent Contributor
timestamp: December 02, 2017, 10:02:45 pm
content: Had two of these on the bench this past week. Johnsons coming out of the wood work around here.

author: German_EE
author_rank: Super Contributor
timestamp: December 09, 2017, 09:38:27 am
content: Please keep on doing the old tube gear Buddy, I find it fascinating to see something that was manufactured before I was born being stripped down and repaired.

author: AF6LJ
author_rank: Unknown
timestamp: December 09, 2017, 04:36:35 pm
content: Very Cool I shall add it to my watch list.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: December 10, 2017, 04:45:26 pm
content: Quote from: German_EE on December 09, 2017, 09:38:27 amThanks. I love old tube gear. It is easy to work on compared to modern day stuff. very enjoyable. More to come. I am rebuilding a Viking II and a 122 VFO for it.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: December 10, 2017, 04:48:14 pm
content: Quote from: AF6LJ on December 09, 2017, 04:36:35 pmCool deal Sue.Hope you like it.BTW, I just posted a thread here on this group. Hoping someone can give a old dog new tricks. This is dealing with the Icom 745 ram board.I like to be able to read the content of the old board with modern programming.https://www.eevblog.com/forum/rf-microwave/programming-volatile-memory-boards-in-older-icom-rigs/

author: AF6LJ
author_rank: Unknown
timestamp: December 10, 2017, 07:52:21 pm
content: Quote from: Radio Tech on December 10, 2017, 04:48:14 pmI'll check it out.
FM Sweep? - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: December 03, 2017, 02:24:56 am
content: Is it possible to do a sweep for all FM devices in a given band with the PLUTO SDR?I was using GNU Radio, but I want something that will sweep a given bandwidth and locate all FM modulated signals.
Yaesu Ft-5200 and scanning problem - Page 1
Forum section: electronics / rf-microwave

author: G4BXD
author_rank: Newbie
timestamp: November 30, 2017, 03:26:28 pm
content: Hi. I have an FT-5200 dual band rig which is fine except, when scanning the memories it will not lock on M1 for P setting or 5 sec setting if receiving a signal.It locks on all the other channels if a signal is present.Anyone else have this rig?thanks, Ben.
4 radios 1 extension speaker ? - Page 1
Forum section: electronics / rf-microwave

author: Flump
author_rank: Frequent Contributor
timestamp: November 29, 2017, 11:35:43 pm
content: I have 4 different ham radios and would like to use one extension speakerwhich has sound from each radio all the time, so no switching.I dont need a volume control on the speaker as the radios have thatso could I use a 4 diodes, 1 in series in each of the + speaker cablesthen connect them all to the same speaker ?The diodes would be to stop audio signal going back in to the radiosseeing as they are all connected together.

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 29, 2017, 11:44:08 pm
content: A diode in the audio path will rectify the audio signal into something unintelligible.But the concept is correct, you want to allow audio signals from the sources to be combined into the destination.The easiest way of doing that properly is probably to use apowered speakerand a simple resistive mixer.The relatively low output impedance of the sources (which are designed to drive speakers directly) will allow using a very simple mixer circuit without worrying about signals feeding back into the other sources.Apowered speakercould be as simple as a recycled $2 "computer speaker" from a charity shop, etc. (or free from the trash bin).

author: Flump
author_rank: Frequent Contributor
timestamp: November 30, 2017, 12:54:29 am
content: Thanks very much Richard.Would this Mixer work ?http://www.ebay.co.uk/itm/Soundlab-4-Channel-Portable-Lightweight-Mono-Microphone-DJ-PA-Mixer-Patch-Lead/162606916680?epid=1578034833&hash=item25dc20a448:g:654AAOSwCcZaGZCzRadios to the Mixer inputs, Mixer output to Audio amp then to a Speaker ?

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 30, 2017, 01:42:46 am
content: That would work only if you pad down the signals. That mixer wants to see microphone level, and your radios (presumably?) are outputting speaker-level. And if you are going to make pads, it would be easier to just make a passive mixer with 5 resistors. As you say, you don't need volume controls on the inputs because you can control the audio levels on each of the receivers.There are similar mixer products like that which are designed to take line-level inputs. Line-level is roughly equivalent to speaker-level (at least for voltage which is all that counts here). I would look for a line-level mixer rather than fool around padding everything down to mic-level.
need help matching chip antenna M620720 - Page 1
Forum section: electronics / rf-microwave

author: bug13
author_rank: Regular Contributor
timestamp: November 28, 2017, 04:30:41 am
content: Hi guysI have done a couple PCB antennas matching, but I have trouble matching this chip antenna M620720 with a PI network to 50ohm:M620720https://www.ethertronics.com/wp-content/uploads/2016/11/M620720-ISM-868-915MHz-Ethertronics-Savvi-Ceramic-antenna-datasheet-20161020.pdfI found an example in this developer guide:Multitech xDothttps://www.multitech.com/documents/publications/manuals/s000645.pdfIn P33, they use two caps? I don't understand this configuration, can someone give me some pointers? Thanks a lot!PS:I am able to turn the frequency with the minor and major turning, but with no luck matching it 50ohm.I only have a USB desktop VNA
25M-6G signal source, signal generator, simple spectrum, USB interface - Page 1
Forum section: electronics / rf-microwave

author: halfmac
author_rank: Newbie
timestamp: November 25, 2017, 01:10:01 am
content: I just recently purchased one of these units. The CD-Rom does not work so I have no software. It would be great someone could give me link to the software. Alanhttp://www.ebay.com.au/itm/NEW-25M-6G-signal-source-signal-generator-simple-spectrum-signal-source-tracking/263004176910

author: tggzzz
author_rank: Super Contributor
timestamp: November 25, 2017, 09:25:53 am
content: I suspect you have two options.Complain that the item is not as described, and get you money back.Sometimes these devices are merely copies of the chip manufacturer's eval board plus a USB to serial/SPI/etc interface. If that is the case, then find the chip manufacturer's eval software and try that.

author: Emo
author_rank: Regular Contributor
timestamp: November 26, 2017, 07:33:07 pm
content: Hi,check out the software from member Vitor Bicuricohttps://www.eevblog.com/forum/rf-microwave/simple-spectrum-analyser-signal-generator-25mhz-6ghz/msg1251666/#msg1251666Eric

author: ChristofferB
author_rank: Frequent Contributor
timestamp: November 27, 2017, 03:26:26 pm
content: +1If this is anything similar to the identical looking 35-5.4 GHz model, it's just an RF frontend and an atmega8-something with a serial to usb interface.Mine came with the software 'winNWT4' - as these devices are clones of the german NWT4000. I think you'll be able to dl it from here:http://www.dl4jal.eu/hfm9.htm

author: ch_scr
author_rank: Frequent Contributor
timestamp: November 27, 2017, 09:30:57 pm
content: I have one of the earlier versions that go up to 4.4Ghz. The Devil is in the Details of initially setting up the Software. Under settings->options->frequency limit area (at the bottom) is a frequency multiplier dropbox, for mine it has to be set at 10 or it would not work. Also adjust frequency limits there as applicable. Leave "one channel" and "math correction" checkboxes alone.Also, you propably already know this, but dont try to measure something by connecting it between in and out, that wont work. These "simple" aka cheap units work only as signal source or spectrum analyzer, not both at once. Im just mentioning it as i had to learn that the hard way, and spent a while fiddeling without success.
MiniVNA Tiny users: quality issues? - Page 1
Forum section: electronics / rf-microwave

author: borjam
author_rank: Unknown
timestamp: March 20, 2017, 08:17:06 am
content: Hi,Last month a local colleague mentioned on a mail list that he had two miniVNA Tinys with problems. One of them was unusable for transmission (S21) measurements, the other one for reflection (S11).Mine works fine, but I am wondering wether they have some quality control issues. We can "compare notes" here to check how well ours work.Mine was purchased from Wimo in Germany. I have seen miniVNA Tiny units for sale on Aliexpress, but I am not sure wether they are knock-offs or Mini Radio Solutions just purchased a product in China to sell as their own. Data points should be completed with the origin, please.I include two sample plots. One of them is a FM broadcast band notch filter designed by F1JKY, the other one is my MFJ 1788 loop antenna on 40 m. The matching of the latter is not perfect, but it's placed indoors.The measurements are certainly usable in my case, and what I see on the VNA matches what I see on the HF transceiver when Iuse the antenna.

author: Andy Granis
author_rank: Contributor
timestamp: March 20, 2017, 02:09:43 pm
content: Hi,I have had the miniVNATiny for about a year and I have observed that when measureing S11 (reflection) at the DUT-port the result changes slightly if DET-port is terminated with a 50 Ohm termination or left open.So I have taken the habit to terminate DET-port with a 50 Ohm resistive termination when measuring S11 and calibrating S11.

author: vaughn22
author_rank: Newbie
timestamp: November 26, 2017, 03:19:06 am
content: Mine works okay as far as I know, although I observed something similar to Andy where results change in reflection mode depending on the DET termination. I got mine from Aliexpress, and have made some matching circuits with it with modest success, so I don't think it's a knockoff. The real issue is figuring out all it's noise and response drift quirks. I wrapped mine in foil to harden it from external rf interference and I make sure to only use it once it has warmed up to fix stability issues, but there's still that DET termination phenomenon I still have to figure out. Don't think it's broken though.
For Flex SDR1000 users - Page 1
Forum section: electronics / rf-microwave

author: sv1eia
author_rank: Contributor
timestamp: November 25, 2017, 09:12:04 pm
content: Hi,Please allow me to let you know some great news for Flex SDR1000 users, as now they can have a new solution tailor-made for SDR1000 to re-vitalize their rig and work in modern PC and new Windows versions. That solution comes with a dedicated included LPT control interface.More detailed information is in thehttps://pi-sdr.compages.Best regards & 73,Christos SV1EIA
Biquad: Optimal distance between element and reflector - Page 1
Forum section: electronics / rf-microwave

author: steenge
author_rank: Newbie
timestamp: November 10, 2017, 02:45:47 pm
content: Hi All,I am planning to build a double biquad antenna with a centr frequency around 5.4 GHz. Several people state that the optimal distance between the driven element and the reflector should be one quarter wavelength, but intuitively I think that would mean that the reflected signal will be in opposite phase compared to the directly received signal, effectively cancelling the two signals.I think the optimal distance should be one half wavelength.Could anyone tell me if I am correct, and if I am indeed wrong, the reason why 1/4 wavelength is the correct distance?// Steen

author: xaxaxa
author_rank: Regular Contributor
timestamp: November 11, 2017, 12:49:35 pm
content: The waves will be in phase with a 1/4 wavelength separation because EM waves invert when reflected by a metal surface; this is because at the conducting surface the E field is zero, which means there has to be a reflected wave that cancels the incoming wave at that point. (this is a very hand-wavy explanation; the full explanation involves the fact that the E field can not be discontinuous at the boundary)In practice the distance doesn't have to be exactly 1/4 wavelength and is often shorter; the impedance can be tweaked this way. The best way to design this antenna is using a EM simulator and running an optimization algorithm (generally optimizing for low reflection coefficient and high forward gain). I've used 4nec2 to tune biquad antennas before and the results are very good.Quote from: steenge on November 10, 2017, 02:45:47 pm

author: steenge
author_rank: Newbie
timestamp: November 11, 2017, 03:47:39 pm
content: Thanks! Now it makes sense

author: hagster
author_rank: Frequent Contributor
timestamp: November 12, 2017, 09:46:54 pm
content: Previous BiQuads I have made at 2.4ghz have had spacing of about 10mm. Thats much closer than 1/4 lamda. I did lots of simulations in nec2 to arrive at this and the real measurements were in close agreement.Basically i dont think the ground plane is working as a reflector in this antenna. Instead its providing capacitance to balance out the inductance of the wire elements. You can adjust the spacing to get the right impedence match.

author: Richard Head
author_rank: Frequent Contributor
timestamp: November 25, 2017, 01:18:18 pm
content: 0.18 Lambda is the figure normally used for a Yagi-Uda array.
SIGLENT SSA3032X input related spurious - Page 1
Forum section: electronics / rf-microwave

author: RFDUK
author_rank: Regular Contributor
timestamp: November 22, 2017, 10:01:28 am
content: Recently received new SSA3032X and extremely pleased with performance and would highly recommend.Thing is the only performance issue I've found is a bit annoying and well outside Siglent input related spurious spec of -65dBC.Am waiting on Siglent feedback response.Wondering if anyone else has noticed this input related spurious ...An input related spur appears 60.0MHz below the wanted input signal at -57.5dBC.The spur appears across the whole input range to 3GHz and is very consistent.The spur is not changed by input level from -30dBm down, that is it's always -57dBC.No change in spur dBC with any parameter settings.Not a show stopper for me I guess and Siglent -65dBC spec would be exceptional for a budget instrument if it met it.Have done sanity checks with other signal sources and analyser, it's the Siglent for sure.Wonder what other SSA3000 instruments out there do on this one?Cheers, Martyn.

author: Simon
author_rank: Unknown
timestamp: November 22, 2017, 12:24:00 pm
content: Please don't double post, it severely irritates people.
HP8566B wobbly trace at narrow spans - Page 1
Forum section: electronics / rf-microwave

author: w2kv
author_rank: Newbie
timestamp: November 17, 2017, 09:31:58 pm
content: Hello to the forum,My HP8566B has developed a problem where the trace when looking at a signal (either externally applied or from the 100 MHz CAL port) is noticeably wobbly at spans below 100 MHz. At a span of 5 MHz or below the trace is a broad mess. It looks like one of the LOs has come unlocked. Any ideas on which one? How to check? I have used 8566s at work and home for many years but never had to repair one, so any thoughts would be appreciated.73 Dave W2KV

author: cncjerry
author_rank: Unknown
timestamp: November 21, 2017, 07:10:41 am
content: Have you checked the RF deck power supply voltages with a scope?

author: AF6LJ
author_rank: Unknown
timestamp: November 21, 2017, 03:47:50 pm
content: Quote from: cncjerry on November 21, 2017, 07:10:41 amThat's a good start.Check all the power supply voltages first.Also you might use AC line synch for the sweep and see if the trace is stable with line frequency synch. that will tell you if it is power supply related or not.
FT-817ND cost down? - Page 1
Forum section: electronics / rf-microwave

author: rz
author_rank: Contributor
timestamp: November 22, 2017, 02:01:27 pm
content: I have bought a FT-817ND recently. After compare to my friend's 817ND, I found the original FM radio IC CXA1611 is replaced by UTC TA2003, and the 3-stage helical resonator filter is gone...So, is the UHF performance worse than the old revision? Anyone has the technical supplement for the new revision of the FT-817ND?Thank you.

author: Diabolo
author_rank: Regular Contributor
timestamp: November 23, 2017, 06:01:04 am
content: Hello,The Yaesu Collins Filter Xf-115c The 500hz CW Filter is an option to buy and install on "filter unit".The master slave 22.625 Mhz (top left of the image) can be replaced by TCXO sold on Ebay for +/- $ 12 delivered.73'sDiabolo

author: denverpilot
author_rank: Regular Contributor
timestamp: November 25, 2017, 02:56:43 am
content: Quote from: Diabolo on November 23, 2017, 06:01:04 amI thought I read somewhere that Collins stopped manufacturing those and all their filter lineup.Or are you saying to find used ones. Usually once they’re installed in one of those rigs they rarely get removed. Either the filters or the TXCO.

author: Diabolo
author_rank: Regular Contributor
timestamp: November 25, 2017, 07:02:08 am
content: Hello,Here is where to buy 1 TCXO-9 for Yaesu.-https://www.ebay.fr/itm/Compensated-Crystal-Components-Module-for-YAESU-FT-817-857-897-TCXO-9-22-625MHZ/142288127481?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649For example, Yaesu filters can be found on Ebay.-https://www.ebay.fr/itm/YAESU-YF-122S-2-3KHz-COLLINS-S-S-B-MECHANICAL-FILTER-FOR-FT897-857-817-RANGE/322897702800?hash=item4b2e33ef90:g:gUoAAOSwTM5Y22j3----FYI, I installed 1 TCXO-9 in an FT847.To feed correctly this TCXO I built in smd 1 stabilsée power supply with filter starting from 8V general: 10uf tantalum, 100 nf ceramic, regulator 3,3V smd, self of 10uH, 10 uf tantalum and 100 nF ceramic.I also built in smd a 22.625 mhz output filter: R10 K, 18 pf, self 4.7 uH, 15 pf.The whole thing (3.3v power supply and 22.625 mhz filter) is wired under the TCXO-9 board which I "etched" with a fine dentist's cutter.To have room I replaced a capacitor cms 10uF Yaesu that did not generate a smd 10uF tantalum.The TCXO board is 6 mm above the Yaesu Control Unit main board, and the 2 (V+ and F out) connections do not exceed 1 cm in length.Of course I deleted R1111 (2k2) and R1109 (100 ohms).I have also made all the existing modifications for the Yaesu FT847 to improve it.73'sDiabolo
Possible to see if packet radio activity exists local to me easily? - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: November 18, 2017, 06:18:06 pm
content: I have VHF/UHF (SDR) receivers and my computer, and would like to get a feel for the local packet traffic activity and see if it exists and is something I'd be interested in, but frankly, I don't know where to begin.My OS is Linux, do any packet programs work in a receive only mode so I can monitor activity without a call sign? I live in the NE US if that matters.What frequencies should I listen on? Its been something like two decades since I last saw a packet station in operation and that was in an area where I suspect there was likely more packet activity than here (the SF Bay Area)

author: Nusa
author_rank: Super Contributor
timestamp: November 18, 2017, 06:36:42 pm
content: Probably not too much going on in Antarctica.

author: cdev
author_rank: Super Contributor
timestamp: November 18, 2017, 08:23:41 pm
content: Its my understanding that there are always hams operating from /in Antarctica.Quote from: Nusa on November 18, 2017, 06:36:42 pm

author: loxodes
author_rank: Contributor
timestamp: November 18, 2017, 10:21:12 pm
content: I can only speak about McMurdo and Pole, but I don't recall any packet activity over VHF/UHF amateur frequencies. All the radios that I recall in the ham shacks were HF.You could listen to (probably unencrypted) pager traffic at McMurdo, but pole is kept pretty quiet to avoid interference with sensitive experiments (the neutrino observatory, microwave telescope..).The comms shop would have the most up to date information.(Here are some local stations:https://aprs.fi/#!addr=New%20England)

author: cdev
author_rank: Super Contributor
timestamp: November 19, 2017, 01:27:35 am
content: Yes indeed.. very very cool. There are some packet people in my current location.

author: denverpilot
author_rank: Regular Contributor
timestamp: November 19, 2017, 07:49:22 am
content: For APRS listen on 144.39.Generally old school packet stuff would be up at 145.01.All depends on local bandplan of course.
Free radio listening with ICOM PCR-1000 …. (beta) - Page 1
Forum section: electronics / rf-microwave

author: max-bit
author_rank: Frequent Contributor
timestamp: November 18, 2017, 08:27:54 am
content: Free radio listening with ICOM PCR-1000 …. (beta)More :http://www.rflab.pl/rflab_wp/2017/11/18/free-radio-listening-with-icom-pcr-1000-beta/

author: max-bit
author_rank: Frequent Contributor
timestamp: November 18, 2017, 10:47:27 am
content: Please test the stream. In case of problems please report