hybridfree/eevblog-posts huggingface dataset:
AMT-200 UV mini - Page 1
Forum section: electronics / rf-microwave

author: sundance
author_rank: Regular Contributor
timestamp: February 02, 2019, 06:45:10 pm
content: Anybody happens to to have a schematics and/or service manual for this rig?It's a quite new Chinese 2m/70cm dual bander (seems to have a "real" double superhet receiver) and the price tag is interesting (~120 Euros)If you have this transceiver it would be interesting to read your experience here.Thanks in advance

author: eb4fbz
author_rank: Regular Contributor
timestamp: February 02, 2019, 11:40:34 pm
content: Not a superhet, just another direct conversion radio (AT1846 based).

author: sundance
author_rank: Regular Contributor
timestamp: February 03, 2019, 01:15:29 pm
content: According to this "User Manual", page 38, there's some indication for a superhet receiver (IF1 = 49,950 MHz, IF2 = 450 kHz):https://www.maas-elektronik.com/data/shop/download/1289/maas-AMT-200-UV%20User%20Manual.pdf@Carlos: Where's your information from that this is a direct conversion SDR?Maybe there's some confusion about the rig's name: Sometimes it goes by the name of "AMT-200-UV mini", others just call it "AMT-200 UV", but I guess it's the same thing.-Joe

author: eb4fbz
author_rank: Regular Contributor
timestamp: February 03, 2019, 03:46:59 pm
content: Yes, i saw those wrong specs. The radio OEM is Kydera KD-200UV.Here you have Kydera user manual, with same confusing specs:https://fccid.io/VO6-200UV/Users-Manual/user-manual-4061435And here you have the internal photos. No IF filters, no PLL, discriminator... Just two infamous AT1846:https://fccid.io/VO6-200UV/Internal-Photos/int-photos-4061432

author: sundance
author_rank: Regular Contributor
timestamp: February 04, 2019, 08:09:43 am
content: Thanks Carlos for the valuable input!I was really close to buy one of these radios. But in the end, you get what you pay for...
Transceiver recommendations? - Page 1
Forum section: electronics / rf-microwave

author: 0culus
author_rank: Super Contributor
timestamp: February 13, 2019, 03:10:29 am
content: So my Icom IC7000 is now well and truly dead. It went from turning off on keying the transmitter to not turning on at all after I reassembled it. I suspect I was sold a half dead unit for starters for way too much money. So much for getting on the air soon.In terms of roughly equivalent base stations that are out there, what are the top ones? I don't necessarily need one that does HF/VHF/UHF (VHF/UHF is sufficient for me, as I'm not likely to have room for a good HF antenna for a while) and I'd quite honestly like to get a dedicated radio for that when I do have the ability to try it out.

author: Wirehead
author_rank: Regular Contributor
timestamp: February 13, 2019, 10:39:10 am
content: check the driver amp on your 7000. They frequently fail. There are some mods to stop it from happening.

author: TheSteve
author_rank: Unknown
timestamp: February 13, 2019, 05:17:35 pm
content: Also check the power cord fuses - they like to oxidize in the holders. If it powered off repeatedly while trying to transmit it will eventually kill something - could just be an internal fuse though.

author: 0culus
author_rank: Super Contributor
timestamp: February 15, 2019, 04:13:17 am
content: Good point on fuses, I'll check them. I *think* the driver amp is ok, but could be wrong. If something major is wrong this unit may be beyond my current repair capabilities due to the SMD components.

author: Wirehead
author_rank: Regular Contributor
timestamp: February 15, 2019, 07:05:37 am
content: Quote from: 0culus on February 15, 2019, 04:13:17 amTry and find a local club. Plenty who would give it a go

author: GDK_ATL
author_rank: Contributor
timestamp: February 16, 2019, 08:03:19 pm
content: Icom 7300. You can't go wrong. It's got the best receiver around for the price.

author: bd139
author_rank: Super Contributor
timestamp: February 17, 2019, 09:00:19 am
content: From a trade off perspective I’d go for a Yaesu FT450D. I played with a lot of rigs right up to expensive SDR ones before I landed on this. Everything is right on the panel and the user interface is excellent plus it’s got a full DSP IF qhich is decent and easy to use and built in ATU. Plus it’s cheap! It doesn’t do VHF/UHF. I’d use a separate HT for myself so you can sling it in the car etc.I’m now running an FT818 for both as the thing is portable and I value that more now. My entire HF station is 3.8kg including pole and goes in my bag and weighs less than the FT450D does. That gives me 20m,30m,40m,2m,70cm SSB, FM and CW! Thing lasts about 10 hours RX and 4 hours heavy TX at 6W out.(minus pole which is outside at moment - it's a light weight 7m sotapole). Only thing that sucks is I could do with a better 2m antenna.
[Event] Melbourne QRP by the Bay - 3pm Sat Feb 4 @ Chelsea beach - Page 1
Forum section: electronics / rf-microwave

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: January 19, 2017, 11:28:13 am
content: A twice yearly social event for those into electronics, radio construction and operating.We've had up to 25 - 30 people share ideas on their projects, try out antennas and get on air.Bring a project, ideas or just yourself.The venue is Victory Park, Chelsea near the life saving club.Venue served by frequent train from the city & Frankston and 902 bus from Doncaster, Nunawading, Glen Waverley and Springvale.It's right by the beach, a playground and food.Facebook event pagehttps://www.facebook.com/events/433501210374030/Video of the last oneWrite-up of the last onehttps://vk3hn.wordpress.com/2016/11/08/qrp-by-the-bay-saturday-5th-november-2016/

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: February 03, 2017, 11:01:26 pm
content: UPDATE: 34 degrees forecast so if you're heading down to the beach why not make it Chelsea. Look for antennas in Victory Park near the lifesaving club.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: November 22, 2017, 08:18:15 pm
content: The next event will be this Saturday November 25, 2017. 3pm again at Chelsea beach. Suggested theme: VHF / UHF portable.Event page athttps://www.facebook.com/events/1873697052890624/

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: January 31, 2019, 12:03:28 am
content: And the for for 2019 is this Saturday Feb 2, also at 3pm at Chelsea beach.Facebook event page athttps://www.facebook.com/events/220696472182095/
new toy teardown ICOM AH-4 - Page 1
Forum section: electronics / rf-microwave

author: GeoffreyF
author_rank: Regular Contributor
timestamp: January 30, 2019, 10:25:09 pm
content: For ease in shipping, the control and coax cables are not installed. So, opening is required for using. This thing will tune just about any long wire over 24 feet. (As long as it is not an integral of 1/2 Wave length). It's pretty cool inside. Note the antenna wire insulator at the bottom of the picture. Notice outside it says "Danger High Voltage".KC1KNS

author: TheSteve
author_rank: Unknown
timestamp: January 30, 2019, 10:56:31 pm
content: The Icom series of wire tuners are pretty legendary. My first side band contact on 20m to Japan used one with a piece of wire running from the house to the back fence.They benefit greatly from a choke on the coax close to the tuner so your coax isn't "hot".
GNSS and Antenna selection - Page 1
Forum section: electronics / rf-microwave

author: vignesh_shan
author_rank: Contributor
timestamp: January 30, 2019, 05:58:27 am
content: How to select a antenna for the GNSS module. There are plenty of GNSS/GPS modules and Antennas in the digikey and other distributers. So shall i use any antenna(except passive and active antennas) for any modules. Please suggest me !!!

author: hagster
author_rank: Frequent Contributor
timestamp: January 30, 2019, 06:23:14 am
content: We would need more information about your project to provide good advice.Active antennas are worth it when you have long cables. For very short runs it doesnt help.Its generally a good idea to have a SAW filter built in. Especially true if its an active antenna.Bigger antennas are generally better than smaller antennas. To a point.Try and pick a trusted brand. I.e one that you have seen in other products that work well. Eg Toaglass, Mobilemark, Pulse-larsen.(or other). This minimises your chance of getting an antenna that doesnt work opyimally.

author: cdev
author_rank: Super Contributor
timestamp: January 30, 2019, 03:13:00 pm
content: If you're using a basic L1 GPS it's fairly easy. Most commercial GPS antennas will do. The most important thing is placement, meaning having a decent ground plane, in the case of a patch antenna (the most common kind) and a clear sky view, especially one free of reflective metal objects.The GPS antenna almost always needs to be facing "up" to work well. Unfortunately, only a very few kinds of GNSS antennas can function acceptably well in other orientations.Which brings up another issue, what kind of accuracy is needed for an application. Is it acceptable to just have a general idea of where the GPS unit is or does it need to be very very specific? Basically does the location need to resolve to a few meters, centimeters or millimeters. And how often does it need to be updated?As far as an SAW filter, yes and no. With multi system GNSS systems, its starting to become problematic to use existing L1 designs (that are optimized to the band around 1575.42 MHz.) Glonass for example, requires slightly different (higher) frequencies.L2 frequencies are quite a bitlower.
Vent holes and EMI - Page 1
Forum section: electronics / rf-microwave

author: Pack34
author_rank: Frequent Contributor
timestamp: January 28, 2019, 02:09:54 pm
content: I can't seem to remember the rule of thumb for the acceptable diameter for vent holes for immunity. I could have sworn it was something like the diameter of the vent has to be less than 1/2 of the maximum wavelength, but that seems large.

author: OwO
author_rank: Super Contributor
timestamp: January 28, 2019, 03:40:28 pm
content: Depends on how much isolation you need. I recall it's more like 1/20th of the wavelength for good isolation (>50dB). The amount and density of the holes are also important, as well as how close the holes are to your circuitry.

author: coppercone2
author_rank: Super Contributor
timestamp: January 28, 2019, 05:02:00 pm
content: There are example radiation graphs to give you an idea. Rf honeycomb is an option.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: January 28, 2019, 07:07:13 pm
content: The other suggestions are correct. For more details, see "Noise Reduction Techniques in Electronic Systems" by Henry W. Ott.Key takeaway: watch out for slot antennas. These are very easy to accidentally design in, particularly if penny-pinching mechanical engineers are involved.
40dB power tap? - Page 1
Forum section: electronics / rf-microwave

author: orbanp
author_rank: Regular Contributor
timestamp: January 21, 2019, 04:27:38 pm
content: Hello Everyone,I built some time ago the AD8307 based RF-power meter designed by W7ZOI et. al., and it is working fine.Here is the QST article describing it:https://www.qsl.net/sz1a/download/build%20an%20rf%20power%20meter.pdfNow I would like to test a 2m HT with it, clearly, I would need a power divider to do that.The article discusses a "40dB power tap" (Fig. 3.).It uses a voltage divider made from 3 x 820 Ohm and a 51 Ohm resistor.Nominally that would be a 1 : 50 voltage division.That would give 34dB power ratio and not 40dB!(The accurate numbers are 33.98dB nominal and 33.845dB with the given resistors.)I think that is a mistake in the article, or am I missing something?Thanks, Peter

author: awallin
author_rank: Frequent Contributor
timestamp: January 21, 2019, 05:11:57 pm
content: The meter itself has a 50R input impedance.So in your voltage divider calculation you should have two 50R (or 51R) resistors at the 'bottom'I get 0.0103 voltage-division or 39.8 dB (power) for the divider, with J3 (fig3) terminated to 51R.if the meter nominally handles +10dBm and this attenuates ~40dB then the max power it can handle rises to +50dBm.

author: EVS
author_rank: Contributor
timestamp: January 21, 2019, 05:30:09 pm
content: Quote from: awallin on January 21, 2019, 05:11:57 pm39.95dB ;-)

author: orbanp
author_rank: Regular Contributor
timestamp: January 21, 2019, 05:41:55 pm
content: Quote from: awallin onTodayat 04:11:57 amNow I see what did I miss!Thanks for everyone clearing it up!Regards, Peter

author: Wolfgang
author_rank: Super Contributor
timestamp: January 21, 2019, 06:05:36 pm
content: Quote from: orbanp on January 21, 2019, 04:27:38 pmI have made and measured some, look here:https://electronicprojectsforfun.wordpress.com/rf-module-gallery/the-rf-splitter-and-combiner-gallery/a-resistive-tap-attenuator-for-rf-measurements/The 40dB (Into 50Ohms) work, and they work to about 500MHz.

author: German_EE
author_rank: Super Contributor
timestamp: January 23, 2019, 07:10:16 pm
content: The short piece of wire from the plate is very important, especially at VHF frequencies. It should run parallel to the first resistor but not touch it. The proper way to fit the wire is to use a VNA to adjust it until the frequency response of the tap is as level as possible but if you don't have access to one then just follow the pictures.Remember to use carbon composition resistors as spiral wound metal film devices will be inductive at VHF.

author: Wolfgang
author_rank: Super Contributor
timestamp: January 25, 2019, 10:28:17 am
content: What you could also do is use a low-pF trimmer instead of the parallel wire. Its true that metal film type resistors are more inductive than carbon composite ones, but you could use this to your advantage because you could add another tripper cap at the 50Ohm resistor at the bottom of the divider to compensate this inductance for a flatter frequency response. An advantage of the metal film resistors is their higher power rating (Carbon: 0.25W, Metal 0.6W)
Vectron Crystal Oscillator Pinout - Page 1
Forum section: electronics / rf-microwave

author: jpanhalt
author_rank: Super Contributor
timestamp: January 01, 2017, 01:46:22 pm
content: I have scavenged a 10 MHz crystal oscillator (probably temperature compensated) from a Wavtek frequency generator of late 1970's vintage (I think). The oscillator was made by Vectron and model # is 216-3293 . Vectron recognizes that as being similar to its part numbers, but has no other information I can find on its site. This drawing shows the connections as used in the Wavtek.The pin numbers are assigned arbitrarily for reference. With -5V applied to Pin 1 and Pins 2-4 grounded (common), Pin 5 gave a nice output pretty close to 10 MHz. All of the pins are physically isolated from the case. Does anyone know the actual connections of the pins? If not, what would be your suggestion for running from a positive supply?Regards, John

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 01, 2017, 03:09:21 pm
content: Can you remember the Wavetek model? I have a lot of documentation, in fact too many to browse them all in search of your oscillator.

author: jpanhalt
author_rank: Super Contributor
timestamp: January 01, 2017, 03:39:57 pm
content: Hi PA0PBZ,Wavtek model 5120A (or 5120-01), S/N 7251372John

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 01, 2017, 05:43:04 pm
content: Quote from: jpanhalt on January 01, 2017, 03:39:57 pmI'm sorry, I have no info for that model.

author: firefly123
author_rank: Newbie
timestamp: January 18, 2019, 10:34:40 am
content: Hi,I was looking for the pinout of a similar "Clock Oscillator" from Vectron Laboratories Inc :Model CO281-2Freq 1 KhzBased on your detective work and a bit of searching around I found a Vectron Laboratories data sheet with an oscillator with a similar pinout this may help youVectron International C4710 datasheethttps://www.digchip.com/datasheets/download_datasheet.php?id=1090390&part-number=C4710The attached pinout of type B might help
Demodulating 4LFSK using an RTL SDR - Page 1
Forum section: electronics / rf-microwave

author: [steven]
author_rank: Contributor
timestamp: January 13, 2019, 12:55:32 pm
content: Hi,I'm trying to demodulate a Satelline tranceiver module at around 430Mhz using an RTL SDR with an R820T tuner.I already have a lot of documentation about the data being transmitted, the data rate and the modulation type.The modulation type is 4 level FSK, the bit rate is 9600bps (so the baud rate must be 4800) and the transmission power is 100mW.When standing close to the transceiver I do see a few bursts at the expected frequency of around 430Mhz.However, when listening in SDR# I simply hear silence when there is a tranmission (NFM mode) and then static noise again when the transceiver turns off.Also analysing the demodulated transmission in Audacity only reveals a vague signal that doesn't look like a demodulated 4LFSK signal to me.What am I doing wrong?
Huawei RRU3928 1800MHz radio base station teardown (part 1 + part 2) (updated) - Page 1
Forum section: electronics / rf-microwave

author: madsbarnkob
author_rank: Frequent Contributor
timestamp: December 06, 2018, 06:54:14 pm
content: The RRU3928 is an outdoor remote radio unit. It processes baseband and RF signal data. With the Software Defined Radio (SDR)technology, the RRU3928 supports the dual-mode operation of any two modes of GSM, UMTS, and LTE through software configuration modification. RRU3928 has a dual-transmitter and dual-receiver structure, which supports higher output power and carrier capacity.It can f.ex. do 6x GSM carriers at each 10 Watt and 1x LTE carrier at 2x10 Watt or 4x GSM carrier at each 10 Watt and 2x UMTS carriers at 2x20 Watt.This is the initial teardown and later on I will release part 2 which is the circuit analysis video.

author: madsbarnkob
author_rank: Frequent Contributor
timestamp: January 08, 2019, 02:10:28 pm
content: Here is the part 2 video, the circuit analysis of the amplifier.I can unfortunately not upload the high resolution pictures here on the forum, so you can see those on my website:http://kaizerpowerelectronics.dk/teardown/huawei-rru3928-1800mhz-radio-base-station-circuit-analysis-part-2-of-2/
Looking for an "commercial" <1W WFM Modulator - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 29, 2018, 04:11:27 pm
content: HiI looking for am WFM Modulator to transmit some Audio Guide Information onboard a Bus or Train. I know the law say 50 nW ERP.The Train is ~100M long so I need a little bit more output power.Lets say the overwhelming 0.5WIts not hard to finde some FM Output stuff but the crap have just an Audio Jack.......I need more! Like the correct RDS Data and the other stuff.Many Phones have an FM Receiver with RDS Decoder.So can someone recommend one who work just connect to an Laptop?THX!

author: Towger
author_rank: Super Contributor
timestamp: December 29, 2018, 04:32:54 pm
content: An 'FM Exciter' is what you need to look for. Plenty of kits and boards available on ebay etc. But an proper commercial one will cost money.

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 29, 2018, 05:22:20 pm
content: QuoteI couldn't find any who have RDS output.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 29, 2018, 06:40:13 pm
content: https://www.ebay.com/itm/113491802509

author: Towger
author_rank: Super Contributor
timestamp: December 29, 2018, 08:23:26 pm
content: The RDS encoder (and Stereo encoder) would typically be separate units. They are daisy chained in front of the exciters audio input.

author: BigMark
author_rank: Contributor
timestamp: December 30, 2018, 12:23:11 pm
content: Quote from: Lord of nothing on December 29, 2018, 04:11:27 pmLook on eBay type in 'FM transmitter RDS' to the search. What you will find is often cheap units costing a few tens of dollars.

author: djococaud
author_rank: Regular Contributor
timestamp: January 04, 2019, 02:34:46 pm
content: You can look for a si4713 based solution like :https://www.google.com/search?q=si4713+breakout&rlz=1C1GCEU_frFR819FR819&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjZibC-q9TfAhXP1uAKHcthBLcQ_AUIDigB&biw=1362&bih=791(if It's still produced)This is a nice audio+RDS transmitter IC, waiting to be hooked to an arduino...(I'm sure you can find complete system based on this IC on ebay)

author: Lord of nothing
author_rank: Super Contributor
timestamp: January 04, 2019, 03:04:56 pm
content: cool but a little bit less poutput power.What is the weired round hole?!
Crystal IF filter response - Page 1
Forum section: electronics / rf-microwave

author: Mrdouble
author_rank: Newbie
timestamp: December 20, 2018, 06:37:57 pm
content: I picked up an old HP spectrum analyzer at local hamfest and I'm trying my best to breath some life back into her. I'm very wet behind the ears when it comes to filters and RF. Going through the service manual is says need to calibrate the crystal IF filter. The first two stages are as expected but the third stage is not symmetrical at all. I understand that filter response isn't ideal but, well, I just don't know if this is bad or not.The first pic is a class signal being injected in the 5th stage looks just like manual says it should, (4th stage looks pretty much the same).This is the 3rd stage, you can see the hook in the left side, I have adjusted the cap symmetry but this is the best I get

author: Mrdouble
author_rank: Newbie
timestamp: December 29, 2018, 04:13:59 am
content: I'm kinda surprised, not one response? I was thinking that certainly this would be an easy question to answer maybe there is a more appropriate category to put this in? If so, would a mod be nice enough to move it please

author: CJay
author_rank: Super Contributor
timestamp: January 03, 2019, 01:09:44 pm
content: Might be better posted in the Test Equipment section of the forum

author: vk6zgo
author_rank: Super Contributor
timestamp: January 03, 2019, 11:44:01 pm
content: You would expect, intuitively that the slope would look exactly the same at both the lower & upper frequency sides of the passband.On second thought, this is an illusion, due to the way diagrams in books show resonance curves.In a display which gives equal horizontal time for each kHz of frequency change, it is not intuitively obvious that the % change in frequency varies, so surprisingly, the apparent "shape" of the curve will vary.Many years ago, working at a HF Radio station, where each shift was a "Master Class" in practical applications of RF theory, I had something very similar demonstrated to me, regarding tuning an LC anode tuned circuit of the PA stage of a transmitter.The number of turns of the tuning knob necessary to reach the resonant peak were more from the low frequency side, tuning up, than the high frequency side, tuning down.
China lands Chang'e-4 on the far side of the moon - Page 1
Forum section: electronics / rf-microwave

author: chris_leyson
author_rank: Super Contributor
timestamp: January 03, 2019, 10:29:12 am
content: China succsesfully landed Chang'e-4 on the far side of the moon, it will be interesting to see what see what the low frequency, 0.1-40MHz, spectrometer (spectrum analyser) picks up or doesn't. Not exactly sure how 0.1-40MHz is a useful part of the radio spectrum for radio astronomy but at least they can hear Jupiter every now and then.

author: chris_leyson
author_rank: Super Contributor
timestamp: January 03, 2019, 03:49:42 pm
content: Forgot to add, they have a relay satellite, Queqiao (‘Magpie Bridge’), in orbit around the second Earth-moon Lagrange point beyond the moon. Another first for China.https://www.skyandtelescope.com/astronomy-news/change-4-probe-heads-to-the-lunar-farside/
VHF marine telephone service fraud - Page 1
Forum section: electronics / rf-microwave

author: Scratch.HTF
author_rank: Regular Contributor
timestamp: December 12, 2018, 01:11:04 am
content: A number of telephone (PSTN) interconnects via VHF marine radio (Telstra operated them in Australia under the Seaphone brand which services were discontinued over 10 years ago) make use of a unique ID programmed in the VHF marine radio transceiver (or its microphone), and there is a possibility that this transmitted ID can be captured for replay attacks resulting in false billing.Another more likely possibility is that someone might capture someone's callsign and name and use it.Do you know of any instances where this fraud (especially the electronic ID) has occured?

author: philpem
author_rank: Frequent Contributor
timestamp: December 13, 2018, 08:01:39 pm
content: If it has happened, I'd be surprised if the telecoms providers would admit it...

author: Lord of nothing
author_rank: Super Contributor
timestamp: December 29, 2018, 05:21:03 pm
content: Trust me here in good old europe are a lot of phone scams still working because the operator get some % from that money.So why the should put something of when the could make money with.
UK source for SMA/BNC DC Blocks and 10/20db attenuators and adaptors - Page 1
Forum section: electronics / rf-microwave

author: djsb
author_rank: Super Contributor
timestamp: December 26, 2018, 05:31:58 pm
content: Hi,Just bought a pair of Signal Hound instruments. Now I need a couple of DC Blocks and 10/20dB attenuators and maybe a couple of SMA to BNC adaptors (if they exist). Is there anywhere in the UK where these can be bought online (had a quick look on Ebay-No luck)? Thanks.David.

author: Dataforensics
author_rank: Unknown
timestamp: December 26, 2018, 06:27:58 pm
content: You could try.J BIRKETT, RADIO COMPONENTS,25 THE STRAIT, LINCOLN, LN2 1JDtelephone (uk) 01522 520767web address:www.zyra.org.uk/birkett.htmThey used to have quite a selection of such things and supply radio amateurs etc.Looks like you have to ring rather than see things on the website.I have not used them in a while though so dont know current stock.

author: Howardlong
author_rank: Super Contributor
timestamp: December 26, 2018, 07:46:45 pm
content: There are many SMA to BNC adapters on eBay.https://www.ebay.co.uk/itm/SMA-Female-to-BNC-Female-Adapter-Connector-for-Baofeng-Wouxun-Quansheng-Kenwood/291589308883?hash=item43e413c1d3:g:nmgAAOSwQiBZwo8c:rk:3:pf:0You may prefer pigtailshttps://www.ebay.co.uk/itm/30cm-SMA-Male-to-BNC-Female-pigtail-cable-RG174-F4921K/232630540649?hash=item3629dc5969:g:13UAAOSwj1haW5rz:rk:10:pf:0Pads:https://www.ebay.co.uk/itm/2W-Attenuator-SMA-JK-Male-to-Female-RF-Coaxial-Attenuator-0-6GHz-10-30db/401542692518?hash=item5d7dcf3ea6:rk:1:pf:0&varDC blocks:https://www.ebay.co.uk/itm/New-SMA-male-to-female-Stainless-steel-RF-Coaxial-DC-block-6000MHz-50ohms-Sag/281664186989?epid=505886456&hash=item41947e6a6d:rk:1:pf:0The quality isn't always great though, but may well be good enough for your purposes.

author: JohnPen
author_rank: Regular Contributor
timestamp: December 27, 2018, 09:20:12 am
content: Here is a set of SMA/BNC converters available on ebay and sourced in UK that may be of interest.https://www.ebay.co.uk/itm/UK-4Pcs-Set-RF-BNC-to-SMA-Type-Male-Female-Connector-Adapter-Test-Converter-Kit/152584028276?hash=item2386b78074:g:fbAAAOSwlEdZr7MK:rk:1:pf:0They are fine for everyday use.

author: German_EE
author_rank: Super Contributor
timestamp: December 28, 2018, 10:10:32 am
content: www.minicircuits.comTheir European office is in Surrey.

author: djsb
author_rank: Super Contributor
timestamp: December 28, 2018, 12:04:07 pm
content: Thanks everyone. I finally ordered them off the Minicircuits website. Bit more expensive than some of the Ebay stuff but probably better quality. My signal Hounds arrive next week from the Netherlands.
Symmetricom X72 Rubidium clock 1pps disabled - Page 1
Forum section: electronics / rf-microwave

author: testpoint1
author_rank: Frequent Contributor
timestamp: January 13, 2019, 05:08:33 pm
content: Hi all,I got a X72 module, try to make a GPSdo Rubidium clock, but seems the X72's firmware is low (terminal info as following):--------------------------------------------------------X 7 2 by Datum, Inc., Copyright 2002SDCP Version 4.10 of 10/2002; Loader Version 2Mode CN18 Flag 0004 nokUnit serial code is 0111AB0044-h, current tuning state is 6Crystal: 60000000hz, ACMOS: 10000000.0hz, Sine: 10000000.0hzCtl Reg: 0200, Res temp off: -1.5439, Lamp temp off: -2.0133FC: enabled, Srvc: highEnter Run ModeFC mode is enabled1pps mode is disabled-------------------------------------------I checked manual, the best firmware seems is 5.08, does some know how to do it? if you have fw 5.08, maybe can read it by a programmer, the fw is in a 128KB AT29LV1024 chip:

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 13, 2019, 07:11:29 pm
content: Did you try 'h' for help? It seems that at least in some versions you can zet the 1pps mode with 'k'r>ha: Set FC Modef: Adjust DDS Frequency (delta e–11)i: Info (show program info)j: Display 1pps Delta Regk: Set 1pps TICl: Set Service Pin Senseo: Set ACMOS Output Frequency ‘N’p: Display Control Regq: Set Control Regt: Dave Tuning Dataw: Display Health Datax: Exit Run Moder>http://www.rdrelectronics.com/skip/nov/X72.pdf

author: testpoint1
author_rank: Frequent Contributor
timestamp: January 14, 2019, 01:53:40 am
content: thank you, the command is for set 1pps out, not in;r>ha: Set FC Modef: Adjust DDS Frequency (delta e-11)i: Info (show program info)j: Display 1pps Delta Regk: Set 1pps TICl: Set Service Pin Senseo: Set ACMOS Output Frequency 'N'p: Display Control Regq: Set Control Regt: Save Tuning Dataw: Display Health Datax: Exit Run Mode
Sources to guide for PCB antenna design ?. - Page 1
Forum section: electronics / rf-microwave

author: sangar
author_rank: Regular Contributor
timestamp: December 24, 2018, 05:46:39 am
content: Hello All,I want to learn about PCB antenna designing...There are Application note regarding this from Manufacturers like Texas Instruments, NXP, etc... Though, I am looking for Generic one for Antenna designing...Please share if anyone came across them...Thanks,Muthu

author: hagster
author_rank: Frequent Contributor
timestamp: December 24, 2018, 06:56:54 am
content: Thats a very open question. PCB Antenna design is just Antenna Design.In my opinion its not a good idea to just copy designs from Application Notes and hope that they will work. These designs are generally only tested for the exact PCB dimenisions specified. As soon as you change the board dimensions, run tracks through the ground plane, stick components on, or put it in a case you have changed the antenna and it needs to be measured again and probably adjusted to compensate.Now all antenna's do "work", but by not doing things properly you can very easily have a very inefficient antenna.For a GOOD guide on antenna design I recomend..http://www.antenna-theory.com/m/antennas/main.phpThe PIFA antenna (or microstrip patch) is probably the most common PCB antenna design. The theory for the basic configuration is fairly simple, but you will still need to measure and tweak it to be confident that its working optimally.
455Khz IF can color code - Page 1
Forum section: electronics / rf-microwave

author: cncjerry
author_rank: Unknown
timestamp: December 16, 2018, 12:27:34 am
content: I see these tunable 455khz inductor cans come color coded. What range does each color cover? I need tunable inductors in the .8 to 1.2 uH range.ThanksJerry

author: retrolefty
author_rank: Super Contributor
timestamp: December 16, 2018, 02:03:32 am
content: I don't think that there is any industry standard color coding for IF transformers involved, every manufacture would have there own part number and coding method. Any further information you could provide?

author: cncjerry
author_rank: Unknown
timestamp: December 16, 2018, 04:59:29 am
content: I saw a radio kit once, maybe it was for WWV, and also if you look on eBay for the cans, you'll see they are sometimes listed as for instance "yellow" or "black". So I assumed there was a coding. I could be wrong. I need tunable cans from .6 to 1.4uh.ThanksJerry

author: vk6zgo
author_rank: Super Contributor
timestamp: December 16, 2018, 09:13:46 am
content: The IF transformers which go between the mixer stage & the 1st IF stage have different impedance windingson the secondary to those between that IF stage & a diode detector.From memory, those "El Cheapo" IF transformers only have one tuned winding, with the other untuned, but I may be wrong.The sets of transformers usually come with two IF transformers & one local oscillator coil .VK2TIP offers the following on his website:-https://www.electronics-tutorials.com/filters/if-amplifier-transformers.htm

author: cncjerry
author_rank: Unknown
timestamp: December 19, 2018, 05:50:48 am
content: vk6, thanks for the info, just what I needed.Jerry
Where is the instrument's name and related material? - Page 1
Forum section: electronics / rf-microwave

author: youngwug
author_rank: Contributor
timestamp: December 18, 2018, 12:33:01 am
content: Where is the instrument's name and related material?I do not have a name on the instrument.

author: youngwug
author_rank: Contributor
timestamp: December 18, 2018, 05:34:08 am
content: This is the Frequency Counter.Product name and manual are required.There is also this inside.(add pic)

author: helius
author_rank: Super Contributor
timestamp: December 18, 2018, 06:49:27 am
content: It is AN/USM-207 Digital Readout, Electronic Counterhttp://www.navy-radio.com/manuals/usm207-operator.pdfIt seems to be made by Computer Measurements Company.

author: youngwug
author_rank: Contributor
timestamp: December 18, 2018, 07:23:14 am
content: Dear helius.I've been looking for a few days, thank you.
Hagenuk preselector? (also huge old HF receivers generally) - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: December 16, 2018, 12:59:53 am
content: I would love to find the schematic for and learn how to build something like this- a Hagenuk-Preselector (for HF) alsolabeled as HMK Preselector RX 1001Mhttps://www.flickr.com/photos/kai-erik/3109501476/https://www.flickr.com/photos/kai-erik/3109503976/in/photostream/It looks a bit like the well regarded Yaesu FT-101 preselector.Does anybody know where I might find the schematic or have any of you ever built anything like this/ It requires slug inductors, which are getting hard to find, ive read.It looks like a helical resonator for VHF/UHF and likely uses similar principles.

author: cdev
author_rank: Super Contributor
timestamp: December 16, 2018, 02:29:10 am
content: Found some info, I wish the scanning was more legible. Still, this is interestinghttp://www.premium-rx.org/hagenuk_rx1001.htm>>http://www.premium-rx.org/ref%20mans/rx1001mvb/section%204-2.pdfA description of the rx-1001 receiver sans-preselector. It looks pretty solid. Not like most modern gear. Love the long German words.http://www.fenu-radio.ch/Hagenuk_RX_1001_M-en.htmhttps://archive.org/details/ShortwaveReceiversPastAndPresent-2ndEdition
Find the real input impedance of an LNA MMIC from S-parameters or experimentally - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: January 19, 2019, 10:17:28 pm
content: I would like to be able to figure out what the real input impedance of a naked front end input pin is for RF amplifier MMICs because I'm curious how well they would do as e-field probes / active antennas.proposed experimental method.."make a couple of transformers with various turns ratios that are specced to be good transformers at the frequency you want to test at, put them on a 50 ohm signal generator that has an 50 ohm N-db (high) attenuator on its output feeding into these different transformers and see which one works the best as far as energy transfer into the unknown impedance input"Can I extract the putative real input impedance from S-parameters? Most manufacturers will supply S-parameters files at various frequencies/voltages/temperatures for their devices.

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: January 19, 2019, 10:29:42 pm
content: You can obtain input impedance from S11using Zin=Znorm*(1+S11)/(1-S11), if the MMIC is specified for 50 ohm then Znormis 50. Otherwise, measure S11with a VNA and do the same.

author: dmills
author_rank: Super Contributor
timestamp: January 19, 2019, 10:41:38 pm
content: But note that best noise match and lowest reflected power may not occur at the same point!Regards, Dan.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 19, 2019, 11:06:24 pm
content: Quote from: radar_macgyver on January 19, 2019, 10:29:42 pmAssuming s12 ~= 0, of course, otherwise there is a feedback term as well.Tim
Do I need an expensive Power meter? - Page 1
Forum section: electronics / rf-microwave

author: cncjerry
author_rank: Unknown
timestamp: December 14, 2018, 01:40:53 am
content: I've been thinking about a power meter lately, something like the HP 437, 438, etc. I have 4 or 5 spectrum analyzers but every now and then I think it would be nice to have a somewhat accurate power meter. Ok, so I can't fully justify it...But here's the issue, a 436, 437 or 438 with a cable and sensor is going to set me back easily $300, more likely closer to $400. So I pulled out a board that I bought from Analog Devices a while back that has an ADL5511, ADL5513 and an ADL5902 on it and ran some tests. I'll be damned if I can tell the difference between the traces on the following graph until it gets over 2Ghz and even then, the issue is probably my cable and lack of enclosure vs the chip.In the attached graph, I used and HP 8648C and traced 2Mhz, 20Mhz, 200Mhz and 2Ghz. The yellow trace is 2Ghz. You can see the attenuator on the 8648C clicking in every 10dB. The others traces are pretty much right on top of each other. I would think with a little tweaking, a descent ADC feeding an STM32F4, I could build a power meter that would meet my needs, accurate to less than .5dB, probably less closer to .1dB I would think. I would use frequency dependent tables I guess but then again, since I really don't have an accurate source above 30Mhz, some of it would be guess work for calibration.So is it worth my money to purchase a power meter, cable, sensor when I can get performance like this (and I have other toys if needed)?ThanksJerryBtw: the plot is dBm on the X axis and adl5513 voltage output read with a 3457a on the Y axis. It is easy to figure out the power based on voltage. You subtract a fixed voltage amount and divide the remainder to get the value per dBm, .1dBm, etc. Once you have those numbers you can calculate any value based on voltage read to that level of resolution.

author: rhb
author_rank: Super Contributor
timestamp: December 14, 2018, 02:27:37 am
content: It depends entirely on what power levels you want to measure and how accurately. I bought a 438A, 8481D and 8382A with calibration certificate on eBay. The sensors are as much or more than the meter. It was not cheap.The 8482A has a range of 0.3 uW to 100 mW from 100 KHz to 4.2 GHz.The 8481D is 100 pW to 10 uW (-70 to -20 dB) from 10 MHz to 18 GHz.I bought the set so I could calibrate other stuff. I'd like to build a low cost power meter. I'm a bit T&M gear obsessed. I want to design cheaper options. I waited until I was about to turn 65 to buy a proper bench. I'd like to make it possible to have a decent bench at age 30 without having to work somewhere where old gear is tossed in the trash or be financially irresponsible.Would you redo your plot as log-log instead of log-linear?I'd like to suggest using external attenuators to verify the readings below - 40 dB.But perhaps your problem is too many SAs ;-)
Low Cost eBay Tracking Generator?  - Page 1
Forum section: electronics / rf-microwave

author: Electro Fan
author_rank: Super Contributor
timestamp: December 13, 2018, 12:17:35 am
content: (This is a repost from the Test Equipment forum.... didn't get much feedback there so thought I'd try here.)Anyone have any experience or thoughts on one of these? Thxhttps://www.ebay.com/itm/HP8590A-HP8591-HP8565A-HP8568A-HP8569B-Spectrum-Analyzer-Track-Source-Generator/253690266561?hash=item3b111e43c1:g:ooUAAOSw2Ehanrqs:rk:191:pf:0

author: xrunner
author_rank: Super Contributor
timestamp: December 13, 2018, 01:26:30 am
content: What's the third picture they show on Ebay?

author: Electro Fan
author_rank: Super Contributor
timestamp: December 13, 2018, 09:25:05 pm
content: something random that isn't the product?
Yagi antenna with too thick of boom - Page 1
Forum section: electronics / rf-microwave

author: tkamiya
author_rank: Super Contributor
timestamp: December 28, 2018, 01:54:26 pm
content: On Amazon and other places, I've been seeing Yagi antenna with too thick of boom relative to element length.https://www.amazon.com/d/Network-Antennas/Tupavco-TP513-Antenna-2-4GHz-17dBi/B008Z4I7WQ/ref=sr_1_7?ie=UTF8&qid=1546005033&sr=8-7&keywords=yagiAs you can see, 1/3 of element is inside a metal boom. (please be reminded element length is measured from tip to tip) If nothing else, it's really odd looking. I wonder if elements properly resonate?Has anyone tested these? I wonder if it still function as a beam antenna? Because element is so thick relative to length, Q to be very low. That will result in very lossy but broad banded characteristics.I'm almost tempted to buy one and test it myself if no one has experience with these.

author: okz00k
author_rank: Newbie
timestamp: December 29, 2018, 12:25:57 am
content: I have used the 2.4GHz versions for extending the range of WiFi successfully. With one at each end I managed a good signal between house and shed over approx 200m.
What is the thread size for GPS antenna mast - Page 1
Forum section: electronics / rf-microwave

author: rbm
author_rank: Regular Contributor
timestamp: December 05, 2018, 12:37:51 am
content: Hi,I'm hoping someone with radio/ham experience can steer me in the right direction to pick out the correct antenna mast. I've purchased a PCTEL GPS timing antenna kit, part number GPS-TMG-26N, for use with my GPSDO. The mounting kit includes a plastic base with a threaded female socket. It states that the antenna mast needs to be 1-1/4" diameter but it gives no information about the male threaded portion needed to secure the antenna base to the mast.I have searched for the proper mast both in stores and online but have turned up little to nothing. Does this antenna mount want NTP pipe threads? Or should I be selecting some sort of PVC schedule 40 pipe? Or are there really zinc-plated steel antenna masts with threaded ends? Can someone please point me in the right direction to get a suitable mast. Stock picture to show the mount and thread:If it helps, I'm planning on mounting the antenna against the roof soffet preferably on an 8' mast secured using Y-supports. The RG-6U feeder will run through the mast and out the bottom. I'll run it inside the house to the basement.

author: GBowes
author_rank: Contributor
timestamp: December 05, 2018, 02:07:43 am
content: The standard thread on most antenna bases is 1" x 14tpi.You can probably find better and cheaper models but here is a base for a boat that may get you pointed in the right direction.https://www.amazon.com/Boat-Radio-Antenna-Ratchet-Mount/dp/B01A20SRRUGrahamQuote from: rbm on December 05, 2018, 12:37:51 am

author: rbm
author_rank: Regular Contributor
timestamp: December 05, 2018, 02:10:21 am
content: Thanks very much Graham. That help immensely.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: December 11, 2018, 10:13:09 pm
content: The thread size on Symmetricom GPS antennas are 3/4" pipe.Typically a short piece of PVC is used, and then you clamp that, to the mast, or mounting point, of your choice.
synchronous signal definition - Page 1
Forum section: electronics / rf-microwave

author: khatus
author_rank: Regular Contributor
timestamp: December 05, 2018, 11:17:28 pm
content: It is probably a very simple question1) In telecommunication signaling within a network or between networks, synchronous signals are those that occur at the same clock rate when all clocks are based on a single reference clock. (Plesiochronous signals are almost but not quite in synchronization and asynchronous signals are those that run from different clocks or at a different transition rate.)https://whatis.techtarget.com/definition/synchronousWhat does it mean by 'based on a single reference clock'?? Can anybody explain?

author: LapTop006
author_rank: Unknown
timestamp: December 06, 2018, 01:07:23 pm
content: Probably easiest to understand by example.Take two function generators.Set both to 1MHz exactly.If you look at the output on a scope you'll almost certainly see one waveform move relative to the other.This is because both generators have slightly different references.If you essentially remove one of the references, and have both generators use the same signal for frequency reference, that stops happening, and this is exactly what's done in synchronous networks (which, outside cellular networks, and some very specific scientific use cases, are obsolete), as well as many RF labs.

author: ejeffrey
author_rank: Super Contributor
timestamp: December 07, 2018, 10:48:54 pm
content: If you look at the back of a lot of better test equipment, especially RF stuff, it will have a 10 MHz input and possibly a 10 MHz output for synchronizing their internal clocks. In our lab we use a SRS rubidium clock as a source plus some distribution amplifiers to synchronize a bunch of arbitrary waveform generators that need to start at the same time. If they weren't synchronized, then there would be +/- 1 clock cycle uncertainty when each generator started. The rubidium source is actually overkill for the most part, the only important thing is that all the generators start at the same time.
Paper: "A 3D Printed Millimeter Wave Absorber" - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: December 01, 2018, 01:02:08 am
content: A 3D Printed Millimeter Wave Absorberhttps://arxiv.org/abs/1808.00820Matthew Petroff, John Appel, Karwan Rostem, Charles L. Bennett, Joseph Eimer, Tobias Marriage, Joshua Ramirez, Edward J. Wollack(Submitted on 2 Aug 2018)We present the design, manufacturing technique, and characterization of a 3D-printed broadband graded index millimeter wave absorber. The absorber is additively manufactured using a fused filament fabrication (FFF) 3D printer out of a carbon-loaded high impact polystyrene (HIPS) filament and is designed using a space-filling curve to optimize manufacturability using said process. The absorber's reflectivity is measured from 63 GHz to 215 GHz and is compared to electromagnetic simulations. The intended application is for terminating stray light in Cosmic Microwave Background (CMB) telescopes, and the absorber has been shown to survive cryogenic thermal cycling.

author: coppercone2
author_rank: Super Contributor
timestamp: December 04, 2018, 02:22:36 am
content: I get warm and fuzzy when i see things other then enclosures and shitty firearms made with 3d printers.If enough appealing stuff accumulates i might try to tackle the 3d printer field but right now i am too scared of process problems.So its like super metamaterial ferrite anechoic liner.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: December 04, 2018, 03:34:47 pm
content: Quote from: coppercone2 on December 04, 2018, 02:22:36 amYou should check out Swissto12 then.http://www.swissto12.com/

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2018, 02:00:52 am
content: cdev's I think uses cheap 3d printer. That one looks like its a laser powder fusion printer
4G module with integrated GPS require separate antenna? - Page 1
Forum section: electronics / rf-microwave

author: sangar
author_rank: Regular Contributor
timestamp: December 10, 2018, 05:03:37 am
content: Hello All,For our project, we need 4G connectivity and GPS functionality...When I explored them in Sierra, I found some with 4G+GPS...But, I am wondering that they need separate antenna since our GPS signal is at 1.5GHz and 4G at either 1800 MHz or 2300-2400 MHz...(Or) a single antenna with large bandwidth will be used for this...Please suggest...Thanks,Muthu

author: mjs
author_rank: Regular Contributor
timestamp: December 10, 2018, 08:19:53 pm
content: You need a separate antenna. The frequency bands and polarization are different and you can't make good antenna to serve both functions. In addition, separate antennas offer some isolation to prevent 4G causing interference for GNSS. (I've seen combined antennas, but those are... difficult and contain $magic).