Відео

BY DEFINITION: Common-Mode Current is current moving in the SAME DIRECTION down BOTH SIDES of the wire (or choke). To test for Common-Mode Suppression of a Common-Mode Choke (CMC) you must connect BOTH CMC inputs to the center pin of the NanoVNA Port 1, BOTH CMC outputs to the center pin of Port 2, tie the grounds of both Ports together and set the NanoVNA to “thru” or S21 mode with the display set to LogMag. You will see the curve dropping down to show suppression in dB across the frequency spectrum. For a good CMC it should be at least -25dB. Coax or wires wound on an FT-240-31 ferrite core will give about -43dB which is excellent. DO NOT use magnet wire as a nick can lead to an RF arcing and really mess with your system. Hope this helps-K7RAW The Antenna Whisperer.

And thank's for the links! 73

I have one these, gift from a big "Bud" Work fine!! 73 from BRASIL!

Well, RED will never be dead unless you unplug the antenna from the radio. In which case we don't care about Common Mode Currents. We will have no CMC if RED and GREEN are equal in size, but opposite direction. CMC comes when this is not the case. RED and GREEN are opposite, but no longer equal. Which means we have a noise component on the transmission line. This will be cancelled by the choke until RED and GREEN again are equal in size and noise is thus greatly reduced.

Why you simply don't measure the insertion loss?

isn't a raid 1 a mirror?

nice enough video but when you connected two ends of each pair it wasnt as a transformer , it was as more of a capacitor or two separate antennas and at 8:00 ish the resistance was 25 ohm :-)

Where did you order the Toroids from ?

40:22 first echo we've heard 😆

Novo inscrito no canal, parabéns guerreiro, abraço do Brasil.

wis ... wis ... du vollpfosten!

I really enjoyed your video. It has such a peaceful and relaxing vibe, beautifully connected to nature. You got my subscription!

Lovely episode man, place looks really interesting and enjoyable! Happy trails 🥾

(I realise this is along time ago now) It's possible you had the same problem I once did about 30 years ago. There are 75 ohm and there are 50 ohm BNC connectors. Though the centre pin diameters are about the same on the main shank , they look a little different - IIRC the 75 connectors have a "sharper" pin at the tip, though the nominal diameter is the same after the tapered tip. (people _think_ they are different but I have a feeling the main shaft diameter is the same - I think, anwways) Anyways, what can happen is that if you use 75 Ohm BNC males in 50 ohm BMC females, the narrower end of the tip sometimes doesn't make perfect contact especially if the female is old and the centre receptacle has been flared out through longterm usage. Many terminators from the days of late 1970s and 1980s coax ethernet used cheaper (in those days) 75 ohm plugs even if they used a 50 ohm resistor. So this problem occured more in the 80s and 90s. Now, when you test it with a ohmeter, it reads fine probing the BNC male to male directly. It ALSO tends to read fine if you fit a BNC to N or BNC to PL259 or SO239 adapter too. Why? Because when we probe the adaptor's pin, we tend to push it slightly sideways and the very slight movement transfers through to the problem BNC plug in a seesaw motion, unless the adaptor is extremely high quality. This means it reads OK at DC, because the slight sideways movement makes the circuit. However, at VLF-HF and into low VHF, there's an open circuit (in fact it's a tiny capacitance so will read high SWR at lower frequencies) . At UHF, there will be enough pF there to have relatively low reactance. So you may not notice much loss or high VSWR at 400 to 2GHz, but at HF or MF it's pretty bad. Even if all connectors are 50 ohm, you could still have an old or widened female centre receptacle. To see if that's the problem - using a good eye magnifier use a sewing needle to bend one of the leaves of the female centre receptacle in towards the centre to tighten it up - if that solves the problem you either have poor new connectors or old worn ones. They don't last forever in the lab especially if you homebrew a lot and these days everyone uses 50 ohm modules much more than they used to 30 years ago so coax connectors get a lot of wear. This can cause arcing and RF plasma in the connector with high enough power. My first clue was mysterious ozone smell coming from the BNC connector when I was doing a high power PA test into a dummy load on HF. The same cable was fine into the same load even running 1KW pulsed at 1or 2 GHz (radar testing)

where is gps?

Hi! Thanks for the video! I want to calibrate a radio S meter. Where can I set the 50uV or -73dBm attenuation?

Lovely hike man, this looks and feels absolutely gorgeous! Fantastic scenery!

I love your positive attitude hoping you're able to continue on take care of those feet! What solar charger are you using and what was your results of it

What is the maximum RF Frequency of the FY6800?

Filters of this kind should use iron powder core!

Sorry but your presentation did not show how exacly looks frequency response of that filter. What is attenuation at 3,7MHz and 14,2MHz (f/2 and f x 2). I see that SA you using has very small dynamic response as scalar network analyzer. Maybe it is due to wide RBW. OK it looks that filter has more than -45dB at 3,7MHz and close to -50dB on 14,2MHz but there are a lot of noise, not a trace. Price depends on the seller but anyway filters are quite cheap. Question is how good capacitors are used - 1000V or more, we do not know. I would be very carefuly to use that filter at higher power - let say 100-200W. Reactive power that capacitors handle is far over 1kW (check 5B4AGN filters manual) so voltage and dissipated power raitings are important. There is no information from sellers about capacitors used, just how heavy filter is. Some of them publicate screens from vna that looks interesting. Anyway - thanks for video.

so you don’t have to wrap the toroid with coax wire? Can I use 16 gauge speaker wire?

The bandpass looks good on the SA. I would like to see the maximum RF that this device is rated for pass through it and into a dummy load while observing the ferrites with an IR camera for heating. Thank you. 73

does not work anymore K3ng keyer for the arduino plus the add of #define HARDWARE_NANOKEYER_REV_D and #define FEATURE_COMMAND_LINE_INTERFACE #define FEATURE_SERIAL_HELP. makes it big to the memory

Love it. Really work Bruh!

I don't know anything about signal generators, so can you tell me if I want to generate a Wifi or GPS signal using a vector signal generator, will the generator put out or broadcast the signal internally or would I need an antenna?

So to measure the power, the two buttons must be open, and put on the scale 30w or 300w, is that it? thanks.

this is very cool! thanks for doing this demonstration.

Just curious. At 6:55. I did that too! I removed the plastic rails from an old Aprilaire 413. It WAS a giant pain. Why didn't you try that, stapling them on and a few dabs of hot glue? I bet that would work. Let me know if you did try and what you ran into. Thanks for your video.

What is the swr and loss at hf? On vhf using repeaters it is not a big deal! I am building a hf/6m go box and I was going to use one in it.

It would have been better to use flexible insulated wire, than the solid wire. Much easier to work with and crimps better

Puts fingers in peril multiple times ... films safety gloves on the ground in the background 😂

what GPS unit are you going to use? I too am just starting to build the GPS unit for my D700A as well. Waiting on Amazon to deliver my parts now so I can finish this up. I went with the neo-6m. and an even much smaller in size buck converter, it measures only 20mm x 11mm x5mm , but allows to be shoved into a small case and tucked away in my work truck.

Fun component :)

Using ferrite core instead of power core for filter is absolutely ridiculous!

Remember that when your car's generator is charging, the voltage can easily be 14 volts, and even a bit more. But I'm sure the step down converter can handle that just fine.

so.. how well did it work?

Thanks for posting this. Was great to get a look inside.

Nice demonstration, it gives me the knowledge and confidence to construct one myself.

Very cool.

Thanks for this series of videos, it's helped me understand how chokes work and I will be making some for my shack soon. 👍

Thanks for this series of videos, it's helped me understand how chokes work and I will be making some for my shack soon. 👍

Every time you change the span you need make a zero again

Promo-SM

Sounds like SSTV.

The title of the video says Low Pass Filter but in the video you are talking about Band Pass. Which one were you actually aiming for?

Well I once bought some no name elbow adapters. Today I came across your videos and with some trepidation I watched them with my Nano VNA ! phew! At 500 MHz they have about -0,5 dB ! Lucky me !

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In English, I believe we would call the company am-fen-ol. British and American accents would make then sound slightly different.

Ever take one apart? Most are compressed fittings. No real electrical connection. Had lots of them fall apart and cause problems