#566b

Episode 566b
Be a Patron:
/ imsaiguy

[@PapasDino]

"Don't worry....be happy!" ;-)

[@mikesimpson6757]

That is awesome. I have always wondered how adapters affected loss on my ham radios

[@joaopaulocoelho5401]

I really love your videos!

[@oseyedian]

God bless

[@matteo234321]

PLEASE EXPLAIN for the lay person!... Please tell me, the problem isn't the connections or resistance of interconnects, but in RF it is the matched impedance and attenuation? Thus a slightly bad connection isn't nearly as bad as a mismatched waveguide or improper termination? With RF there needs to be a specific amount of inductance and capacitance through the transmission line? Therefore, the size/shape/spacing as well as the material of the conductor/isolator of the transmission line needs to be designed around a specific impedance? I would love to see a video further explaining why people misconceive connectors as bad, while their cable is even worse! I love your videos and am a newbie to RF, Please keep 'em coming!!!!

[@IMSAIGuy]

Yes it is rarely the resistance and more of a mismatch as you say. If it is not 50 ohms or there is a mechanical discontinuity in the waveguide shape there will be reflections that cause a loss. Having said that, it's pretty hard to go wrong below a 1000MHz. The video would be much different had I measured it up to 18GHz :).

[@matteo234321]

@@IMSAIGuy Thanks! I figured that would be it, at work some of the most expensive items we use in design is the RF interconnects and receptacles. Makes sense that this is why. A lot of engineering going into ensuring that there remains a constant impedance through waveguides built into the mechanical design of the connector!

[@galileo_rs]

Do that with cheap connectors from AliExpress ;)

[@M0UAW_IO83]

The N to BNC, the right angle BNC, the two SMA to BNC-M, BNC-F to SMA, BNC-F to BNC-F all look like pretty cheap connectors to me. The SMA swept right angle, SMA-M to SMA-M, SMA-F to N, N-F to N-F and the BNC-M to BNC-M look like decent quality ones. For the kind of work you can do with a Nano-VNA, the cheap stuff works. If you want to be able to measure -135dBm at 46GHz then yeah, you'll need to chuck the price of a decent car at your connectors and spend the equivalent of a nice house in the country on your analyser.

[@galileo_rs]

@@M0UAW_IO83 I have some BNC to SMA adapters from Ebay, back to back just the 2 of them about 1dB of loss at 900MHz. Some are decent some are just plain terrible.

[@IMSAIGuy]

at least 4 of them are cheap

[@M0UAW_IO83]

@@galileo_rs I've seen some horrors too and they weren't all cheap. But! Ask yourself this, for measurement purposes does 1dB matter if you know it's 1dB and it's always 1dB? (If you're using interseries connectors in cable from a TX/RX for on air use then you're doing it wrong and should be making up a proper cable)

[@M0UAW_IO83]

@@IMSAIGuy Curious to know if they were the ones I pointed out...

[@egbertgroot2737]

Could you do a video on how to demodulate FM?

[@IMSAIGuy]

that is a broad subject. are you looking general knowledge or a specific question? an off the shelf part or discrete design?

[@egbertgroot2737]

@@IMSAIGuy I have built a HAM radio receiver and AM and SSB were relatively simple by using LPF, but FM signals ... where do i start? I do not wish to use modern circuitry. How was FM demodulated in for example the simple 80's boys transistor radio's?

[@IMSAIGuy]

@@egbertgroot2737 OK Will post in a couple days

[@egbertgroot2737]

@@IMSAIGuy Great!

[@IMSAIGuy]

a video will post on the 4th to answer this