Power and Decibels ( DB ) - Quick Guide
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- เผยแพร่เมื่อ 8 ก.ย. 2024
- A fast and relatively simple way to work with decibels in relationship to power when dealing with antennas, amplifiers, coax, etc., Most people should be able to do this in their heads. Works great for ham exam purposes.
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Randy you should be teaching. You have taken a subject I was totally confused by and made it so simple. I feel my test scores going up!! Thanks again!! 73 Len
I'm doing my final chapter of my advanced amateur radio exam and you made this so easy to understand. I can go to sleep now. ;)
You have to go past the number and work back was the key to understanding odd combinations for me. Thanks.
Thankyou for the informative and useful video's!
Glad you like them!
Excellent way to do a quick calculation. Just what I was looking for, thank you.
After searching the Internet, tirelessly, for some reasonable explanation on calculating the gain/loss of dBs all I got was incomprehensible physic courses. Your video was SO helpful in understanding the very concept of figuring out dB gain and Loss. Thanks for the time you put into this. Off I go in a few weeks to take the ‘general’.
I have spent the entire day trying to understand this calculation for an attempt at my technicians license. I thought all was lost until I watched your video. thank you
Thanks
I'm studying for me Tech. And trying to learn instead of memorizing. And you just help out a lot. I was stuck at 3db not realizing it is meaning double or half. And you showed me a lot more than my first mental barrier question was. Thank you very much.
Thomas Stroud You are quite welcome .. Hows the studying coming .. Get that Technician License yet?
Always feel free to ask questions or give ideas for future videos ..
Also please subscribe and share if you haven't already done so.. Your kind words and support are always welcome.
Its an excellent guide and helpful for me as a student
Glad to hear that! Thank you 👍
Thanks for doing that , I'm studying for my full uk licence and was told to revise Db . You nailed it for me very helpful ..
Cbx1963 You're very welcome ..
Cbx1963 Always feel free to ask questions or give ideas for future videos ..
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The most understandable explanation yet! Thanks!
This made sense. Thank you.
Really awesome video, easy to understand and very much appreciated.
Thanks
Studying for my technician license and was getting stuck on dB. Nice clear explanation. Thank you!
Thank you very much, excellent explanation
Outstanding job. Keep up the good work.
thank you - informative and very useful
Wow, that makes it really easy thanks, never heard an explanation making it that easy
Martin H. You are welcome .. Always feel free to ask questions or give ideas for future videos ..
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After 2 days of racking my brain on this subject , you made it clear , thanks !!1
Thanks
Ohh, so this is how you do it
Amazing
Yes, thank you
Thanks. Very helpful and well explained.
1 dB gain = x1.25; 1 dB loss = x0.8. Another shortcut. So 50w + 14db would be: 50w + 10db (10x) = 500 + 3db (2x) = 1000 + 1db (1.25x) = 1250. It's not perfect but within reasonable rounding error. Nice vid!
Thanks
Thanks, this is actually helpful
Glad it helped
This will definitly help with my ham exam:-)
מארק רוברסון Thanks .. Always feel free to ask questions or give ideas for future videos ..
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Thx for great Video !
This is so helpful!
Glad it was helpful!
well .. wow.. that makes more sense now.. thanks again for your time.
Very helpful!
Thanks for the help
Excellent
Thank you so much 😀
Huge help, much appreciated. Thanks!!
Thanks
so nice, thank you!!!!
Glad you like it!
I can not explain my enjoy enough. Your demonstration is really good! Thank you. Although I would have liked to have the writing a bit bigger, but who cares. The explanation is really good!
Thanks
This is a good video. It helps explain exactly what effective radiated power is, something that just dawned on me when I watched this video. What would be great is if you had this stuff worked out ahead of time and redid this video, going clearly step-by-step through the calculations. A good video would then become an outstandingly excellent video. But thank you for helping me understand. 73 de K9RFT
It was simple and very instructive.
That was great. Thank you again.
Jeet rawti Thanks .. Always feel free to ask questions or give ideas for future videos ..
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Made it simple - many thanks!
Paul Thompson Armstrong You are very welcome. Always feel free to ask questions or give ideas for future videos ..Also please subscribe and share if you haven't already done so.. Your kind words and support are always welcome.
Love u Randy
Thanks, very helpful! Would be cool to see more radio engineering theory.
***** Thanks .. what kinds of radio engineering theory did you have in mind ? Always feel free to ask questions or give ideas for future videos .. Also please subscribe and share if you haven't already done so.. Your kind words and support are always welcome.
Thanks this really helped.
Much appreciated
thank you Sir
Hi very much enjoying watching you TH-cam videos and have just upgraded my old 400mhz Marconi twin suitcase job to the new rigol and you vids have help me get started with that. Regarding this dB tutorial I would love to hear you take on antenna gain. Obviously in the example once you lost you 3dbs in the coax cables it's not actually coming back. I would love see a video on both radiation resistance and also effective radiated power. Out of the two it's radiation resistance that I'm struggling with. Thanks keep those TH-cam vids coming. Regards Chris in the UK
Christian Fletcher Thanks for your question, comments and suggestion. Unfortunately I'm not sure I would do the concept of radiation resistance any justice. However, heres a link to a awesome ham that loves explaining those kinds of things .. www.w8ji.com/radiation_resistance.htm
I hope that helps and if not, let me know and I'll see what else I can find to help .. A far as antenna gain goes .. that I might be able to do ..
Thanks, that helps a lot.
excellent 🔥
Thanks 🔥
If the signal power doubled at a given transmitter what is the decibel increase?
Good job, thanks!
Thanks for the help hope it does help
Good explanation.
brazhell thanks.. Always feel free to ask questions or give ideas for future videos ..
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Is that really easier than trying to understand how to use the formula?
Complete noob here. But how would this work, if you have a 15dB antenna? If you go to 20dbs, how do you work down the 5 dBs, when you have only 3 and 10 dBs? Please let me know - I want to learn. And keep making videos. Cheers!
Wouldn’t for 14dB be 3750 Watts? 5000-1250?
Great vid.
Thanks
That's how you do it
Thanks!
why 3dB is equal to 1/2?
do we call this Dbm?
Great video! How would the calculation be carried out for an antenna with a gain of 4.5dB? Thanks
With a calculator and the appropriate formula ..
thanks a lot.
Changting Luo Always feel free to ask questions or give ideas for future videos ..
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Does anyone know how to do this question (a power amplifier has a power gauner of 29dB and the output is 80watt find the input
first off we know if it was 30 db .. you would move the decimal point to the left 3 places .. making it .08W or 80 milliwatts ..
you know .. forget I said that lol .. here ya go .. ok you basically have 20DB and 3 - 3DBs ... so .. 20 db would be 2 decimal places to the left giving you .8 Watts .. then .. 3DB more would be .4 W and 3 more would be .2 W and 3 DB more would be .1 W or 100 milliwatts .. Now .. you armed with that info can confirm the answer by taking the 100 mw and go the other direction .. first by 20 db and then by 3 db , 3 times .. and see if you end up with the original level of 80W .. Hope that helps
wow, i am studying for the tech exam, i have it all down pat EXCEPT this Decibel part. the question is not worded or configured like you are demonstrating here, probably because i'm on a newer version of the test from the 2013, so I am still not getting it, do you possibly have another video or know of one for me to learn this , i just don't want to memorize the answers , i would ruther learn it, u did a great job, if the test had a question about what the final output would be , i would have no problem, and im sure your explanation probably addresses the same but i am just not getting , but thanks very much for the video, i know it takes alot of time and patience to do one.
Sorry I missed this some how .. Did you get it all figured out and take your test or do you still need help .. If you do .. what part of it does make sense to you and what part doesnt?
Hammer USN is there a video that explains this from the beginning?
sir, I am going to built a sound level meter..the output will be the voltage..How can I convert the o/p voltage to the dB units..Can we explain the formula..
Well first .. the question doesnt really relate to the concepts presented in the video. However, I do know that there are certain standards that apply to VU Meters .. something like 1v P-P into 600 ohms .. and that if you by a VU meter made for that application then it should be close to start with .. only other advice I can give is in the form of a link .
www.discovercircuits.com/V/vu-meter.htm
That website has a lot of VU meter type circuits to do what you ask .. good luck and thanks for watching my videos and please subscribe and share if you havent already
thank u..
so for 15db would you use 30db and minus five 3's?
How many 3's are in the first 15 DB you are referring to?
ahhh 5 lol. I should of though of that.
thank you, this will help on the test. one question, how would you break up 16db? I'm having a brain block. thanks again
10 DB + 3 DB + 3 DB
You're welcome
thank you for the quick response. the test is worded just a little different but with your instructions I get it now. thank you very much for teaching and sharing.
so to bouble check. With your example of starting with a 100 watts, 3db coaxial loss and an antenna gain of 16db. would the answer be 2000 dB ?
ok I think you meant is the answer 2000 W ?
Thats correct
Thanks, that helped a lot, KF4TKL
Dee Williams Thanks .., Always feel free to ask questions or give ideas for future videos ..
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Good video! 73 de PX2Q2328
Meant to say your not you. Must get that new keyboard
Thanks
Folks...understand the video first then use the knowledge to learn logs...it is not that hard!!!!!