Hey Dave, great video. I found that Belden 9913F7 cable works great for an antenna system. The LMR series is also a very good coax cable to use for antennas. Both of the 9913F7 and the LMR-400UF cables are the flexible type cables and work very well for an antenna that rotates. Again, thanks for a very informative video. 73’s….....
The counter-intuitive fact that aircraft wiring prefers higher current per gauge to reduce weight is really interesting, it makes sense but I would not have expected it either. Thanks for throwing that in! :)
The losses in the cable determine the heat. The size of the cable bundle determines the ability of a cable in the center of the bundle to get rid of the heat. If you are designing an airplane, you also have the time to consider this along with signal integrity at the other end of the wire. For house wiring, it is just a value that always works. No calculations are required.
I have never considered using DC theory on an RF calculation. I would have gone with cable losses, heat, compaired with the ability of the cable to dissipate the heat.
Cable losses are greater for longer cables. For DC and low frequencies, like house wireing, yes. If your 12v power is only 5v when it gets to the other end of the wire, it may not work. For RF, look at the cable loss of your cable at the frequency that you are using. It will be given per a particular length. With that, you can determine the max length you can use for your application.
what about coax cables in RF situation where the skin effect rise with the frequency.. most of us start with the cheap RG-58 but nobody know the Frequency vs Power limits (we only see the power loss tables vs frequencies).. also i never saw the power limit of a BNC connector often saw in the field.. anyway, thanks for this subject!!
Good question, I had to look it up. For BNC, I found 3.5 amp typical, but there are some that are rated at 5 amps. The losses are dependent on frequency, and that will affect how hot they get. You don't want to melt the dielectric.
Great content, as always! I have a quick question: My OKX wallet holds some USDT, and I have the seed phrase. (alarm fetch churn bridge exercise tape speak race clerk couch crater letter). What's the best way to send them to Binance?
WHAT? find a way to dissipate the heat? LOL... also note rf voltages are peaks. Insulation has a lot to do with the power level. DC current is the same as rf and ac. Current is current.
Thank you.
A simple uncomplicated way of viewing the situation.
Have a Happy Hanukkah and Happy New Year too. N0QFT Glen
Great explanation! 👌👊
Hey Dave, great video. I found that Belden 9913F7 cable works great for an antenna system. The LMR series is also a very good coax cable to use for antennas. Both of the 9913F7 and the LMR-400UF cables are the flexible type cables and work very well for an antenna that rotates. Again, thanks for a very informative video. 73’s….....
The counter-intuitive fact that aircraft wiring prefers higher current per gauge to reduce weight is really interesting, it makes sense but I would not have expected it either.
Thanks for throwing that in! :)
Don't aircraft use 400 HZ instead of 50/60 HZ. I do know that you still get a shock, that will wake you up, from the voltage that the aircraft use.
The losses in the cable determine the heat. The size of the cable bundle determines the ability of a cable in the center of the bundle to get rid of the heat. If you are designing an airplane, you also have the time to consider this along with signal integrity at the other end of the wire. For house wiring, it is just a value that always works. No calculations are required.
I have never considered using DC theory on an RF calculation. I would have gone with cable losses, heat, compaired with the ability of the cable to dissipate the heat.
Thanks Dave - Happy New Year! - Cheers - VE3GHP
Does the length of the run factor into the calculation when selecting the wire gauge?
Cable losses are greater for longer cables. For DC and low frequencies, like house wireing, yes. If your 12v power is only 5v when it gets to the other end of the wire, it may not work. For RF, look at the cable loss of your cable at the frequency that you are using. It will be given per a particular length. With that, you can determine the max length you can use for your application.
what about coax cables in RF situation where the skin effect rise with the frequency.. most of us start with the cheap RG-58 but nobody know the Frequency vs Power limits (we only see the power loss tables vs frequencies).. also i never saw the power limit of a BNC connector often saw in the field.. anyway, thanks for this subject!!
Good question, I had to look it up. For BNC, I found 3.5 amp typical, but there are some that are rated at 5 amps. The losses are dependent on frequency, and that will affect how hot they get. You don't want to melt the dielectric.
Great content, as always! I have a quick question: My OKX wallet holds some USDT, and I have the seed phrase. (alarm fetch churn bridge exercise tape speak race clerk couch crater letter). What's the best way to send them to Binance?
I expectecd some mention of skin rffect.
1500 W into Z=50ohm is about 5,5A
1,500 watts into 50 ohms its a little less then 5.5amps.
WHAT? find a way to dissipate the heat?
LOL... also note rf voltages are peaks. Insulation has a lot to do with the power level. DC current is the same as rf and ac. Current is current.
Hmmmm. If P/I=Z=50 then multiply both sides by 50/I to get I = P/Z = 100/50 =2. I think P = V*I or P/I = V.