cctv

[thegadgetguy]

Yea, neat! Yes, they should be as easy to use as they look.

[PSCG]

I have I have a lot of baluns that are made for TV antennas (75 to 300 ohms conversion). Can i use these instead of the normal CCTV baluns?

[SoakedinVancouver]

They would let you use "flat" antenna cable, which has an impedance of 300 ohms, but I don't see what would be gained? You would lose some noise immunity, that's for sure (no shielding).

[PSCG]

Because the tether i use (85m of telephone wire - 2 wire pair cable) has also 300 ohms resistance in RF. In fact, any unshielded 2 wire cable pair has 300 ohms resistance. And as i see from the CCTV camera extension cables, cable run longer than 50m are always 2 wire pair (as the telephone wire).

[greenkarson]

just a quick up date. tested my camera through my 500' teather using my video baluns everything worked great.

[SoakedinVancouver]

So, no video noise at all when engaging one or more thruster(s)?

[greenkarson]

I havent actually had thrusters on yet since the camera hook up. hopefully by this evening.
One weird thing i did find is (i hope i can explain this right) My cctv camera is gets its power from the on board batteries. and sends the signal throught the first balun through the 500' cat5 in the second balun then back into a little piece of coax cable, which plugs into my portable dvd player. The dvd player gets its power from a seperate 12v battery in the the control box. when i hooked it all up the first time no signal at all. Was starting to get depressed when just out of curosity i touched the outer shielding of the coax cable to the negative of the dvd player battery. And the video came through crystal clear. I have no idea what thats all about.
just to test it again i hooked the camera directly to the dvd player without the tether but still to seperate batteries with the same results. No signal untill i ground the coax to the negative of the dvd player battery. So i hooked everything up to the same battery and no problems no need to ground the coax.
I guess its not really a problem but just wondering if any ones has any ideas why this is?

[greenkarson]

tried the thrusters with the camera on tonight. When the thusters first kick on there is a little flicker on the screen. Once the thrusters are on there is no distortion at all.

[SoakedinVancouver]

...
One weird thing i did find is (i hope i can explain this right) My cctv camera is gets its power from the on board batteries. and sends the signal throught the first balun through the 500' cat5 in the second balun then back into a little piece of coax cable, which plugs into my portable dvd player. The dvd player gets its power from a seperate 12v battery in the the control box. when i hooked it all up the first time no signal at all. Was starting to get depressed when just out of curosity i touched the outer shielding of the coax cable to the negative of the dvd player battery. And the video came through crystal clear. I have no idea what thats all about.
just to test it again i hooked the camera directly to the dvd player without the tether but still to seperate batteries with the same results. No signal untill i ground the coax to the negative of the dvd player battery. So i hooked everything up to the same battery and no problems no need to ground the coax.
I guess its not really a problem but just wondering if any ones has any ideas why this is?

Electrical signals must have a common point. Like, all the electrons out of a battery come out of one of the terminal, through a circuit and then back into the other terminal. The electrons generated by one battery were directed to your VCR and once there had no path back to their battery of origin. No circulation of electron means no work done means no picture in this case. Once you connected the two batteries negatives together, via the outer shield (connected to the connector shell), the electrons found their way back, creating work out of the current circulating through the VCR circuitry.

Sorry if I oversimplified.

it's OK to have fully independent power sources if the circuitry they each power have nothing to do with each other. If the signals have to be related/transferred/modified then you must have a "common" connection.

[SoakedinVancouver]

tried the thrusters with the camera on tonight. When the thusters first kick on there is a little flicker on the screen. Once the thrusters are on there is no distortion at all.

You could probably get rid of these noise but they do tell you something about your thruster reacting to your commands. Now, if there was noise at all time, noise hunting and annihilation-through-filtration would be in order. How do you feel about the noise as it is?

Save your test videos, so that you can compare with the first few runs you do in water, with everything connected as it should be, it will tell you if the noise has got worse more efficiently than your memory.