Can Cat5 Passive Baluns Be Used With Active?

[SUBS]

i beleive its passive (tx end) to active if over 250m.

only need active both ends if going for big distance.

also if you have an active at the tx end and a passive at the rx end how will you equilise the signal?

Same way you used to with the old Baxall ZR4 and all the other kit that had amps fitted. eng at rec end, with a phone, goin 'up a bit - down a bit'........sort of like the golden shot my grandad told me about......

I only really suggested it cos Martin said he had both to hand.

[james.wilson]

yes but launch amps had full adjustment (baxal stuff had gain and lift and we used it a lot to much success.... used a scope mind to set up)

but i have only used nvt baluns and the active tx have a 3 way switch. something like 500m, 1.3km or 3 km.

pretty coarse adjustments.

The rx has 2 pots for proper adjustment.

we have only used passive at the tx end unless the run is long.

i do agree that in theory a launch amp is better (like a mast head amp for tv i guess) but do you know of an active balun with full adjustment?

also have never had an issue with nvt baluns ever.

[SUBS]

yes but launch amps had full adjustment (baxal stuff had gain and lift and we used it a lot to much success.... used a scope mind to set up)

but i have only used nvt baluns and the active tx have a 3 way switch. something like 500m, 1.3km or 3 km.

pretty coarse adjustments.

The rx has 2 pots for proper adjustment.

we have only used passive at the tx end unless the run is long.

i do agree that in theory a launch amp is better (like a mast head amp for tv i guess) but do you know of an active balun with full adjustment?

also have never had an issue with nvt baluns ever.

As I said, I'm not familiar with SysQ stuff, only baluns I have used much have been NVT, incl' hubs with active Rx, but the pic TBH never looks quite as clean as it would have with ct125. one day, when I have time, I might try using a launch amp with passive baluns at each end, just to see what happens. I thought setting it up with a scope would be taken as read, how else could you accurately set up the hf lift ?, getting it wrong with Baxall kit used to cause some strange effects with Baxall, like no telemetry after dark, and running on etc. Actually I miss ZR4s, used to make good money repairing the PCBs.

Back to the original topic though, I cant see why Martin has had to use both on 300M, my guess is its hiding a cable problem.

[martinnitram]

Thanks for all your ideas,

Still clear as mud.

But just to answer a few questions brought up in the replies,

1) There does'nt seem any problem with signal, ive swapped reciever baluns and fault follows.

2) Also as stated if i poke (sparky term here!) said balun with screwdriver picture briefly gives decent picture.

3) Why did i use Active transmitter and reciever? cos i didnt know you could mix em.

4) I have already rang system Q tech dept and they didnt suggest using passive and active mix.

So im summary am i right in thinking that if i put a passive on transmitter end and active on reciever end ill be able to turn the gain and brightness screws up untill i get the right picture???

regards martin.

[camerabloke]

use 2 passive baluns and try that

[justin]

So im summary am i right in thinking that if i put a passive on transmitter end and active on reciever end ill be able to turn the gain and brightness screws up untill i get the right picture???

regards martin.

Yes that is the best way. The distance would proberbly be ok passsive to passive on a mono camera. If it's colour do passive to active and adjust accordingly. You will find that the DVR needs a stronger signal present at the input than connected directly to the monitor. Any problems from this point then try using a spare pair. I normally use genie balluns with good results.

[ilkie]

Yes that is the best way. The distance would proberbly be ok passsive to passive on a mono camera. If it's colour do passive to active and adjust accordingly. You will find that the DVR needs a stronger signal present at the input than connected directly to the monitor. Any problems from this point then try using a spare pair. I normally use genie balluns with good results.

With regard to camera input into the DVR you will often find it is the amplitude and shape of the sync pulse which determines if the DVR sees it or not. Monitors will often display any picture signal (it would have to be pretty bad before the monitor gives up).

With any analogue video transmission system the only way to set it up is with a scope and pulse & bar generator.

Anything else is guess work.

You may as well try to guess the resistance of a cable (although I did know an electrical engineer who reckoned he could tell stray voltages by touch)!

Ilkie

[dmitry]

Dmitry, how come your location says 'UK' when I strongly suspect it isn't my old china, say no more, nudge nudge.

And what?

[SUBS]

Seem to be getting posts flom a rot of newbies in China recentry.

[martinnitram]

Thanks all,

Im going back some time this week so should get problem solved.

Martin.

p.s.

nice to find a site with people on it who actually have an idea of what they are talking about!