NASA Clipper depth transducer cable extension. Is it just TV co-ax?

[sealegsjim]

I need to extend the transducer cable on my new NASA depth sounder by a few metres as the cable supplied is very short. It looks just like just a standard TV co-ax cable so could I just buy a TV aerial extension cable with moulded M&F terminals?

 

[markleuty]

I need to extend the transducer cable on my new NASA depth sounder by a few metres as the cable supplied is very short. It looks just like just a standard TV co-ax cable so could I just buy a TV aerial extension cable with moulded M&F terminals?

I did exactly that. TV co-ax adapter and cable from B&Q works a treat.

Mark

 

[alexrunic]

are the connectors not BNC ones, can't see a problem using coaxil cable though

 

[NorthUp]

Yes, TV Co-ax, info from NASA themselves.

 

[padge]

A quick google reveals the coax impedance is 50 ohms

radio/comms coax is 50 ohms

Tv coax is 75 ohm

pop to some where like maplins - they do extension leads (not the cheapist but they are easily available )

Using a short length of wrong impedance cable won't make much difference but anything more than a couple of feet will degraded the signal ,which can be significant in low power systems

 

[colvic987]

just buy an extension cable from nasa marine.

http://www.nasamarine.com/proddetail.php?prod=06_7_metre_cable

 

[sealegsjim]

Thanks for your replies. The forum, as usual is a wealth of information. B&Q or Maplins it is.

 

[Strathglass]

Thanks for your replies. The forum, as usual is a wealth of information. B&Q or Maplins it is.

Not B&Q you should use 50 ohm cable not TV cable - Nasa or Maplin.

 

[st599]

Thanks for your replies. The forum, as usual is a wealth of information. B&Q or Maplins it is.

Cable from B&Q will be 75 ohm. You may need 50 ohm cable. If you use the wrong impedance, you'll get reflections running up and down the cable. May not be significant depending on frequency.

 

[Billjratt]

The "ping" is transmitted by a transducer connected via the cable you are talking about.
Both the cable and transducer form part of the tuned output circuit.
If you alter this, you are likely to have poorer results - possibly 'freezes' on last known depth, or an inability to measure anything other than pretty shallow water.
This may be acceptable if you're an Eastcoast mudhopper, but not for the abyss's of the WestCoast.
If the manufacturer offers a solution ( ie an extension cable) it should be matched to the circuit, and may have extra components to redress the inbalance. ( hence the apparently inordinate cost).
If you go with telly wire you have to live with the results - using the correct cable at least allows you some come-back if it performs poorly.

 

[savageseadog]

TV Coax is plain copper which can be a problem with corrosion.

 

[nigelmercier]

Not B&Q you should use 50 ohm cable not TV cable - Nasa or Maplin.

Or get a "Thin Ethernet" cable; that is also 50 ohms, and often tinned.

 

[Kwik Decision]

I need to extend the transducer cable on my new NASA depth sounder by a few metres as the cable supplied is very short. It looks just like just a standard TV co-ax cable so could I just buy a TV aerial extension cable with moulded M&F terminals?

I've just sent you a PM.....

 

[sealegsjim]

NASA has just responded to my enquiry and says, I quote '' Yes use ordinary 75 ohm coaxial cable, keep extension as short as possible and no loner than 7 metres''

 

[Tintin]

NASA has just responded to my enquiry and says, I quote '' Yes use ordinary 75 ohm coaxial cable, keep extension as short as possible and no loner than 7 metres''

Thats what they advised me to do 2 yrs ago. So far no problems at all. KISS

 

[NorthUp]

aye, sounds familiar!

 

[st599]

A quick google reveals the coax impedance is 50 ohms

radio/comms coax is 50 ohms

Tv coax is 75 ohm

pop to some where like maplins - they do extension leads (not the cheapist but they are easily available )

Using a short length of wrong impedance cable won't make much difference but anything more than a couple of feet will degraded the signal ,which can be significant in low power systems

No, 50 is high power transfer, 75 is lower noise. In comms and radio you choose based on usage.

 

[apollo]

Also paired off transducers from different makes of echo sounder to head units in the past. Most seem to be fairly generic.

 

[VicMallows]

No, 50 is high power transfer, 75 is lower noise. In comms and radio you choose based on usage.

And just where did this (most unusual interesting) piece of information originate??

Vic

 

[st599]

And just where did this (most unusual interesting) piece of information originate??

Vic

I'll post a reference when I'm in work tomorrow.