Combined TDR / SWR meter ?

[Boo2]

Hi,

Does anyone know of a well priced combined time domain reflectometer (TDR) / standing wave ratio (SWR) meter for use at marine VHF frequencies ? I know it's a lot to ask...

Thanks,

Boo2

 

[Plevier]

Talk to Des - can't think of his other name - who does safety boat duty for the dinghy section at SYC.
He is a radio ham and has various meters and has checked aerial systems out on yachts, or he may know of such a device if you want to get one.
(I think some experience is necessary to be sure of the significance of results.)

 

[nigelmercier]

I don't see how you would get a combined unit (or indeed why you would need one) as they do very different things. Any TDR is going to be priced at several times the cost of replacing the cable anyway.

 

[Boo2]

I don't see how you would get a combined unit (or indeed why you would need one) as they do very different things. Any TDR is going to be priced at several times the cost of replacing the cable anyway.

Yes, they are very different instruments in how they work and what they do but a pulse TDR must surely be a p.o.p. to implement to implement on a modern ASIC ? The combination would make a great cable fault tracer so I wondered if anyone had done that ? From your answer I guess not...

Boo2

 

[wooslehunter]

If you want to check out VHF cables & antennas, then a simple VSWR meter will do just fine. The cost of replacing the complete cable is not too expensive & finding the exact position of the fault which the TDR would do isn't IMO much help. If it's damaged, replace it. Since the marine environment is so hard, cutting out a damaged bit of cable isn't really a longer term option. You'd have to use 2 in-line connectors & as few connectors as possible is best; not only for corrosion reasons but connectors are lossy too.

Ham radio shops like Nevada Radio or Waters & Stanton will supply a VSWR meter for 2m at a reasonable cost. These will cover marine VHF too. A simple VSWR meter fits in line between the radio & the antenna & requires the radio to transmit to make a measurement.

If you want something a bit more exotic (& expensive), then something like the MFJ-259 from MFJ is a nice bit of kit. This little beasty is a self contained antenna analyser that covers HF & VHF beyond the marine bands. Just connect it to the antenna lead & tune to the right frequency. It has its own oscillator which you can tune over the whole band to see how the antenna responds & gives lots of different types of measurements. You can also check out the cable loss altough you do have to remove the antenna to do it.

 

[septiclecky]

Depends upon how long your cable is as if it is only a short run then a TDR will not be much use.

 

[Boo2]

Talk to Des - can't think of his other name - who does safety boat duty for the dinghy section at SYC.
He is a radio ham and has various meters and has checked aerial systems out on yachts, or he may know of such a device if you want to get one.
(I think some experience is necessary to be sure of the significance of results.)

Thanks, Mike, I will ask around for him next time I'm up at the yard.

Boo2