Hey guys just wondering whats the difference between LMR400 and RG213 cable I know they are a similar size but is one better than the other?

Basically the difference between LMR400 and RG213 is loss.

The first number is the loss in dB/100 feet. The second is the power
handling.

Cable 30 MHz 50 MHz 150 MHz 220 MHz

LMR400 0.7.....2100 0.9.....1700 1.5.....1000 1.8.....830
RG-213 1.2.....1800 1.6.....1300 2.8....620 3.5.....520

If your looking at short lengths there isn't much difference but if your running long lengths of cable the loss will be the biggest difference. I have run several long extensions for radios to antennas mainly satellite communications and we have used LMR400. Loss over 50-60 metre cables have been minimal.

Cheers Jack,
Very helpful reply, sheds some light on the subject.

There's a significant physical difference between the two as well.

RG-213 has a stranded inner conductor while LMR has a solid inner conductor as well as an aluminium tape inner conductor to complement the braid.

JackTheTech wrote:Cable 30 MHz 50 MHz 150 MHz 220 MHz

LMR400 0.7.....2100 0.9.....1700 1.5.....1000 1.8.....830
RG-213 1.2.....1800 1.6.....1300 2.8....620 3.5.....520

any chance you could explain this little segment a little better??
cheers

Blacky wrote:any chance you could explain this little segment a little better??
cheers

The first is dB loss per 30m (100ft) - 3dB being double and 10dB being 10x. So if I put 30dBm down a 30m cable with 10dB/30m loss, I get 20dBm back out. In linear terms, i'm going from 1W to 100mW. This will then be applied to your antenna gain to calculate EIRP.

The second is power handling - how much power in watts the cable can take at it's characteristic impedance. If you exceed this, there will be a short circuit across the cable and probably lots of arcing and the smell of burning PVC.

E.g. LMR400 Cable @ 30MHz Loss: 0.7dB/30m PH: 2100W.

Something I found with a quick google

http://www.timesmicrowave.com/cgi-bin/calculate.pl

It's a coax cable calculator

Punch in the cable type, the frequency and click calculate.

E.G.

RG58
Frequency: 476.675
Run Length (feet): 100
Total Run Attenuation(dB) 10.3
Efficiency(%) 9.3

Cheers Jimmy, That made it a bit eaiser for us to understand.