Re: Too many VHF aerials?

Brent Cameron

Thanks Scott/Ryan/JP. 

Scort, I had seen your post on the bend radius of LMR-400 and why you chose RG8X but thought you had them backwards (I’m sort of dyslexic myself so let it slide). You are absolutely right about not violating the minimum bend radius but If you look at the RG8X specs you’ll see that it has a pretty wide (2.5”)minimum bend radius because it has a very compressible dialectic unlike the TMS LMR-400 which has got a 1” minimum bend radius and is very flexible. 

The difference in signal loss  between the two is fairly significant. If you have say an 90’ cable run, with zero losses at the connectors (possible with good installation techniques) and a good antenna with a 1.5:1 SWR at Channel 16, your 25W radio will only be sending out only 9.9W of power with RG8x while with LMR-400, you would be sending out 17.7W.  For your little Class B AIS transceiver, the difference is even bigger.. 0.7W for RG8x and 1.4W for LMR-400 (they transmit at only 2W) despite being 5W radios (they also monitor 2 other channels concurrently).  

Now, lest everyone go ripping out all their old COAX cables…. Remember that the little old Voyager spacecraft only has a 25W radio and it’s still communicating with us from beyond the solar system now!  Power doesn’t increase your range… but it does help you increase your signal strength to overpower background noise and other signals (and squelch settings turned too low).   In a storm with lots of lightning, you might just want that extra power someday.  

Brent Cameron

Future Amel Owner & Amel Owner Registry Moderator

Oro-Medonte, Ontario, Canada

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