<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
[quote]Originally posted by Dick Renaud:
You are attempting to keep the resistance of the cable balanced with the radio and antenna to get maximume power transfer. </div></BLOCKQUOTE>
I hear two possible things here (and I may be way off so bear with me, please):
1. More length = more impedance which = less transmit power?
You are close, but impedance should remain constant at 50 ohms. Length = resistance which = heat which = power loss. the more lenth the more loss and at about 4 watts or less output power at best (the 5 watts is input power) you need all you can retain. Also, there is some increase in recieve (mostly in noise reduction) with shorter coax.
I had a choice between Firestik and Wilson. The shop owner was very high (to say the least) on Wilson so based on his recommendation and my desire for a flex unit, I bought the
Wilson Silver Load Flex 4 . Any thoughts on that?
Wilson is a good antenna, but generally longer and more difficult to tune. If the additional length is not a problem its fine. I should mention that a flexable antenna changes radiation pattern as it sways back and forth or lays back at high speed. The Firestick is ridgid and holds it pattern better. I would use a spring with a firestick to take minor hits better, but as mentioned earlier, a ridgid antenna on the trail may be damaged. The only antenna that will take the trail is a short rubber antenna and you loose distance with that. A comprimise that we used to use on police vehicles is a Larsen with an NMO mount mounted into the roof with a backer plate. The Larsen is very flexable and with a solid mount will take a lot of abuse as long as it is not hit to close to the base.
You mentioned the antenna can be retuned when something new is added to the roof ...
When I'm headed off-road, I mount quite a bit of metal recovery gear on the roof rack. Will that effect the tune? If yes, given that I'll most often use the radio when off-road, would you advise I tune with the gear on?
Absolutely tune with everything on that you will normally run with. Anything in proximity to the antenna can de-tune it. One addition though, the rack etc should be grounded to the roof with braid. The regular mounts are not a very good ground. Also, any loose body metal ( hood, lift gate etc) should be Bonded (grounded) with braid. Again, refer to Alans web site referenced in my earlier post.