It really doesn't matter which mode you are using (fm, code, ssb). The frequency is what matters for loss. The higher the frequency the more the loss matters. If you were doing 80 meters then you can use a piece of string for coax. On microwave you better not have any loss. VHF is Very High Frequency and Marine is above 2 meter so loss is important. At 100 feetish of coax if you use something with high loss you are going to see a big drop in your receive and how good your transmit is. Get good low loss cable trust me. Even though it's more important for a repeater try not to use LMR 400. Much too big for a mast anyway but anything like it has issues as well. The foil tends to causes some issues with noise on the radio.
Vern -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jim Sent: Sunday, November 22, 2009 5:32 PM To: [email protected] Subject: Re: [Liveaboard] FW: VHF ant Flying Pig wrote: > Hi, Ron, yours below for reference, > Just starting to look around, and I see that I can get 9913 (looks to > be a huge cable - .405??) for $.79 plus $10 for pro installed > connectors > (http://www.theantennafarm.com/catalog/index.php?main_page=product_info&prod ucts_id=1473 > <http://www.theantennafarm.com/catalog/index.php?main_page=product_info&prod ucts_id=1473>), > of which, of course, I could only use one, as I'd have to get one end > or the other through the smaller hole in the top of the mast - which, > if it really IS that big, I'd have to enlarge, which might be a bit of > a challenge with the existing cable already in it! > So, at a nominal 70-80' (my 80' cat5 is considerably more than I > need), I'm in for new cable at a pretty low cost ($70 for 75' with one > connector installed). Sounds more attractive than chasing ghosts > especially as I rather enjoy being up the mast. > So, suggestions for specific cable to use (as, milspec? or something > else)? Presumably, given the cable sizes being different, each would > have different connectors required, too, no? > L8R > Skip > Morgan 461 #2 > SV Flying Pig KI4MPC > See our galleries at www.justpickone.org/skip/gallery > <http://www.justpickone.org/skip/gallery> ! > Follow us at http://groups.yahoo.com/group/TheFlyingPigLog > and/or http://groups.google.com/group/flyingpiglog > "You are never given a wish without also being given the power to > make it come true. You may have to work for it however." > (and) > "There is no such thing as a problem without a gift for you in > its hand > (Richard Bach) > > ----- Original Message ----- > *From:* Ron Rogers <mailto:[email protected]> > *To:* [email protected] > <mailto:[email protected]> > *Sent:* Saturday, November 21, 2009 9:56 PM > *Subject:* Re: [Liveaboard] FW: VHF ant > > *Hopefully, someone else can remind us, but the Metz (excellent > choice) may have "a designed dead short to ground" in this case > the mast. That's what a tech told me. The SWR for my Metz, atop a > 52' mast with no intervening break in mil spec RG8U was 1:1 > occasioning that tech's remark. Good is anywhere between 1.5:1 and > 1:1. In *theory* coax that old isn't any good anymore. The default > for most installs these days is tinned RG8X. Some advocate a newer > cable: RG213 which is supposedly lower loss. My personal opinion > is that a tinned shield is more important than type. Soldered > terminations should be used. At the masthead, I used silicone, > shrink tubing, and a self-sticking silicone tape. Nothing got > through in 6 years. Today, I'd use black shrink tubing lined with > adhesive and protected with rigging wrap as a sun shield.* > > * * > > *I had an outstanding signal surpassing all other boats. Part of > that was delivering maximum voltage to the VHF. Some brands are > much more tolerant of low voltage than others. Icom is good in > that respect. "Practical Sailor" has periodic reviews of VHFs and > is worth checking as sometimes there are surprises.* > > * * > > *Good luck and keep us posted,* > > *Ron* > > * * > Hi, Skip, I agree with Ron. I highly recommend staying with the RG-8X, marine. While there is less loss with 213 or the mil spec 9913, you won't lose enough signal to matter. Working with the larger coax is a royal pain. If you were doing small signal work on something other than FM it might pay to use the better coax, however on FM you probably will never see any advantage. I suspect finding marine 213 might be difficult and really expensive. You wouldn't want to run non marine grade coax outside in any event. Jim. _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [email protected] To unsubscribe send an email to [email protected] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [email protected] To unsubscribe send an email to [email protected] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
