Not only the shock absorption value provided, let’s not forget the savings when a looped jumper at the antenna also saves you on a direct lightning hit. I am a firm believer in a 2 to 3 foot piece of 9913, 9914 or even (dare I say this out load) LMR 400 at the antenna. Key here is a loop from the hard line to the antenna. You get that lightning hit and all you have to do is replace the jumper. Antenna saved, equipment saved. Now granted my experience has been with Mastr II's and I don't know how well the new microprocessor radio's will survive but as an old timer that’s my 2 cents, for what its worth. Good Luck -Richard
________________________________ From: MCH <[email protected]> To: [email protected] Sent: Sunday, September 13, 2009 4:07:34 PM Subject: Re: [Repeater-Builder] Re: coax cable Key word... --->jumpers< --- You didn't have the feedline connected directly to the antenna. Although I have to question the logic in using 1/2" that isn't Superflex for a jumper for the same reasons. Standard hardline doesn't have much absorbing properties compared to Superflex or coax, and please don't tell me it was used to reduce the loss. With a couple feed of coax, the loss doesn't get significant until around 5-10 GHz, if that low. Joe M. Joe wrote: > We had thousands of 1/2" hardline jumpers connected to antennas at my > last job. It was the standard to use 1/2" LDF4-50A for the jumper. > > Joe > > > MCH wrote: >> To reduce vibrations from the antenna being conducted to the feedline. >> As it's not flexible, it will crack and/or break. I've also seen cases >> where the antenna connector was vibrated right out of the antenna. >> >> Adding the flexible jumper acts as a 'shock absorber' and absorbs any >> vibrations. >> >> That's why they include jumpers with commercial antennas. >> >> Joe M. >> >> Joe wrote: >> >>> OK, why? I've had this argument before...... Joe >>> >>> MCH wrote: >>> >>>> Hardline/Heliax should *never* be connected directly to an antenna. >>>> ALWAYS use a jumper. >>>> >>>> Joe M. >>>> >>>> >>> ------------ --------- --------- ------ >>> >>> >>> >>> Yahoo! Groups Links >>> >>> >>> >>> >>> ------------ --------- --------- --------- --------- --------- - >>> >>> >>> Internal Virus Database is out of date. >>> Checked by AVG - www.avg.com >>> Version: 8.5.387 / Virus Database: 270.13.38/2274 - Release Date: 07/31/09 >>> 05:58:00 >>> >>> >> >> ------------ --------- --------- ------ >> >> >> >> Yahoo! Groups Links >> >> >> >> >> > > > > ------------ --------- --------- ------ > > > > Yahoo! Groups Links > > > > > ------------ --------- --------- --------- --------- --------- - > > > Internal Virus Database is out of date. > Checked by AVG - www.avg.com > Version: 8.5.387 / Virus Database: 270.13.38/2274 - Release Date: 07/31/09 > 05:58:00 >
