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## Re: [TowerTalk] cutting phasing lines

 To: "Tower and HF antenna construction topics." Re: [TowerTalk] cutting phasing lines "Jack/W6NF" "Tower and HF antenna construction topics." Sun, 11 Apr 2010 16:34:20 -0700 mailto:towertalk@contesting.com>
 ```I also double-checked the coax after doing the calculations suggested by Jim Lux...they checked nicely. I'd forgotten about that...thanks for reminding me... On Sun, Apr 11, 2010 at 4:29 PM, jimlux wrote: > vk3pa@vk3pa.com wrote: > > Gdy all, my Q is I need to cut phasing lines for 7.050 Mhz of 84 > > degrees es 71 degrees! ok So far, now 360 degrees = 1 wave length, so > > 0.5 wavelrngth (=180 degrees) would be 468/freq /vf es / by 180 would > > be 1 degree so x by required degrees eg 84 es 71 ok ! so now how do > > I convert 84 es 71 degrees to a frequency so I can cut the lines WITH > > my antenna bridge rx vector analyst autek VA1?? OR AM i WAY OFF IN MY > > THINKING!! 73 es tnx Al vk3pa > > > > > I tend to use metric for this, since 3E8 m/s is a nice round number. > > 7.050 MHz = 42.553 meters > 84/360 * 42.553 = 9.93 m > 71/360 * 42.553 = 8.39 m > > Multiply those lengths by the velocity factor of your coax (e.g. .80 or > whatever) > > But, to cut it with your antenna analyzer... > > Say you want it to be 74 degrees at 7.050 but 90 degrees (e.g. it looks > like a short) at the test frequency. That means your test frequency > needs to be higher (e.g. more degrees for the same physical length).. > > 7.050 * 90/74 = 8.574 MHz... That is, a piece of coax that is 90 degrees > at 8.574 MHz will be 74 degrees at 7.050. > > > So, if you've got 80% VF, cut that coax to around 6.7 meters (80% of > 8.39m).. hook up the analyzer, and start trimming til it reads shorted > at 8.574. > > > _______________________________________________ > > > > _______________________________________________ > TowerTalk mailing list > TowerTalk@contesting.com > http://lists.contesting.com/mailman/listinfo/towertalk > -- Jack, W6NF Silver Springs, NV DM09ji _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
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