Jim, Thanks for the suggestions on reducing noise. I can put common mode chokes (at least I think I can) on my DC wiring but I cannot effectively put in twisted pair unless I take out what exists now and replace it with twisted pair. Therefore, hoping not to have to do that I ask the following question.
Question: How much difference will the twisted pair have in reducing noise versus having common mode chokes only? Currently with my Icom 706 the noise due to ignition and other sources is pretty high but the noise blanker does real good and getting it down to acceptable levels though not dead quiet as the case if the engine is off. I have a 2004 Chevy HD2500 (3/4 ton) crew cab pickup truck. The Hi-Q antenna is mounted on the rear (driver's side) on top of the side panel with my own custom made mount. I have ground straps at a number of locations and ground for the Hi-Q is very good (bolted to the frame itself after cleaning the frame for good contacts. The frame is also grounded to the under side of the body where I have cleaned off attach points to achieve good ground contact. 73, phil, K7PEH On Jan 12, 2014, at 10:57 AM, Jim Brown <j...@audiosystemsgroup.com> wrote: > On 1/12/2014 10:26 AM, Matt Zilmer wrote: >> Wiring to the >> KXPA100 is 8 AWG, with two "transfers" to APPs at a relay enclosure >> for power control in the trunk. The source is the Civic's battery. >> The KXPA is located in the trunk. > > Several thoughts about this. First, noise pickup on the power wiring will be > greatly reduced by making it twisted pair. Second, unless the SWR is REALLY > high, much less power will be lost in coax than in the DC wiring. Third, ALL > of this wiring should have common mode chokes on it to further minimize noise > pickup and RFI. > > My strategy would be to locate the amp based on convenience, on making the DC > cable shorter, and on the practicality of paths for routing the needed wiring. > > I would use the best quality coax I could fit into the available wiring > routes. This is an application for the best quality transmitting coax with a > heavy copper braid shield. Remember that the shielding provided by coax > depends upon a shield that has very low resistance and very good uniformity. > Belden 9258 would be a great choice -- it's a RG8X form factor (0.242-in > o.d.), with #16 stranded copper center and a 95% copper braid shield. > > Finally, there is probably little benefit to bonding the radio or the amp to > the frame of the vehicle. Thanks to the excessive application of paint and > the use of lots of non-metallic parts, chassis bonding of modern vehicles is > flaky at best, and a train wreck at worst (it is in my 2006 Toyota big SUV). > Indeed, one of the major challenges in a modern vehicle is finding enough > conductive structure to form a counterpoise for an HF antenna. > > 73, Jim K9YC > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
