It is worth the effort

Discussion in 'Mobile Radio Systems' started by N7WR, Mar 22, 2012.

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  1. N7WR

    N7WR Subscriber QRZ Page

    Some time ago, anticipating my now realized retirement, I realized that I would be spending more time traveling in my Ford F 150 truck rather than the government issued vehicle I had been assigned for years. Having enjoyed mobile HF many years ago I thought it was time to prep the F 150 for HF. I consulted K0BG's web site many times and in depth to pick up as many tips as I could. I already knew that the Kenwood Ts 480SAT would be my HF rig of choice. I already had a Yaesu Ft 8800R in the truck for 2/440. I had a collection of hamsticks as well as a Tarheel II but decided that if I could get it tuned properly an Outbacker Perth would suit my needs just fine. I picked one up used, got it tuned properly on 40 and it works great on all bands for which it was designed.

    My initial 480 installation (done right with ample size wire straight to the battery) revealed that there was a LOT of noise being generated from the truck. It was due for a tune up anyhow, so step one was to replace the "plugs" with the noise reduction version. Some improvement, but noise was still bothersome. The judicious placement of some ferrite chokes helped some but did not reduce the noise to the level desired. Fortunately early on I determined that the fuel pump was not one of the noise producers and I was pleasantly surprised by that.

    The process of bonding all metal parts to the frame with 3 inch copper strap began and with each addition of strap the situation improved. In the case of the truck bed itself I wound up using 4 copper straps, one at each corner and with each additional strap in place the noise was reduced further. The final strapping, which made an amazing difference, was to strap each muffler (it's a dual exhaust system) and each tailpipe to the frame..once on the engine side of the muffler/cat converter and once on the rear (exhaust) side.

    Proof of why it was worth the effort was obvious this morning when on 20 meters I heard a very faint but distinquishable HS station (Thailand) calling CQ. Were it not for the noise reduction efforts I would never have heard him as he was an S2 at best. Got him on the first call.

    The moral? Keep working on noise reduction using the right techniques and devices and eventually you will be successful. K0BG's page is a must read for any mobile operator.
  2. KC8QVO

    KC8QVO Ham Member QRZ Page

    The exhaust ground is the most important one I've found for noise reduction in mobile setups. The exhaust pipes are directly connected to the engine and isolated from the frame to reduce noise - vibration going down the road = rattle. At the same time the rubber hangers make the exhaust pipe a nice antenna to radiate off any RFI generated at the engine (injectors, coils, plugs, alternator, etc). When you ground/bond the exhaust pipe towards the rear of the vehicle it destroys the radiating properties of the exhaust pipe.
  3. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    One thing to keep in mind Steve, the exhaust system on most vehicles isn't congruent. That fact requires more than just one ground strap, especially if there are two cat converters.
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