Breedlove front bed bracket RF grounding

Discussion in 'Mobile Radio Systems' started by KB7FSC, Jul 21, 2018.

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  1. KB7FSC

    KB7FSC XML Subscriber QRZ Page

    Sorry if this has been asked before, but I didn’t turn anything up specifically on grounding a Breedlove front bed bracket. I am looking to add this clamp style front bed bracket (not the stake pocket mount) to the front of the box on my 2016 Ram for a HF setup. It is designed to clamp to the front bed rail without needing any holes drilled, thus no direct electrical connection to the bed because of the clamping action over the paint. The website describes the fact that the mount has a grounding screw. My understanding is that braided strap between the Breedlove mount and the pickup bed isn’t the best practice nor a substitution for an RF ground plane. Am I correct in this understanding? Would I be better to add some holes in the bracket and use some star washers & screws between the bracket and my bed for improved grounding so that the mount actually contacts the metal of the bed? Or, should I use a very short section of 1 inch braid between the bracket and the box? Or something else?

    Thanks for any good advice here!

    Wane - KB7FSC
     
  2. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    You are correct. The only issue about the mount is the fact it can lessen over time. Just check it once in a while, to make sure it isn't loose.

    I don't know what antenna you're planning to use with the mount, but anything much more than a hamstick is too heavy.
     
  3. KB7FSC

    KB7FSC XML Subscriber QRZ Page

    Good morning Alan and thanks for the advice. I will keep an eye on the mount. I am planning on using Hamsticks to start with because I already have a set of them.

    However, I was giving some consideration of maybe purchasing a Tarheel M40a or M75a to put on the mount at some point. To this end, I purchased a Breedlove 1 1/2 inch pedestal mount with 3/8 - 24 top thread so I can mount my Hamsticks or a smaller Tarheel. My thought here was that the spacing of the front bed bracket will keep the extended coil of either model Tarheel just above the roof to minimize coupling to the metal on the roof, but still give me clearance to park in my garage if I take off the top whip. This should also minimize the amount of aero push on the Tarheel antenna because only the top portion of the coil and whip will be above the cab, and the larger diameter mast on bottom of the coil will be shrouded by the cab.

    Would you offer any advice on the diameter of star washer/ screw to use to get a better connection to my bed? Would I be better off with a single, large diameter connection, or two smaller diameter connections? Also, my understanding is to stay away from a 1 inch ground strap if I screw the bracket to my bed to avoid any possible ground loops. Is this sound thinking?

    I am planning on bonding my bed, hood, exhaust and doors as outlined on your website as well. Thanks for your advice and all the information on your website!

    Wane - KB7FSC
     
  4. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    Star washers are what the are, and if they fit, use them.

    I like the ones with cleats both inside and outside, but sometimes they're just too big for the job.
     
  5. KB7FSC

    KB7FSC XML Subscriber QRZ Page

    Thanks again Alan. I acquired the requisite hardware that I needed this weekend and will be starting on my installation when time allows. With harvest around the corner, my installation might be a bit delayed, but I will report back here with my outcomes. 73,

    Wane - KB7FSC
     
  6. KB7FSC

    KB7FSC XML Subscriber QRZ Page

    Here is the update on my first version of HF mobile operation. All suggestions are welcome as I'm still learning.

    All together, I've spent about 2 days over the past 2 weekends with this installation project on my 2016 Ram. I'm not convinced I'm done yet, and there is likely to be some renditions. My criteria for the install was mobile HF operation with 20, 40 and 75M to start with. I also wanted to be able to leave the tonneau cover on my pickup fully functional. The style of tonneau cover I have covers the stake pockets, so that mounting option was out. It left me with a ball mount through the cab (not quite willing to go there yet), a mag mount on the roof, a receiver hitch mount or Breedlove bed clamp mount. I opted for the latter, understanding it is all a compromise.

    I spent the better part of a day running power, mounting the control head for my TS 480 and main body, installing the antenna mount, and running the coax. Upon initial installation, the radio was deaf, and my MFJ 259c antenna analyzer showed major problems. After further inspection, I found that the Breedlove SO-239 connector was shorted to ground. I had a MFJ gum-drop mount, and I substituted that while I wait for a new SO-239 connector from Breedlove (great to deal with by the way).

    I currently have 10 bonding straps installed between the various components and the frame: 2 on the exhaust; 1 on the engine; 1 on the hood; 2 on the box; 2 on the cab; and 2 between the antenna bracket & box. All of the straps except for one are 1" straps and they are all less than 10 inches. I suspect I will probably do more bonding. I started with a S9 ignition noise level and now have about an S6 noise. Thank goodness for the NB in the TS-480! AS for the RF choke on the feedline, I did not have any 3/4 inch clamp on ferrites, so I used two 1/2 inch ferrites. I have six loops of RG-8X, but I can only run 3 loops through each ferrite. I ran the first three loops through the first ferrite and the last three loops through the second ferrite.

    This is what I see for antenna analyzer readings on 20M using an MFJ 259C. Resonance is 14.784 - 3.2 SWR - R=21 - X=0. Lowest SWR is 14.321 - SWR 1.6 - R=45 - X=23. My TS 480 SAT believes the SWR is a little lower across the 20M phone band, and has no problem tuning from 14.000 to 14.350

    40 M is acting very strange. The MFJ analyzer is claiming resonance from 6.800 to 7.150. Making contacts on 40M has not been very fruitful. I'm suspecting a bad hamstick?

    This is what I'm seeing for 75M. I'm a little puzzled on these values. Any insight would be appreciated here. I see resonance at 3.817 - SWR 6.1 - R=29 - X=0. X stays at 0 from 3.817 to 3.856 while showing decreasing R. At 3.856, I see 3.0 SWR - R=17 - X=0. My kenwood shows lowest SWR around 3.860, and with the internal tuner allows me to work down to 3.820 up to 3.925. I'm not sure why my analyzer shows X=0 across 40KC. Seems strange, and with what I'm seeing on 40 M, makes me question my analyzer. BTW, I purchased the analyzer new in July of this year.

    I'm considering winding a matching coil for the base to bring up impedance a bit, but I might wait on that.

    As far as interference issues, I've had a few instances where transmitting on 20M has upset my front ultrasonic parking sensors on the front bumper while transmitting at 100 watts. Experimenting yesterday, I could also cause problems with the infotainment system and make it restart while transmitting a solid carrier at around 70 watts. My first thoughts here is to re-do my RF choke with 3/4 ferrites, and use two for increased impedance.

    Here are my overall impressions. It has been an interesting project, and I'm sure I will continue to revise. One big drawback is that I'm crawling in and out of the bed when I want to park my pickup in the garage. I'm going to try a spring at the base and see if I can tether the antenna back for easier parking. I've been pretty impressed with the results on 20M this week, and have had poor results with 40M and limited usage on 75M. K0BG's website has been a big help, although I admit I haven't followed all his advice to the letter.

    As far as version 2.0, I'm already pondering a tarheel M75a, primarily for better performance on 40 and 75M. I have a breedlove pedestal mount to put on top of the bed rail clamp, and would love to hear from anyone who is running a screwdriver on top of this type of mounting system.

    Any and all advice is welcomed for this newbie mobile operator.

    Pictures will be in a future post as soon as I figure out how to do that! :)

    Wane - KB7FSC
     
  7. KB7FSC

    KB7FSC XML Subscriber QRZ Page

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    2016 Ram
    Kenwood TS-480 SAT
    Breedlove Front Bed Clamp Mount
    MFJ Hamsticks
    Version 1.0


    Wane - KB7FSC
     
  8. KB4QAA

    KB4QAA XML Subscriber QRZ Page

    Which is exactly what we would expect for 40m and 80m hamstick antennas. They are very short electrically, with very lossy small loading coils, and have single digit efficiencies, probably approaching 1% or less.

    A Tarheel type antenna will have better results due to 1. Larger size 2. More efficient, larger, loading coils.
     

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