Let's see your mobile radio setup

Discussion in 'Mobile Radio Systems' started by N4CYA, Jan 17, 2012.

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  1. AD5MB

    AD5MB Ham Member QRZ Page

    baja bugs have multiple limitations - small interior, puny alternator, notalotta real estate for antennas.




    that's 2 meter, chicken band, APRS top to bottom. All mode all by itself

    HF goes on the table from the Westfalia camper, on a bracket jammed into the jacking point

  2. KC8QVO

    KC8QVO Ham Member QRZ Page

    Alan, I notice that you point out problems with all of those installs in your HOS album. Ones I see you reference quite often are how close the coil is to the vehicle body, choke wraps, and grounding.

    Can you, for everyone on the forum, please explain your mobile HF installation and tell us why your install performs so much better than all the installs in your HOS photo album? In your explanation can you please address the following: antenna location and ground connection?

    As per the original thread starter's question on mobile installs I will present mine to the "firing squad" also. I have had good luck with it. It may not be the most efficient but it makes contacts and the antenna is on a VERY solid mount.

    My truck is a 2011 F350 SRW with the 6.7L diesel engine, the HF antenna is a Tarheel Model 400, and the radio is an FT-857D. My mobile antenna is either a Commet SBB-5 or a Diamond SG-7900A (which is what is on there currently).

    Here is the mount:


    This is the finished up base of the antenna and wiring. It did not come with a matching coil, so I left that off as well as the choke on the motor leads. The motor is a Pittman and makes very little noise, and the antenna/radio set up also doesn't cause RFI that I've noticed so I am not worried about it. The big doughnut is a coax choke, 5 turns. I had an antenna on another truck that this solved some RFI issues so I implemented it here, warranted or not.


    This picture is of the whole antenna, before I got the new mount fabricated:


    My VHF/UHF antenna is mounted on the drivers side hood with a lip mount (I know I will get scrutinized for that too). There is no backing plate and the screws bite through to the metal = better ground than the capacitance of the backing plate through the paint. The picture is from when I was installing it setting the angles, I don't have one with the antenna installed yet. The black/red wires there are not part of the radio install, and I'm still scratching my head what I had them hooked to?? The power wires run through a grommet in the drivers side floor board, as do the rest of the wires up in the dash panel and coax to the VHF/UHF antenna on the hood. See next picture down.



    The radio is an FT-857D. Note the panel on the dash. There was a switch panel there, Upfitter Switches (if you're familiar with the super dutys). It has 4 on/off toggles. This panel used to be a coin holder in my 2010 F250. I cut out the coin part and fitted my own switches and jacks in it. So now, instead of having just 4 on/off toggles, I have the 4 on/off toggles AND a DPDT momentary switch for my screwdriver up/down, an 8 pin modular mic jack, and a 1/8" stereo jack for a CW key (stationary use). The cup holder mount for the face plate irritates me but I haven't come up with a better way to do it yet. The mic jack on the dash works extremely well, though.

    I usually run out to lunch every day and fire up the HF, mostly 17 meters but I've been checking in to MIDCARS on 40m a lot too, if I catch them before they pack up shop for the day at 2pm eastern...

    That is it for my mobile install/operation. Ask questions or fire away.

    Throwing on the Kevlar vest,
    Steve, KC8QVO
    Last edited: Jan 22, 2012
  3. K0BG

    K0BG Ham Member QRZ Page

    Okay Steve, let's see what is wrong with yours from my perspective. What I say here should be taken as constructive criticism.

    First, the antenna is mounted low on the vehicle, without much metal mass under it. Therefore, the ground losses will be more than if it was mounted atop a bed rail for example. As a result, there will be more common mode flowing on the coax cable. I can't say how good the common mode choke is, because I don't know the material used, or the number of turns made. I do know that 7 turns of RG8X through a 3/4 inch ID, mix 31 bead will produce a choke with an impedance of ≈2,2kΩ at 10 MHz, and is mostly resistive from 1.5 MHz up.

    There is no motor lead choke in evidence. There may indeed be one, but it needs to be at the base of the antenna. It pays to remember, that any wiring before the requisite choke(s) is part of the antenna, and will radiate. If RF can get out, it can get in as well. That means more received noise. Here too, a 3/4 inch, mix 31 split bead with 13 parallel turns of #18 Nylon insulated wire, will result in a choke of ≈10kΩ at 10 MHz, and most resistive from 1.5 MHz up. That's more than enough even for the most finicky of automatic controllers.

    You brought your wiring up through the floorboard right under your feet. That might be okay, but you take the chance of damaging the wire with your feet even though you did use some split loom over it. I haven't looked at a F350, but the F250, and F150 have extra access teats on the main wiring harness grommet.

    I don't like small speakers, with tiny magnets, as they reproduce the highs much better than the lows. We all have to put up with a lot of high frequency hash. To minimize that (a DSP notwithstanding), is to use a communications speaker like those supplied with GE and Motorola two way radio equipment. They're 5 or 6 inch, and have a very heavy magnet. And, if you mount it under the driver's seat, even more of the hash will be attenuated.

    The question remains, does it work? Of course, but it could work much better.
  4. KC8QVO

    KC8QVO Ham Member QRZ Page

    Where did you address my questions?

  5. K0BG

    K0BG Ham Member QRZ Page

    I believe I did. Anything will work. I often hear a W7 on 17 meters who uses 3 foot long CB Firestick, driven with an LDG tuner through about 15 feet of RG58. The ERP can't be much more than 5 watts. Yet, I hear him work a lot of DX— the standard measurement for efficiency it would seem. The problem is, he can only do so when the band conditions are very good. So, why is mine better than his? Mainly because my window of opportunity is much longer than his. In other words, that extra few dB of ERP, and that extra few dB of noise reduction allows me to work stations he doesn't know exists. It is sort of like comparing a tribander at 50 feet, and a monobander at 100 feet.
  6. N5USR

    N5USR Ham Member QRZ Page

    I do have a mobile setup in the truck, but it isn't anything special.

    This one was a bit more "fun" though:


    A very messy, very temporary setup but amazingly it works. (Not saying it works *well*, it just works!) The ATAS even tunes on all bands.

    Awfully heavy to cart around though, and I'm not too sure how long the 857D would last bumping down the lousy roads we have here. Sometimes you can hear the relays chatter when I hit a bump! It was fun to see how it would work though...

    A few more details are here: http://n5usr.net/hamradio/hfBike.html
  7. VA3JMK

    VA3JMK Ham Member QRZ Page

    well I was having some issues with my ATAS antenna but think I have them worked out. Working now, I know it's a compromise in antenna performance but it dose work. Worked the Falkland Islands on 14.225 the other night and I sure was not the only one trying...I was have tuning issues with antenna movement (tuning that is). Rechecked all the mount screws and added another ground cable from the Body to the Mount itself.
  8. WX9DX

    WX9DX Ham Member QRZ Page

    Watch my video on you tube about my truck! Only One thing to say, WOW! Yeah it's from a cell phone LOL:) But for my first video " using a cell phone" yeah I had stage fright LOL, said Fans insted of relays. OH well LOLOL:) Oh yeah, and the lens was right under my fingers!

    Last edited: Feb 1, 2012
  9. WX9DX

    WX9DX Ham Member QRZ Page

    Ok snap shot of truck !

    A couple of the guys wanted to see a snap shot of the truck, so here it is! So catch me on MidCars OM and we'll talk " 7.258MHz"... :cool:

  10. KJ3N

    KJ3N Ham Member QRZ Page

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