20m mobile?

Discussion in 'Mobile Radio Systems' started by AK4PX, Jul 29, 2014.

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  1. K0BG

    K0BG Ham Member QRZ Page

    Justify it anyway you want. Watch the photos and movies with or without dummies present, or whatever makes you feel warm and fuzzy. But... If you're ever involved in an accident where both airbags explode, you'll find out the hard way why you don't mount radios or remote heads atop the dash. This goes for those suction cup mounts holding cellphone and GPS units as well.
     
  2. KK4YDR

    KK4YDR Ham Member QRZ Page

    It may not be what you are looking for but I get absolutely beautiful contacts on 20 meters with my Yaesu ATAS-120A so maybe a screwdriver of some sorts. Yes its lossy but my QSOs and all the contacts I have made with it show proof other than what all the naysayers say.
     
  3. KK4YDR

    KK4YDR Ham Member QRZ Page

    I have my head of my 857D mounted to the floor on one of those snake arm mounts. It is about as high as my knee. No chance it will get smashed into my face from airbag. Good point you make.
     
  4. M3KXZ

    M3KXZ Ham Member QRZ Page

    That could actually seriously damage your knee in an accident.
     
  5. KK4YDR

    KK4YDR Ham Member QRZ Page

    Better my knee than my face. There is just not anywhere safe to do anything in a car that the manufacturer didn't spend millions on engineering and crash testing. For that matter the clothes you are wearing could kill you in a wreck because they were not crash tested and made to engineering standards.
     
  6. M3KXZ

    M3KXZ Ham Member QRZ Page

    True. And things in pockets. I often end up driving with screwdrivers, secateurs and all sorts in a pocket and at some point have that "what if?" thought!
     
  7. K0BG

    K0BG Ham Member QRZ Page

    I have a file I called Installed Database. It contains almost 3,000 photos, and takes up just over 1.3 GB. About 700 of these are posted in my photo gallery, representing about 350 installations. The reason the vast majority are not in the gallery is simply the fact most are life threatening. I have one which depicts an Icom IC-706 mounted atop the driver's airbag! While this is an obvious faux pas, others aren't so obvious, but all apparently have been justified in the owner's mind. Seemingly, the owners must think they'll never be involved in an accident, but statistically (in the US), one in seven drivers will be within their lifetime.

    In the last two years, the number of accidents per 1,000,000 has increased almost 6%. Most of this is caused by cellphone use, with texting leading the charge as it were. The key word here is—distraction. Mobile operators often use this (distraction scenario) as justification of mounting their gear in the manner they do.

    As I said before, justify your installation anyway you wish. But... Please remember, you're not the only one on the street. Remember too, what happens to you is immaterial—what happens to them, is!
     
  8. K3DAK

    K3DAK Ham Member QRZ Page

    I use 20m while mobile, and while the hamstick or MFJ1720 HamTenna isn't ideal, it does receive and transmit a bit better than my 9ft whip into an AH4. I have an original hamstick for 10m, and the mfj 1720 looks almost identical, so take that for what it's worth. Keep in mind that the hamtenna is a tuned monoband, and the system bandwidth depends on your installation I get about 50khz of bandwidth w/o a tuner. They're not short by any stretch of the imagination, so any parking garages are off-limits.

    It's certainly better than no antenna.
     
  9. KH6AQ

    KH6AQ Ham Member QRZ Page

    KC2LZO can you give us more data on your MFJ-1720 20 meter VSWR? What is the minimum VSWR and what is the VSWR at the edges of the 50 kHz bandwidth?
     
  10. K0BG

    K0BG Ham Member QRZ Page

    One thing to keep in mind is that bandwidth doesn't mean much. As a comparison data point, it doesn't mean the coil Q is higher; It doesn't mean the ground losses are higher or lower; it doesn't mean the antenna is more efficient; it doesn't mean it is less efficient either. All of the losses in an antenna system are in series with one another. Change one, and you affect them all including the bandwidth at any specific measurement point. Thoughts to the contrary notwithstanding.
     
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