This is not looking good.

http://www.coshoctontribune.com/article/20100428/NEWS01/4280306

I'm amazed its taken this long for something like this to happen.

Sometimes there is far too much drama on vhf/uhf repeaters.  If you listen to Dstar for a while you'll hear a mix of "USA local repeater style banter" and the rest of of world; its fascinating to listen to the contrast....I wonder what the rest of the world is thinking.

Well, you've got to admit that the guy built the car.  If an individual can do it why can't a large team of auto engineers?  Where there's a will there's a way and if there is no will, there are excuses.

I think Buffet's investment in the China electric car product will drive (pardon the pun) competition world wide.  Till then we can put our radios in 12v electric system cars and we won't have to worry about the 48v or 100v rigs of the future.

Alan,

I've got an edition of the Mobile Manual with the VE2CV calculations; mine is the 1960 one.  I've not looked at my older one to see when his work was first put into the Mobile Manual series.  

I'm a little lazy but a good exercise would be to put those formula in Excel.....on my bucket list.

The QEX article references Jack's work.  Evidently in 1998 Jack used NEC to do some further predictions which the author (of the QEX article) attempts to verify empirically.  

The prediction was that shortened radials (less than 1/4wave) produce a more efficient ground than 1/4 wave ones.  The author shows that this theory holds for small number of radials (I'm giving away part of the conclusion).

These mobile installs in some ways are a sub optimal ground mounted vertical.  Sub optimal in that there is usually insufficient control of the ground effects thus some installs are more effective than others.  For the case of few radials, N6LF and VE2CV (Jack) found a 3.5db change from radial length shortening of 4 radials.  That's big.  

Though impossible to do such a controlled experiment w/mobile installs, the variance is likely there in the same magnitude. The mechanism for the swing was the resonant effects of the small number of radials.

When I lowered my feed point, I had a length of 3/4" mast made to raise the coil back up at the original level.  

The inductance required to cancel the capacitance of the mast is a little greater as the coil is at a different location on the mast (further up).  The location to shoot for is mid-way but for me its more important to keep it well above the top of my SUV so as to preserve the Q.

I personally like the coil to be a bit higher on the mast as there are fewer shorted turns required to resonate the antenna.

Alan,
Lowering the feed point of the antenna to gain radiator length will move two variables.  The feedpoint impedance should increase due to the added radiator length and some additional ground losses will appear due to the closer proximity to the pavement.

A brute force way to isolate the two when making the change and measuring it is to.....don't laugh....roll the car up on some racks after you lower the feedpoint and look for a change in the impedance.  Honestly, you can see it with a good analyzer, honestly.

All you need are four racks from the auto supply store.  The kind used to allow for changeing your own oil.  Although these days, what are you going to do with the dirty oil??  I digress.

Alan's reply to yet another mounting query got my attention.  He discussed the radiator length vs. efficiency,  vs. feed point location's capacitance/ground lose effect vs. efficiency (wrap your mind around that).

http://www.eham.net/forums/MobileHam/14415

A very subtle balance.  

Now with antenna analyzers so affordable a good experimenter can lower the mount a couple of inches at a time, raise/lengthen the radiator to the legal limit and look at the trade off rather accurately.  I did that myself when I got rid of a 10"+ foldover and replaced it with a horizontal mount (no "L").  But alas, I'm not a good experimenter so I didn't write an article.  

Indeed I got a little higher feed impedance with the 10"+ pickup in radiator length (40mtr).  To me, this indicated a tradeoff that was positive. Anyway....back to the topic point.

Alan's reply made me re-read the article in QEX Jan/Feb by Rudy Severns, N6LF.  It is a two part article with both parts in the same issue, go figure.  Part II was a tedious analysis of the ground current changes in a ground mounted vertical with the cutting of radials from resonance to shorter than a 1/4 wave.  He analyzed the case of no radials (a baseline of sorts), 4, 8, 16, etc.

You say you've done that?  Not like Rudy did.  Very interesting article.  Not that it is totally applicable to mobile aficionados but, it was close and it was analytical and it was a good read; twice.

Good read, good job Rudy.

Humm... I was just that it is the ID 800 that will be replaced.  So much for rumors.

Does anyone have any info on the rumored replacement for the IC 2820 that is supposed to be shown/announced at Dayton this year?

Thanks but I found him. Sadely he was in the death list that was recently posted on the web by the county.  He passed away in the late 80's.

I read the article after you posted this topic.  Great job.  Also, note the review just posted...

http://www.eham.net/reviews/detail/8055

Looks like MFJ is going to get some business.  

I run a balanced feed antenna and used a section of open wire feedline with two bulbs shunted along a 12" portion as a balance indicator. (old QST article idea).  I've been satisfied with it to show me "balance".

I think a more metered approach would be fun so, I'm looking at a build/buy decision on a balanced rf meter that is calibrated.  Why don't you do a review for QST of available units?  Sounds like you'd be the perfect author for the job.

Thanks for your article.

My first tower was a 30 foot pole.

Mount it along side your house so you can climb on the roof from a ladder to get to the pole.  Put two very large eye bolts through the plole (you can get them from the power company scrap too) that have eyes big enough to run a 10 foot section of conduit through..this will be your mast.  You can tighten them to draw the mast tight to the pole to hold it up.  You can loosen the bolts and slide the conduit down to where you can put on antennas from your roof top position, then push it up and tighten down the eye bolts.  I put a lag screw under the end of the conduit to keep it from sliding down and to "lock" it.

It supported a cubical quad and an inverted Vee for me for many years.  I'd say the quad was up over 30'.  You'll be the envy of your peers.

Your parents will grow to like it too.  Mine was at my folks house so I always left a rig there to work with when I visited...for years.  I visited a lot more than I would if I'd only had a tv to watch while I was there.

Go for it.

http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=17338

I've got one of these J-poles for 2m, one for 440, and one for 220.  Its hard to find a better antenna for the money and after a few months in the weather they look great.

Best way to mount it is to solder a copper male pipe thread on the end; that makes it sort of universal with lots of ways to mount, pvc, pipe stand, etc.

"He also said 95" which is a far cry from the 50" or so that is a 2m 5/8ths wave...."

You are probably right.  Point is, when you get beyond 5/8 verticals and want a lot of metal in the air, you might as well start thinking J-poles.  Like you said earlier, the radiation pattern becomes somewhat bizarre when you build verticals longer than 5/8 waves.

I generally stay out of the VHF debates since the density of repeaters makes propagation a mute point but, opinions are like noses; everyone has one and here's mine.

Could be that KD4PDQ meant to say 5/8 wave?

I had a 5/8 wave dB Products 2mtr antenna in '87 on my Jeep Cherokee and would say it was my best 2mtr mobile antenna experience; kept the car 10 yrs+.  

I used to frequently make the trip from Dallas to LA. In that period, there was a network of linked repeaters called the ZIA Network.  It was all across NM, AZ, CA, etc.

I could generally hit the first linked repeater around Abilene and from then on it was like an intercomm all the way to LA with chats with stations on the west coast all the way.  I know the network is gone now.

I still head that way several times a year but now I go north out of ABQ through Utah, Idaho, etc.  I have a lot of observations on distance operation because of this roaming bug I've got.

I now have a dual band Larsen mounted in virtually the same place and find limited range noticable compared to the 5/8's wave.

If you want to use as much of the whip as possible, build you a 5/8 wave.  Be prepared to match it though.

dB Products was bought by Andrew and I don't think they make the mobile 140 to 160 mhz antennas anymore.  Still got mine.