HF mobile antenna

[Radio75]

Anyone here have any experience with the MFJ 1624 mobile antenna?
I am looking for something to put on my van when I am traveling but don't want to spend the money for a nice screwdriver type antenna, and besides that, this antenna will be on the top of the van where I already have a 3/8 24 mount.
(yes, very heavy duty mount)
I already have a 10 meter antenna, so it's either the 1624 or something like the HF Stick single band antennas they sell. I for sure want to work 10,12, and 20 meters, and probably want to at least try 40.
I have read however, that those stick antennas are not very good?
Thoughts?

op:

 

[n8fgb]

http://www.eham.net/reviews/detail/2448
Does not look very good here.
Rich

 

[BJ radionut]

Mobile HF Antennas

R75: Welcome to the world of HF mobile...
When it come to HF mobile antennas...they are like A** Holes everyone has an excellent opinion.
I have run them all since I've had my call....HamSticks/Hustlers/Screwdivers/Homebrew...etc...
I always come back to HUSTLERS and a custom built wand.
You can run a band at a time or 2 or 3 with adapter plates. I prefer a couple on my truck...one for each band...normally 10m and 75m right now. I have loads for every band and in the case of 75m/ I have 2 or 3 (tuned for different sections)]

Screwdrivers are convenience antennas....can work very well/some better than others...but one does it all....but mounting can be the biggest issue and good control over tuning

Hamsticks...cheap/work OK/if set-up correctly with good grounding and mounts...but not for the long hall.

OPEK...makes some great mono-band antennas/shorten profiles/common mounts...but low power 100w or less....I've melted several(stories there)

Though I have seen op's with HF antennas mounted on roof top vans, it takes a little work and experience to get them to transmit effectively...

I still can make a Hustler Super 75m(or 10m) out do most of the above at the same power level... and at about 1/2 the cost(or less) of some premium screwdriver models....though I used a ATAS-120A Yaesu and it was very good...but no 75m due to it's small profile...

Biggest thing with good producing 75/40/20m mobile antennas you have got to be willing to forget cosmetics and think getting the antenna to radiate...and on those bands, just because you have a low SWR...it don't mean squat! op:IMHO
All the Best
BJ

 

[Moleculo]

I'm with BJ. If you want something inexpensive that will work pretty good, try the Hustlers.

 

[Radio75]

Thanks everyone for the replies.
BJ & Moleculo, I had Hustler stuff years ago, 10M and 75M resonators I think, but not the high power versions and I remember them working OK.
My problem is that I think they would be too tall to mount on the top of the van, and I don't want to cut any more holes in the thing.
I mean, my boss said he didn't care if I put a ham antenna on it, but I have two now, and think three would be pushing it.

Since I recently purchased an MFJ-269 I think I will try the MFJ mini bug catcher. It will clear all the overpasses easily enough, and with that big coil, ought to be fairly efficient. I have plans on adding an amp, and buying so many separate resonators, or stick antennas can rapidly add up to more than the MFJ
I think that's the route I will go. I was going to just make a coil and try and make my own, but buying all the parts was nearly 3/4 the cost of the MFJ anyway. Later on, I might make a higher power version, just to investigate the potential.
I love playing with antennas!

Thanks again gents!

 

[W5LZ]

With HF mobile antennas, the bigger and uglier they are, the better. None of the lower HF band antennas are very efficient, but that's not as terrible as it sounds. The larger that loading coil (to some extent) the shorter the thing can be, but there are limits to that "shorter" thingy.
Something like a 'bugcatcher' as long as you can live with tends to do just fine. If that loading coil is made from something like #12 wire, and each turn of the coil is something like 1/8" separation, it ought'a handle any power you want to feed it.
Matching the thing can get sort of 'touchy'. A tapped inductive matching coil at the base is the easiest method of doing that. Not the only way, but probably the easiest (at least for me).
Lot's of option in all that, do it how you think best for you.
- 'Doc

 

[Moleculo]

Make sure and show us some pictures of whatever you decide to do.

 

[Radio75]

Pictures you say? OK, will do. I am seriously thinking of homebrewing something like the Hot Rodz that DX Engineering sells
Hot Rodz Capacity Hat Hustler Antennas Top Hat
on top of the MFJ mini bug catcher. It's food for thought, but will have to wait for some warmer weather. Well, it's going to be 39 degrees this weekend they are saying, but I'm talking another 30 degrees above that before I want to spend hours outside experimenting with antennas. When I get the initial antenna setup done I'll snap a couple of photos for you guys.

 

[Radio75]

So I got the antenna mounted and tuned, (even with the somewhat cryptic instructions) for a couple of bands.
I haven't had much time to fool with it, but found the resonant point for 40 and 10 meters.

It comes with an expandable whip for the "stinger", very reminiscent of the old car aerials of yesteryear,
but I decided to just mount my 5/8 wave 2 meter antenna for a little more tree limb forgiveness, and that's the black coil
you see in the picture.

The antenna mount, or "puck" is one of the most heavy duty-built-like-a-brick-outhouse yet sexy as hell pucks I have ever seen.
Built right here in the USA by an ex Marine. Go visit Gunny's website for more info.

And yes, that is snow in the background. That helps explain why I have only got the thing resonant on two bands so far.

Stay tuned.....


The antenna comes with the single "wander lead" but I'm going to make it a multiple, but not until I get the materials
to make my own capacitance hat. I have ordered a 4" long by 2" diameter aluminum rod, and plan on getting the materials
and getting it built and hopefully installed by the end of this weekend.
(I am shamelessly copying DX Engineering's capacity hat for this project)

Here's a different perspective of the antenna with my little 2M 5/8's wave installed on top.

Next update, hopefully in less than a week. . . .

 

[W5LZ]

Just for grins, if/when you mount that 'cap-hat', put it a couple of inches above the top of that smaller coil. The closer to the coil, the less effective that 'cap-hat' is.
Also just for grins, using a capacitive hat that doesn't have any 'sharp points', is more of a 'loop' looking thingy, make it more efficient. The ones with 'sharp points' tend to cause corona discharge at higher power levels. You'll probably never run into that, but the effect is present. Don't misunderstand, the 'pointy' cap-hats' do work, the 'rounded' ones just work better.
There are all kinds of 'tricks' with loaded HF antennas, the above is just one of them...
- 'Doc

 

[Radio75]

Great points Doc, I completely forgot to mention that I have ordered a Hustler MO-4 22" stainless shaft, so I will mount that on the coil, and my home made capacity hat on top of that.

I actually thought of making the type of cap hat you are referring to, (I have been studying KØBG's website for all the great info he has there) but I think that may be beyond my meager fabricating skills. I am using copper plated steel brazing rods of 1/8" diameter for the cap hat elements.
Instead of one set of long elements, I am planning on having two or maybe 3 sets of 3 elements, with lengths of around 36", 24", and 18". Now that I think of it, probably just 2 sets of 3 elements.

Hmmm, I wonder if just soldering a continuous wire on all the ends of my cap hat elements would function is a similar fashion?
It seems more research is in order.

Isn't if fun playing with antennas?!

 

[Radio75]

So I added my Hustler MO-4 mast section, and went to Ace Hardware and bought some 3/8X24 threaded couplers to make the cap hat since my big aluminum mounting thingy is not going to work until I can beg/borrow/steal a drill press.

The result so far is the lowest resonant frequency is now 5.27 Mhz.
Bandwidth on 40 is only about 3 Khz.
2:1 bandwidth on 20M is 225 KHz
2:1 bandwidth on 17M is 470 Khz
2:1 bandwidth on 15M is 700 Khz
2:1 bandwidth on 12M is 1.0 Mhz
2:1 bandwidth on 10M is 2.8 Mhz

I still need to experiment with running multiple taps on the coil for each band.
To this end I called MFJ and ordered more "clips" like those that came with the antenna, but they sent me something completely different. What they will send me will work to find the correct tap points, but once done I will just solder the jumpers to the coil. Before I do that though, I think I will get my mounting scheme for the cap hat just a little more permanent. I need to find some heavy duty double sided circuit board to solder the elements to, with a 3/8 dia hole in the center. Used to be able to buy double sided copper clad board from Radio Shack. I wonder where to find it now????

In the meantime, here are some more pics.....

More fabricating will be done, but probably not much more tuning/experimenting since the forecast is for 1/4' of ice and 4-8 inches of snow for the next two days...
C'mon SpringTime!!!