Maco 103C Beam for HF?

[KB1TPX]

I'm about to get my first HF Radio (TenTec Triton IV, mod 544). It's supposed to be ok with just about any antenna accompanied by an antenna tuner. Anyone ever heard of a Maco 103C (3 element beam) being used for HF? The darn thing is already up on the house, rotator and all and it's only less than a year old. My thought is it should be ok for most bands 10-80m. All helpful feedback appreciated.
BTW, I am also hanging a G5RV as well, and I do own a good antenna tuner.

 

[Captain Kilowatt]

When they say "It's supposed to be ok with just about any antenna accompanied by an antenna tuner.". they really mean any reasonable antenna. A Maco 103C is a CB antenna and will work on 10m and maybe on 12m. Forget trying to operate it below that. Just because a tuner can/will show you a good SWR at the radio does not mean that the antenna will work. Sure anything can be made to radiate a signal but how well it does that is another story.A dummy load presents a great SWR on every HF frequency but won't radiate worth a damn. For decent efficiency an antenna has to be properly scaled in size for the frequency it is operating on. That is why there are sooooo many different sized antennas for the different bands. While a half wave dipole for 10m is only about 16 feet long, one for 160m is about 270 feet long but they both have the same efficiency on their respective bands with all other things being equal.

Although I am not a great fan of the G5RV, I will admit that it will work better than the M103 on all bands below 15m and especially on 20m which is where the G5RV works best.

 

[wcsd106]

With some tuning it will work great on 10m.. in a pinch I would probably use it on 12m.

As for anything below 20m, by the time the tuner makes a "match" most of your power will be wasted in the tuner...

For the lower HF bands, go with a wire antenna if you have the room. Compromise antennas such as the G5RV and Windoms work well also.

This past summer I built what I refer to as a 1/4 size G5rv.. It's around 25 feet long, (12.5'/side) and is fed in the center with around 8 feet of 450 ohm ladder line. The ladder line is connected to a SO239 and regular mini-8 coax runs the rest of the way to the shack. No baluns, line isolators, or chokes are installed, but a choke wouldn't hurt as I sometimes get RFI in the shack. Since it is only a temporary antenna until this spring, I'm not too worried about it.

I get a good match on 20m, and the internal tuner in my Kenwood 440s is capable of loading the thing up on 40, 17, 12, and 10m. I've gotten good signal reports as far away as Austria and Germany on 20m during band openings.

 

[packrat]

Try it! What have ya got to lose. Since it is already up, use it till you need something better. With a good tuner, it will "work"! Compared to what a lotta people run, it will be great. ALL antennas are a compromise, so see what happens. You might just be pleasantly surprised, and if you are vigilent, you wont hurt anything.

PR

 

[KB1TPX]

Well guys, I obviously know that it (Maco) is a CB antenna, and that it wasn't designed for HF, but I do have it and was actually trying to gather info in an attempt to find a way to possibly re-configure or adjust it to use for HF. I'll probably, eventually take it down and sell it anyway. In no way was I even thinking of using it as my main antenna. I'm well aware also, that a tuner is not a "fix all" for the wrong antenna either.
I plan on experimenting with many different antenna configurations, as there are many to try (the internet is loaded with plans). I actually prefer dipoles and longwires. Maybe someday when I can afford to buy a different antenna for each individual band, I might.
Thanks for the info so far. Keep it coming.

 

[packrat]

When they say "It's supposed to be ok with just about any antenna accompanied by an antenna tuner.". they really mean any reasonable antenna. A Maco 103C is a CB antenna and will work on 10m and maybe on 12m. Forget trying to operate it below that. Just because a tuner can/will show you a good SWR at the radio does not mean that the antenna will work. Sure anything can be made to radiate a signal but how well it does that is another story."


Not exactly true. With a 102" whip and a tuner, you can work the world mobile on all bands. Maybe not too efficient, but how many antennas are? You are correct that tuner does nothing for swr at the antenna, but people put WAY too much importance on swr, and not enough on what actually counts. Talking.

 

[Cat Driver]

The manual with the 103c has the dimensions in it for either 11 or 10 meters...page 6 of this link.....And it will work just fine at the 10 meter settings

http://www.macoantennas.net/assembly/support2/Assembly_M103C.pdf

 

[Captain Kilowatt]

When they say "It's supposed to be ok with just about any antenna accompanied by an antenna tuner.". they really mean any reasonable antenna. A Maco 103C is a CB antenna and will work on 10m and maybe on 12m. Forget trying to operate it below that. Just because a tuner can/will show you a good SWR at the radio does not mean that the antenna will work. Sure anything can be made to radiate a signal but how well it does that is another story."


Not exactly true. With a 102" whip and a tuner, you can work the world mobile on all bands. Maybe not too efficient, but how many antennas are? You are correct that tuner does nothing for swr at the antenna, but people put WAY too much importance on swr, and not enough on what actually counts. Talking.

Believe me I know all about how well a 102 whip and a tuner works on HF mobile. I run a Yaesu FT-857 and an FC-40 autotuner.The vehicle is well bonded and the feedline from tuner to antenna base is heavy strap about 10 inches long,just the way it should be.The antenna whip is about 9'8" and the very tip is at 13'6", the max legal height. It works well on 10-20m but after that it sucks just like all other short mobile antennas of similar design. I still stand by my assertion above that the M103 will NOT work worth a damn below 15m. It will simply look like a feedline with a capacity hat at the other end.


AS for reconfiguring it to another band,that will be difficult for anything other than 10m. To go lower in freq requires longer elements and the M103's elements are not strong enough to be adding much more to the length. Then comes the matter of boomlength.

 

[packrat]

Must be a Canadian thing. In the states, we dont have no stinkin max height for antennas.

Anyway, tell the millions of hams running a short mobile antenna that they dont work. We know better.

PR

 

[Captain Kilowatt]

Must be a Canadian thing. In the states, we dont have no stinkin max height for antennas.

Anyway, tell the millions of hams running a short mobile antenna that they dont work. We know better.

PR

Oh but you do have max legal height limits. They are put in place by the dept. of transportation and are for bridge and overpass clearances just like up here.

Also I never said it WON't work nor did I say a short mobile whip WON't work. I said they will not work worth a damn. The screwdriver antennas and especially the Bugcatcher types work quite well but are designed for all band use not like a simple non-resonant 102 whip.Translated that means that they will radiate a signal and someone will indeed hear but the sucess rate is far below that of using a superior antenna. Since the thread starter is new to HF I thought it best to educate him in the deficiencies of using that antenna on 10-80m rather than tell him "Yes it will work so go for it!" and have him dissapointed with the results and become discouraged with the poor QSO count on 40 and 80m using it. I can only begin to imagine just how much loss the gamma match assembly will present just by itself when operating so far from the design frequency.

BTW, don't you have a shed to go build. :laugh:

 

[W5LZ]

I think if you were really desperate you could make that 10/11 meter beam work at least as well on 80 through 20 meters as the average dummy load. Unfortunately, that's not as much of a joke as you may think it is. In fact, it's probably an optimistic estimate.
Depending on a lot of things, the typical 'small' 80, and 40 meter antennas (small as in a non-bugcatcher or 'skinny' screwdriver type) will be very lucky to ever see more than about 2% efficiency. The bugcatcher and 'fat' screwdriver types may see 3 or 4%. As you move up in frequency the 'small' and 'fat' size thingy makes less difference, but still a considerable one. Somewhere around 20 meters the 'smaller' types such as the 'hamsticks', etc, start coming into their own. That means at least as 'good' as the average 'non-102" whip' on 11 meters, sort of. Same ball-park anyway. For the 'larger' bugcatchers and fat screwdrivers, you're talking maybe even as much as 10% efficient! Which all things considered, is quite a bit.
Nothing in all that is exact by any means, just too many variables. It's very safe to say that a 10/11 meter beam on the lower HF bands is the equivalent of a 'rubber-duck'. If that kind of antenna will satisfy you, then why not try it? Consider yourself lucky if you can get out of town with it! You'd have to be either really desperate, or really bored.
- 'Doc


An 80 meter loaded beam typically would have elements about 60 feet long. With my city lot, I couldn't turn the thing!

 

[hookedon6]

... if you were really desperate you could make that 10/11 meter beam work at least as well on 80 through 20 meters as the average dummy load...

:blink::blink::blink::blink: i have to agree, a short (non-screwdriver type) vertical on the low bands really sux. heck, they are even worse than an isotron(aka: dummy load).
there's a reason most of them have large coils/cap hats.

i like to experiment with antennas, but i won't waste my time

 

[packrat]

Gotta say that there are NO limits on antenna size for vehicles in the states. You can hit whatever you like with your ol antenna here. Heck, you can even hit the bridge with your truck if ya want. Nothing in the books to stop ya. You will pay for any damages, yes, but I have never SEEN an antenna that will damage a concrete overpass. I will stand by this til someone shows me otherwise.
( its my story and Im sticking to it)

op:

PR

 

[Captain Kilowatt]

Gotta say that there are NO limits on antenna size for vehicles in the states. You can hit whatever you like with your ol antenna here. Heck, you can even hit the bridge with your truck if ya want. Nothing in the books to stop ya. You will pay for any damages, yes, but I have never SEEN an antenna that will damage a concrete overpass. I will stand by this til someone shows me otherwise.
( its my story and Im sticking to it)

op:

PR

Here ya go.There ar no federal limits but each state sets their own. Note the 13'6" limit without special permits. This section of the act is applicable to all vehicles on the road and not just commercial vehicles. It is irrelevant if an antenna will damage a bridge,the relevant part is the max height of any part of the vehicle. Overhead electrical wires are something to be considered as well but if you want to drive under a 66,000 volt line that is 14 feet off the ground with your 15 foot high antenna then by all means go for it. :laugh:

Statutes & Constitution :View Statutes :->2006->Ch0316->Section 515 : Online Sunshine

 

[Cat Driver]

Here ya go.There ar no federal limits but each state sets their own. Note the 13'6" limit without special permits. This section of the act is applicable to all vehicles on the road and not just commercial vehicles. It is irrelevant if an antenna will damage a bridge,the relevant part is the max height of any part of the vehicle. Overhead electrical wires are something to be considered as well but if you want to drive under a 66,000 volt line that is 14 feet off the ground with your 15 foot high antenna then by all means go for it. :laugh:

Statutes & Constitution :View Statutes :->2006->Ch0316->Section 515 : Online Sunshine

Kinda like "Back to the Future"....that'll get ya somewhere....hahahaha