Found this article interesting on bandwidth and efficiency.
http://www.copperelectronics.com/articles/big_coil_antennas_exposed.php
http://www.copperelectronics.com/articles/big_coil_antennas_exposed.php
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AT-6666 MOBILE
- Thread starter HomerBB
- Start date
That's interesting, the old school ads are just down right awesome. Those were definitely the days. The big momma ad is top notch marketing, would all kinds of upset and offend a certain crowd this day in age though.
Thanks for the share
29 MHz is very close to 27 MHz for a quarter wave (non-loaded) whip, which is why the 102 inch whip SWR is 2:1 at 29 MHz. It is the opposite of "very out of band", it is in-band. You only lose 11% power heating your coax at 2:1 SWR. Here's the power loss chart:
http://www.firestik.com/Tech_Docs/SWRLOSS.htm
A 17m HamStick is a center-loaded (center coil) antenna which is inherently a narrowband design. You're right in that if the OP wanted to run 40 meters mobile as well as 20m, 17m, 15m, 12m, 11m, and 10m, then yeah, a base loaded screwdriver tunable coil would be best.
The OP only wanted to cover 10m and 11m. A full quarter wave whip at 27 MHz has no loading coil and can easily cover 27 to 29 MHz with a tuner with no appreciable loss in power, maybe 11% at most for a 2:1 SWR. If you're worried about maximizing performance and really need that 11% additional power on the ham band, then cut a quarter wave whip to 28 or 29 MHz and use the tuner at 27 MHz. But you probably need the antenna more efficient in the CB band where you're power limited to 4 W AM carrier or 12 W PEP SSB.
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You really want the base of the antenna up at the roofline if you're that close to the back of the cab. Try getting the antenna above the roofline, or move the antenna back along the bed so it is further away from the cab. At 6 meters, the majority of the antenna is going to be below the roofline on a toolbox mount. At 54 MHz and above, consider a mag mount on the roof or through-the-roof NMO hole mount centered on the roof.
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A lot of great input. Thanks everyone.
I carried it to the garage corner shack and tested it on a dummy load on both 11m and 10m. From the factory:
AM - High 12w to ~50w, Low 2w to 8w
SSB - " ~60W
FM - " 50w
Running it on my Imax2k base antenna @49' feedpoint I am getting really good reports on both dx and local station from 1/4 mile out to 20 miles. Reports are about the audio quality, and some signal reports, which, of course, are very subjective. The receive is good. And the SSB is right on to my ears.
I am both pleased and a little put off by its appearance.
On the positive, it is a good size for mobile mounting, and will compliment any interior mounting. Not gaudy, and seems to have the characteristics of streamlined operation I need in a mobile environment.
What is a little off putting is that it resembles more a VHF/UHF mobile than most HF units I've used. This doesn't matter, but I'll have to get used to it visually.
It's definitely not unattractive, in fact, it is a good looking radio. It certainly packs a punch for its size.
The heft of it is surprising. Weighty, but that seems to come primarily from the heat sink.
About the heat sink, the only thing that I dislike so far is the coax connector is crowded by the heat sink. This makes cable hookup testy. Fortunately, I won't be needing to attach coax frequently.
I will say more about my impression when I get it installed in the pickup truck.
I carried it to the garage corner shack and tested it on a dummy load on both 11m and 10m. From the factory:
AM - High 12w to ~50w, Low 2w to 8w
SSB - " ~60W
FM - " 50w
Running it on my Imax2k base antenna @49' feedpoint I am getting really good reports on both dx and local station from 1/4 mile out to 20 miles. Reports are about the audio quality, and some signal reports, which, of course, are very subjective. The receive is good. And the SSB is right on to my ears.
I am both pleased and a little put off by its appearance.
On the positive, it is a good size for mobile mounting, and will compliment any interior mounting. Not gaudy, and seems to have the characteristics of streamlined operation I need in a mobile environment.
What is a little off putting is that it resembles more a VHF/UHF mobile than most HF units I've used. This doesn't matter, but I'll have to get used to it visually.
It's definitely not unattractive, in fact, it is a good looking radio. It certainly packs a punch for its size.
The heft of it is surprising. Weighty, but that seems to come primarily from the heat sink.
About the heat sink, the only thing that I dislike so far is the coax connector is crowded by the heat sink. This makes cable hookup testy. Fortunately, I won't be needing to attach coax frequently.
I will say more about my impression when I get it installed in the pickup truck.
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Thanks for that report/review. The “gap” from an ordinary enough vertical waaay up to a screwdriver is a biggun.
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I run a Sirio Fighter hard mounted to the left rear above the taillight for my AT 6666. Works great on 10 and 11.
I didn't notice this one until now. Here are my experiences with the AT-6666 in my truck.
I took a ~3000 mile trip last summer with my truck camper, AT-6666 to a 102" whip with spring hard-mounted on the hood about 2/3 of the way to the front so as to clear the camper. It worked with decent swr from the "lowers" (26 MHz) through the FM portion of 10M. No tuner nor adjustments needed. I made several contacts throughout that range on the trip with excellent signal reports.
After I returned home and wasn't toting the camper around, I relocated the antenna to the driver's side bedrail about 30 inches back from the cab. That yielded similar results. With that antenna in both locations, I got unsolicited reports that it sounded as good as a base station.
I decided awhile back to take the 102" whip off and run something less obtrusive for awhile. So I swapped out the 3/8" mount on the hood for an NMO and mounted a Larsen NMO27B antenna there. That is a base-loaded whip antenna that is right at 48 inches long after trimming to resonance. I no longer have access to 29 MHz; 3:1 bandwidth is about 26.5-28.5 as it is right now, with nearly 1:1 at Channel 38 D (38 CB).
That's not what I was going for; just where I stopped for now. I'm thinking about buying a replacement whip and trimming it to cover all of 10M. The whip is quick and easy to swap on the loading coil, with no tools needed. The way it is setup now it works perfectly on cb and allows me to also make the occasional 10M SSB contact. With a second tuned whip, I will be able to swap it out and get serious about working some 10M, both 28 MHz SSB and 29 MHz FM and AM.
The reason I chose that specific antenna is I have heard good reports from people in the commercial and public safety sectors who have used them on lowband FM.
I took a ~3000 mile trip last summer with my truck camper, AT-6666 to a 102" whip with spring hard-mounted on the hood about 2/3 of the way to the front so as to clear the camper. It worked with decent swr from the "lowers" (26 MHz) through the FM portion of 10M. No tuner nor adjustments needed. I made several contacts throughout that range on the trip with excellent signal reports.
After I returned home and wasn't toting the camper around, I relocated the antenna to the driver's side bedrail about 30 inches back from the cab. That yielded similar results. With that antenna in both locations, I got unsolicited reports that it sounded as good as a base station.
I decided awhile back to take the 102" whip off and run something less obtrusive for awhile. So I swapped out the 3/8" mount on the hood for an NMO and mounted a Larsen NMO27B antenna there. That is a base-loaded whip antenna that is right at 48 inches long after trimming to resonance. I no longer have access to 29 MHz; 3:1 bandwidth is about 26.5-28.5 as it is right now, with nearly 1:1 at Channel 38 D (38 CB).
That's not what I was going for; just where I stopped for now. I'm thinking about buying a replacement whip and trimming it to cover all of 10M. The whip is quick and easy to swap on the loading coil, with no tools needed. The way it is setup now it works perfectly on cb and allows me to also make the occasional 10M SSB contact. With a second tuned whip, I will be able to swap it out and get serious about working some 10M, both 28 MHz SSB and 29 MHz FM and AM.
The reason I chose that specific antenna is I have heard good reports from people in the commercial and public safety sectors who have used them on lowband FM.
Can you give us a performance report for the larsen nmo vs the 102 whip?
How about just using a small auto tuner?
I'd use a longer antenna cut for a low SWR on CB and then use an auto tuner when on 10 or 12 meters if needed.
Or maybe adjust the antenna for the band you are most likely to be on the most and use the tuner for the other.
Now that I think of it, I suppose the power level that some radios are at might make the choice of auto tuner a problem.
I'd use a longer antenna cut for a low SWR on CB and then use an auto tuner when on 10 or 12 meters if needed.
Or maybe adjust the antenna for the band you are most likely to be on the most and use the tuner for the other.
Now that I think of it, I suppose the power level that some radios are at might make the choice of auto tuner a problem.
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I really don't like using a tuner with coax because it's too lossy and adds complexity that is just not needed for 10-11M.
The exception is if the tuner is located at the feedpoint of the antenna, like the SGC tuners. That way you don't have the coax loss because you are not tuning the coax.
I have one of those, but it's a bit much for just 10-11M. Works great for mobile on all HF bands, though. In fact I have used it to work 160M mobile in Colorado and Wyoming.