If I have an antenna up for 11 meters and i want to operate it at 40 meters is there a way to quick estimate the antenna characteristics based on the known values of 11 meters? Never have gotten the hang of the program everyone uses
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Antenna calculator
- Thread starter nfsus
- Start date
Sounds like he wants to use an 11m antenna on 40m. That aint gonna happen
Oh its gonna happen. Maybe. With a tuner.
I run a 102" steel whip on the car at 11/10m. I want to run the same whip on different hf bands. If I put an atu at the feed point of the whip I should be good. IF the atu will tune that far. It's an atu-100 chinese tuner off amazon. I use one in the shack and it's nice. Fast too. Might need a loading coil switch setup. Dunno. But I could always just hook up the nanovna and look at all the dips. If theres more than one. Just playing around.
I run a 102" steel whip on the car at 11/10m. I want to run the same whip on different hf bands. If I put an atu at the feed point of the whip I should be good. IF the atu will tune that far. It's an atu-100 chinese tuner off amazon. I use one in the shack and it's nice. Fast too. Might need a loading coil switch setup. Dunno. But I could always just hook up the nanovna and look at all the dips. If theres more than one. Just playing around.
Yeah .... and you've been listening to the stories that you can tune up a bedspring out in your yard to "work" on 80 meters if your tuner is good enough .... but what they don't say is that it will be horrifically inefficient and may you may only talk 1 mile away to a neighbor who has a real antenna.
I used to run a 102 whip on the rear of my SUV many years ago. I had a Yaesu FC-40 remote mount auto-tuner at the feedpoint just inside the rear hatch door. On 20m and up it worked great. On 40m not so much. On 80m I did make a few contacts to Europe with 100 watts and a few more throughout the USA but it was pretty rough going. The efficiency is only a couple percent on 80m and around 10% on 40m if that.
"You had it TUNED to 15M with NO TUNER" ..... Well thanks for clearing that up.
Anyway .... Yes the 102 will work fine on 15 & Up but below that it won't do very well no matter what.
Get Ampro40 and put it instead of that tank whip.
Other wise you need to make LC circuit to get good SWR on tank whip.
Mike
Other wise you need to make LC circuit to get good SWR on tank whip.
Mike
Looking around the house. I have a wilson "5/8" top loaded silver tip for 11m. Wonder what I could do with a long stinger in there? Just curiosity. I did look at the ampro just now though. Cheap enough for sure!
Now after all this, i do have a tarheel. I just like thinking and playing around
Since you want to roll your own, here are the coil specs from Texas Bug Catcher site. The #640 sounds like what you want - Minimum 72" whip with no cap hat. This should work with your 102" whip.
# 680 COIL
The #680 HQ Coil is 6-3/8 inches in diameter and 7 inches long. It is wound with 12 Ga. wire at 4 turns per inch. Because of its larger diameter, shorter length and wider turn spacing the Q of the coil is higher than the #480 which improves the radiation efficiency. The #680 HQ has a total inductance of approximately 85 microhenrys which will allow 75 meter operation with a whip length of 72 inches without the use of a capacity hat. Adding a capacity hat will allow whip lengths as follows:
20 Inch Hat----- 36 Inch Whip
16 Inch Hat ----- 48 Inch Whip
12 Inch Hat ----- 60 Inch Whip
These whip lengths are intended as a reference only. The length of the whip should be kept as long as practical. The “Higher Q” makes this coil the best choice for 40 and 75 meter operation.
# 640 COIL
The #640 HQ coil has the same mechanical construction as the #680 but is only 4 inches long . This coil is best suited for 10 through 40 meter operation. The # 640 will require a whip at least 72 inches long for 40 meter operation. As with all coils the whip may be shortened by adding a capacity hat.
HD80 MATCHING COIL
As with all high “Q” mobile antennas (especially on 40, 75 & 160 meters) the feedpoint impedance is quite low. This necessitates some method of feedpoint impedance matching. This matching can be done several ways. An inductor, capacitor, toroidal transformer or other method can be used. Because of the ease of use we recommend the shunt inductor. The GLA Systems Heavy Duty Matching Coil is easy to tune and will match our antennas in all cases. It can also be used to match other types of HF antennas with great success.
The HD-80 matching coil is 2 inches in diameter and 2.5 inches long. The base of the coil is a solid piece of copper that is the full diameter of the coil. This copper plate has a 3/8” hole in the center that allows the stud of the mast to secure the coil to the mount. The coil wire is wound on a solid CPVC form. The coil form has a 1 inch hole in the center to allow the mast to pass through and secure the coil to the mount. This greatly increases the strength of the coil and also reduces coil vibration.
The coil is shorted to ground with a jumper and coil clips that are provided with the HD-80.
www.mtcradio.com
# 680 COIL
The #680 HQ Coil is 6-3/8 inches in diameter and 7 inches long. It is wound with 12 Ga. wire at 4 turns per inch. Because of its larger diameter, shorter length and wider turn spacing the Q of the coil is higher than the #480 which improves the radiation efficiency. The #680 HQ has a total inductance of approximately 85 microhenrys which will allow 75 meter operation with a whip length of 72 inches without the use of a capacity hat. Adding a capacity hat will allow whip lengths as follows:
20 Inch Hat----- 36 Inch Whip
16 Inch Hat ----- 48 Inch Whip
12 Inch Hat ----- 60 Inch Whip
These whip lengths are intended as a reference only. The length of the whip should be kept as long as practical. The “Higher Q” makes this coil the best choice for 40 and 75 meter operation.
# 640 COIL
The #640 HQ coil has the same mechanical construction as the #680 but is only 4 inches long . This coil is best suited for 10 through 40 meter operation. The # 640 will require a whip at least 72 inches long for 40 meter operation. As with all coils the whip may be shortened by adding a capacity hat.
HD80 MATCHING COIL
As with all high “Q” mobile antennas (especially on 40, 75 & 160 meters) the feedpoint impedance is quite low. This necessitates some method of feedpoint impedance matching. This matching can be done several ways. An inductor, capacitor, toroidal transformer or other method can be used. Because of the ease of use we recommend the shunt inductor. The GLA Systems Heavy Duty Matching Coil is easy to tune and will match our antennas in all cases. It can also be used to match other types of HF antennas with great success.
The HD-80 matching coil is 2 inches in diameter and 2.5 inches long. The base of the coil is a solid piece of copper that is the full diameter of the coil. This copper plate has a 3/8” hole in the center that allows the stud of the mast to secure the coil to the mount. The coil wire is wound on a solid CPVC form. The coil form has a 1 inch hole in the center to allow the mast to pass through and secure the coil to the mount. This greatly increases the strength of the coil and also reduces coil vibration.
The coil is shorted to ground with a jumper and coil clips that are provided with the HD-80.
Texas BugCatcher HF Mobile Antenna Info
www.mtcradio.com