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#1
March 2nd 04, 09:33 PM
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433MHz or 916MHz ?
hi, I'm still in process of designing some little tracking
transmitters (10-50mw) for model airplanes ( take my tech test on Saturday!! ) and I'm trying to decide if to go the 400 or 800MHz band approach. The higher frequency would allow a little shorter antenna ... but would be a little more directional (?) ... considering what I'm trying to locate may be out in the weeds somewhere does anyone have any experience which one would be better and why ? TIA stan |
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#2
March 2nd 04, 10:26 PM
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"stan" wrote in message ... hi, I'm still in process of designing some little tracking transmitters (10-50mw) for model airplanes ( take my tech test on Saturday!! ) and I'm trying to decide if to go the 400 or 800MHz band approach. The higher frequency would allow a little shorter antenna .. but would be a little more directional (?) ... considering what I'm trying to locate may be out in the weeds somewhere does anyone have any experience which one would be better and why ? TIA stan 800MHz? That's one question you'll miss... They'll both be line-of-sight, 900MHz will theoretically have a bit more absorbtion by the vegatation and the circuit will be touchier, but 900MHz is less used -- the ARRL will thank you for populating the band better, and the 70cm crowd will thank you for not adding to the band congestion. If you can design transmitters you should be taking the Extra. 5WPM is a joke to learn, too. My kid is studying for the tech, since the speed requirement is so absurdly low I'm thinking of upgrading to Extra myself. ------------------------------------------- Tim Wescott, KG7LI Wescott Design Services http://www.wescottdesign.com |
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#3
March 2nd 04, 10:43 PM
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most newer generation ELT devices are on 406.028, so using 70cm is probably
better for longer range, not as much line of site. another thing to realize is what mode you will be using , im guessing some type of FSK. for what you lack on transmit power, a better designed antenna system and ground tracking receivers wll make up the difference .in range for you i know you want to build it yourslef, but ou might want to check out ramsey electronics website. they sell 433 and 916MC transmitters and recievers. i have used them in model rockets (433) and they worked great up to about 2000 feet high. i used a 70cm ht with a small beam. to track it. "Tim Wescott" wrote in message ... "stan" wrote in message ... hi, I'm still in process of designing some little tracking transmitters (10-50mw) for model airplanes ( take my tech test on Saturday!! ) and I'm trying to decide if to go the 400 or 800MHz band approach. The higher frequency would allow a little shorter antenna .. but would be a little more directional (?) ... considering what I'm trying to locate may be out in the weeds somewhere does anyone have any experience which one would be better and why ? TIA stan 800MHz? That's one question you'll miss... They'll both be line-of-sight, 900MHz will theoretically have a bit more absorbtion by the vegatation and the circuit will be touchier, but 900MHz is less used -- the ARRL will thank you for populating the band better, and the 70cm crowd will thank you for not adding to the band congestion. If you can design transmitters you should be taking the Extra. 5WPM is a joke to learn, too. My kid is studying for the tech, since the speed requirement is so absurdly low I'm thinking of upgrading to Extra myself. ------------------------------------------- Tim Wescott, KG7LI Wescott Design Services http://www.wescottdesign.com |
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#4
March 2nd 04, 10:43 PM
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most newer generation ELT devices are on 406.028, so using 70cm is probably
better for longer range, not as much line of site. another thing to realize is what mode you will be using , im guessing some type of FSK. for what you lack on transmit power, a better designed antenna system and ground tracking receivers wll make up the difference .in range for you i know you want to build it yourslef, but ou might want to check out ramsey electronics website. they sell 433 and 916MC transmitters and recievers. i have used them in model rockets (433) and they worked great up to about 2000 feet high. i used a 70cm ht with a small beam. to track it. "Tim Wescott" wrote in message ... "stan" wrote in message ... hi, I'm still in process of designing some little tracking transmitters (10-50mw) for model airplanes ( take my tech test on Saturday!! ) and I'm trying to decide if to go the 400 or 800MHz band approach. The higher frequency would allow a little shorter antenna .. but would be a little more directional (?) ... considering what I'm trying to locate may be out in the weeds somewhere does anyone have any experience which one would be better and why ? TIA stan 800MHz? That's one question you'll miss... They'll both be line-of-sight, 900MHz will theoretically have a bit more absorbtion by the vegatation and the circuit will be touchier, but 900MHz is less used -- the ARRL will thank you for populating the band better, and the 70cm crowd will thank you for not adding to the band congestion. If you can design transmitters you should be taking the Extra. 5WPM is a joke to learn, too. My kid is studying for the tech, since the speed requirement is so absurdly low I'm thinking of upgrading to Extra myself. ------------------------------------------- Tim Wescott, KG7LI Wescott Design Services http://www.wescottdesign.com |
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#5
March 2nd 04, 10:26 PM
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"stan" wrote in message ... hi, I'm still in process of designing some little tracking transmitters (10-50mw) for model airplanes ( take my tech test on Saturday!! ) and I'm trying to decide if to go the 400 or 800MHz band approach. The higher frequency would allow a little shorter antenna .. but would be a little more directional (?) ... considering what I'm trying to locate may be out in the weeds somewhere does anyone have any experience which one would be better and why ? TIA stan 800MHz? That's one question you'll miss... They'll both be line-of-sight, 900MHz will theoretically have a bit more absorbtion by the vegatation and the circuit will be touchier, but 900MHz is less used -- the ARRL will thank you for populating the band better, and the 70cm crowd will thank you for not adding to the band congestion. If you can design transmitters you should be taking the Extra. 5WPM is a joke to learn, too. My kid is studying for the tech, since the speed requirement is so absurdly low I'm thinking of upgrading to Extra myself. ------------------------------------------- Tim Wescott, KG7LI Wescott Design Services http://www.wescottdesign.com |
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#6
March 4th 04, 04:18 AM
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Don't shortchange 4-8kHz... an audible, high intensity piezo buzzer can be
heard for quite some distance :-) "stan" wrote in message ... hi, I'm still in process of designing some little tracking transmitters (10-50mw) for model airplanes ( take my tech test on Saturday!! ) and I'm trying to decide if to go the 400 or 800MHz band approach. The higher frequency would allow a little shorter antenna .. but would be a little more directional (?) ... considering what I'm trying to locate may be out in the weeds somewhere does anyone have any experience which one would be better and why ? TIA stan |
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#7
March 4th 04, 10:48 PM
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GOOD POINT !
You can turn it on with full up elevator to save batteries. Assuming your crash isn't fatal. "KD7TOG" wrote in message hlink.net... Don't shortchange 4-8kHz... an audible, high intensity piezo buzzer can be heard for quite some distance :-) "stan" wrote in message ... hi, I'm still in process of designing some little tracking transmitters (10-50mw) for model airplanes ( take my tech test on Saturday!! ) and I'm trying to decide if to go the 400 or 800MHz band approach. The higher frequency would allow a little shorter antenna .. but would be a little more directional (?) ... considering what I'm trying to locate may be out in the weeds somewhere does anyone have any experience which one would be better and why ? TIA stan |
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#8
March 4th 04, 10:48 PM
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GOOD POINT !
You can turn it on with full up elevator to save batteries. Assuming your crash isn't fatal. "KD7TOG" wrote in message hlink.net... Don't shortchange 4-8kHz... an audible, high intensity piezo buzzer can be heard for quite some distance :-) "stan" wrote in message ... hi, I'm still in process of designing some little tracking transmitters (10-50mw) for model airplanes ( take my tech test on Saturday!! ) and I'm trying to decide if to go the 400 or 800MHz band approach. The higher frequency would allow a little shorter antenna .. but would be a little more directional (?) ... considering what I'm trying to locate may be out in the weeds somewhere does anyone have any experience which one would be better and why ? TIA stan |
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#9
March 4th 04, 04:18 AM
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Don't shortchange 4-8kHz... an audible, high intensity piezo buzzer can be
heard for quite some distance :-) "stan" wrote in message ... hi, I'm still in process of designing some little tracking transmitters (10-50mw) for model airplanes ( take my tech test on Saturday!! ) and I'm trying to decide if to go the 400 or 800MHz band approach. The higher frequency would allow a little shorter antenna .. but would be a little more directional (?) ... considering what I'm trying to locate may be out in the weeds somewhere does anyone have any experience which one would be better and why ? TIA stan |
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