Hi John and others,
Thanks for the picture lovely set up. If only I could get the XYL to let me stick something similar on the roof :) I do have an elevation rotator already :) IIRC a Kenpro 550 or 450. I have played about in the past with satellites, at that time I had a 11 element 2 meter RHCP and a 19 element 70 RHCP (Hence the elevation rotator). I mainly listened rather than transmitted.
So really I have all the equipment except for a way to automate the antenna control, which as you say isn't too difficult to do manually and an antenna. I really don't thing the XYL will let me put up the 11 and 19 element antennas which I still have, as she thinks I have enough antennas in the air already <g> As you can see the sats aren't a passing fad with me, it's just that I will be on LEO's as a way of compromise. It has taken me a while to get back to them, but i bought the 847 recently to motivate me to actually put my words into action rather than just wishing on a star :P
Several people have suggested using a vertical antenna such as a colinear. I have actually already tried this and the results are very disappointing, which I put down to my location rather than anything else as where I am is not particularly that good certainly form a VHF/UHF point of view.
Other things I was wondering about was the ERP at the satellite, would it be too high causing me to be an alligator? Roughly the ERP on 2 would be about 50 watts and higher on 70 as the gain would be about 13 dBd plus whatever 5 watts equals. losses should be very small as the run of coax would be less than 30 feet, most of that being Westflex 103 and just the a very short length of RG 213 for getting the antenna hooked up and round the rotator/s. I'm not sure how to work out the path loss from my location (is there a standard figure or equation to use?) so at present I'm still very tempted to go with the Tonna, as it certainly seems to be better than the arrow antennas in that it has a higher gain figure. Please note I am not commenting on the quality of the construction of the Arrow. The other aspect I'm wondering about is cross polarization losses, the way that I plan to have it configured is with the 2 meter section horizontal and the 70 cm vertical. So would that be significant for the LEO's?
73 Gary G7USC
At 23:12 21/02/2007, you wrote:
The antenna by Tonna with 13 DBi on 2 and 16 DBi on 70 is going to have a fairly narrow beamwidth and is obviously a fairly long antenna. It will need to be pointed with reasonable accuracy. If you are 30 degrees off you might as well be pointed the other way. With that much gain, you should be able to work most satellites without the preamps. The problem is aiming the antennas. I recommend using azimuth and elevation rotors. Azimuth alone won't do it with narrow beamwidth antennas if the satellite pass reaches a significant elevation.
Gary McKelvie G7USC Web : www.garym.org.uk Mobile : +447968501863 MSN Messenger : [email protected] So Long and Thanks for all the Fish
Quoting Gary McKelvie [email protected]:
Several people have suggested using a vertical antenna such as a colinear. I have actually already tried this and the results are very disappointing, which I put down to my location rather than anything else as where I am is not particularly that good certainly form a VHF/UHF point of view.
Gary:
We look forward to working you on this side of the pond. If I remember the details of this thread correctly, one of your design goals for this system is to not require preamps. I would venture to say that most every antenna design or recommendation pertaining to satellite work assumes low-noise preamps as close to the antenna as possible. This might explain the difference between your experience and others' with vertical antennas.
What I love about this aspect of the hobby is the experimentation. Though my antennas are down right now, there have been many silent mid-Atlantic passes of VO-52 where I have amused myself by testing the minimum signal required for reception, used varying antennas, and switched in and out a preamp or two. Just me and an orbiting radio laboratory; thank you, ISRO!
Conducting such experiments with my pair of FT-817s and TS-2000 suggests that a preamp is terribly important, especially for 70cm downlink operation. In fact, my 70cm preamp is an indoor model, and it *still* makes a crucial difference. I think this is because the NF of these radios' preamps is just not devised for small-signal work. To put it more strongly, I would rather spend an evening doodling around on 70cm with a (indoor) preamp and a coathanger-and-bnc vertical than I would with my 8 element rotating outdoor beam and no preamp!
Your high-gain, narrow bandwidth antennas will make up for this, of course. But other beginners might be interested to know that by using preamps and shorter, wider bandwidth antennas it is possible to have exceedingly enjoyable LEO satellite operations with a single, azimuth-only TV-type rotor. The approach offers some advantages: such short antennas are also easier to build from scratch materials, easier to put up on in the air; and the wide beamwidth of the antenna makes it possible to manually control the rotor without too much fuss. The advantage of your az/el system is that it will be closer to HEO-ready when P3E and SSETI are launched next year. However, I venture to say that you really will need preamps then.
I started out using HRD, but like others, I have found that recent versions do not track SSB/CW correctly, and it seems that Simon's focus is now on the latest digital Swiss Army Knife. If you have difficulties of this nature, try the demo of SatPC32 or other dedicated programs.
Again, for others with a different set of resources, there's a great discussion of why a fixed-elevation rotor system works well at: http://web.usna.navy.mil/~bruninga/rotator1.htm I would advise that homebrewers begin avoiding circular polarization and the mechanical challenges that entails. Many of us have had good luck building the so-called 'cheap yagis': http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf My 70cm one is 8 elements; I found my 4 element 2m to be a bit under-powered for receiving AO-7, but I had fun with it for 2 years!
73, Bruce VE9QRP
I was unable to access Bob's rotator site. Is it just me?
73 de Tim, K4SHF
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bruce Robertson Sent: Thursday, February 22, 2007 12:11 PM To: Gary McKelvie Cc: [email protected] Subject: [amsat-bb] Re: Advice on antennas for working the LEO's
Quoting Gary McKelvie [email protected]:
Several people have suggested using a vertical antenna such as a colinear. I have actually already tried this and the results are very disappointing, which I put down to my location rather than anything else as where I am is not particularly that good certainly form a VHF/UHF point of view.
Gary:
We look forward to working you on this side of the pond. If I remember the details of this thread correctly, one of your design goals for this system is to not require preamps. I would venture to say that most every antenna design or recommendation pertaining to satellite work assumes low-noise preamps as close to the antenna as possible. This might explain the difference between your experience and others' with vertical antennas.
What I love about this aspect of the hobby is the experimentation. Though my antennas are down right now, there have been many silent mid-Atlantic passes of VO-52 where I have amused myself by testing the minimum signal required for reception, used varying antennas, and switched in and out a preamp or two. Just me and an orbiting radio laboratory; thank you, ISRO!
Conducting such experiments with my pair of FT-817s and TS-2000 suggests that a preamp is terribly important, especially for 70cm downlink operation. In fact, my 70cm preamp is an indoor model, and it *still* makes a crucial difference. I think this is because the NF of these radios' preamps is just not devised for small-signal work. To put it more strongly, I would rather spend an evening doodling around on 70cm with a (indoor) preamp and a coathanger-and-bnc vertical than I would with my 8 element rotating outdoor beam and no preamp!
Your high-gain, narrow bandwidth antennas will make up for this, of course. But other beginners might be interested to know that by using preamps and shorter, wider bandwidth antennas it is possible to have exceedingly enjoyable LEO satellite operations with a single, azimuth-only TV-type rotor. The approach offers some advantages: such short antennas are also easier to build from scratch materials, easier to put up on in the air; and the wide beamwidth of the antenna makes it possible to manually control the rotor without too much fuss. The advantage of your az/el system is that it will be closer to HEO-ready when P3E and SSETI are launched next year. However, I venture to say that you really will need preamps then.
I started out using HRD, but like others, I have found that recent versions do not track SSB/CW correctly, and it seems that Simon's focus is now on the latest digital Swiss Army Knife. If you have difficulties of this nature, try the demo of SatPC32 or other dedicated programs.
Again, for others with a different set of resources, there's a great discussion of why a fixed-elevation rotor system works well at: http://web.usna.navy.mil/~bruninga/rotator1.htm I would advise that homebrewers begin avoiding circular polarization and the mechanical challenges that entails. Many of us have had good luck building the so-called 'cheap yagis': http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf My 70cm one is 8 elements; I found my 4 element 2m to be a bit under-powered for receiving AO-7, but I had fun with it for 2 years!
73, Bruce VE9QRP
_______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Subject: [amsat-bb] Re: Advice on antennas for working the
LEO's
I was unable to access Bob's rotator site. Is it just me?
http://web.usna.navy.mil/~bruninga/rotator1.htm
Use the EDU version instead:
http://www.ew.usna.edu/~bruninga/rotator1.htm
Bob
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bruce Robertson Sent: Thursday, February 22, 2007 12:11 PM To: Gary McKelvie Cc: [email protected] Subject: [amsat-bb] Re: Advice on antennas for working the
LEO's
Quoting Gary McKelvie [email protected]:
Several people have suggested using a vertical antenna such
as a
colinear. I have actually already tried this and the
results are very
disappointing, which I put down to my location rather than
anything
else as where I am is not particularly that good certainly
form a
VHF/UHF point of view.
Gary:
We look forward to working you on this side of the pond. If I remember the details of this thread correctly, one of your design goals for this system is to not require preamps. I would venture to say that most every antenna design or recommendation pertaining to satellite work assumes low-noise preamps as close to the antenna as possible. This might
explain the
difference between your experience and others' with vertical antennas.
What I love about this aspect of the hobby is the experimentation. Though my antennas are down right now, there have been many silent mid-Atlantic passes of VO-52 where I have amused myself by testing the minimum signal required for reception, used varying antennas, and switched in and out a preamp or two. Just me and an orbiting radio laboratory; thank you,
ISRO!
Conducting such experiments with my pair of FT-817s and TS-2000 suggests that a preamp is terribly important, especially for 70cm downlink operation. In fact, my 70cm preamp is an indoor model, and it *still* makes a crucial difference. I think this is because the NF of these radios' preamps is just not devised for small-signal work. To put it more strongly, I would rather spend an evening doodling around on 70cm with a (indoor) preamp and a coathanger-and-bnc vertical than I would with my 8 element rotating outdoor beam and no preamp!
Your high-gain, narrow bandwidth antennas will make up for this, of course. But other beginners might be interested to know that by using preamps and shorter, wider bandwidth antennas it is possible to have
exceedingly
enjoyable LEO satellite operations with a single, azimuth-only
TV-type
rotor. The approach offers some advantages: such short antennas are also easier to build from scratch materials, easier to put up on in the air; and the wide beamwidth of the antenna makes it possible to manually control the rotor without too much fuss. The advantage of your az/el system is that it will be closer to HEO-ready when P3E and SSETI are launched
next year.
However, I venture to say that you really will need preamps
then.
I started out using HRD, but like others, I have found that recent versions do not track SSB/CW correctly, and it seems that Simon's focus is now on the latest digital Swiss Army Knife. If you have difficulties of this nature, try the demo of SatPC32 or other dedicated programs.
Again, for others with a different set of resources, there's a
great
discussion of why a fixed-elevation rotor system works well
at:
http://web.usna.navy.mil/~bruninga/rotator1.htm I would advise that homebrewers begin avoiding circular polarization and the mechanical challenges that entails. Many of us have had good luck building the so-called 'cheap yagis': http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf My 70cm one is 8 elements; I found my 4 element 2m to be a bit under-powered for receiving AO-7, but I had fun with it for 2 years!
73, Bruce VE9QRP
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings:
I'm working LEO sats with a Kenwood D7AG HT and an Arrow II antenna. I have settled on putting the Arrow on a light tripod in a way that allows me to aim it both in azimuth and elevation and adjust for polarization. In addition, I've added a Hamtronics pre-amp to the 70 cm receiving end of the antenna. It is powered by the smallest 12v SLA battery I could lay my hands on. The amplifier is definitely the best addition to the system. I can now hear satellites at full scale quieting and tune for Doppler by ear and by looking at the scale. Recently, as I'm planning on a trip, I've gone back to work my Pryme AL-800 antenna, just to get more experience with it. Yes, I can work satellites with it and make contacts, but the difference between the Pryme and my regular setup is rather substantial.
So Bruce, I'm definitely with you on pre-amps at the antenna.
73' de Amir K9CHP Member ARRL, AMSAT #36083 Cayuga County Highland SAR www.highlandsar.org 1st Special Response Group www.1srg.org Apprentice Tracker Joel Hardin Professional Tracking Services http://www.jhardin-inc.com
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bruce Robertson Sent: Thursday, February 22, 2007 12:11 PM To: Gary McKelvie Cc: [email protected] Subject: [amsat-bb] Re: Advice on antennas for working the LEO's
Quoting Gary McKelvie [email protected]:
Several people have suggested using a vertical antenna such as a colinear. I have actually already tried this and the results are very disappointing, which I put down to my location rather than anything else as where I am is not particularly that good certainly form a VHF/UHF point of view.
Gary:
We look forward to working you on this side of the pond. If I remember the details of this thread correctly, one of your design goals for this system is to not require preamps. I would venture to say that most every antenna design or recommendation pertaining to satellite work assumes low-noise preamps as close to the antenna as possible. This might explain the difference between your experience and others' with vertical antennas.
What I love about this aspect of the hobby is the experimentation. Though my antennas are down right now, there have been many silent mid-Atlantic passes of VO-52 where I have amused myself by testing the minimum signal required for reception, used varying antennas, and switched in and out a preamp or two. Just me and an orbiting radio laboratory; thank you, ISRO!
Conducting such experiments with my pair of FT-817s and TS-2000 suggests that a preamp is terribly important, especially for 70cm downlink operation. In fact, my 70cm preamp is an indoor model, and it *still*
makes
a crucial difference. I think this is because the NF of these radios' preamps is just not devised for small-signal work. To put it more
strongly,
I would rather spend an evening doodling around on 70cm with a (indoor) preamp and a coathanger-and-bnc vertical than I would with my 8 element rotating outdoor beam and no preamp!
Your high-gain, narrow bandwidth antennas will make up for this, of
course.
But other beginners might be interested to know that by using preamps and shorter, wider bandwidth antennas it is possible to have exceedingly enjoyable LEO satellite operations with a single, azimuth-only TV-type rotor. The approach offers some advantages: such short antennas are also easier to build from scratch materials, easier to put up on in the air;
and
the wide beamwidth of the antenna makes it possible to manually control
the
rotor without too much fuss. The advantage of your az/el system is that it will be closer to HEO-ready when P3E and SSETI are launched next year. However, I venture to say that you really will need preamps then.
I started out using HRD, but like others, I have found that recent
versions
do not track SSB/CW correctly, and it seems that Simon's focus is now on the latest digital Swiss Army Knife. If you have difficulties of this nature, try the demo of SatPC32 or other dedicated programs.
Again, for others with a different set of resources, there's a great discussion of why a fixed-elevation rotor system works well at: http://web.usna.navy.mil/~bruninga/rotator1.htm I would advise that homebrewers begin avoiding circular polarization and the mechanical challenges that entails. Many of us have had good luck building the so-called 'cheap yagis': http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf My 70cm one is 8 elements; I found my 4 element 2m to be a bit under-powered for receiving AO-7, but I had fun with it for 2 years!
73, Bruce VE9QRP
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
I continue to be amazed that folks have still not gotten this message:
USE A PREAMP! It is the single most significant item for operating satellites --- succesfully!
Repeat after me: If you cannot hear em - you can not work em! If you cannot hear em - you can not work em! If you cannot hear em - you can not work em! If you cannot hear em - you can not work em! If you cannot hear em - you can not work em!
OK, got it now! You can use a very simple antenna for LEO satellites --- IF YOU USE a PREAMP! For AO-51 mode-U, I have used a 2m whip - 1/4 wavelength (20-inches high) with a 432-MHz preamp. That's it!
You can run a small yagi for your 2m uplink, pointed 20 degrees elevation and either manually rotate it or use a cheap TV rotator. I have used my 3-element Arrow antenna and 5w. Bob Bruninga has explained this a "million" times --- I admire his patience!
So what is the most important part of a satellite station? huh? eh? what?
a preamp
73's Ed - KL7UW
At 12:24 PM 2/22/2007, Amir K9CHP wrote:
I'm working LEO sats with a Kenwood D7AG HT and an Arrow II antenna. I have settled on putting the Arrow on a light tripod in a way that allows me to aim it both in azimuth and elevation and adjust for polarization. In addition, I've added a Hamtronics pre-amp to the 70 cm receiving end of the antenna. It is powered by the smallest 12v SLA battery I could lay my hands on. The amplifier is definitely the best addition to the system. I can now hear satellites at full scale quieting and tune for Doppler by ear and by looking at the scale. Recently, as I'm planning on a trip, I've gone back to work my Pryme AL-800 antenna, just to get more experience with it. Yes, I can work satellites with it and make contacts, but the difference between the Pryme and my regular setup is rather substantial.
So Bruce, I'm definitely with you on pre-amps at the antenna.
73' de Amir K9CHP Member ARRL, AMSAT #36083 Cayuga County Highland SAR www.highlandsar.org 1st Special Response Group www.1srg.org Apprentice Tracker Joel Hardin Professional Tracking Services http://www.jhardin-inc.com
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bruce Robertson Sent: Thursday, February 22, 2007 12:11 PM To: Gary McKelvie Cc: [email protected] Subject: [amsat-bb] Re: Advice on antennas for working the LEO's
Quoting Gary McKelvie [email protected]:
Several people have suggested using a vertical antenna such as a colinear. I have actually already tried this and the results are very disappointing, which I put down to my location rather than anything else as where I am is not particularly that good certainly form a VHF/UHF point of view.
Gary:
We look forward to working you on this side of the pond. If I remember the details of this thread correctly, one of your design goals for this system is to not require preamps. I would venture to say that most every antenna design or recommendation pertaining to satellite work assumes low-noise preamps as close to the antenna as possible. This might explain the difference between your experience and others' with vertical antennas.
What I love about this aspect of the hobby is the experimentation. Though my antennas are down right now, there have been many silent mid-Atlantic passes of VO-52 where I have amused myself by testing the minimum signal required for reception, used varying antennas, and switched in and out a preamp or two. Just me and an orbiting radio laboratory; thank you, ISRO!
Conducting such experiments with my pair of FT-817s and TS-2000 suggests that a preamp is terribly important, especially for 70cm downlink operation. In fact, my 70cm preamp is an indoor model, and it *still*
makes
a crucial difference. I think this is because the NF of these radios' preamps is just not devised for small-signal work. To put it more
strongly,
I would rather spend an evening doodling around on 70cm with a (indoor) preamp and a coathanger-and-bnc vertical than I would with my 8 element rotating outdoor beam and no preamp!
Your high-gain, narrow bandwidth antennas will make up for this, of
course.
But other beginners might be interested to know that by using preamps and shorter, wider bandwidth antennas it is possible to have exceedingly enjoyable LEO satellite operations with a single, azimuth-only TV-type rotor. The approach offers some advantages: such short antennas are also easier to build from scratch materials, easier to put up on in the air;
and
the wide beamwidth of the antenna makes it possible to manually control
the
rotor without too much fuss. The advantage of your az/el system is that it will be closer to HEO-ready when P3E and SSETI are launched next year. However, I venture to say that you really will need preamps then.
I started out using HRD, but like others, I have found that recent
versions
do not track SSB/CW correctly, and it seems that Simon's focus is now on the latest digital Swiss Army Knife. If you have difficulties of this nature, try the demo of SatPC32 or other dedicated programs.
Again, for others with a different set of resources, there's a great discussion of why a fixed-elevation rotor system works well at: http://web.usna.navy.mil/~bruninga/rotator1.htm I would advise that homebrewers begin avoiding circular polarization and the mechanical challenges that entails. Many of us have had good luck building the so-called 'cheap yagis': http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf My 70cm one is 8 elements; I found my 4 element 2m to be a bit under-powered for receiving AO-7, but I had fun with it for 2 years!
73, Bruce VE9QRP
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (6)
-
Amir K9CHP -
Bruce Robertson -
Edward Cole -
Gary McKelvie -
Robert Bruninga -
Tim Tapio