What Mode is AO-7 In?

[KD8KSN]

Could anyone tell me how I can tell when AO-7 is supposed to go from mode A to B and vice versa?? Also, is there a certain time it switches (i.e. goes from A to B at 04:00 UTC)? I would like to give mode B a try (only have 2/440 right now), but I do not know when to listen for it.

[N0MIO]

Could anyone tell me how I can tell when AO-7 is supposed to go from mode A to B and vice versa?? Also, is there a certain time it switches (i.e. goes from A to B at 04:00 UTC)? I would like to give mode B a try (only have 2/440 right now), but I do not know when to listen for it.

Sadly There is no way to know which mode it will be in. Due do the fact it is only active in sunlight it's pretty much a guessing game. It does have a 24 hour timer that switches from Mode A to mode B and vice versa but that's also if it in sunlight fir a 24 hour period lol. So just listen to the beacon's and you'll be able to tell if it's in mode A or mode B

[KB1PVH]

Could anyone tell me how I can tell when AO-7 is supposed to go from mode A to B and vice versa?? Also, is there a certain time it switches (i.e. goes from A to B at 04:00 UTC)? I would like to give mode B a try (only have 2/440 right now), but I do not know when to listen for it.


Zach,

Check this site out, it will give you an idea as to what mode it is in. http://www.planetemily.com/ao7/ao7log.php

Dave - KB1PVH

[KD8KSN]

Thank you for the responses - this helps me out a lot! Now another question: I was thinking of using the 857d for AO-7 - how is the receive on that radio? Is a preamp needed/necessary? I know that both of you guys have 857s, so what is your experience with them?

[M3ONL]

[QUOTE=KD8KSN;2006426]Thank you for the responses - this helps me out a lot! Now another question: I was thinking of using the 857d for AO-7 - how is the receive on that radio? Is a preamp needed/necessary? I know that both of you guys have 857s, so what is your experience with them?[/QUOTE

(edited, apologies not had my morning coffee yet).
I've never used the 857 but have monitored AO-7 using a kenwood th-f7 HT and signals on the ht were good and strong, cannot see you needing a preamp.
Ok now it's coffee time before i reply to anybody else.

M3ONL

[KD8KSN]

(edited, apologies not had my morning coffee yet).
I've never used the 857 but have monitored AO-7 using a kenwood th-f7 HT and signals on the ht were good and strong, cannot see you needing a preamp.
Ok now it's coffee time before i reply to anybody else.

M3ONL

That was my thinking as well. I get an S7-S9 reading on my meter when I work AO51 and it is putting out 740mW, and I believe that I read that AO7 puts out 8W - can anyone confirm that?

[M3ONL]

That was my thinking as well. I get an S7-S9 reading on my meter when I work AO51 and it is putting out 740mW, and I believe that I read that AO7 puts out 8W - can anyone confirm that?

According to details on Amsat's page it is using an 8watt PEP power amplifier

M3ONL

[KD8KSN]

Okay - I have generated another question in my "question making factory"..... I understand that mode B (V/u) on AO7 is inverted - uplink on one sideband and downlink on the other. My question is, how do I know what sideband I should uplink/downlink on (i.e. do I uplink on LSB and downlink on USB, or vice versa)??? For all I know I may have this completely switched around in my head.

Secondly, what is the "gentleman's agreement" as to the frequencies on AO7 - is voice usually at the top and CW at the bottom or vice versa??

[KB1PVH]

,
Okay - I have generated another question in my "question making factory"..... I understand that mode B (V/u) on AO7 is inverted - uplink on one sideband and downlink on the other. My question is, how do I know what sideband I should uplink/downlink on (i.e. do I uplink on LSB and downlink on USB, or vice versa)??? For all I know I may have this completely switched around in my head.

Secondly, what is the "gentleman's agreement" as to the frequencies on AO7 - is voice usually at the top and CW at the bottom or vice versa??



You have it correct, TX on LSB, RX on USB. To answer your other question about needing a preamp with the 857. I used a pair of 857s to work the linear birds with an Arrow and no preamp. It does a good job. You are also correct about where to find voice and CW in the bandpass.

Dave - KB1PVH

[KD8KSN]

,



You have it correct, TX on LSB, RX on USB. To answer your other question about needing a preamp with the 857. I used a pair of 857s to work the linear birds with an Arrow and no preamp. It does a good job. You are also correct about where to find voice and CW in the bandpass.

Dave - KB1PVH

Wow - I am surprised that I gussed that correct..... Thanks for the help! Hopefully I can get something going in a week or two.

[W9GB]

Could anyone tell me how I can tell when AO-7 is supposed to go from mode A to B and vice versa??
Is there a certain time it switches (i.e. goes from A to B at 04:00 UTC)?
I would like to give mode B a try (only have 2/440 right now), but I do not know when to listen for it.
Zach -

The batteries on Oscar 7 (AO-7) are non-functional after 7 years of operation (occurred in 1981) ....
this satellite was launched 35 years ago (November 1974) -- my first semester in college!
http://www.amsat.org/amsat-new/satellites/satInfo.php?satID=9
So, power is ONLY available when the satellite is in sunlight (solar panels) ...
hence the on-board computer "re-starts" on every power cycle!!

USE your satellite prediction software and LISTEN ..
that is the ONLY reliable method to know which mode (A or B) that AO-7 will operate on before its next eclipse.

In January 2006 AO-7 precessed to a point where it remained completely out of eclipse until May 15 2006. During this period AO-7 has returned to it's previous schedule of alternating between Mode A and Mode B. This period of non-eclipse will return sometime in late Autumn each year for the foreseeable future and will extend well into the Spring.

AO-7 Resource Site
http://planetemily.com/ao7/main.php

Operational OSCAR Satellite Status Summary
http://www.amsat.org/amsat-new/satellites/status.php

w9gb
AMSAT-NA life member
AMSAT-UK

[KD8KSN]

Thanks for the reply. It looks like the AO7 log and resource site gives you an idea of when it goes/is going from A-B and vice versa. As long as I have a ballpark, it should work fine.

[WA9SVD]

Thank you for the responses - this helps me out a lot! Now another question: I was thinking of using the 857d for AO-7 - how is the receive on that radio? Is a preamp needed/necessary? I know that both of you guys have 857s, so what is your experience with them?

That will depend upon your antenna or antennas more than anything. With a decent beam antenna (3 el. on 10 Meters, 5-7 on 2 Meters, or 10 el. on 70 cm) you should be able to work the bird wilth not much effort.
Remember, AO-7 has linear transponders, so use only SSB or CW.
Check the AMSAT site for details as to modes to use. Mode V/A is NON-inverting, using Upper Sideband USB for both transmit and receive; while mode V/U is inverting, using LSB on 70 cm, and receiving the 2 Meter downlink on USB.

Good luck. Remember, the bird only operates when it's in sunlight, and the mode in which it operates is unpredictable; listen to the beacon(s) to determine which mode is in operation.

[KD8KSN]

That will depend upon your antenna or antennas more than anything. With a decent beam antenna (3 el. on 10 Meters, 5-7 on 2 Meters, or 10 el. on 70 cm) you should be able to work the bird wilth not much effort.
Remember, AO-7 has linear transponders, so use only SSB or CW.
Check the AMSAT site for details as to modes to use. Mode V/A is NON-inverting, using Upper Sideband USB for both transmit and receive; while mode V/U is inverting, using LSB on 70 cm, and receiving the 2 Meter downlink on USB.

Good luck. Remember, the bird only operates when it's in sunlight, and the mode in which it operates is unpredictable; listen to the beacon(s) to determine which mode is in operation.
Thank you for th help - I think I am about ready to give this thing a try.

[M0SAT]

I tend to find using Live OSCAR Satellite Status Page (Live OSCAR Satellite Status Page) gives you a good "visual" idea of which mode AO-7 is in and also if it and other satellites are on when they are mean't to be, or not.

It is a very useful resource for the ground stations if all operators "logged" their findings via this page as they are not always able to monitor all of the passes all of the time and this log helps them, which helps us.

Hope thats of use.

73 de Dave

[M0SAT]

For some reason the link failed in my earlier email so please use this URL to find the Live OSCAR Satellite Status Page http://oscar.dcarr.org/

73 de Dave

[KD8KSN]

For some reason the link failed in my earlier email so please use this URL to find the Live OSCAR Satellite Status Page http://oscar.dcarr.org/

73 de Dave

I actually use that page as well. I find that extremely useful, especially when you don't hear a bird and you want to confirm that it really was off.

Thanks for the tip!