[amsat-bb] Re: AO-7 Milliwatt Report

n3tl@bellsouth.net n3tl at bellsouth.net
Wed Jun 3 09:25:14 PDT 2009

Hey everyone,

Please forgive the pun (that is a warning!) ... but to amplify Bruce's thoughts....

Milliwatt contacts on VO-52 will be routine for anyone who chooses to take this approach. It is a wonderful little satellite, with outstanding performance. 

As mentioned in my earlier post, I intend to see how my ability to hit AO-7 on a half-watt changes when I use CW instead of SSB. There should be another pass yet this week that will permit this, and I'm looking forward to it.

Bruce also is right about the coverage of AO-7. According to the map that Orbitron displays when I'm in simulation mode, here is a general idea of the satellite's footprint at 13:17 UTC, when K8YSE and I were finishing our contact.

The southern edge of the footprint literally was on the equator, and the northern edge appears to have been at roughly 70 degrees North. The eastern edge was at roughly 40 degrees west, with the western edge at roughly 130 degrees West. As a result, all of the lower 48 states were in the footprint, along with about the eastern 70 percent of Canada. All of Central America was in the footprint, along with portions of Ecuador, Colombia, Venezuela and Guyana. All of the islands representing various DXCC entities in the Caribbean were in the footprint, as was Bermuda. 

73 to all,

-------------- Original message from Bruce Robertson <ve9qrp at gmail.com>: -------------- 

> On Wed, Jun 3, 2009 at 10:57 AM, wrote: 
> > Hey everyone, 
> > > My thanks to K8YSE, who heard my faint CQ on AO-7 at 13:16 UTC this morning and called me. We had a contact that lasted about a minute with a few exchanges, which is really a thrill here because I was transmitting a half-watt out on a 
> Yaesu FT-817ND. 
> > > As I suspected from the "test run" the other night, my setup here requires that AO-7 reach roughly 50 degrees elevation before I can hear myself at all on this lowest-of-all power settings for my SSB/CW satellite station. I also suspect I can lower that elevation some by working CW instead of SSB, and I 
> intend to find out on the next really high pass over me. 
> This is an interesting experiment. It is worth pointing out to those 
> who might not be familiar with this bird that 50 degrees as a minimum 
> elevation on AO-7 is much more practical than for lower elevation 
> birds, such as AO-51. I suspect the time that AO-7 is above 50 
> degrees on some passes is about the same amount of time that VO-52 is 
> above the horizon! Moreover, because of the greater footprint, when 
> you transmit to AO-7 overhead, you might still reach a different 
> continent or other excitingly distant stations. 
> Another consideration regarding Tim's experimental approach is that it 
> is ideal for situations in which a low-gain antenna is being used for 
> reception. It is better for everyone if in these circumstances we do 
> not increase our transmission power until we can hear ourselves 
> (especially on AO-7, which FMs quite a bit). Keeping the xmit power 
> low and waiting until it can be heard is a good way to experiment 
> without causing problems. 
> 73, Bruce 

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