Pat,

The command team is constantly working on optimizing the Battery Charge/Discharge system. This is the most critical system in a satellite. One of the tricks is to reach your battery discharge depth at the same time you come out of eclipse, a non-trivial task and one that requires a constant tweaking process. Add mode, transmitter and power changes to the mix and it becomes a fine tuning act.

The team is analyzing and compiling the information from the testing a few weeks ago. The control software is not something that gets changed very often due to the extensive effort needed to test it. There is NO simple change. As mentioned many times, we are all volunteers and we need to maximize our efforts for the things that effect the health and well being of the satellite. While there may be a some additional information that people may want published, there is just so much volunteer time in a day/night.

There may appear to be many 'simple' solutions to power management and transmit power issues, but most of them fall back to changing control software which is not a simple solution. As with any control software, adding a feature is usually pretty straight forward, it is the inadvertent change/effect to some other part of the system that causes a problem, often major.

AO-51 will be in high power mode Sept 4-11. You may see that more is not necessarily better, the fact that more people can hear the satellite means there is more competition for the satellite. You may experience more difficulty getting through the satellite. The BEST advice for any satellite operation is to maximize your receive system - i.e. beam antenna, AZ/EL rotor, and preamp. For LEO operation a small downlink yagi at a fixed elevation and AZ rotor will work very well and is inexpensive.

73, Gould WA4SXM

----- Original Message ----- From: "McGrane" [email protected] To: "Amsat BB" [email protected] Sent: Thursday, August 31, 2006 7:42 PM Subject: [amsat-bb] ECHO duty cycle

hello again-

Does anyone know what percentage of a day or orbit the echo transmitters are ON?

I've been thinking about the battery depth of discharge issue. Being that they are as a whole 4 amp hours, a 10 percent discharge would equate to about 1.6 amps for one quarter of an orbit on-time. According to drew, the transmitters are drawing about .8 amps.

I hope people are viewing depth of discharge as a function of amp-hours more than voltage ( I realize also important ).

Any comments are welcome.

Thanks, pat n2oeq

---

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On 8/31/06, McGrane [email protected] wrote:

Hi gould- thanks for information. Hopefully the command team will manage to eeck out a little more power. I'm not just thinking of myself. As I recall, one of the purposes of echo was to attract new people ( myself included ) with an easy to operate satellite. After 2 years, I now use an 8 element beam and preamp to hear echo. Take care, pat

As one of the new people who was attracted to sats in general and AMSAT in particular by Echo I'd just like to say it has worked to attract me at least. I got interested in sats just days before Echo launched and it was the first sat I had a confirmed QSO on. Right now though I'm only active when I'm out and about since I don't have a rotor for my antenna and haven't been impressed with the performance of Omni antennas on any of the FM LEO's, and I got tired of my neighbors staring at me as I waved antennas around in my driveway...but I've consistently found Echo to be the easiest to hear.

Heck I've listened to passes with just an Alinco DJ-C5 and the joke of an antenna that it comes with! It takes a good ear and some funny looking waving around to find the sweet spot but even so it amazes me at just how little antenna is needed to hear this sat. I usually use a 4el Yagi I built based off of VE6AB's handheld design ( http://va6bc.no-ip.com/jerry_pix/yagi/handheld_yagi.htm) and find it's so easy to recieve Echo that it's almost no fun! Before I built my current antenna I used a 3el yagi I built in 15 minutes for free out of junk I found in my garage based on K5OE's design ( http://members.aol.com/k5oejerry/handi-tenna.htm) and even that worked great on Echo. It was a challenge to hear AO-27 and SO-50 was hit or miss.

With my current homemade 4el antenna it's so easy I've stopped operating from home as there just isn't enough challenge to it to keep me interested. I now pretty much only bother to operate when I'm camping unless a friend wants me to demonstrate in town. With my current antenna I can hear AO-27,SO-50 and Echo all extremely easily. The hardest part is not trying too hard in regards to aiming and tuning - I tend to overcorrect too much and have to keep reminding myself to relax and not make things harder than they have to be since it seems too easy.

I sometimes wonder if people are overthinking this and making it harder on themselves than it has to be. I borrowed an arrow from a friend for awhile and really didn't care for it. It was heavier and had a tighter pattern than my homemade antennas both of which combined to make it harder to use. The s meter in my FT-470 isn't a super accurate test instrument but switching between my 4el homemade antenna and the arrow I had no difference in readings even at low elevations. However I did find it MUCH easier to aim the smaller antenna.

One of these days I'll come up with a rotator setup and be able to armchair operate....and when I do I'll probably just whip up a 3el yagi and run it at a fixed elevation as I've found it's got plenty of gain to work the current crop of FM sats.

Of course with the sat in V/S today I can't verify that it's still that easy to hear as it's been a few week since I listened to a pass. And I still haven't finished getting my S downconverter ready to go...need to find someone here in Yuma, AZ who has more experience with the higher freqencies to help me out still.

---- Jason Hitesman N8INJ

Hi Pat (N2OEQ - there are a bunch of Pats in this thread now)!

Hi gould- thanks for information. Hopefully the command team will manage to eeck out a little more power. I'm not just thinking of myself. As I recall, one of the purposes of echo was to attract new people ( myself included ) with an easy to operate satellite. After 2 years, I now use an 8 element beam and preamp to hear echo. Take care, pat

I've read your posts on other threads about the problems you seem to have in hearing AO-51. Have you tried other combinations of radio, antenna, coax, preamp or no preamp, etc. to see if you are able to either duplicate your current situation or possibly have better luck in hearing it?

Most of the time, I use an HT with a handheld Yagi. I have also used an HT with a long telescoping whip or long duckie, and have been able to work the current crop of FM satellites (AO-51, SO-50, and - when operational - AO-27) with success. I have operated from several locations around Phoenix, one site in eastern Arizona, and several locations in/around Dayton since I started with AO-51. I've never used a preamp when working these satellites. If something isn't working with your current setup, and others are reporting success with similar setups (or simpler/less-sophisticated setups), maybe some troubleshooting is in order for your station.

As for running more power, my thought is that if AO-51 was running noticeably more power than the other FM satellites, it might be a deceptive thing to a new satellite ham trying to get started. If anything, the normal AO-51 configuration is a good way to get started. If you can get on AO-51, you can get on AO-27 when it's available, and should be able to get on SO-50 even with its lower TX power. I like the high-power times on AO-51, as I get to try other antenna and radio combinations to see how small I can go and still hear and work the satellite, but I think the normal setup isn't bad either. And, based on my logs over the past few months, I actually seem to make fewer QSOs on AO-51 when it's in high-power mode compared to the normal configuration.

I have worked lots of new stations on AO-51, mostly when the satellite is *not* on high power. Just like I was a newbie last December, trying AO-51 for the first time while it was in the normal configuration. And I'm operating most of the time near the downtown area of a large US city, with lots of RF around, and I can sometimes hear these satellites down to about 4-5 degrees elevation with my HT/Yagi setup without a preamp and when the satellites running no more than 400-500mW from their transmitters.

Back to work... and looking forward to some V/S passes before the next mode change over the weekend. 73!

Patrick WD9EWK/VA7EWK - Phoenix, Arizona USA http://www.wd9ewk.net/