[amsat-bb] Re: AO-51 power levels

[Jeff Yanko]

Hi Gould!

Thanks for the update.  I recalled seeing that the power has been dropped 
because of the 2 transmitter setup for Field Day.

Apparently, what I am seeing is that if the bird is a low pass I have a hard 
time receiving it because of the distance.  A fairly high pass, 63 degrees 
turned out alright though I did notice a number of station having poor audio 
into the receiver.  If the uplink was strong the downlink was strong.  AA5PK 
and myself were a good example tonight.  We had the bird practically to 
ourselves for the first 3 to 4 minutes of the pass.  We could hear others 
trying to get in but their audio was pretty bad and hard to understand.

The good news is once Field Day is over then the eclipses begin to get 
shorter, though no connection between the two. :)

Again, thanks to you and Drew for keeping the bird healthy and the operators 
happy. :)


73,

Jeff  WB3JFS
Las Vegas, NV
DM26



----- Original Message ----- 
From: "Gould Smith" <gouldsmi at bellsouth.net>
To: <n3tl at bellsouth.net>; "Jeff Yanko" <wb3jfs at cox.net>; 
<amsat-bb at amsat.org>
Sent: Thursday, June 25, 2009 7:25 PM
Subject: AO-51 power levels


>I am still trying to tweak the power levels to get through all the eclipes 
>during the day.
>
> Tonight I changed TXA (L/U) to 210 mW and TXB (V/U) to 290 (as low as I 
> can get it without turning it off).
> The eclipse I measured on one pass tonight was 16:05 minutes +- 5 sec. 
> The eclipse time should start to decrease over the next few days.
>
> 73,
> Gould, WA4SXM
> ----- Original Message ----- 
> From: <n3tl at bellsouth.net>
> To: "Jeff Yanko" <wb3jfs at cox.net>; <amsat-bb at amsat.org>
> Sent: Thursday, June 25, 2009 9:45 PM
> Subject: [amsat-bb] Re: AO-51
>
>
>> If I recall correctly from a post last week, the U/V pair is operating at 
>> roughly 290 milliwatts RF out on transmit, and the L/U pair is at roughly 
>> 260 mW. In other words, each transmitter is operating on slightly more 
>> than SO-50 (250 mW) power levels.
>>
>> I have had passes this week where the satellite was armchair copy on one 
>> pass, and about like has been described this evening on another. I 
>> suspect the lower power levels (half or less of what has been nominal for 
>> most of the past year) and the inevitable mismatch (depending on the 
>> angle between the satellite and a given ground station) of its 
>> circular-polarized antennas to many ground stations' linear-polarized 
>> antennas are contributing to the reception differences.
>>
>> Drew (KO4MA) or Gould (WA4SXM) can comment - and I hope they will if this 
>> is incorrect - but I suspect that AO-51 continues to operate as it has 
>> recently. I appreciate very much their efforts to maintain the satellite. 
>> That being said, it will definitely prove to be a challenge to work for 
>> many Field Day stations.
>>
>> I hope I can get the one contact on it that I can count for the club FD 
>> effort I'll be a part of. And I hope that other stations will make their 
>> one allowed contact and give other stations the same chance to get 
>> theirs.
>>
>> Best of Field Day luck and 73 to all,
>>
>> Tim - N3TL
>> -------------- Original message from "Jeff Yanko" 
>> <wb3jfs at cox.net>: -------------- 
>>
>>
>>> Wondering if AO-51 is operating? Just listened for the 2357z pass and
>>> nothing received. The last time I checked the status of the bird it 
>>> shows
>>> that the 435.300 downlink was active. I also listened for the 435.150 to 
>>> no
>>> avail.
>>>
>>>
>>> 73,
>>>
>>> Jeff WB3JFS
>>> Las Vegas, NV
>>> DM26
>>>
>>>
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>
>