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Re: Power on AO-7.



I absolutely agree. In fact, I have used my FT-817 and Kenwood TS-440
for receiving the downlink and without a preamp and using a Butternut
vertical (differently not the best for satellite work) and have done
reasonably well. Although granted, a preamp or some other form of
antenna such as a loop, dipole, sloper, or even a beam would do better
most of the time, the signal (when there is no skip) is respectable.
However, due to my own deficiencies, I prefer mode "B". I found that a
sloped (radiating element sloped 30 degrees) ground plane for the
downlinks on most frequencies work quite well. I have one for 70cm, and
2 meters and thought about doing one for 10 but picked up the loop and
plan on trying it first.

Although the 10 meter downlink is weaker than before, it has been a
dependable and predictable bird (minus the mode it appears in of
course), and has been fun to work in both modes. I plan on putting up an
MFJ active loop that I have and see how it perrforms on mode "A".

AO-7 is quite easy to work, almost as easy as old RS-5/7 so most anyone
with hf/vhf should be able to work it. Also, if I had a 10 meter preamp
I would do even better on the downlink, but I seem to manage okay. On
mode "B" however, I find myself reducing my power down to 2 watts to
keep from over-loading the transponder due to AO-7's sensitivity on that
mode and even then it still comes though rather strong.

Hope to see others of you on AO-7. It still a reasonably quiet bird and
should be busier with AO-40 down. It has a nice foot print as well due
to its orbit height. I will not be on myself for a few weeks as I will
be out of town, but mid next month I should be back on.

By the way, we have even had up to 10 in a roundtable with little
problems. Join the fun!!!!



john hackett wrote:

> This note is copied from THE EU AMSAT pages.
>
> <http://groups.yahoo.com/group/eu-amsat>
>
> Hi All,
>       We all know about the power problem
> on AO-7. What some people might not know is
> that the mode-A transmitter originally only
> had 2 watts. These days, almost 30 years on
> the estimated output power is probably only
> about 500mW.
>
> Therefore, don't expect BBC/CNN type signal
> strengths. A good 10m antenna is a *MUST*.
>
> I work mode-A with 5w EIRP! on 20 year old
> equipment so there's no excuse for...."but I
> don't have the latest all singing, all dancing
> Icom/Kenwood/Yaeso".....etc etc.
>
> I use a simple sloping dipole feeding a homebrew
> BF981 preamp to a Microwave  Modules 10m to
> 2m converter to a 20 year oldFT-290 on receive.
>
> I use a similar (barefoot) transmitter with an
> EIRP of approximately 5 watts. This setup works
> fine for CW QSO's (providing one uses the ears!)
> but is obviously not recommended for SSB.
>
> For more information check out W0EEC's excellent
> AO-7 Resource Page. (link from AMSAT-NA's site
> under AO-7 information).
>
> See you on mode-A.
>
> 73 John. <la2qaa@amsat.org> <la2qaa@hotmail.com>
>
> _________________________________________________________________
> MSN Hotmail http://www.hotmail.com Med markedets beste SPAM-filter. 
> Gratis!
>
> ----
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>


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