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Re: WiSP, AO10 & FM sats



Hi Michael

Fodtrack will show uplink/downlink freqs in real time without connecting to
a rig (you might have to specify a dummy rig like an FT-847). It shows the
frequencies whether or not my rigs plugged in or not. It's a DOS app but has
worked OK for me under W95 & W98 (_not_ NT).

I'm not sufficiently experienced to comment on the AO-10 beacon.

It sounds like you're suffering with some inband intermod quite badly. What
RX are you using, and do you have any idea where the packet intermod is
coming from, eg what power, how far away etc? Inband intermod is quite
tricky to remove, normally requiring purpose built or tuneable notch
filters.

Intermod when you transmit under mode J may be sorted out either by a 2m
bandpass (or low pass) filter on your TX, or you may have a 2/70 duplexer in
your shack where you can use just the 2m side, terminating the 70cm port
with a 50 ohm dummy load. This attenuates the 2m third harmonic. Placing a
70cm bandpass filter on the RX to rid yourself of the third harmonic of your
2m transmitter will unfortunately do nothing to help you.

73 Howard G6LVB

----- Original Message -----
From: "Michael Hart" <mhart@terrigal.net.au>
To: <amsat-bb@AMSAT.Org>
Sent: Thursday, September 28, 2000 8:12 AM
Subject: [amsat-bb] WiSP, AO10 & FM sats


> Well.  I have quite a lot of things to ask.  I know I have asked this
before
> but didn't get any response.  Do any satellite tracking software tell you
> the doppler shift on both the uplink and downlink freqs.  I know some of
the
> software will calculate it and automatically adjust the freqs in a CAT
rig -
> but I have an old radio which I have to tune by hand so would liek the
> numbers to be displayed.
>
> I have put "nominal" freqs into the satellites I am interested in for WiSP
> under the Setup|Satellite Setup option.
>
> There is a "Doplr" space in the main window and a "Doppler" space in the
> Graphics tracking window [after I finally got the program to actually
work]
> but there in no numbers there.  How do I get the program to fill in these
> numbers?
>
> OK.  Item #2.  AO10.  I think I heard AO10's beacon yesterday but haven't
> heard it before or since.  Also I cannot hear myself on the downlink.  I
get
> quite a number of birdies on 2m here so I find it difficult to be sure I'm
> listening to a real radio signal or some weak signal interference (or even
> some intermod interference).  It would be helpful if someone were able to
> give a reasonably detailed description of what AO10's beacon is currently
> meant to sound like, how far off 810 I should stop searching for it and
> generally its current status.
>
> FM sats.  I seem to be able to get into these for about one over again -
> particularly when they are going down the eastern coast of australia.  I
> have some mountains to the north and west (and a little further away to
the
> south also) which limit my view until they come up to about 25 to 30
degrees
> on the 70cm downlink.  I belive WiSP has facilities for taking into
account
> surrounding high objects.  This means I will have to go back up on the
roof
> and actually measure the angles to the mountaintops some how in the
various
> directions.  I am not sure if my antenna has "holes" in its pattern.  I am
> using a 5/8 ground plane tuned for 70cm for bothe the downlink (70cm) and
> uplink (2m) - I expect there will be a hole when the sat is directly
> overhead but otherwise these antennas don't have too much gain.
>
> One of my biggest problems is trying to sort out real (wanted) signals
from
> the muck.  I seem to get some "birdies" as I have said before.  I also get
> some intermodulation when I transmit.  This has thrown me a number of
times.
> I though I was getting a real return from UO14 for over 30 minutes ;).
Then
> I turned the 70cm preamp off and it went away.  I find that with the 70cm
> preamp on I get a lot of blanking on the receiver when I tune the
> transmitter across the 2m band.  In some cases it blanks it out completely
> with a huge signal strength and at other times I also get packet data in
> with the distortion (but only when I am transmitting a carrier - I don't
> have any packet gear).
>
> Today I thought I hear a carrier from my transmitter on the AO10 downlink.
> I was xmitting on 435.125 and rcving on 145.900.  I heard the signal only
> when transmitting and it would change freq as I adjusted the VFO.  OK 0-
> well then I adjusted my output power from 100w down to <1W and turned the
> antenna side on to the satellite (90 degrees away from it).  When I keyed
up
> the transmitter again it was still there :(((  Must be another intermod
for
> my radio.
>
> Michael
>
>
>
>
> ----
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>

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