[amsat-bb] EO-80 FM Transponder Tested (noise floor?)

Paul Stoetzer n8hm at arrl.net
Wed Jun 17 16:59:24 UTC 2015

The noise peaks on AO-7 are actually coming through the transponder,
not local interference. I don't know if they've always been there or
not, but often the noise peaks are stronger than any of the signals in
the passband.

As far as SO-50, the transmitter running at just 250 mW is probably
part of the reason why the batteries have lasted 13.5 years. AO-27
could only operate the FM transmitter for short periods during it's
orbit and AO-51's batteries lasted only 7 years.

Keep in mind that you'll be able to hear EO-80 and Fox-1 much better
through the trees, but now your uplink signal will be impacted more by
the trees. One medium deciduous tree attenuates signals on 70cm by up
to 10.5 dB.

SO-50 is lots of fun, but it can be frustrating because so many people
just can't hear it and continue to transmit anyway. I hope lots of the
problems we see day-to-day using SO-50 will be reduced by the stronger
signals of EO-80 and the Fox-1 series. One minor thing is that tuning
the uplink will be a bit trickier than tuning the downlink for
stations that are running half duplex. They'll have to remember to
tune the transmit frequency up 5 kHz about 4 times during the pass.

Anyone who wants to program memories for EO-80 should follow this plan:

EO-80 AOS - TX 435.070 MHz 210.7 Hz CTCSS, RX 145.840 MHz
EO-80 2      -  TX 435.075 MHz 210.7 Hz CTCSS, RX 145.840 MHz
EO-80 TCA  -  TX 435.080 MHz 210.7 Hz CTCSS, RX 145.840 MHz
EO-80 4      -  TX 435.085 MHz 210.7 Hz CTCSS, RX 145.840 MHz
EO-80 LOS -  TX 435.090 MHz 210.7 Hz CTCSS, RX 145.840 MHz


Paul, N8HM

On Wed, Jun 17, 2015 at 12:42 PM, Nicholas Mahr <nicholasmahr1 at gmail.com> wrote:
> I notice 2M has a high noise floor when im working AO-7, Theres a few same
> spots on the passband that have these giant swooshing sounds/etc, It wont
> be a problem on EO-80 as I as well have found it dosent affect me on FM,
> maybe EO-79. Looks like we wont have to wait for FOX-1 in september to
> cover for SO-50... Its really hard to do portable FM operations here where
> I live, theres lots of trees, so it makes working SO-50 very difficult
> because of its 250 mw power, I wish they would just increase the power on
> the thing.
> 73 KE8AKW
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