[amsat-bb] Re: ISS SSTV Active on 145.800Mhz, Stuck PTT

[MM]

The stuck PTT while running SSTV on ISS has been a known issue
since the vox box was first connected to the TM-D700 in the year 2005.  The ISS crew soon discovered the stuck VOX
transmitter issue.

One ISS crewmember left
the radio running all night sending SSTV images.  The next morning the radio was excessively hot
and would not respond to button commands until after the radio was “power
cycled”.

The Ariss vox box does not have any RF filtering inside the
device.  The devices was originally
designed to run on its own 9-Volt battery.  At the last minute, it was modified to extract power from the TM-D700. The
Ariss vox box gets its power from the D700 via a special modification to the
D700 transceiver.

The unfiltered power
is full of RF energy when the D700 starts transmitting.

The RF energy causes the VOX PTT circuit to
get stuck in a transmitting mode until the Watch dog timer in the D700
times-out and forces the radio back to receiving mode.

Marexmg, the organization that supplied the Marex SpaceCam1 SSTV
software for ISS has recommended to ARISS several times to replace the ARISS
vox box with a stable USB vox box.
ARISS has repeatedly ignored any attempt to correct the
problem.
Sincerely 
Miles WF1F  Marex
 
 
http://www.marexmg.org/fileshtml/futureprojects.html


________________________________
 From: Fabiano Moser <fabianomoser at gmail.com>
To: amsat-bb <amsat-bb at amsat.org> 
Sent: Thursday, September 5, 2013 6:57 AM
Subject: [amsat-bb] Re: R: Re: ISS SSTV Active on 145.800Mhz
 

Hi,

SSTV active with problems, PTT was activated but no audio, then after
20seconds± the audio started and goes out before the end of image.
PTT still ON without audio till LOS.




On Thu, Sep 5, 2013 at 10:22 AM, Claudio Ariotti, IK1SLD <
claudio at ariotti.com> wrote:

>
>
> Hi Jan, about your comment I read on your web, the Luca Parmitano don't use
> the Kenwood TM-D710, this radio is used by Russian crew.
> The MAI-75 Experiment is a Russian experiment and the crew activates it
> when
> Moscow has AOS, so we lost 50% of the pass.
> Luca only use the Ericsson radio in the Columbus module.
>
>  73 Claudio IK1SLD
>
>
> -----Messaggio originale-----
> Da: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] Per
> conto
> di PE0SAT | Amateur Radio
> Inviato: giovedì 5 settembre 2013 10:35
> A: amsat-bb at amsat.org
> Oggetto: [amsat-bb] Re: ISS SSTV Active on 145.800Mhz
>
> Hi Cor,
>
> Via this link: http://www.pe0sat.vgnet.nl/2013/iss-sstv-reception/ you can
> download the SSTV images I received yesterday.
>
>
> 73 Jan PE0SAT
>
> On 04-09-2013 20:47, Cor . wrote:
> > Hello All,
> >
> > Several ISS SSTV images are received from several ground stations.
> > See ISS SSTV images and info:
> > http://ariss-sstv.blogspot.nl/
> > http://www.dk3wn.info/satblog.shtml
> >
> > I asume the Russian ISS crew have sended 4 different SSTV images
> > today.
> > If someone have received other images please send them to
> > me via e-mail (see my QRZ.com page).
> >
> > Tommorow Sept. 5  between 09:00 and 10:40 UTC last day of the event.
> >
> >
> > 73's Cor PD0RKC
> >
> >
> >
> > _______________________________________________
> > Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the
> > author.
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>
> --
> With regards PE0SAT
> Internet web-page http://www.pe0sat.vgnet.nl/
> _______________________________________________
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>
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