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Re: AO-7 Mode A difficulties



> I hope that this helps,
> Auke, VE6PWN

Well, everything helps.  :)  I do hear a very few stations, and I hear
them fairly well.  But, I guess from your post and from Bob's, I don't
have quite enough power for SSB.  Oh well.

tnx & 73

Bob - AE6RV

--- "Auke de Jong, VE6PWN" <sparkycivic@shaw.ca> wrote:

> Is there any issue with using circular polarization for uplink to AO-7?  I 
> have heard that some sats prefer left-hand uplinks, while others prefer 
> right-hand.  I presume that it is most likely linear-polarized up and down.
> 
> Personally, I think the big difference in modes could be to do with two 
> issues:
> 1: the transverter design is  very different between those modes, the mode B 
> is the newer "helaps " design that is aparently very efficient compared to 
> conventional designs such as what makes up the mode-A portion.  This might 
> be enough to make a difference in being heard in ssb.  Since there's limited 
> power from the aging solar panels, it seems logical to assume that the 
> less-efficient components would be struggling to work proplerly.
> 2: There's likely a lot of broadband QRM making it up to space on the145 
> uplink... it would eat-up the available power without being detected unless 
> you used a spectrum scope on the entire downlink band.  Also consider that 
> the mode-A transverter is twice the bandwidth of the mode-B(50kHz compared 
> to 100kHz), therfore there's twice as much input noise getting to the 
> amplifier and hogging-up the available power even under ideal conditions.
> 
> I hope that this helps,
> Auke, VE6PWN
> 
> 
> ----- Original Message ----- 
> From: "Robert Turlington" <rob_g8ate@hotmail.com>
> To: "Bob Stewart" <bob@evoria.net>
> Cc: "Amsat Buleitin Board" <amsat-bb@amsat.org>
> Sent: Sunday, November 04, 2007 1:21 AM
> Subject: [amsat-bb] Re: AO-7 Mode A difficulties
> 
> 
> 
> Hi Bob
> you are not the only one that struggles with AO7 mode A,I find that even 30w 
> into a 6 el Quad pointed at the bird gives a good downlink ,it also depends 
> on how good your Rx antenna is as well as things like background noise 
> levels.Regards Robert G8ATE > Date: Sat, 3 Nov 2007 16:18:10 -0700> From: 
> bob@evoria.net> To: amsat-bb@amsat.org> Subject: [amsat-bb] AO-7 Mode A 
> difficulties> > I've made several attempts efforts to work AO-7 on > Mode A, 
> but I just don't seem to be able to manage it. > I can hear CW signal, and 
> if I whistle into the mike, but I > just can't hear my voice well enough to 
> even attempt a > QSO.> > I'm using an 80 watt Mirage brick into an RHCP 
> moxon > pair pointed straight up. I don't have any problems getting > into 
> the FM sats with this setup. Is it because I'm only getting > about 40 watts 
> EIRP from this and that's simply not enough> for AO-7 Mode A?> > Bob - 
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