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" [email protected] To: "Bob Stewart" [email protected] Cc: "Amsat Buleitin Board" [email protected] 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: [email protected]> To: [email protected]> 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 - AE6RV> _______________________________________________> Sent via [email protected]. Opinions expressed are those of the author.> Not an AMSAT-NA member? Join now to support the amateur satellite program!> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb _________________________________________________________________ Celeb spotting – Play CelebMashup and win cool prizes https://www.celebmashup.com _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb