[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: ao-27

> What is the polarization on the uhf side I'm having trouble hearing it I
> a right-hand polarization is this good thanks and 73s kb3cyu 

That's a good question.  I think it all depends on whether Mars is in
alignment with Mercury and......

Seriously, AO-27 appears to be one of the most polarization-diverse LEOs.
I've experimented with both linear and circular polarizations and I find
vertical-linear to be the best for almost all conditions except very high
elevations.  At high elevations, RHCP appears to work almost 3 dB better, but
the signal is strong enough that vertical-linear will work just fine.  That is
one of the reasons the Arrow is so succesful on that bird.

The FO birds work well with horizontal at the horizon, but once they get over
20 degrees, they are definitely CP and random.  My antennas right now are
fixed RHCP (but I'm working on that little limitation), and I sometimes
suffer, especially when the shift to LHCP is on an already marginal signal.

If you are having trouble hearing (AO-27 is the hardest of the mode J birds to
hear), you might want to try a preamp.  I use one even with my Arrow.  I find
the combination of a preamp and an MFJ duplexer to completely eliminate the
3rd harmonic de-sense when using the Arrow.

Good luck,
Jerry, K5OE
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org