Topband: Diversity-capable transceivers

[Barry N1EU]

Thanks Tom.  FWIW, Ten-Tec offered an upgraded subreceiver (RX366) for the
last year or two of Orion2 production (very similar to main rx, adapted
from their Eagle xcvr).  At the same time, the Orion firmware was updated
to offer a front panel feature to manually adjust the RX366 oscillator
frequency in 0.1Hz steps to precisely zero beat again the main rx.  It
works well and maintains the phase relationship over time as well as across
the bands.

73, Barry N1EU


On Tue, Dec 1, 2015 at 12:19 AM, Tom W8JI <w8ji at w8ji.com> wrote:

> Barry,
>
> It is more than just second receiver quality. For maximum diversity
> effect, the receivers must use a common time base for both channels. They
> do not have to be phase synced (unless blended into mono), a person's brain
> will learn around that. The channels should not drift phase when on a given
> frequency, and if phase changes with tuning, it should be very gradual.
>
> This can be checked by running a common oscillator or carrier signal into
> both channels and listening in mono. Another test is observing background
> noise with a single antenna common to both channels. Listening in mono can
> be as simple as laying the headphones on the desk. There should be no beat
> warble or no fading and peaking on a carrier, and when the band is swept on
> noise any change in apparent audio level with frequency change should be
> very gradual.  Ideally there should be no changes at all.
>
> My R4C's, because I used one receiver's oscillators to run both channels,
> were perfect. The K3's I have are imperfect, they have a gradual phase
> change between channels with frequency.
>
> My FT1000D was terrible, as was the Orion I had. They gave some diversity
> effect, but were so far unsynced they did not give the deep noise digging
> the K3 or R4C system would.
>
> If you never use a system that is phase locked, you might not realize the
> difference. The channel audio phase relationship has to be stable without
> drift to get the real enhancement.
>