[TenTec] Omni vi+ and Alpha 87A

John, ke5c ke5c@hot.rr.com
Sun, 15 Jul 2001 14:32:15 -0500

Last weekend my friend unplugged the cables from his FT1000D, removed it,
set my Omni vi+ into the same physical space, and reconnected the cables.
We determined the drive level which made his Alpha 87A happy.  (Jay, that
plus a three antenna stack of 15 total elements is why I was loud on the net
last week.)  He used the Omni and Alpha several times during the week, but
early on during IARU, I kept tripping the 87A out.  I reduced drive to get
about 1000W out instead of 1500W, and had the same *intermittent* problem.
I would make several QSO's without difficulty, not change the band or
antenna direction, and suddenly the 87A would trip out.  I soon noticed that
the forward and reflected power on the 87A jumped just as it kicked out.
Thinking maybe there was a loose connnection in the antenna system, I
changed from 40M to 15M with the same result.  We uninstalled the Omni and
put his FT1000D back in place, and I operated the next 12 hours without

Another interpretation of the forward and reflected power surging would be
slow or poor ALC performance allowing a spike in the drive to the 87A
transiently harder.  Does anyone have any experience with the Omni vi+ or
perhaps just generically with TenTec power amps and ALC driving an 87A which
is just loaded with protection circuitry?

73, John
P.S. the FT1000D is a fine rig, I just wanted to operate with my own rig for
psychologic reasons, so no comparisons please.

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