David Lesher writes:

You writes:


It is attached to a 30 ft RG58U coax cable that runs back to a TNC-
to-FME adapter, then to the Sierra card.

Only a Dufus, would expect to get ANY signal down 30Ft of RG-58U at those
Frequencies......

I would be more polite but would say 30 ft of RG-58 is an excellent
dummy load at 1900...

Indeed.

But nonetheless, an el cheapo yagi for 900 MHz GSM with 10 m of RG-58
boosted the indication on my phone from no bars to all 5 bars. The
yagi sees more signal because it is higher up. The yagi gain is
probably just a but more than cable + connector loss. And it looks
like the built in antenna in the phone has a significant negative
gain.

Around here, marginal areas mostly have 900 MHz. So if you need an
external antenna at all, you probably need one for 900.

OP: There has to be something wrong with your antenna system.

73
Jon