wrote:

Hello. I currently use a WSP255RS RCA 900MHz transmitter

http://tinyurl.com/a6y5e

to send MP3s to a Sony Spiar Receiver.

http://tinyurl.com/8ayyg

The range of the RCA is 300'.

Perhaps you mean "the quoted range is 300'". This will an absolute maximum
in an open field, /not/ through the walls of a house.

I would like to know
if there is an easy way to slightly increase the range of transmission.

Is there a 900MHz antenna amp or kit available to maximize range?

Forget amplifying it. The cheap (and pretty nasty) transmitter circuitry
won't provide a /clean/ enough signal for amplification, and 900 MHz
electronics isn't trivial - layout is /really/ crucial.

Would desoldering the flimsy antenna and putting a thicker/longer
antenna increase range?

Possibly. Try it and see.

How about making a better antenna?

Possibly. Do a Google search for a suitable 900 MHz home brew antenna -
perhaps a corner reflector type.

Something like
http://www.shed.com/tutor/mr26ant.html.

Definitely not. That's truly hideous, on the wrong frequency, and probably
doesn't work at all - he'd be better off with a random length of wire! The
"FM balun" he suggests would be seriously lossy at 900 MHz, and the
dimensions are wrong.

Bob

--
Everything gets easier with practice, except getting up in the morning!