use a different antenna...that is the best suggestion really.
Even a long piece of wire....as long as you can get in your circumstances.
There are quite a number of different adapters you can get for the female 
SMA connecter on the ic t90 to hook a wire up to.
the stock antenna is designed for 2M 70CM and barely for 6M...so it's 
certainly not a short wave antenna.
even 10 feet of copper wire with an end taped or tacked to the wall or 
ceiling will work far better for swl.
If you can get your hands on 10 or 15 feet of wire, you can also just wrap 
the bare end of the wire around the metal threaded end of the ic t90a stock 
antenna.
It has a small removable tip where you would normally thread on the 6 meter 
part of the antenna.  Just take that little tip off and there is a metal 
part that you can wrap a bare wire around.
This would certainly improve reception on the HF bands.
Just remember to take the wire off before transmitting on 2M or 70CM lol.
This is the quick and dirty way, but the design of the rubber duck antenna 
is going to attenuate frequencies below 50MHZ to one extent or another...so 
finding a connecter to go right on the radio itself where you can hook up a 
piece of wire would be even better.
A simple SMA male to so239 adapter, and sticking the bare wire into the 
center hole of the so239 would work well.

73
Colin, V A6BKX
----- Original Message ----- 
From: "Christopher Moore" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, October 09, 2012 9:39 AM
Subject: AM ans SW reception on the icom t90a


> Hello,
> I have an Icom t90a, and the reception on AM and SW is crap with the
> stock antenna.  Any suggestions for improving it?
>
> 73 Chris