What kind of antenna do I need for the XM?

You shouldn't have to. The radio has it's own antenna. In some cases you can use the existing antenna for your radio.

You will not be able to tune in TV stations unless you first have a TV antenna installed. Once connected to a working antenna the set should find stations easily enough ?

But you do not need to tune anything in to use it with your skybox -simply connect the skybox to the TV using an HDMI cable (available anywhere that TV's are sold) noting the number of the HDMI socket that you plug in into on the TV. Then, using the TV's remote, set the TV to input signal from that input (HDMI 1 for example) and you should be fine?

If you are getting the same "check antenna" message with two different antennas, it is likely that the tuner itself is the problem. You can get just the mini tuner here:

http://www.tss-radio.com/products/xm-mini-tuner-replacement-home-dock


As far as the two plug connection, there are adapters available. Its likely a dual fakra connection, though I don't know for sure. At any rate, this is one adapter available. (I would call to confirm)
http://www.tss-radio.com/products/sirius-dual-to-single-antenna-adapter

To receive XM weather or audio, the GPSMAP 740s requires a GXM 40 Smart Antenna with XM subscription.

The GXM 40 Smart Antenna (010-00730-00) is used to receive weather and audio service from XM satellite radio. For details on XM services please visit our XM webpage.

Once a GXM 40 Smart Antenna has been connected to the GPSMAP 640, the device can display the subscription information for the antenna.

From the Home Page in Boating mode:

1. Select Configure
2. Select System
3. Select System Information
4. Choose Weather Subscription

From the Home Page in Driving mode:

1. Select Tools
2. Select XM Services
3. Select XM Radio
4. Set the channel selector to channel 0
5. Select Radio ID

The subscription information will now be displayed on the screen.

Unit is very straightforward to operate. Hold down O/1 button for power. Use the "mode" pusbutton to cycle thru AM/FM/CD/AUX/XM. Treble & Bass settings are made by turning the 'tuning' knob.
For radio and satellite presets, hold in the numbered pushbutton until it beeps, and then it's set. You should be able to hear previews on XM channel 1,and that will help you with antenna setup. I highly suggest using the remote XM antenna. The built-in XM antenna need to be put 'propped-up' outslde, otherwise you have to use the external antenna. Use AC power as it eats batteries, or use rechargeable D batteries. Let me know if you have any more quesions. okay?

what kind of deck is it? what kind of car? its possible you have the amp turn on mixed up with power antenna wire

You best bet - if you can get to the rear of the XM tuner unit, is to temporarily connect a magnetic-mount XM antenna and see if it works. A bad antenna usually says "check antenna" - not loading could be a good antenna with a bad location. I would try the little XM antenna by itself, then go from there. $20 is a lot cheaper than $500. Let me know how it works out.

You begin by setting up your existing (((XM))) antenna the one that came in your home kit (not included in repeater package) in a location that gets good reception of the (((XM))) signal. This may be outside, or on a south facing window sill. This antenna gets plugged into the rear of the Delphi (((XM))) Radio Signal Repeater Transmitter. A power jack is right next to the antenna connection, and should be plugged in and to the wall with the included power supply. There is also a "PWR OUT" selector switch on the rear of the unit which allows you to control the strength of the signal transmitted from the unit.

Once the power and antenna are attached, both blue indicator lights will light up on the face of the unit. The blue antenna indicator will light up only to signify that the antenna is attached correctly. It does not let you know whether your antenna is in a location receiving a good (((XM))) signal or not. You will have to look at the signal strength indicator on your (((XM))) radio receiver do determine best location for the (((XM))) antenna.

Once you have this setup, place the Repeater Antenna close to your existing (((XM))) Radio and plug it into your antenna jack on the (((XM))) radio cradle. This connector is identical to your (((XM))) Home Antenna provided with all Boom boxes and (((XM))) home receivers and kits so compatibility is guaranteed. The Repeater Receiver Antenna does not require any separate power connections. Hope this helps!
SATELLITE RADIO WAREHOUSE

hi there..this will be like a walk in a park...first, in your home kit you should be having the ff: antenna, rca cable(audio cables), power adapter & docking station. We just have to 'placed the radio into the docking station' then we just have to plug in the ff cables into the xm receiver..we can start plugging in the rca cable(one ended connector) into the ' audio out ' of your xm radio...the other ends of the rca cables should be plug in into the 'audio in'(at the back/infront of your sound system)...plug in the antenna in the 'antenna out' of your xm( the antenna should be placed into a south facing window and not being block by tall trees and buildings outside)....plug in the power source and turn on the radio....if you got it right you should now be getting the prev.channels/emergency allerts...u can call xm to send a refresh for you to get the complete channels..or you can do it online by logging into www.refresh.xmradio.com(if the radio was already activated) if not, you have to call xm radio to activate it..enjoy listening to xm..Godbless..

Broken antenna cable. Likely you have a kink or worn thru point on the wire somewhere.