I am trying to install Marantz RX77 rf remote extenders in my house. They work but only at very short range. I have had similar problems with other remote extenders and also with wireless internet cards which worked but only at very short range.
Do I have an interference problem? How can I cure it?
Any help advice would be much appreciated. IR works perfectly

By a television broadcast antenna? I would have the cable company come out and do an RF leakage test.

I have a rf amp in my roofspace distributing the tv signal to about 30 sockets around the house could this cause it?

How easy/expensive is it to test for interference?

This is a very difficult problem to diagnose sight unseen.
There could be a dozen interference issues that might not be obvious to someone with minimal experience in RF transmission.

As for getting the cable company to come out and test this is a great idea and it would be up to them to quote you a price on this but make sure theyare thorough if they do come out. Check major appliances (fridges, laundry etc) as well as your phones and any thing else in the house that MIGHT cause RF interference.

Have to go now, will try to respond later.

Interesting. I have 2 rx-77's one not yet in use. swapped them and things have improved considerably. Now I have both working reasonably well but not perfectly. The probem is worst with the unit that is controlling a Pace Sky tv box.

Put apart the RX-77 far away of any metal stuff. Also try diferent locations.

I have had a similar problem with a Sony SAT-A2 DSS receiver with RF remote; it was placed within four feet of both a Panasonic phone system and a burglar alarm box. I was never able to kill those things to see if the interference went away, but I used my signal meter, located the frequency of the Sony remote (around 318 mHz), then "sniffed" around with a short wire antenna; the phone system and/or alarm were definitely the culprits. I could not move the DSS so I had to convert to Xantech XtraLinks from four different rooms.

Another time, I had the same Sony DSS model near one of those Sony receivers with the "egg" RF remote; the remote control antennas for the two components had to be about four feet apart for both components to work properly. Apparently, while the remote antenna is built beautifully to receive RF, RF garbage that is generated inside the component is not blocked from radiating from the antenna!

if you are sure there is rf interference in the house, put a variable cable line drop in the antenna cable for the rf reciever. The variable attenuator is avail. at radio shack. Start w/ 0 drop and increase level til you have the best reception. This helps to reduce the amount of stray rf recieved by the system. Once you have a value of the drop necesary, pull the variable unit out, and put in a fixed cable drop for the value you need. Good Luck.

OK guys,quick test.Disconect the CATV at the "D" Mark and terminate with a barrel spice an a 75ohm terminater then test the IR again.As said before RF leakage is a issue although you want to correct the problem without the Cable Guys unles you want to battle them.Nothing worse than a cable guy locating a bad fitting you put on......Unfortunatly I was a Cable Dog/guy back in the day