Friday, October 15, 2010

The First Remote Extender modifications

Already having a remote extender "transmitter" (which picks up infrared from the remote and transmits it on radio frequencies) in the bedroom, to add remote control to the modified Sony XDR-F1HD tuner in the living room I first put a remote extender "receiver" (which picks up the RF and converts it back to IR) in the living room next to the tuner.  That basically didn't work at all.

About the same time, I got my first RF spectrum analyzer, a used boat anchor, from an eBay seller.  This was a useful test.  I used a small antenna to probe the room background noise and signals at 413Mhz, the frequency that remote extenders use.

I discovered to my horror that my beloved Tact 2.0 Room Correction Preamp is for some reason pumping out as much noise at 413Mhz as the remote extenders produce signal at that frequency.  So obviously no remote extenders are going to work in the vicinity of the Tact.  And I have two Tact's, one in the living room and another in the bedroom.  (Somehow the one in the bedroom doesn't seem to interfere with remote extenders.)

So, obviously remote extenders aren't going to work in the vicinity of the Tact, which is located very close to the Sony tuner.  I tried putting the receiver in nearby locations and using the 6 foot extension wire that comes with them with an LED at the end.  That way I could locate the receiver as much as 6 feet away from the tuner (and the nearby Tact).

Well, it seemed to work.  Several times I got it working by finding some clever location for the receiver where it didn't get as much interference from the Tact.  I tended to get it working in the night time when I do most of my listening.  Then I tended to discover that it didn't work in the morning.  I still don't quite understand why it doesn't work in the morning.  Obviously there is more radio frequency interference in the morning.  But where is it coming from?  Is there some way I can block it?

Finally I got really fed up with this approach when the clever receiver locations I found at night didn't work on the following night.  It was almost OK if it didn't work during the day.  But not working on some nights was not acceptable and before long it seemed not to be working on any nights.

About this time I also tried a bunch of different brands of wireless remote control extenders.  I found they are all very similar, with similar sensitivity.  Actually at first I thought one new brand was better.  Then I found it was worse.

Ultimately, to make this reliable, I decided to make my own extension wire with an LED at the end.  I made it long enough so that I could plug it into the known working receiver in the Kitchen.  That took 50 feet of wire, and conveniently I had a 50 foot roll of cheap 18 gauge speaker wire.  The hardest part of this was running a wire through the kitchen doorway.  I ran the wire up and around the doorway as inconspicuously as possible (but you can imagine my non-WAF house already) using AV staples (one of the most useful things to have).

Then I discovered that while the receiver in the Kitchen continued to receive signals from the transmitter in the bedroom, it would not simultaneously send them down my new wire and control the components in the kitchen.  Either plugging in the wire switched off the internal LED's, or it simply soaked up so much power that the internal LED's were no longer bright enough.

So I had to put a second receiver in the kitchen just to power the 50 foot extension wire with LED going into the kitchen, and leave the first receiver, which controls my kitchen video components, untouched.

Then while all this seemed to be working for awhile, eventually it wasn't working any more again.  I tried moving the receiver in the kitchen around a bit, putting it in different locations to see if it could pick up the bedroom signal better.  This sometimes seemed to work, but only for awhile.

Finally I decided something even more radical was required.  I would need to take either the transmitter or receiver apart to see if I could somehow juice them up a bit.  I had read stories online about other people doing it.  It sounded like something I could do, I even have equipment to test that my modifications are working properly.

1 comment:

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