Re: XTB - the Future of X10 has arrived!

[nobody@xxxxxxxxxxxx (Dave Houston)]

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

[snip]

>That's interesting because I have a CM11A with a date code of "4A7" (which I
>believe means 1984 but could be 1994) whose output appears to be greater
>than much more recent TM751's.  At least that's what I thnk I am seeing
>based on attenuation extrapolation since both my meters peg out at under 5
>volts.   The CM11A's got a revision code of PG0281M in case that's any help
>in figuring out whether it's 84 or 94.  I seem to recall buying it at
>Egghead just before I changed jobs, which would have made it around 1985.

It could even mean 2004. I believe the CM11A was introduced in 1997 although
it may have been in beta testing a year earlier. Where did you park your
tardis in 1985?

>When testing the XTB I plugged in various transmitters to a power strip in
>my PC room.  Then, for each one in turn, I read the output at the far end of
>the house.  To my surprise, while the TM751 was outputting from .42 to 48
>millivolts the CM11A clocked in at .58 to .62 millivolts.  Now I realize
>that there could be a number of factors that attenuate each transceiver's
>output differently but it really surprised me to see since I recall having
>measured it before and seeing an output that was half that of the RR501's
>that I been using.  I am certain I've seen lots of tables that indicate the
>CM11A's relatively anemic output yet that's not what I am seeing in the real
>world.

Since you really can't measure the maximum output, you can't draw
conclusions. Different transmitters may also react differently to loading. I
have measured several CM11As (or HD11As) as well as several other
transmitters using both a scope and one of the pre-ELK ESM1 meters which was
calibrated for 10Vpp fullscale. The CM11A, CM15A, 30001 (Stanley Homelink
tramsceiver), and HCPRF (Leviton All Housecode Transceiver) output 5-6Vpp
while every other transmitter I've tested is in the 10Vpp neighborhood.

It's easy to recalibrate the ESM1. Open it up and you'll see a
potentiometer. Using an RR501 or TM751 in the same powerstrip, adjust it for
fullscale. You should then see about halfscale with a CM11A.

>I also realize it could be just a fluke of the Monterey's measuring
>circuitry as well.  The numbers are too small to make sense of with the
>ESM1.  When the new XTB's arrive, I'm going to try to do as formal a
>comparison as I can without an o'scope and may finally come 'round to buying
>the USB o'scope you had suggested a while back.  I've regained interest in a
>lot of X-10 gear that I had to abandon because the signals just wouldn't
>reach everywhere no matter how much filtering I did.

I haven't tried to keep up with this but I think this was the best
reasonably priced USB scope a year or so back.

     http://www.usb-instruments.com/oscillo_stingray.html

>Do you think the CE limits are safety based or are they just in place to
>limit interference to nearby buildings?  I'm assuming interference is more
>important in Europe than the US because European population density is so
>much higher.

I spent nearly 20 years in the machine tool industry, importing capital
equipment from Europe (and elsewhere). In those pre-CEdays many of the
"safety" regulations in various European countries were intended to protect
local manufacturers from foreign competitors. I suspect there's still an
element of that in most CE rules with frequencies and limits set to maximize
inconvenience for US and Asian companies.

European power limits for wireless transmitters (e.g. Palmpad) are many,
many times greater than FCC limits so I doubt population density is a
controlling factor.

     http://www.radiometrix.co.uk/apps/apnt102.htm

Remember, also, that Europe uses 230V instead of 120V.