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🛡Home Security => Problems and Troubleshooting => Topic started by: mike on October 29, 2011, 01:42:30 PM

Title: SC12A (aka SC1200) range measured on 4 units
Post by: mike on October 29, 2011, 01:42:30 PM
Just bought 5 SC1200's from last seller on ebay.  They came in marked SC12A which I guess is synonym for them. 1 of the 5 is dead so must be returned;  since WE are the QC department for X10 nowadays, I figure this 20% failure rate is not too bad.......

I used a DS10 held in my hand to check range.  I set the SC12A on a wood workbench 20' inside my workshop from outside.  I used a couple GMRS radios, one in front of SC12a set on VOX and proceeded to do my walkabout with the DS10 in my hand.  Found all did about the same range:  60 feet thru 2 walls.  Went east, went west.  still 2 walls, about 60' range.  One did maybe 65' but all relatively the same.

I then opened one case (5 screws on bottom, no hard tabs to break - just carefully pull apart and use a small screwdriver to assist the sorta-tabs that dont have hooks to come apart).  antenna is wrapped as many have stated, just pulled it up (not glued in or anything) and slid it out the closest keypad door hinge hole;  it fits nicely.  CAreful to get batt clip in holder and sonalert in slot oriented right, then back together.  Antenna vertical of course as that is orientation of all the sending devices and if left horizontal you loose I forget how many db of sig from cross polarization;  just dont go there.

60' went to 90' range.  But also was much more robust within this range;  ie., when approaching 50-60' as std, it may miss 1 of 3 DS10 sigs;  with antenna out, it was close to if not 100% solid on every DS10 magnet trip thru 60 feet and close to the 90 feet.

Added about 3' alligator clip lead to make 36" total length and retried.  OK, so 310mhz 1/4 wave is around 8" as they put in the case, but in our case as receivers, the mismatch is more than made up for with the longer length to capture more signal.  Result was 90' maybe went to 100', but again, the robustness of each DS10 trip was closer to 100% anywhere within this range.  So I say an extension is probably better.

If I were retired and had all kinds of time I would try a vertical dipole on this to get the longer antenna length and yet keep it matched.....  if someone wants to try that and repeat these tests.....  just solder another 8" or so wire to ground on the pcb and bring it too out that hinge.  run it down while the antenna runs up - walla - dipole. 

I think from what I see so far the range with the wire simply brought out rather than bent over with 3 nintey degree  bends makes the major improvement.  At this point I have not replaced my DS7000 yet but think the range will be about the same......