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measuring cable loss
Down in the lab here at work we have a whole rack of precision misterminations (1.1:1, 1.2:1, 1.5:1, etc.) that some talented engineer built and calibrated some decades ago. They're built on the Maury bluedot N terminations. I have always though that a budget priced set of mismatches would be real handy, and have wondered why MFJ (or someone else for that matter) don't offer a set for checking / calibration of the MFJ259B etc. Owen I've looked into this, and it's non-trivial to do in small quantities at a (ham)reasonable price. My late father-in-law owned a small company doing video and audio equipment for the broadcast industry, and one of their larger selling product was a high quality 75 ohm BNC termination. However, it took a fair amount of research on his part to find appropriate components from which to assemble them, and even so, I doubt his manufacturing cost was low enough to get to a reasonable retail price for the ham market. FWIW, 75 ohm terminations are readily available, as a mismatch standard that might be useful. In F connectors they are available for less than a dollar, but I'd be a bit leery of their precision (1% DC resistance is easy to get, but over DC-100 MHz, a bit trickier). Good quality (mechanical and electrical) seem to run about $4-5 each. In small quantities, it would be hard to make and sell such things for less than about $5 each (by the time you factor in mfr time, material costs), and then there would be shipping. You might be able to do better with selling a set (say, open, short, 50, 25, 75, 100, etc.) because there would be economies of scale, both in mfr and in shipping/handling. Maybe $30/set plus shipping? I can see all the folks going.. $30, for half a dozen connectors and resistors? I have a box of connectors out in the shack, and resistors, and I'll just fire up the soldering iron... |
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