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On Jan 17, 2:54 am, MGFoster wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I saw this 50 ohm "terminator" BNC connector at Radio Shack today and was wondering if it could be used as an antenna dummy load? It is designed as a computer network terminator - just a female jack without any output connector. I believe the only question would be "Could it stand the power output?" What if the output was just 5W? Anybody know about this product or have used it as a dummy load? It'd sure save the price of a "real" dummy antenna (it was priced about $4.00 USD). Thanks -- MGFoster:::mgf00 at earthlink decimal-point net Oakland, CA (USA) ** Respond only to this newsgroup. I DO NOT respond to emails ** -----BEGIN PGP SIGNATURE----- Version: PGP for Personal Privacy 5.0 Charset: noconv iQA/AwUBR48zz4echKqOuFEgEQJ4OwCeKdWRKG4P8cxND+FGxpF38I Syc+4AoNoU T4vopRD2S1IPgrw9CO/dW50t =TmNl -----END PGP SIGNATURE----- As others have noted, beware of the power rating. On the other hand, I have a dummy-load-on-BNC-jack that I made with four 200 ohm 2 watt metal-oxide resistors (and the connector, of course). The connector is one with a square base, four ground pins and a pin in the center, for mounting on a PC board, like DigiKey A24512-ND. I cut the lead completely off one end of each resistor, and trimmed the lead at the other end of each so when folded over back against the body it reached not quite all the way to the end with the lead cut off. The four leads are soldered around the center pin of the connector. The insulating covering is scraped off the resistor ends with no lead, exposing the metal cup that contacts the resistive element. The four ground pins are clipped off the connector, and the cups are soldered directly to the connector ground, one in each corner. The result on my HP8753E network analyzer (freshly calibrated and all that) shows return loss greater than 40dB (S11 below -40dB) out to beyond 300MHz, and greater than 20dB to about 850MHz. In other words, it is as good as my semi-precision loads out to 300MHz, and quite a bit better than a whole bunch of other 50 ohm BNC loads I have -- quite adequate for any ham work I would do out to 500MHz at least, and able to dissipate a moderate amount of power. YMMV, of course, depending on the particular metal-oxide resistors you use, and admittedly it is really helpful to have a good network analyzer around to test it on. But it should be no problem making a load that way, usable through at least VHF. Cheers, Tom |
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