Re: [Repeater-Builder] UHF Power

[Kevin Custer]

Jeff DePolo wrote: Would you not agree that a good UHF repeater receiver with a GaAsFET ahead of it will have better sensitivity than a typical mobile radio? If so, by what amount? Chuck Kelsey wrote: No. A "typical" UHF ham rig will have better sensitivity than most repeaters with a preamp. I disagree that a typical ham rig will have better sensitivity than a repeater receiver with a good preamp.  I have tested many repeaters with a good preamp, and many typical Japanese mobile radios, and there is about a 3 to 6 dB of difference in most cases, sometimes even more, with the repeater always being better.  If not, something is way wrong (deaf repeater receiver). A few weeks ago, Scott and I tested a 220 Micor conversion with a good preamp (ARR).  It breaks squelch at -133 dBm and has a 12 dB SINAD rating of -128 dBm.  Most of my UHF repeaters have similar sensitivity.  Most of my Japanese mobiles make 12 dB SINAD at .25 uV or -119 dBm.  This relates to a 9 dB greater receiver capability, not including site conditions, or anything else, just basic sensitivity.  Even if it were only 6 dB better, (very typical), you would need 140 watts for a matched system (considering a 35 watt mobile), or 200 watts, considering a 50 watt mobile. The math is simple, and with good repeater site conditions, this better receiver sensitivity can be realized. Besides the math, in real practice it's easy to see how well matched a properly working 200 watt repeater operates.  If it didn't make a difference, no one would pay the price to run this much RF.  The equipment costs more, as well as the electric bill, and I don't know anyone around here that would enjoy running a repeater that out-talks the receiver. Kevin YAHOO! GROUPS LINKS  Visit your group "Repeater-Builder" on the web.    To unsubscribe from this group, send an email to:  [EMAIL PROTECTED]    Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.