Nate, Ok,
73, ron, n9ee/r From: Nate Duehr <[EMAIL PROTECTED]> >Date: 2007/10/24 Wed AM 10:25:31 CDT >To: Repeater-Builder@yahoogroups.com >Subject: Re: [Repeater-Builder] Re: duplexer isolation and reciever noise > > >On Oct 24, 2007, at 5:56 AM, Ron Wright wrote: > >> An active element does not have to have gain. I have designed op- >> amp circuits which had no voltage, current or power gain and these >> are most certainly active elements. The last I designed was to >> covert the roll of a B52 aircraft from it 70-90 volt swing to 0-10 >> volts. This op-amp did not have any gain, but was certainly an >> active element. > >You have to read carefully -- I said "capable" of gain. Not >"designed into the circuit in such a way that they EXHIBIT gain". > >> Whether a device has gain has nothing to do, by definition, with it >> being defined as active. Many transistor circuits have no gain. >> Many transistors can have no gain, but are active devices still. > >Look, are we talking about RF systems here or general terms? It >really doesn't matter. Yes, no-gain transistors are active devices. >No, we're not talking about systems that typically use them hooked to >antennas. > >For people building repeaters, "active" devices are typically the >GaAsFET's in their pre-amps, the transistors in their PA's, and >things like that. RF gain devices. > >Again, I said the english definition has some holes in it -- but for >the purposes of people working on repeaters, it's fine. > >They're not hunting down an "active diode junction" on the tower, >because they'll never find such a thing. > >If there's rusty bolts on the tower, that's passive diode action. If >there's RF getting into their PA backwards (no isolator), that's active. > >For purposes of this group's discussion, I think my definition works >fine. If you want to argue that it's inaccurate for other >electronics projects and system, I'm fine with that too. I'm easy. > >But, this is R-B, and we're talking about typical RF systems and >repeaters here. > >What's your point as it applies to repeaters? If this is leading >somewhere useful for someone building a repeater or maintaining one, >let us know. Otherwise, I'm done. I was just trying to help make >the idea of active/passive clear in a way that made sense for folks >working on repeaters. > >-- >Nate Duehr, WY0X >[EMAIL PROTECTED] > > Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
