The "golden screwdriver" is someone who does not know what the hell he is doing nor should own the "screwdriver".
-------------- Original message -------------- From: "Don Kupferschmidt" <[EMAIL PROTECTED]> Hi Jeff, "Then, last week, a friend brought over his 440 duplexer (Wacom 678) and asked me to tune it on the network analyzer as it had been victimized by the golden screwdriver." For those who are inquiring minds and not up to all of the terminology, what is a "golden screwdriver"? Don, KD9PT ----- Original Message ----- From: "Jeff DePolo" <[EMAIL PROTECTED]> To: <Repeater-Builder@yahoogroups.com> Sent: Friday, February 09, 2007 3:32 PM Subject: RE: [Repeater-Builder] Advanced Receiver Research Preamp 144-148 > > Has anyone else looked at the input return loss on their ARR preamp? I > had > one that, when put in place, was throwing off the tuning of a two-cavity > bandpass filter I had ahead of it. I swept it and found the return loss > to > only be about 5 dB. I put an Angle Linear preamp in its place and all was > well. That was a few years ago. > > Then, last week, a friend brought over his 440 duplexer (Wacom 678) and > asked me to tune it on the network analyzer as it had been victimized by > the > golden screwdriver. He had an ARR preamp mounted to the duplexer bracket. > Once the four cavities were properly tuned, I hooked the preamp back up > and > swept again, providing power to the preamp, terminating the preamp with a > good 50 ohm terminator, and sweeping at -50 dBm instead of 0. As I had > found years ago, the duplexer was severely detuned via the additional of > the > ARR preamp. A sweep of the preamp alone showed about 6 dB. Yuck. > > I'm starting to wonder if ARR tunes these using a noise figure meter only, > without regard to input return loss, gain, or anything else? Bad news if > you're terminating a cavity filter into one of these preamps. All of the > Angle Linears I've tried, on 2, 440, and 900, all had very good input > return > loss, in some cases > 20 dB. > > --- Jeff > > > > > > > Yahoo! Groups Links > > > > > !DSPAM:1016,45cce8c0690733712038390! > >
