At 12/23/2006 10:22, you wrote: >In a message dated 12/23/2006 4:43:05 A.M. Pacific Standard Time, >[EMAIL PROTECTED] writes: >Actually the famous GLB preamp is still available. After a couple coporate >buy-outs the new company is called Simrex and they still sell the original >GLB unit....and the even offer and amateur radio discount. >Here is the web page..... ><http://www.simrex.com/site/products/special.htm>http://www.simrex.com/site/products/special.htm > > > >Dan Hancock N8DJP >The GLB units are excellent but they have no resemblance to the ARR >preamps. To be fully effective, they need to be fine tuned with a >tracking generator. They are essentially zero gain preselector devices >that are more like active cavities than amplifiers. The ARR preamp is also >an excellent cost effective unit but it is a relatively broad device and >is more vulnerable to overload. Another short suit is that it's easy to >blow the Gasfet without taking the precaution by griefly grounding any >antenna connected to it to eliminate static spikes.
If you have the room, you'd be much better off with the ARR or Angle Linear GaAsFET preamp preceded by a pass cavity, or if you need a window filter (broader passband), a filter from DCI. The GLB unit is going to have an overall high noise figure (several dB), negating the benefit of the preamp. A pair of pass cavities from Angle Linear, OTOH, have ~0.5 dB of loss. Add that to a 0.5 dB NF preamp & your overall NF is only 1 dB. The GLB amplified preselector is best suited for space-constrained applications and/or where optimum sensitivity is not important. Bob NO6B
