Re: [Repeater-Builder] GLB Preselector Preamp, Re: midland 13-509 220mhz to convert to repeater

[Kevin Custer]

Bob Dengler wrote: At 8/2/2005 06:55 PM, you wrote: Joe wrote: I had an FM76 convered to a 220Mhz repeater and used a GLB preselector in front of the receiver. It helped a lot. Unfortunately, the GLB is no longer available. Are you sure? <http://www.aria-glb.com/products/reset_frames.htm?/products/preselector.htm> Kevin Anyone measure the noise figure of one of these units? Even with the GaAsFET preamp, the overall NF is going to be high if the helical resonator loss is too high (resistive loss = NF). Bob NO6B While I have never measured it, I can tell you the noise figure is higher than a stock Hamtronics receiver with GaAs Fet's.  Of course, this unit should be used to filter out of band signals on receivers that don't include a good front end filter, not as a preamp.  The preamp is only there to recover some of the loss of the unit, not to add sensitivity.  If the receiver is already good, this preselector/preamp *can* make it worse, but, I'd bet it would add usable sensitivity to a Mastr Pro type receiver with a basic sensitivity of .5 uV.  I have found that the resulting sensitivity is slightly better than a good Micor or Mastr II (without a preamp) with this P/P combination added to an already decent receiver (Hamtronics R100, or the like).  On VHF (including 220) , I have found nothing that beats a good Micor RX with its companion helical preamp. 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.