This unit looks like the answer for me......I think! I am in the process of building 2 repeaters on 70cm for possible emergency use by our Amateur Radio Club. Both will be very portable, I have Vertex VX-2200 radios for one, Hamtronics T304/R306 boards for the other. In keeping the units very portable, I am using these filters
http://www.polarelectronicindustries.com/model.php/model_id/983/ These filters are being used due to portability, but I have reservations about performance IF my systems end up sited close to other equipment. Would the Simrex unit offer advantages when used with my filters? I would look to getting the higher selectivity spec, in preference to gain. 73, Jack. VK4JRC Sent from my Apple iPad Tablet PC On Jul 30, 2010, at 6:20 AM, "Steven M Hodell" <[email protected]> wrote: > More great info from Frank @ SIMREX. > > Steve ~ KA1RCI > > ----- Original Message ----- > From: Frank Neuperger > To: [email protected] > Cc: Steven M Hodell ; maqui >> Mike Aquilino ; [email protected] > Sent: Thursday, July 29, 2010 4:15 PM > Subject: Re: [Repeater-Builder] Fw: TKR750 -Preamp > > Steve, > > That did not post to the list because I don't have membership. I would > appreciate if you would forward to the list on my behalf. > > Regards > Frank > > On 7/29/2010 3:58 PM, Frank Neuperger wrote: >> >> Steven, >> >> Thanks for the vote of confidence. We sell them to Hams (Ham >> frequencies) for $275($25 less than 2-way dealers) as a gesture to Gil >> Boelke (silenet key) who developed the preselector and founded GLB (now >> owned by SIMREX). >> >> Note that the standalone preselector is still made in house by staff that >> were trained by Gil and on tooling built by Gil. >> It is also the front end of every SNRDS-II radio. Same radios that are part >> of many FAA and other Federal systems. >> >> Standard gain is 8 db >> >> For +$25, you can order it with ~4 dB gain and steeper skirts on the filter >> or >> ~11 dB gain and gentler slope on the filter skirts. >> >> For extreeme interference, one usage of the preselector has been to place >> a coax stub notch filter between the antenna and the preselector. I have >> done ~3MHz spacing of the notches of the comb for a marine radio BASE >> application using ~ 35?? feet of LMR 400 for my stub. One of the notches >> was placed directly onto the frequency of collocated marine base station >> giving us an extra 22dB of suppression at that frequency. Using excessive >> length of coax resulting in a comb allows the overallbandwidth to repeak >> steeply and with minimal loss between the notches of the comb. A single >> notch approach (not a comb) when placed close to your desired carrier will >> often have unacceptable insertional loss at your desired frequency. The >> comb notch filter is just extra coax and minimizes the insertion loss close >> to the notch. . The calcs for length are not too difficult. >> >> Warmest Regards >> Frank Neuperger >> Simrex Corporation >> VE3FNZ >> > > ----- Original Message ----- > From: Steven M Hodell > To: [email protected] > Cc: [email protected] > Sent: Thursday, July 29, 2010 2:34 PM > Subject: Re: [Repeater-Builder] Fw: TKR750 -Preamp > > > Another very good choice for this application is the GLB Preselector / Preamp > from Simrex Corp. > > I have several of these deployed on 144 / 220 / 440 Amateur repeaters and > they all perform very well. They can be tuned to maximize gain or selectivity > per your requirements and their support is outstanding. > > http://www.simrex.com/site/products/special.htm > > PRESELECTOR PREAMPLIFER > > Low cost solution to interference, intermodulation and desensitization > problems. > Helical Resonator Design. > Preselector Specifications (pdf 63k) > Preselector Example Diagram (pdf 10k) > >
