At 3/4/2007 20:28, you wrote: >Re: Kenwood TM-271A
>The DCI filter is only "ok" for use in a casual application. It's not >narrow by any means nor should it to be trusted to help a receiver >at a very busy location. Also depends on which dci filter you have >and how it's installed. The typical DCI 2 meter band filter is a >pretty wide beast. It's not going to help as well (on a busy radio >site) as most people would expect/hope. Check the plots at <http://dci.ca/?Section=Products&SubSection=Amateur>; they're not that bad. It did fine for this application, as all the mixes we got were in-band 2 meter signals. Ideally, you'd want to pair it with the PAR notch filter to take care of the 152 MHz paging TXs, as the rejection of the DCI filter @ 152 is ~30 dB. > > Also had problems with the IF filtering, causing the squelch to > > close on reasonably strong signals when a strong signal 15 kHz > > away was present. > >I'm not sure if I'd blame the IF section for the trouble unless I >did a lot of testing. I did; it was. I was able to tame the problem somewhat by reducing the 1st IF gain somewhat, resulting in significantly mitigating the adjacent channel squelch problem while losing maybe a dB or two at most in sensitivity. IMO, a combination of too much IF gain & defective or not enough 1st IF filtering. > > In short, one of the poorest receivers I've ever worked with. > > TX was OK though, just throw a fan on the heat sink. > > Bob NO6B > >So what did replace the radio with and how well does it work? What >type of filtering and pads did you put in front of the replacement >radio? Never got around to that. The RBI-1 kind of limits your choices. I was going to build my own "equivalent" of the RBI-1 to talk to a Yaesu FT-8500, but antenna restrictions at the site put an end to the 2 meter remote base. Bob NO6B
