Paul, If i remember correctly there was gent on this board awhile back that reported some issues with the RF switching of Ramsey preamps. I believe the problem had something to do with the switching cutting in and out while using SSB. I can't remember the exact issue. though. Still you may want to take this into consideration when making the decision whether to go with hard switching or not. 73, Michael,W4HIJ ----- Original Message ----- From: "corner5" corner5@comcast.net To: amsat-bb@amsat.org; corner5@comcast.net Sent: Sunday, October 19, 2008 4:22 PM Subject: [amsat-bb] Re: beginner question re: uplink power
Thanks for replys (Re: beginner question re: uplink power)
In response to two points contained in replys from helpful others...
Ed - KL7UW: I wonder if the Ramsey preamps allow for "hard" switching. That is
by separate control line that the radio PTT controls. Then You have no issue with RF power and would run the units with the RF sense disabled. I should state that "many" (dare I say most) experienced VHFers that run high power (>100w) use hard-wired switching. I know of NO eme stations that use RF sense control lines.
A: Ed, yes this is a good suggestion. In fact these preamps are very simple units. No, they do not have any switching that would allow for external PPT communication from the TS2000 (0-100w@2m, 0-50w@70cm). That said, I certainly could add my own mast mount external relay to do the switching. I also could simply install a DPDT or TPDT switch at the shack end and manually do the switching. This last approach could lead to smoking the preamp the one time I forget to toggle it out of line. So, in the end I chose to go with the RF sense remote switch. I hope the need to contain my uplink RF withing a chosen range (0-10 or 10-30 or 30-100 watts) will not be too limiting.
Roger,WA1KAT: Hard wiring, as has been suggested, is your safest choice. As the switch has
the relay in it, maybe Ramsey can tell you where to tap in to directly switch the sensor.
A: This is a very interesting approach. If I understand your idea here, you suggest to use the relay that is on the RF switch board and toggle this relay with a PPT signal from the TS2000 (and not make use of the RF sense at all. Yes? I do not know about the details of using the PPT signal in this way. I guess I need to hope that the PPT signal is compatible with the relay (voltage). And then if I need to abandon the RF switch all together, are there suggestions as to what is a good (not too expensive) remote relay design?
thanks all! .paul AC0z