Jim, The M12M will actually put out +5V to the antenna. The antenna voltage that you supply from your electronics are just "passed through" to the MMCX connector on the board. If you have 5V available on your board you can simply use this to run the antenna. The only thing the M12M electronics do is that they will protect the antenna supply against short circuits. If you draw over about 80-90mA (or short the coax) the M12M will interrupt the antenna power.
In general, timing antenna electronics are just about the same as "good" mobile antennas. By good I mean that they have at least one ceramic/SAW filter. These usually add about -20dB of rejection at +/-50MHz from Fo (1575 MHz). This really helps reject nearby RF, especially if you are surrounded by cell phone towers and the like. The major physical difference is that timing antennas carry around their own ground planes (that's why they are usually bigger than typical mobile antennas). Timing antennas are also more easily mounted to a mast or other structure. They also are usually just terminated with a TNC or N type connector so that the user can size the antenna cable to fit the application. They'll last a lot longer outside too.... My suggestions: Budget installation: AR-10N, AR-10S, or ART-10S. I have a lot of experience with all of these. They all have dual-pole filters (-40dB @ +/-50MHz). Low-Budget Timing: Timing3000. Again, dual-pole filter. High-End Timing: VIC-100. Triple filter. If you are in a bad RF environment, this is the one to get. -60dB @ +/-50MHz. Cable: 10m of cable will not be a problem. You could get away with RG-58 (-6.5dB for 30'). If you go with the Timing3000 you might want to bump up to RG-8X as the Timing3000 LNA gain is a little on the low side. If you can find some dual shielded cable (LMR-195 (RG-58 equivalent) or LMR-240 (RG-8X equivalent) these would be preferable due to the better shielding and RF characteristics. They will also stand up to the weather much better because the jacket is much tougher than PVC. Hope this helps, Randy Warner ___________________________________________________________________________ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Miller Sent: Thursday, June 14, 2007 9:12 AM To: time-nuts Subject: [time-nuts] Antenna recommendation for Timing Amateur I'm planning on getting a M12M and would like a recommendation for an antenna for timing purposes. I'm just an amateur looking to discipline an oscillator. No scientific uses planned. My antenna coax is likely to be 30ft or more so I suspect I'll need an amplified antenna. The M12M outputs 3v so the "timing" antennas offered by Synergy don't directly apply. What is the real difference between a "timing" antenna and one meant for mobile use? Synergy offers several amplified mobile antennas that would work with 3v. tia jim ab3cv _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
