Hi Not all modern “5V" antennas are bothered by a +12V feed. Some are happy up to 15V. One generic white body antenna without a label on it is not always the same as other generic white body antenna without a label on it. It’s a wild and crazy world out there.
It is reasonable to check the voltage out of these older boxes and to be cautious if they are putting out +12V on the feed. It’s also reasonable to consider that there are a few older (mostly survey) antennas that claim to be “damaged by input voltages below 7V”. One wonders of course if they suffer damage when powered down on the shelf … :) Bob > On Feb 27, 2015, at 4:46 PM, Björn <b...@lysator.liu.se> wrote: > > Hi, > > AT575-142TTW-TNCF-000-RG-41-NM > > Not all 575 antennas eat the same power. Its the RG in the part number above > that specifies 4.2V to 15V DC power for the internal LNA. > > This is the most common option - but there are others. > > -- > > Björn > > <div>-------- Originalmeddelande --------</div><div>Från: Bob Camp > <kb...@n1k.org> </div><div>Datum:2015-02-27 20:21 (GMT+01:00) > </div><div>Till: Discussion of precise time and frequency measurement > <time-nuts@febo.com> </div><div>Rubrik: Re: [time-nuts] XL-DC was Re: > time-nuts Digest, Vol 127, Issue 33 </div><div> > </div>Hi > > One important caution on antennas: > > The 575 is quite happy with anything from 5 to 18V as a feed voltage and > only pulls 35 ma. There are antennas out there that don’t like voltages over > 6V. There also are antennas on the market that pull well over 50 ma. > > If the “original” box sourced 12V to the antenna and triggers as “overload” > around 50 ma, the 575 will work great with the box. If you plug a modern > timing antenna (= 5V version) into the box the antenna may be > damaged and / or the over current may trigger. > > There also are 3.3 V antennas out there, but they are rarely seen in timing > applications (yet). > > Simply put - the 575 is a great antenna and it will work on a lot of stuff. > The problem is not at all with the antenna. It’s with the stuff specified to > work with it. You have no way of knowing if it’s a 12V gizmo or a 5V feed. > > The same issue can come up with downconverter feeds. They often put +12 on > the feed to run the downconverter. It’s best to put a DVM on the feed before > attaching a nice new $1,500 antenna to it …(or even a $20 one) > > Bob > >> On Feb 27, 2015, at 1:11 PM, Russell Rezaian <r.reza...@earthlink.net> wrote: >> >> I can confirm there are at least two common varieties of the XL-DC GPS RX >> board. >> >> One uses a "normal" GPS antenna (no down-converter, provides DC on the >> antenna line for an amp in the antenna, the typical antenna provided seems >> to be an AeroAntenna AT575 variety, but I suspect other antennas that are >> similar should be fine). The specific antenna part I have is: >> AT575-142TTW-TNCF-000-RG-41-NM >> >> It's been a while since I last decoded that part number but it's a very >> easily re-useable general use GPS antenna with an integrated RF amp. Works >> over a fairly wide range of DC supply voltages and claims a slightly higher >> gain than some other standard timing GPS ice cream cones. >> >> There are also versions of the GPS module for the XL-DC that use a GPS >> antenna with an integrated down converter that is actually physically part >> of the antenna provided. >> >> The down converter antenna is normally a single integrated unit. The part >> numbers I see on one I have handy are 140-614 (TrueTime) or Model 142-6150 >> on the Symmetricom label. >> >> I don't have any details for the voltages or whether there is a reference >> frequency provided for the down converter style receiver. >> >> I have seen some suggestions that they also had a dedicated down converter >> module that could be used with "normal" GPS antennas, but I don't have any >> details on that option. >> >> If you have a RX module that needs the converter antenna there should be a >> clearly visible little label indicating this on the module itself near the >> antenna connector. If you don't have that label the RX should work with >> most GPS antenna systems (and also with most antenna splitter systems too). >> -- >> Russell >> >> Al Wolfe wrote: >>> I have an XL-DC and it has an internal GPS receiver in it. It supplies and >>> monitors 5 volts to a BNC antenna jack for an external amplified GPS >>> antenna. I don't know what the internal GPS engine is but doubt if it is >>> anything special. >>> >>> The manual describes the down converter system as an option. >>> >>> Al, k9si >>> >>> >>>> Boy I ran out to mr google and did a search and now I am wondering if some >>>> versions of the xl-dc just used a plain old GPS antenna. It sure looks like >>>> that could be the case. The manual does say down converter. Maybe it >>>> changed over time. >>>> Regards >>>> Paul >>>> WB8TSL >>>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
