I recently acquired a Zephyr Geodetic Model 2 (GPS+GLONASS) when I bought a used R7 receiver.
On the NGS antenna calibration pages there are two similar antennas: 55971.00 (trimble antenna code: GS) and 57971.00 (trimble antenna code: GE). The calibrations are very similar, typically differing by a fraction of a millimeter (probably in the noise of the calibration measurements.
The NGS page has a diagram of the 55971 but not of the 57971. I assume the dimensions are the same (for reducing slope measurements to ARP).
Anyone know what the difference is between these two antenna models? The 57971 has "RoHS compliant solder" after the name, which is some kind of hazardous material compliance spec, and the 55971 has "lead based solder" after the name. Is that the reason for the slightly different model number?
John, my understanding is they are the same antenna other than the solder, why they both got a calibration AND model numbers that are only one digit different is a confusing Trimble mystery that has plagued me AND many CORS operators too since about 1/2 the time the listed antenna is in disagreement with the photos!
That is what I believe, that they are exactly the same other than the solder, but the different numbers made me wonder.
How is that R7 working out? I was looking at buying a R8 model 3 or eying that R7 model you bought and I am leaning toward the R7 model 2 in the future.
Works great. The only thing I noticed is that it draws a lot more power than an R8 or R10. I guess I haven't used my 5700 (CF card problem-intermittent) in a while to notice that. We use 7AH "brick" batteries for base stations (static), and the R7 only lasts a little over 4 hours. But of course it has two slots for the smaller batteries, so I can put two of those in. Or use a bigger external battery.
I asked Charles Geoghegan at NGS a similar question back in 2010 and this is a portion of his answer:
"Trimble used to use lead in the solder for the 55971, but stopped. Trimble says the model you have is identical in every way except for no lead in the solder, but did not submit samples of the revised model to us for testing."
James
John Hamilton, post: 384473, member: 640 wrote: Or use a bigger external battery.
I've mostly gone to 18ah SLA batteries for static work. Even with my clunky old 4000SSi units, I can run a 12-hour session and still have juice left over.
The change is a change in the part number by Trimble. Even though it's essentially the exact same antenna, they changed the part number due to using the different solder. It's probably in order to comply with some ANSI spec or something.
The IGS would also probably prefer that the antenna identification code is not the same even for minor changes.
-FGN.
there is also a newer one, 77971, that would probably also fall into the same group but I haven't heard that for sure.
JaRo, post: 384706, member: 292 wrote: there is also a newer one, 77971, that would probably also fall into the same group but I haven't heard that for sure.
The IGS says it has an additional filter in the low-noise amplifier:
<"> https://igscb.jpl.nasa.gov/igscb/station/general/rcvr_ant.tab>
"TRM77971.00: Zephyr GNSS Geodetic II - RoHS compliant solder, additional filter in LNA; p/n 77971-00; L1/L2/L5/G1/G2/G3/E1/E2/E5ab/E6/BeiDou."
-FGN.