The Eggfinder Mini - A Very Small GPS Tracker

[cerving]

Eggtimer Rocketry is proud the announce the Eggfinder Mini, a compact version of the Eggfinder TX transmitter. At only about 3 1/2" long INCLUDING THE EXTERNAL ANTENNA and under 0.7" wide, it can fit into an 18mm body tube, and is small enough so that you can put it just about anywhere. In fact, the PC board is actually smaller than most RDF trackers, and the antenna is much shorter. We've seen it put into a little Kevlar sleeve with a small 2S LiPo battery, and simply taped to the shock cord... just like you'd do with a RDF tracker. It's 100% functionally identical to the Eggfinder TX, including the ability to program the frequency/ID with the LCD receiver.

Availability should be "any day now" (waiting on the PC boards, in transit). Price for the kit (yes, like all Eggtimer Rocketry products it's a kit... warm up your iron!) will be $75, including the external antenna.

Here's a picture of the Mini alongside an Eggfinder TX... the TX's antenna actually runs another 2" or so off the edge of the picture.



As usual, thanks for your continued support!

Cris Erving
Eggtimer Rocketry
www.EggtimerRocketry.com

 

[Cl(VII)]

The crowd goes wild!!!!!!!!

:wave::wave::wave::wave:

Where are all of the components? The back of that thing is dense, isn't it?

 

[ksaves2]

Pretty impressive. I take it the Rf module is on the other side of the board?`Is that antenna one piece or is it screw on? Possible for a different antenna if the room were available for
more efficient transmission? Kurt

 

[mad4hws]

Just in time for a project!

 

[Charles_McG]

Oh, my poor wallet.

A picture of the back would be great.

 

[dhbarr]

Sweet! My hands are -still- too shaky to do anything like this.

Anybody want a free one? I'll send you two kits and then you send me one working unit....

 

[Cl(VII)]

Sweet! My hands are -still- too shaky to do anything like this.

Anybody want a free one? I'll send you two kits and then you send me one working unit....

I'll take that

 

[dhbarr]

I'll take that

Awesome, now they just need to go live on the eggsite

 

[ksaves2]

Perfect for a smaller project..... They don't have to go very high to disappear. Now if Mr. Beans comes up with a chute release for 18mm or even 24mm a lot of small rockets
are going to be heading for kingdom come with a modicum of confidence they'll be recovered. Kurt

 

[dhbarr]

Perfect for a smaller project..... They don't have to go very high to disappear. Now if Mr. Beans comes up with a chute release for 18mm or even 24mm a lot of small rockets
are going to be heading for kingdom come with a modicum of confidence they'll be recovered. Kurt

Yup, this stack of g65's and my 24mm MD CF 3FNC just got a big ol' green light . Been afraid to fly it since, y'know, I want it back.

 

[emckee]

Hi Cris,

I expect all the components are SMT. Can you say what sizes you've got on there? I find that the smaller ones may be the defining characteristic of how difficult these are to assemble.

Also, are you offering the antennae for sale separately? And are those RP-SMA and compatible with existing eggfinder TX/RX/TRX units?

Thanks!
Erik

 

[Banzai88]

My wallet hates you, but my rocket loves you. It's complicated.

 

[rharshberger]

He shoots, He scores! Now to free up some cash, I have the perfect rocket for one of these.

 

[ksaves2]

Hi Cris,

I expect all the components are SMT. Can you say what sizes you've got on there? I find that the smaller ones may be the defining characteristic of how difficult these are to assemble.

Also, are you offering the antennae for sale separately? And are those RP-SMA and compatible with existing eggfinder TX/RX/TRX units?

Thanks!
Erik

I will venture the SMT components are no smaller than the ones he already uses. He mentioned he wouldn't go smaller in other posts. That antenna looks like it is incompatible with
other Eggfinders. I wonder if it is in one piece or if the antenna portion can be screwed off and replaced with a longer (spell that higher gain unit). The flat base looks like it's screwed onto a pad on the board. If the antenna assembly is one piece, I'm afraid it's WYSIWYG. I have a ton of SMA PC board edge antenna sockets from other projects so my antennas are plain SMA and interchangeable. I do carry an RP converter to screw on if someone wanted to borrow my LCD with their antennas or if someone with an SMA-RP LCD wanted to borrow my large Patch antenna to use.

I like this site to do antenna comparisons: https://linxtechnologies.com/wp/p/antennas/small-external-antennas/ Look at the frequency to SWR plots. The closer to 1:1 frequency vs.
SWR plot gives the best transmission efficiency. That is the most power is imparted to "free air" as opposed to being reflected back to the transmitter electronics.

If one uses an antenna with a known plot, ideally tune the EggFinder to the frequency as close to 1:1 SWR as you can get. A little bit on either side is still highly workable but if one wants the best efficiency keep it as close to 1:1 as possible.

Kurt

 

[Chrisn]

put me down for one! will email as soon as they are available

 

[ttabbal]

Keep in mind that you don't want a higher gain antenna on the transmitter for these sorts of things. Gain is produced in the antenna by creating directionality. In the case of a high gain omni, it takes the pattern from apple shaped to pizza shaped. This makes it harder to receive in a non-perfect alignment situation. Use a handheld beam on the receiver if you want antenna gain, that will be better in the long run.

 

[ksaves2]

Keep in mind that you don't want a higher gain antenna on the transmitter for these sorts of things. Gain is produced in the antenna by creating directionality. In the case of a high gain omni, it takes the pattern from apple shaped to pizza shaped. This makes it harder to receive in a non-perfect alignment situation. Use a handheld beam on the receiver if you want antenna gain, that will be better in the long run.

You're confusing a directional antenna with omni directional. A little tuned stub is not going to be much help. Alternatively, a high gain Yagi on the 33cm band has too narrow a beam width to keep pointed accurately at the receive station or point at the rocket in flight. It is true the little screw on antennas are little vertical dipoles but a 1/2 wave antenna should outperform a 1/4 wave antenna.

I've come to the conclusion that a tumbling rocket with the changing polarity of the transmitted signal leads to dropped data be it on 900Mhz/33cm band or 400Mhz/70cm band.
Some of this can be overcome with antenna choice or with more horsepower ie. Rf power output. The EF's are 100Mw.

A receiver Yagi can increase the ground foot print of the EggFinder on the ground as long as it's not moving very fast or is stationary. Kurt

 

[cerving]

The antenna is a screw-on part... Linx ANT-916-PW-LP. It's rated at 2.4 dB with a SWR of < 1.9 throughout the 902-928 MHz ISM band, about 1.2 at the 916 MHz center frequency. The SMT parts are 0805 like the TRS, with pads made a little bit larger to make them easier to solder. As far as the footprint, I tracked a rocket to 5 1/2 miles away over the weekend when the main opened near apogee (I think the shear pins were a little bit too loose). That was with a wire antenna on the Eggfinder, so you can expect similar range out of the Mini given the differences in ground plane size and antenna gain. All the flights that I've had with the Mini flying parallel with an Eggfinder TX have produced very similar results.

 

[ttabbal]

I think there's a miscommunication.. What I'm referring to is related to this, just the first google result that made sense..

https://www.techrepublic.com/blog/data-center/80211-time-to-clear-up-some-antenna-misconceptions/

The article is about WiFi, but the antenna theory is the same.

 

[OregonBAR]

:headbang:
Gotta have me one!!

 

[michigander]

Count me In !!!!!!!!!!!

 

[stealth6]

There are of course many things that make me wish I was still flying, or that pull REALLY HARD trying to draw me back in.

Put this way up near the top of that list. Chris/Eggtimer are one of the things that make the rocketry community so great.

There are quite a few "in my mind" rockets, that this would be just the thing for. Way freakin' cool.

Dang it, I might have to buy one and build it "just because".

(insert thumbs up smiley here)
s6

 

[ksaves2]

The antenna is a screw-on part... Linx ANT-916-PW-LP. It's rated at 2.4 dB with a SWR of < 1.9 throughout the 902-928 MHz ISM band, about 1.2 at the 916 MHz center frequency. The SMT parts are 0805 like the TRS, with pads made a little bit larger to make them easier to solder. As far as the footprint, I tracked a rocket to 5 1/2 miles away over the weekend when the main opened near apogee (I think the shear pins were a little bit too loose). That was with a wire antenna on the Eggfinder, so you can expect similar range out of the Mini given the differences in ground plane size and antenna gain. All the flights that I've had with the Mini flying parallel with an Eggfinder TX have produced very similar results.

Wonderful, Count me in for two. The antenna looks like a very great choice: https://www.linxtechnologies.com/wp/wp-content/uploads/ant-916-pw-lp.pdf
Optimized over the EF frequencies too. Perfect! Kurt

 

[KenRico]

My ComSpec AT2B made an untimely death in my last shred of the Mega Der Purple Max , and no one seems happy with the new 20mw tracker .

Cris took pity on me & loaned me one of these new eGGfinder Minis at the last two launches - they work G R E A T !
At the first launch I taped to a scrap piece of G10 and also put a small 2S lipo on the back side .. very quick to the pad . I also tucked in to a redundant sled in a payload section with the dreaded aluminum all-thead and got good packets .

This last launch I had one of the new RECON Nomex Tracker protecters and taped the eGGfinder Mini to the battery and slid it in . Flew on my 5 Inch Jart shock cord to almost Mach and rode along in a UDS flight also . The Nomex Tracker sleeve was literally twice the length needed for the Mini .

Thanks again, Cris !

Kenny

 

[warnerr]

Ordered two! These things are so small you can tape the whole thing including battery right onto your shock cord... the kit is complete including very small antenna. Range in open air is at least five miles based on Cris oops with main early! I will be building this weekend- anyone else?

 

[SpaceManMat]

What is the transmit power on these Cris?

 

[BLKKROW]

I need this, did I mentioned I need this?

 

[cerving]

What is the transmit power on these Cris?

100mW, same as the Eggfinder TX. It's functionally identical to the TX, just shrunken down a bunch.

 

[Worsaer]

Will this model replace the previous one, or be offered concurrently?

 

[ksaves2]

Will this model replace the previous one, or be offered concurrently?

I kinda like the antenna option for the earlier versions but if the mini performs well I suspect the other version might fade out. When I get my hands on one, I'd like to track
with the patch antenna on the ground and see if there is any difference. Kurt