First GPS, Eggfinder

Been looking into different GPS units post L2 and think I have settled on the Eggfinder. Reached out to Connor from McTronics for assembly with an added Bluetooth module for sending the data to Rocket Locator app on Android. Do I need anything more than this for flights under 10k? Should I add the RP-SMA external antenna connections just for future-proofing the design? Just curious as this is my first GPS unit and my experience is limited (a a free Quark is a free Quark). FIgured this would be good for a budget GPS unit and entry into the GPS world.

I think you have decided well. I love the Eggfinder, and Connor's assembly is excellent. I have added the connector, and I have an assortment of antenna in various lengths to suit different tracking bay sizes. Also, at the Eggfinder price point, lawn darting a rocket (the tracker will take you right to the burial site, don't ask how I know) is about $100-200 more tolerable than rapid disassemble of the alternative GPS trackers.

You won't be sorry, I don't think! I had two transmitters, one with the stock wire antenna (lost that one in a crash) and the other with the RP-SMA antenna. I never had a range issue with the stock antenna, I just wanted to give the rubber duck a try. I now, however, am having a tougher time getting the Tx to fit into one of my smaller AvBays (I used to use the stock antenna Tx on this model), so when I buy another, will stick with the stock config.
If you're comfortable with soldering, it is an easy enough upgrade to make to the RP-SMA at a later date if you determine you need it- when I first assembled mine I was able to get approximately 1.25 mile range with the stick on the Tx, and the stick on the USB Rx (this was pre-LCD availability, I haven't tested it with the rubber duck on the LCD Rx yet). Unfortunately, despite flying the Eggfinder on every HP flight I've made, I haven't actually needed it! I have yet to really push the envelope as I'm a recent L2 graduate without a lot of flights to my name! Here's a google map showing the test I referenced- I left the Tx in my backyard, and brought the Rx to work, and was able to pick up the Tx from our parking lot across a wash/canyon:

Eggfinders rock! I've used mine stock and with RP-SMA antennas. The real advantage for sport flying under 10k is not so much range from transmitting (which the stock antenna does fine) but the ability with an RP-SMA cable to relocate your antenna outside of the avionics bay so your signal isn't messed up by allthread or other metal hardware.

I also had one flight where an antenna sticking out of the avbay was damaged by the shock cord whipping around. Using the RP-SMA connector to an 8" patch cable and taping the antenna directly to the shock cord has been foolproof for me so far. If you don't need to stick the antenna out of the avbay because it fits inside the nosecone, then don't worry about it. I've even gone back later with a solder sucker and removed the stock antenna to replace it with a connector, so you can always do it later.

If you're worried about range, I think the general advice is to throw the RP-SMA antenna on the receiver first and the transmitter second. It's pretty cheap to do both.

One other thing to mention- The manufacturer of Eggfinder/Eggtimer products is an active flyer and forum member, who provides an outstanding level of customer support. Not saying you won't get that elsewhere, but it certainly keeps me coming back for more products (check out the Quantum- the only problem with it is it's made my three Eggtimers obsolete!)

Awesome! I figured the additional connector would be an easy add on later. My soldering skills are pretty low, so building the whole board seemed a little daunting for a first time project. Additionally, does anyone know how well the TX does in a LOC 3.9 E-bay? I know looking through the Eggfinder manual that it says all-thread can interfere with signal. Do most of you guys mount GPS transmitters in the nosecone?

smapdiage9 said:

Eggfinders rock! I've used mine stock and with RP-SMA antennas. The real advantage for sport flying under 10k is not so much range from transmitting (which the stock antenna does fine) but the ability with an RP-SMA cable to relocate your antenna outside of the avionics bay so your signal isn't messed up by allthread or other metal hardware.

I also had one flight where an antenna sticking out of the avbay was damaged by the shock cord whipping around. Using the RP-SMA connector to an 8" patch cable and taping the antenna directly to the shock cord has been foolproof for me so far. If you don't need to stick the antenna out of the avbay because it fits inside the nosecone, then don't worry about it. I've even gone back later with a solder sucker and removed the stock antenna to replace it with a connector, so you can always do it later.

If you're worried about range, I think the general advice is to throw the RP-SMA antenna on the receiver first and the transmitter second. It's pretty cheap to do both.

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I just saw your comment regarding the all-thread right after my reply So could I hypothetically have my antenna (stock or upgraded later) sit/poke through the e-bay into my upper payload section? I use a JL Chute release for dual-deploy, so no BP charge in the upper section.

kyled921 said:

Awesome! I figured the additional connector would be an easy add on later. My soldering skills are pretty low, so building the whole board seemed a little daunting for a first time project. Additionally, does anyone know how well the TX does in a LOC 3.9 E-bay? I know looking through the Eggfinder manual that it says all-thread can interfere with signal. Do most of you guys mount GPS transmitters in the nosecone?

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I have only 5 HP rockets, so am far from an expert, but here's how I have mine configured (sorry, no pictures, am at work):

LOC/Precision Norad Pro Max (Level 1 cert) - plywood sled bolted to nose down into payload tube, Eggtimer alt on one side (not yet dual deploy equipped), Eggfinder on the other. The Eggtimer is a rev C which could only handle 3v, so the 3V output of the Eggfinder is perfect, I use it to drive the alt.

Madcow Frenzy (Level 2 cert) - Modified nose cone into removable bulkhead av bay. This was a good bit of work, and I don't feel I got the best bond to the poly nosecone (that stuff is hard to glue/paint, even if you give it a little corona discharge or flame treatment), so I drilled tiny holes and pinned the centering ring in with 7/8" wire nails...I think this one is going to need a picture, will try to remember when I get home.

Rocketry Warehouse Adventurer 3 - Modified nose cone with removable bulkhead av bay. This is the one that lost me my other Eggfinder Tx- I was set up for single deploy, motor eject, and didn't get enough force out of the charge, so it came in ballistic. Amazingly, the Eggfinder was still working, I just physically couldn't get it out of the ground- only 2 feet of the +7' rocket were sticking up out of the hard desert earth, and I could only dig down far enough to get the av bay.

Madcow AGM-Pike - This one is being built now, and because it's 4", I may just use the Frenzy nose cone on this so I don't have to modify the Pike nose...and this way I'll get an extra cone just in case. I may fly this single deploy, in which case I might also just mount it in the payload bay kind of like my Norad? Not sure. I also might just use my Frenzy av bay and get Dual Deploy on this one too.

LOC/Precision Nuke Pro Max - This is being built now too, and will be my test-bed for dual deployment. It flies on everything from an F (maybe even an E28) to a J, so I will definitly be putting the Eggfinder in this, but may see what kind of performance hit I get if I just put it in the AvBay with #6 all thread running through...will let you know. If not, I'll put it in the nose.

kyled921 said:

I just saw your comment regarding the all-thread right after my reply So could I hypothetically have my antenna (stock or upgraded later) sit/poke through the e-bay into my upper payload section? I use a JL Chute release for dual-deploy, so no BP charge in the upper section.

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Yea that should work fine, if I'm understanding correctly that your payload section is empty and the main is in the fin can. For a conventional DD rocket with the main in the payload bay, I'd either position the antenna pointing in the drogue bay or surround the antenna with a short piece of cardboard tube or something to prevent it and the chute from hurting each other under acceleration. Either way they work fine exposed to black powder charges if you just wrap it in blue tape.

smapdiage9 said:

Yea that should work fine, if I'm understanding correctly that your payload section is empty and the main is in the fin can. For a conventional DD rocket with the main in the payload bay, I'd either position the antenna pointing in the drogue bay or surround the antenna with a short piece of cardboard tube or something to prevent it and the chute from hurting each other under acceleration. Either way they work fine exposed to black powder charges if you just wrap it in blue tape.

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That sounds like a neat idea- will have to look into that, as it's far simpler than what I've been doing.

I'm an oddball and used a plain SMA connector as I had a bunch lying around. I flew a TRS at the last Midwest Power and used the LCD receiver and Android program "GPS Rocket Locator" to recover from 1.66 miles away. Flew 8500' and was windy.
I didn't have maps on my Nexus 7 WiFi only device but was able to get a Ham tracking program modified for live photomap tracking I tried out last Saturday in this link: https://www.rocketryforum.com/showt...-Mapping-Program-Update&p=1573624#post1573624 That is not after flight data importation, that is a screen shot of the live map I had to look at out in the field. Rocket went ballistic unfortunately but the two positions that got out, got me to the rocket
and was able to dig it out. Will fly again after nosecone replacement. Trashed the EggFinder but I'd rather lose that, than the whole shebang. Kurt

Does the 3dB antenna and RP-SMA connector sold by EggFinger Rocketry work for BOTH the transmitter AND the LCD receiver? What is the length of this antenna? If I have the room for it, this is a good upgrade for both kits, right?

Buckeye said:

Does the 3dB antenna and RP-SMA connector sold by EggFinger Rocketry work for BOTH the transmitter AND the LCD receiver? What is the length of this antenna? If I have the room for it, this is a good upgrade for both kits, right?

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Yes, the SMA connector works on bith devices. I have upgraded my RX & most of my TX's. The antenna Cris sells is a bit longer than I prefer but there are other antennas that work just as well & are shorter. Mouser sells a rubber duck that is about 3". Here is a link:

https://www.mouser.com/Search/Produ...virtualkey59000000virtualkey712-ANT-916-CW-QW

Can sometimes search on ebay and pickup some Linx Technologies antennas on the cheap. Kurt

Here you go for the RP-SMA connector: https://www.ebay.com/itm/Linx-UHF-1...143189?hash=item4d42429b55:g:BS0AAOSwJQdXBQq7

ksaves2 said:

Here you go for the RP-SMA connector: https://www.ebay.com/itm/Linx-UHF-1...143189?hash=item4d42429b55:g:BS0AAOSwJQdXBQq7

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That's a steal at $2 a piece!

Would there be an issue using a 6" pigtail and running the antenna down the back of the sled, i.e. immediately opposite (behind and parallel) to the EggFinder board?

Cl(VII) said:

Would there be an issue using a 6" pigtail and running the antenna down the back of the sled, i.e. immediately opposite (behind and parallel) to the EggFinder board?

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You may have interference from all-thread. One option is to put the antenna thru the bulkhead.

timbucktoo said:

You may have interference from all-thread. One option is to put the antenna thru the bulkhead.

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No All thread with my setup. Hard to explain, but I'll post a pic at some point. I'm more worried about antenna and GPS module interfering with each other by being about 1/2" apart.

OR you can put the Tx inside a 24mm tube and tape it to the shock cord.

bill2654 said:

OR you can put the Tx inside a 24mm tube and tape it to the shock cord.

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That works well, I've done that a lot. Just make sure the tube is capped off well... don't ask me how I know.

Length, not diameter is more my concern with orienting the antenna parallel to the board.

I have the Eggtimer TRS w/LCD and it's awesome. It was my first electronics project using surface mount components and it wasn't too difficult and a lot of fun to assemble. I've only flown it once on my L1 flight, but it took my right to the rocket using my phone, Google Maps, and a downloaded local area.

I used the RP-SMA connector and an antenna from DigiKey because I decided to overdo everything which is why the rocket is named Do 'er All The Way.

kidrobo said:

I have the Eggtimer TRS w/LCD and it's awesome. It was my first electronics project using surface mount components and it wasn't too difficult and a lot of fun to assemble. I've only flown it once on my L1 flight, but it took my right to the rocket using my phone, Google Maps, and a downloaded local area.

I used the RP-SMA connector and an antenna from DigiKey because I decided to overdo everything which is why the rocket is named Do 'er All The Way.

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All that for an L1 rocket? I do think it's overboard...... unless now you're going for the L2 with that arrangement and after getting that, bump it with an L to "outta sight" land for awhile. In that case, quite a nicely planned arrangement. Kurt

ksaves2 said:

All that for an L1 rocket? I do think it's overboard...... unless now you're going for the L2 with that arrangement and after getting that, bump it with an L to "outta sight" land for awhile. In that case, quite a nicely planned arrangement. Kurt

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Of course it's overboard. I tend to approach projects with the mindset that if it's worth doing it's worth over doing. I am planning on putting a J in it at Fire in the Sky Memorial Day weekend to for my L2 and then see what happens from there. I figured that if I intend to continue with high power I might as well just dive in. Plus I was buying everything during the Black Friday specials and I'm a sucker for discounts.

ksaves2 said:

All that for an L1 rocket? I do think it's overboard...... unless now you're going for the L2 with that arrangement and after getting that, bump it with an L to "outta sight" land for awhile. In that case, quite a nicely planned arrangement. Kurt

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Absolutly not overboard! I frequently fly an Eggfinder GPS and a CSI tracker in the same L1 rocket. Hunting which tree in the forest the rocket is in can be a real pain. I still have all my L1 rockets.....others I fly with do not.

kidrobo said:

Of course it's overboard. I tend to approach projects with the mindset that if it's worth doing it's worth over doing. I am planning on putting a J in it at Fire in the Sky Memorial Day weekend to for my L2 and then see what happens from there. I figured that if I intend to continue with high power I might as well just dive in. Plus I was buying everything during the Black Friday specials and I'm a sucker for discounts.

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That's a good plan then. With the stupid past rules I rushed to the L2 as quickly as possible with a simple 3FNC so I would be able to fly certified motors at a research launch. Back then an L1 couldn't fly a thing at a research launch period.
With the L2 in the can, I did a ton of 29mm DD's with H and I motors along with magnetic anomaly detection apogee deployment. Kurt

Titan II said:

Absolutly not overboard! I frequently fly an Eggfinder GPS and a CSI tracker in the same L1 rocket. Hunting which tree in the forest the rocket is in can be a real pain. I still have all my L1 rockets.....others I fly with do not.

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Nice,
Be aware there are two kinds of fliers. Those that have experienced an adverse anomaly and those who are "going" to experience an adverse anomaly. There is no one out there who's ever had a perfect flight record unless they launched/recovered one rocket perfectly then quit. :wink::surprised: Kurt

Yeah, absolutely not overboard for L1 rockets. My first Eggfinder paid for itself its very first flight (in a Firestorm 54), it didn't even land that far away but it landed in an alfalfa field and perfectly tucked itself between the rows of plants (including the chute), I'd have spent an hour or more searching for it without the LCD telling me right where to go, I saw where it landed and I was in the right area, but it still would have taken a long time to find it because of the good job it did hiding in the crops. The fast recovery let me get two more flights in that day (with similar recovery results, in a game of hide & seek it would have won every time that launch). And then there's my Go Devil 38 mile-shot, which disappeared well before apogee, popped its main at 8500' (not intentional) and blew more than a mile away before landing. If not for the EF I'd have never found it (or even had any idea which direction it went). Those were both L1 flights, an I280DM and an I366R, respectively, as I only got my L2 cert earlier this month.

I'm sure any of the other GPS trackers could have done as well also (and I guess the non-GPS ones if you have the skills/patience to use them), but the Eggfinder makes the barriers to entry so low, between the low cost and no HAM license requirements. I have one for every rocket I fly (well, Eggfinder or Eggtimer TRS) and won't fly without them.

woferry said:

I'm sure any of the other GPS trackers could have done as well also (and I guess the non-GPS ones if you have the skills/patience to use them), but the Eggfinder makes the barriers to entry so low, between the low cost and no HAM license requirements. I have one for every rocket I fly (well, Eggfinder or Eggtimer TRS) and won't fly without them.

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I used to have 2 Eggfinder Tx myself- one with the USB dongle, and a second I bought with the LCD. I lost one in a ballistic reentry, and really haven't flown much since (it really bummed me out!). Been a year now, and am starting back up, and am thinking of buying another Tx. My last two were on the same frequency so I can use the same USB Dongle to record flight, but now I'm wondering if it might be better to have two different frequencies in case someone is flying the one I have (these things are getting justifiably popular now!). What did you decide to do?