dbacque

My Feedback: (3)

Ispoke with the tech at Castle Creations today and discovered an undocumented feature of the Berg Microstamp 4L receiver that all users should be aware of.

I lost a plane and engine yesterday due to loss of signal. The receiver had only been flying a few months and the battery was fully charged. After the crash I had absolutely no reception and the LEDon the receiver was brighter than usual. I finally discovered that when I press hard on the crystal the LEDgoes back to dim and the receiver works again.

When I asked the tech about the difference between the dim LED vs. the bright LED he said that the LED indicated loss of signal, there is no bright or dim. The FAQon the Castle Creations web site says the same thing. The FAQalso states that it lights when frames are being rejected.

My receiver has always had the LED glow dim when powered on since I bought it last year. The tech said that the LED should either be on or off, not dim. I guess dim must mean that it is rejecting some frames but not enough to come on at full brightnes.

The LEDis visible through the blue shrink wrap on the side of the receiver opposite the label. To see the LED, just turn off your transmitter and it will light up to indicate loss of signal.

So I thought I'd let everyone know, if you've got a red light on your 4L, DON'TFLYIT!

Dave

combatpigg

My Feedback: (3)

[X(] Holy Moly! I always thought the led meant that it had been powered up and all is well....

Thanks for enlightening me, I use this stuff in the fastest .40 powered planes I've got too.

Honker1

My Feedback: (4)

I just lost a 1/2a SureShark about 2 weeks ago. It was pretty cool, after rebuilding the right wing from the prior lockout (failsafe, plane was starting to do real large manuevers and on the pull-out from a loop it impacted the ground almost completely level). Well after rebuilding the wing and new film canister tank (they work great by the way) I put her back in the air. About the same amount of time, 5 minutes, into the flight I got lockout (failsafe). I was on the reverse of a split S and it went straight in from about 200 feet up rightinto a corn field. A real viking funeral, engine buried deep, the tail cross above the grave. Upon closer inspection I just need to rebuild the front of fuse and one wing. I have another Sure Shark kit that I will build after I figure out the bugs of these Berg recievers.

I believe that it is the crystal plug in socket that is causing the lock outs. I really like the Berg but I need to feel confident in these things. Mine is at Berg right now, waiting for the diagnosis.

Honker1

MJD

My Feedback: (1)

If so, one could desolder the socket, or solder the crystal into the socket if possible..? That would solve that one for good, I don't recall changing crystals much after installing the first one.

Mike D

combatpigg

My Feedback: (3)

I would gladly have a permanently installed cystal.

MJD

My Feedback: (1)

Better than permanently rekitted aircraft! I only use 18 and 50, I can make a decision and stick with it for a 30 buck receiver.

Honker1

My Feedback: (4)

I agree, but how to secure the crystal in? There is no space for soldering, a blob of silicone might do it, maybee some epoxy, heat shrink tubing, tape.

Any thoughts? Anyone, anyone......

Honker1

MJD

My Feedback: (1)

We'll have to see what the true culprit is before making any decisions I think - if the socket itself is at fault who says mechanically restraining the crystal in the socket will help, for example?

MIke D.

digital_trucker

Bubble Yum can work miracles (it held the plastic cap on our kitchen sink faucet for near on to 20 years...was a bugger to get it loose too).

dbacque

My Feedback: (3)

In my case the tech suspects either a defective crystal or a bad solder connection between the socket and the board.

Dave

Larry Driskill

Very interesting. And concerning . . . Bummer.

I have had excellent service from HiTec 555s. I have several with no bad experiences in several hundred flights.

But, I wanted a smaller unit and so have 3 or 4 Bergs standing by for use in the next projects.

I guess I will start out by making sure the LED is doing the proper thing and securing the crystal carefully.

DeviousDave

If you guys have Berg-4*DSP Micro Stamp recievers (Earlier German made models), the LED functions as a glitch counter:

1 flash = 1 event
2 flashes = 2-3 events
3 flashes = 4-7 events
4 flashes = 8-15 events
5 flashes = 16-31 events
6 flashes = 32-63 events
7 flashes = 64-127 events
More than 128 glitches and the LED will stay on continuously

Glitches are counted when the receiver counts invalid transmitter signals and unrecoverable frame errors in reception due to Loss of Signal and/or Interference.

The instructions also say that the antenna may be shortened down to 12" length as long as you are able to land from test flights with the LEDoff after test flights.

Hope this helps.

combatpigg

My Feedback: (3)

[:-] Do something about that post count, man......

Walther

My Feedback: (1)

I was thinking that Hot melt may work for this.

dbacque

My Feedback: (3)

You know, the crystal in Futaba receivers are held in the same way, they're just pushed down into a socket.

I seriously doubt that the socket's grip on the crystal was the cause of my problem.  Especially since the LED was partially illuminated all along

Dave

combatpigg

My Feedback: (3)

I don't know if the crystal is in the actual signal path, but it seems like a bad idea from an electronics standpoint to have it not soldered in.
OTOH, I've got a nice 35 year old amp / tuner that is built with all wire wrapped components, no solder anywhere.

MJD

My Feedback: (1)

But it doesn't have a vibrating engine strapped to it. Mind you, just how loud do you crank it..?

So is this only happening on small IC powered aircraft, i.e. excellent sources of high frequency vibration?

MJD

Wiggy

Guys,

Almost all the 72 mhz receivers have a plug in crystal. It must work well since it has been done this way for so long. As far as I know, only the synthysized receivers do not have a plug in crystal.

Perhaps this is an isolated case or Burg may have a problem with their sockets. Ionly have one Burg stamp and it has always worked perfectly. I did not get more because Iuse two channels for my ailerons and the stamp is only four channel.

Wiggy

MJD

My Feedback: (1)

Well, exactly. There are a trillion IC's floating around the planet doing this and that in plug in sockets. Every receiver I've used for three decades same thing. It's not a case that "plug in crystals are bad'.. but a bad crystal or a bad socket sure is. Add high frequency vibs and uh oh.

MJD

Wiggy

If you ever dissected a crystal there is a small piece of material that resembles mica suspended between the plug wires by two extremely small wires. When Ihave looked inside a bad crystal that was destroyed in a crash, the mica part was torn. I am very surprised the tiny support wires inside the can do not break.

Wiggy

combatpigg

My Feedback: (3)

Wiggy, Interesting....I wonder how they build them for a certain freq?
Amazing....some folks in this World are still just learning how to use toilet paper and here we are trying to teach toy airplanes how to behave better..

Wiggy

CP, here is a link to some information about how and why crystals work. It even has a picture of what Ibelieve is a Futaba crystal. I studied electornics many moons ago when the vacuum tube was still in use. My knowledge has faded greatly and been technologically displaced. Wiggy


http://en.wikipedia.org/wiki/Crystal_oscillator

combatpigg

My Feedback: (3)

Thanks Wiggy, after reading all that and learning something, now I'm more paranoid than ever before.....[]
I think I'm going to just use a new Berg for every trip to the field and toss it like a used bladder at the end of the day.

MJD

My Feedback: (1)

The crystal material is hard and brittle versus the relatively ductile support wires, so I figure under shock load it fractures easily.

Crystals are cut to size, there are formulae for determining the resonant frequency of the crystal depending on the properties of the material and the orientation of the cut. I have a library of vintage radio electronics texts, maybe in there I can find how they are fine-tuned beyond the original cut as I haven't found that detail elsewhere yet. Perhaps they are cut very closely and are then screened and sorted according to specific frequency within the band..? We'll see.. interesting question. My dad would have known off the top of his head.

MJD

combatpigg

My Feedback: (3)

I'll bet they build the crystals first, then test them to see exactly what they ended up with.
I wonder if any NASA or MILSPEC radio gear is made up with "push in" components?