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  1. #61  
    Headscratching time. There's got to be something very simple that's simply very wrong. Maybe time to put it away for a day, come back with fresh eyes and carefully re-examine everything, especially the lengths that were used to make sure they are right for the band the phone is using.

    Is there a way to tell if the phone is using high or low band at any given time? Cingular used to be able to lock their locks to either band, or to a preferred band, over the air--and wouldn't tell the customers how to set that. I'd expect that continues.

    One pessimistic thought comes to mind. " If I didn't know any better, I would've thought it was ignoring the plug that was in it." Well, maybe the cable IS bad and it simply isn't disconnecting the stubby antenna. This is one of the Taiwanese cables? from...which merchant again? (Of course the best part of being a pessimist, is that it is always a pleasant surprise when you are wrong about this kind of thing.<G>)

    Might be time to disconect the stubby, check the RSSI, then attach the external and see if anything increases. If it doesn't, you know the external simply isn't making a good contact. The way that connector is described, if the center pin was just a hair too short--that could happen.
    Last edited by hellosailor; 03/15/2007 at 12:15 PM.
  2.    #62  
    But I ruled out the possibility of no connection - I was in the driveway getting mid/high 80's RSSI levels. I plugged in the cord, just the cord by itself, and the levels stayed the same. There wasn't even a dipole made, it was just the sealed cord (well, the coax tip was cut off, so it was 99% sealed). When I plugged it in, the levels stayed the same. This told me that the cable wasn't being recognized. However, to verify that, I curled the cable up (while still connected) and enclosed it in my fist. That made my signal worse, so it had to have been going through the external....

    I don't even know what else to do, I've thought about this a lot, but it's not really something that I can brainstorm on because, well, I learned this all specifically for this project. I don't know how to troubleshoot.

    If you don't see anything new for me to try, I'm basically gonna shelve the project until I can find someone locally who is into ham radios or something, who could figure out what's going wrong. (or maybe you'd want to take a look at the cord itself? If you'd consider diagnosing it I'd ship it out to you - If you figured it out, I'd just order another one and make it appropriately).

    As far as hi/lo bands, my phone is CDMA, and it stays on 1900MHz unless it's roaming, when it can go to 800mhz. However, I turned off its roaming ability, so it shouldn't be going away from 1900mhz
  3. #63  
    jd-
    "But I ruled out the possibility of no connection - I was in the driveway getting mid/high 80's RSSI levels." I'm not sure what 80's means. Using the phones native RSSI display (by #*74425 send) I get RSSI levels of 8000 (that's eight THOUSAND) indoors in a weak signal area.
    Since yours is CDMA--that code will not work for your phone, and "80" might have an entirely different meaning.

    Using TreoHelper of GetTime+ those will show "14" versus a signal of 30 outdoors in a good signal area. So, without knowing how you are displaying RSSI...that "80" might mean no signal.

    "I plugged in the cord, just the cord by itself, and the levels stayed the same. " Makes me think the cord wasn't making contact, or the contact inside the cord, where it is attached to the connector itself, is bad. That sometimes happens, believe it or not.

    I'd be glad to take a look at it, but for right now, hold on to it, let's try to out-think the cable.

    "As far as hi/lo bands, my phone is CDMA," Yes and no.<G> If you have Verizon, they have been dropping CDMA support in favor of what they now call "CDMA2000" which is not at all the same thing. Apparently they can continue to use both bands and that's done partly by what you program into the phone, and partly by what they program (separately) into the phone and the towers. Try hard enough to get past the lies, and they'll turn you over to homeland insecurity and say "This fellow is trying to do something to our towers, we're scared." Honest, they think system information is top-secret-classified because you might try to knock them all down. (sigh)

    I'm going to ask around some microwave and radio folks to check about antenna lengths and dual band antennas, although I'm pretty sure about the answers being "that's not your problem" here. We're missing something. Or, the Chinese cable is simply defective. (I've done enough electronic repairs where it turned out the last, least, and simplest thing was the problem, exactly that way.)

    Got some other things higher on the ToDo list but figure I'll order a cable from someone next week, so we'll have answers to compare that might shed more light on it.
  4.    #64  
    Highly appreciated man!

    BTW, about the connection between the plug itself, and the wires in the cable, didn't we rule that out with the impedence testing? They were testing infinite against each other, adn zero ohms on the respective wires, i thought that was how we tested that?
  5. #65  
    Hey sailor. By any chance are you ex Navy radioman? My Father was a HAM operator and I learned loads from him (plus I was once a Motorola service rep) . One thing I can suggest on this custom antenna. DONT sandwitch it in any kind of metal (2 aluminum backs for example) if you really want to have an antenna.
    Thank a teacher because you can read
    Thank a SOLDIER because you are free to read.
  6. #66  
    Hey guys, I have a thought. Why not cut a piece of wire to FULL wave length and connect it temporarily just to see if it helps. Make it a little long so it can be trimmed to fine tune. After finding optimum full wave length,cut to 1/4 & fine tune. (connected "end fed") One thing I have not seen mentioned yet (unless I missed it) The signal itself is FM. As I understand it, FM is either "there or it ain't" I just started reading this thread today, & it interests me. Could it be that the signal comming in is just not strong enough to do much with? (using only antenna technology) This may or may not help, but I did something years ago thjat might shed some light. Just for the fun of it, I strung a "long wire" completely around the roof line of a 3 story house & end fed it into an FM receiver. All I wanted was to see how many long distance stations I could pull in. I had maybe 150 feet of wire hangin' out there. I lived in relativey flat country (Kansas). With only the builtin antenna I could pick up stations about 75 miles away, but with the outside antenna hooked up, I could get stations as far away as 500 or 600 miles. Conclusion: Build and refine this antenna for the Treo. Then, market that dude and make a million! The FCC can't say squat cause you are not modifying transmitters, just refining antennas.
    Thank a teacher because you can read
    Thank a SOLDIER because you are free to read.
  7. #67  
    JohnSc, you've got me confused with Sparks. On the web we look a lot alike.<G>

    "Hey guys, I have a thought. Why not cut a piece of wire to FULL wave length" Well, full wave won't accomplish anything that 1/4 wave won't. A "1/2 wave dipole" actually uses two elements each 1/4 wave long, so that would be something like 88mm. for each leg on 850Mhz or 39.5mm for 1900Mhz. I'd go with 88mm on each figuring it will work best for dual-band use, since there's no way to tell which carrier is using which band in any one place--unless your carrier really only is licensed for one, i.e the old SprintPCS service.

    "As I understand it, FM is either "there or it ain't":
    Sort of. FM radios all work on the "capture effect", the strongest single signal on any frequency is "captured" and that's the only one that is used. For cell users, the relevant point is that every cell customer is sending a signal, and if a tower that is 100% in use sees one stronger signal--that stronger signal probably will knock out the weakest one, creating a dropped call for somebody. That's why phones in cars keep dropping calls, while phones with external car antennas hold them--stronger signal.

    "Could it be that the signal comming in is just not strong enough to do much with? " Sure. Like I said to jdiety, I don't know what his "80" RSSI means without knowing what the RSSI scale in that software is. If there's no signal, or nearly no signal, antennas don't help. But if he gets enough signal for calls--the external antenna SHOULD make the connection better. (Should, ha.<G>)

    Longwires work, the problem is you can't stick 'em in your pocket. You can build a coaxial colinnear antenna (google it) which is made from a dozen sections of coax, each 1/4 wave long, stacked vertically, and keep increasing the gain. But then you wind up with an 8-12' tall stick, which is great for a house rooftop in the boonies--but a little hard to carry around on the street.<G>

    Since a simple 1/4 wave whip, or 1/2 wave dipole, is usually "more" antenna than phones are built with today, it should be some improvement while still being pocket-sized. The old cell phones (brick phones) had big antennas, and the "other half" was inside the case. The phones with pull-up antennas, where everyone complained they broke, had 1/2 wave dipole antennas with one arm (1/4 wave) sticking up. Now...everyone wants tiny, and as one nameless Motorola engineer said to me "You already know the answer. When it comes to antennas, size counts."

    Except, people want "pretty" phones, and cheap phones, and they could care less if the phones WORKED.

    Somewhere between what I'm reading, and what jdiety has been writing, I'm convinced there is something simple that is just wrong. Maybe as simple as a bad cable, but I have to backburner this for a few days and come back to it.
  8.    #68  
    Well, I'm about to be taking on a big project for my business and won't have a second to spare to develop this anymore.... If anyone wants the cable I was using to try and make something work, I'll mail it to you if you pm me your address (reply in this thread that you pm'd me). I'm gonna be renovating a house *and* moving, so it's likely I won't even need a better antenna anymore.

    Hellosailor, thanks a million for all the help. Even though it never panned out, you saved me infinite hours by answering my questions.

    Again, if anyone wants that cable, I only cut off a small amount to play with, so it would be the right angle FME adapter that connects to the treo (650's and 700's only!), with enough cord hanging from the plug that you can play around to learn technique, and still have more than enough to build a full antenna with. I've had the link to this page sitting on my (PC's) desktop for the duration of this project, so I'll keep the link there and check back to see if anyone is interested in that cable (postage is on me. I'd just trash it, but I'd *love* to see someone build a kick *** treo antenna!)
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